From 5837518e78bf71172c4c86f14afd545fa38aa9e2 Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Sun, 7 Jun 2020 13:26:04 -0700
Subject: [PATCH 01/25] `-Zunpretty=everybody_loops` only works after expansion

---
 src/librustc_session/config.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/librustc_session/config.rs b/src/librustc_session/config.rs
index 5bdd7b67723b8..939d5e8ef8358 100644
--- a/src/librustc_session/config.rs
+++ b/src/librustc_session/config.rs
@@ -1954,9 +1954,11 @@ impl PpMode {
         use PpMode::*;
         use PpSourceMode::*;
         match *self {
-            PpmSource(PpmNormal | PpmEveryBodyLoops | PpmIdentified) => false,
+            PpmSource(PpmNormal | PpmIdentified) => false,
 
-            PpmSource(PpmExpanded | PpmExpandedIdentified | PpmExpandedHygiene)
+            PpmSource(
+                PpmExpanded | PpmEveryBodyLoops | PpmExpandedIdentified | PpmExpandedHygiene,
+            )
             | PpmHir(_)
             | PpmHirTree(_)
             | PpmMir

From d6848550393e9cebc734d5b8772b96c3a149a460 Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Sun, 7 Jun 2020 13:26:04 -0700
Subject: [PATCH 02/25] Helper method for whether `ast::Ty` contains `impl
 Trait`

---
 src/librustc_ast/ast.rs | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/librustc_ast/ast.rs b/src/librustc_ast/ast.rs
index efcf95ec706b8..8ae2e81fc5523 100644
--- a/src/librustc_ast/ast.rs
+++ b/src/librustc_ast/ast.rs
@@ -25,6 +25,7 @@ pub use UnsafeSource::*;
 use crate::ptr::P;
 use crate::token::{self, DelimToken};
 use crate::tokenstream::{DelimSpan, TokenStream, TokenTree};
+use crate::visit::{walk_ty, Visitor};
 
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
@@ -1784,6 +1785,26 @@ pub struct Ty {
     pub span: Span,
 }
 
+impl Ty {
+    /// Returns `true` if the kind of this type or any types contained within are `impl Trait`.
+    pub fn contains_impl_trait(&self) -> bool {
+        struct ContainsImplTrait(bool);
+
+        impl<'ast> Visitor<'ast> for ContainsImplTrait {
+            fn visit_ty(&mut self, t: &'ast Ty) {
+                self.0 |= matches!(t.kind, TyKind::ImplTrait(..));
+                if !self.0 {
+                    walk_ty(self, t);
+                }
+            }
+        }
+
+        let mut vis = ContainsImplTrait(false);
+        vis.visit_ty(self);
+        vis.0
+    }
+}
+
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
 pub struct BareFnTy {
     pub unsafety: Unsafe,

From b5fdbbef4e03ab4fb88fcadbb8c370a1126419d9 Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Sun, 7 Jun 2020 13:26:04 -0700
Subject: [PATCH 03/25] Use correct names for things in `ReplaceBodyWithLoops`

---
 src/librustc_interface/util.rs | 130 +++++++++++----------------------
 1 file changed, 41 insertions(+), 89 deletions(-)

diff --git a/src/librustc_interface/util.rs b/src/librustc_interface/util.rs
index 924908e572487..4d33383071e16 100644
--- a/src/librustc_interface/util.rs
+++ b/src/librustc_interface/util.rs
@@ -592,97 +592,48 @@ pub fn build_output_filenames(
 //
 // [#34511]: https://github.com/rust-lang/rust/issues/34511#issuecomment-322340401
 pub struct ReplaceBodyWithLoop<'a, 'b> {
-    within_static_or_const: bool,
+    ignore_item: bool,
     nested_blocks: Option<Vec<ast::Block>>,
     resolver: &'a mut Resolver<'b>,
 }
 
 impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
     pub fn new(resolver: &'a mut Resolver<'b>) -> ReplaceBodyWithLoop<'a, 'b> {
-        ReplaceBodyWithLoop { within_static_or_const: false, nested_blocks: None, resolver }
+        ReplaceBodyWithLoop { ignore_item: false, nested_blocks: None, resolver }
     }
 
-    fn run<R, F: FnOnce(&mut Self) -> R>(&mut self, is_const: bool, action: F) -> R {
-        let old_const = mem::replace(&mut self.within_static_or_const, is_const);
+    fn run<R, F: FnOnce(&mut Self) -> R>(&mut self, ignore_item: bool, action: F) -> R {
+        let old_ignore_item = mem::replace(&mut self.ignore_item, ignore_item);
         let old_blocks = self.nested_blocks.take();
         let ret = action(self);
-        self.within_static_or_const = old_const;
+        self.ignore_item = old_ignore_item;
         self.nested_blocks = old_blocks;
         ret
     }
 
-    fn should_ignore_fn(ret_ty: &ast::FnRetTy) -> bool {
-        if let ast::FnRetTy::Ty(ref ty) = ret_ty {
-            fn involves_impl_trait(ty: &ast::Ty) -> bool {
-                match ty.kind {
-                    ast::TyKind::ImplTrait(..) => true,
-                    ast::TyKind::Slice(ref subty)
-                    | ast::TyKind::Array(ref subty, _)
-                    | ast::TyKind::Ptr(ast::MutTy { ty: ref subty, .. })
-                    | ast::TyKind::Rptr(_, ast::MutTy { ty: ref subty, .. })
-                    | ast::TyKind::Paren(ref subty) => involves_impl_trait(subty),
-                    ast::TyKind::Tup(ref tys) => any_involves_impl_trait(tys.iter()),
-                    ast::TyKind::Path(_, ref path) => {
-                        path.segments.iter().any(|seg| match seg.args.as_deref() {
-                            None => false,
-                            Some(&ast::GenericArgs::AngleBracketed(ref data)) => {
-                                data.args.iter().any(|arg| match arg {
-                                    ast::AngleBracketedArg::Arg(arg) => match arg {
-                                        ast::GenericArg::Type(ty) => involves_impl_trait(ty),
-                                        ast::GenericArg::Lifetime(_)
-                                        | ast::GenericArg::Const(_) => false,
-                                    },
-                                    ast::AngleBracketedArg::Constraint(c) => match c.kind {
-                                        ast::AssocTyConstraintKind::Bound { .. } => true,
-                                        ast::AssocTyConstraintKind::Equality { ref ty } => {
-                                            involves_impl_trait(ty)
-                                        }
-                                    },
-                                })
-                            }
-                            Some(&ast::GenericArgs::Parenthesized(ref data)) => {
-                                any_involves_impl_trait(data.inputs.iter())
-                                    || ReplaceBodyWithLoop::should_ignore_fn(&data.output)
-                            }
-                        })
-                    }
-                    _ => false,
-                }
-            }
-
-            fn any_involves_impl_trait<'a, I: Iterator<Item = &'a P<ast::Ty>>>(mut it: I) -> bool {
-                it.any(|subty| involves_impl_trait(subty))
-            }
-
-            involves_impl_trait(ty)
-        } else {
-            false
-        }
-    }
-
-    fn is_sig_const(sig: &ast::FnSig) -> bool {
+    fn should_ignore_fn(sig: &ast::FnSig) -> bool {
         matches!(sig.header.constness, ast::Const::Yes(_))
-            || ReplaceBodyWithLoop::should_ignore_fn(&sig.decl.output)
+            || matches!(&sig.decl.output, ast::FnRetTy::Ty(ty) if ty.contains_impl_trait())
     }
 }
 
 impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
     fn visit_item_kind(&mut self, i: &mut ast::ItemKind) {
-        let is_const = match i {
+        let ignore_item = match i {
             ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => true,
-            ast::ItemKind::Fn(_, ref sig, _, _) => Self::is_sig_const(sig),
+            ast::ItemKind::Fn(_, ref sig, _, _) => Self::should_ignore_fn(sig),
             _ => false,
         };
-        self.run(is_const, |s| noop_visit_item_kind(i, s))
+        self.run(ignore_item, |s| noop_visit_item_kind(i, s))
     }
 
     fn flat_map_trait_item(&mut self, i: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
-        let is_const = match i.kind {
+        let ignore_item = match i.kind {
             ast::AssocItemKind::Const(..) => true,
-            ast::AssocItemKind::Fn(_, ref sig, _, _) => Self::is_sig_const(sig),
+            ast::AssocItemKind::Fn(_, ref sig, _, _) => Self::should_ignore_fn(sig),
             _ => false,
         };
-        self.run(is_const, |s| noop_flat_map_assoc_item(i, s))
+        self.run(ignore_item, |s| noop_flat_map_assoc_item(i, s))
     }
 
     fn flat_map_impl_item(&mut self, i: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
@@ -723,6 +674,11 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
             }
         }
 
+        if self.ignore_item {
+            noop_visit_block(b, self);
+            return;
+        }
+
         let empty_block = stmt_to_block(BlockCheckMode::Default, None, self.resolver);
         let loop_expr = P(ast::Expr {
             kind: ast::ExprKind::Loop(P(empty_block), None),
@@ -738,39 +694,35 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
             kind: ast::StmtKind::Expr(loop_expr),
         };
 
-        if self.within_static_or_const {
-            noop_visit_block(b, self)
-        } else {
-            visit_clobber(b.deref_mut(), |b| {
-                let mut stmts = vec![];
-                for s in b.stmts {
-                    let old_blocks = self.nested_blocks.replace(vec![]);
+        visit_clobber(b.deref_mut(), |b| {
+            let mut stmts = vec![];
+            for s in b.stmts {
+                let old_blocks = self.nested_blocks.replace(vec![]);
 
-                    stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| s.is_item()));
+                stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| s.is_item()));
 
-                    // we put a Some in there earlier with that replace(), so this is valid
-                    let new_blocks = self.nested_blocks.take().unwrap();
-                    self.nested_blocks = old_blocks;
-                    stmts.extend(new_blocks.into_iter().map(|b| block_to_stmt(b, self.resolver)));
-                }
+                // we put a Some in there earlier with that replace(), so this is valid
+                let new_blocks = self.nested_blocks.take().unwrap();
+                self.nested_blocks = old_blocks;
+                stmts.extend(new_blocks.into_iter().map(|b| block_to_stmt(b, self.resolver)));
+            }
 
-                let mut new_block = ast::Block { stmts, ..b };
+            let mut new_block = ast::Block { stmts, ..b };
 
-                if let Some(old_blocks) = self.nested_blocks.as_mut() {
-                    //push our fresh block onto the cache and yield an empty block with `loop {}`
-                    if !new_block.stmts.is_empty() {
-                        old_blocks.push(new_block);
-                    }
+            if let Some(old_blocks) = self.nested_blocks.as_mut() {
+                //push our fresh block onto the cache and yield an empty block with `loop {}`
+                if !new_block.stmts.is_empty() {
+                    old_blocks.push(new_block);
+                }
 
-                    stmt_to_block(b.rules, Some(loop_stmt), &mut self.resolver)
-                } else {
-                    //push `loop {}` onto the end of our fresh block and yield that
-                    new_block.stmts.push(loop_stmt);
+                stmt_to_block(b.rules, Some(loop_stmt), &mut self.resolver)
+            } else {
+                //push `loop {}` onto the end of our fresh block and yield that
+                new_block.stmts.push(loop_stmt);
 
-                    new_block
-                }
-            })
-        }
+                new_block
+            }
+        })
     }
 
     // in general the pretty printer processes unexpanded code, so

From d8c99f3b1ab28ccadb3b56ba1fd506dce1385ee4 Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Sun, 7 Jun 2020 13:26:05 -0700
Subject: [PATCH 04/25] Preserve expressions that get a `DefId`

Namely closures and `async` blocks. We have to make a few modifications
to closures to make them compile.
---
 src/librustc_interface/util.rs | 83 +++++++++++++++++++++++++++++++++-
 1 file changed, 82 insertions(+), 1 deletion(-)

diff --git a/src/librustc_interface/util.rs b/src/librustc_interface/util.rs
index 4d33383071e16..e446c8c0004c3 100644
--- a/src/librustc_interface/util.rs
+++ b/src/librustc_interface/util.rs
@@ -615,6 +615,12 @@ impl<'a, 'b> ReplaceBodyWithLoop<'a, 'b> {
         matches!(sig.header.constness, ast::Const::Yes(_))
             || matches!(&sig.decl.output, ast::FnRetTy::Ty(ty) if ty.contains_impl_trait())
     }
+
+    /// Keep some `Expr`s that are ultimately assigned `DefId`s. This keeps the `HirId` parent
+    /// mappings correct even after this pass runs.
+    fn should_preserve_expr(e: &ast::Expr) -> bool {
+        matches!(&e.kind, ast::ExprKind::Closure(..) | ast::ExprKind::Async(..))
+    }
 }
 
 impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
@@ -644,6 +650,75 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
         self.run(true, |s| noop_visit_anon_const(c, s))
     }
 
+    fn filter_map_expr(&mut self, mut e: P<ast::Expr>) -> Option<P<ast::Expr>> {
+        if self.ignore_item {
+            return noop_filter_map_expr(e, self);
+        }
+
+        if let ast::ExprKind::Closure(.., decl, expr, _) = &mut e.kind {
+            // Replacing a closure body and removing its callsites will break inference. Give
+            // all closures the signature `|| -> !` to work around this.
+            decl.inputs = vec![];
+            if let ast::FnRetTy::Default(_) = decl.output {
+                decl.output = ast::FnRetTy::Ty(P(ast::Ty {
+                    id: self.resolver.next_node_id(),
+                    span: rustc_span::DUMMY_SP,
+                    kind: ast::TyKind::Never,
+                }));
+            }
+
+            // Replace `|| expr` with `|| { expr }` so that `visit_block` gets called on the
+            // closure body.
+            if !matches!(expr.kind, ast::ExprKind::Block(..)) {
+                let new_stmt = ast::Stmt {
+                    kind: ast::StmtKind::Expr(expr.clone()),
+                    id: self.resolver.next_node_id(),
+                    span: expr.span,
+                };
+
+                let new_block = ast::Block {
+                    stmts: vec![new_stmt],
+                    rules: BlockCheckMode::Default,
+                    id: self.resolver.next_node_id(),
+                    span: expr.span,
+                };
+
+                expr.kind = ast::ExprKind::Block(P(new_block), None);
+            }
+        }
+
+        if Self::should_preserve_expr(&e) {
+            self.run(false, |s| noop_filter_map_expr(e, s))
+        } else {
+            noop_filter_map_expr(e, self)
+        }
+    }
+
+    fn flat_map_stmt(&mut self, s: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> {
+        if self.ignore_item {
+            return noop_flat_map_stmt(s, self);
+        }
+
+        let ast::Stmt { id, span, .. } = s;
+        match s.kind {
+            // Replace `let x = || {};` with `|| {};`
+            ast::StmtKind::Local(mut local) if local.init.is_some() => self
+                .filter_map_expr(local.init.take().unwrap())
+                .into_iter()
+                .map(|e| ast::Stmt { kind: ast::StmtKind::Semi(e), id, span })
+                .collect(),
+
+            // Replace `|| {}` with `|| {};`
+            ast::StmtKind::Expr(expr) => self
+                .filter_map_expr(expr)
+                .into_iter()
+                .map(|e| ast::Stmt { kind: ast::StmtKind::Semi(e), id, span })
+                .collect(),
+
+            _ => noop_flat_map_stmt(s, self),
+        }
+    }
+
     fn visit_block(&mut self, b: &mut P<ast::Block>) {
         fn stmt_to_block(
             rules: ast::BlockCheckMode,
@@ -699,7 +774,13 @@ impl<'a> MutVisitor for ReplaceBodyWithLoop<'a, '_> {
             for s in b.stmts {
                 let old_blocks = self.nested_blocks.replace(vec![]);
 
-                stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| s.is_item()));
+                stmts.extend(self.flat_map_stmt(s).into_iter().filter(|s| {
+                    s.is_item()
+                        || matches!(
+                            &s.kind,
+                            ast::StmtKind::Semi(expr) if Self::should_preserve_expr(expr)
+                        )
+                }));
 
                 // we put a Some in there earlier with that replace(), so this is valid
                 let new_blocks = self.nested_blocks.take().unwrap();

From 1a300427536883739ea30cc3e2c72409dadae4e1 Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Sun, 7 Jun 2020 15:03:24 -0700
Subject: [PATCH 05/25] Remove unnecessary `opt_local_def_id_to_hir_id`

---
 src/librustc_privacy/lib.rs | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/librustc_privacy/lib.rs b/src/librustc_privacy/lib.rs
index cb896810951ba..87b15853a087c 100644
--- a/src/librustc_privacy/lib.rs
+++ b/src/librustc_privacy/lib.rs
@@ -943,11 +943,8 @@ impl Visitor<'tcx> for EmbargoVisitor<'tcx> {
         let macro_module_def_id =
             ty::DefIdTree::parent(self.tcx, self.tcx.hir().local_def_id(md.hir_id).to_def_id())
                 .unwrap();
-        // FIXME(#71104) Should really be using just `as_local_hir_id` but
-        // some `DefId` do not seem to have a corresponding HirId.
-        let hir_id = macro_module_def_id
-            .as_local()
-            .and_then(|def_id| self.tcx.hir().opt_local_def_id_to_hir_id(def_id));
+        let hir_id =
+            macro_module_def_id.as_local().map(|def_id| self.tcx.hir().as_local_hir_id(def_id));
         let mut module_id = match hir_id {
             Some(module_id) if self.tcx.hir().is_hir_id_module(module_id) => module_id,
             // `module_id` doesn't correspond to a `mod`, return early (#63164, #65252).

From e319f203bd005282cf3eaefd577f35bd7cc1eecf Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Sun, 7 Jun 2020 15:13:40 -0700
Subject: [PATCH 06/25] Add `rustdoc` tests from #72088

---
 src/test/rustdoc/macro-in-async-block.rs | 9 +++++++++
 src/test/rustdoc/macro-in-closure.rs     | 7 +++++++
 2 files changed, 16 insertions(+)
 create mode 100644 src/test/rustdoc/macro-in-async-block.rs

diff --git a/src/test/rustdoc/macro-in-async-block.rs b/src/test/rustdoc/macro-in-async-block.rs
new file mode 100644
index 0000000000000..b4aaacf7b3d40
--- /dev/null
+++ b/src/test/rustdoc/macro-in-async-block.rs
@@ -0,0 +1,9 @@
+// Regression issue for rustdoc ICE encountered in PR #72088.
+// edition:2018
+#![feature(decl_macro)]
+
+fn main() {
+    async {
+        macro m() {}
+    };
+}
diff --git a/src/test/rustdoc/macro-in-closure.rs b/src/test/rustdoc/macro-in-closure.rs
index 298ff601de89f..b4411d927e271 100644
--- a/src/test/rustdoc/macro-in-closure.rs
+++ b/src/test/rustdoc/macro-in-closure.rs
@@ -6,4 +6,11 @@ fn main() {
     || {
         macro m() {}
     };
+
+    let _ = || {
+        macro n() {}
+    };
+
+    let cond = true;
+    let _ = || if cond { macro n() {} } else { panic!() };
 }

From 687767af728ce111a7aa24f74cd9068aedb2ab18 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Fri, 29 May 2020 15:09:43 -0700
Subject: [PATCH 07/25] Suggest substituting `'static` lifetime in impl/dyn
 `Trait + 'static` return types

---
 .../nice_region_error/static_impl_trait.rs    |  64 ++++++++--
 src/librustc_middle/ty/context.rs             |  13 +-
 src/librustc_middle/ty/diagnostics.rs         |   8 +-
 ...t_outlive_least_region_or_bound.nll.stderr |  38 +++++-
 .../must_outlive_least_region_or_bound.rs     |  21 ++++
 .../must_outlive_least_region_or_bound.stderr | 117 ++++++++++++++++--
 6 files changed, 232 insertions(+), 29 deletions(-)

diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index f4c86ddae604e..88d6c23d51441 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -4,6 +4,7 @@ use crate::infer::error_reporting::msg_span_from_free_region;
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
 use rustc_errors::{Applicability, ErrorReported};
+use rustc_hir::{GenericBound, ItemKind, Lifetime, LifetimeName, TyKind};
 use rustc_middle::ty::RegionKind;
 
 impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
@@ -20,8 +21,9 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             ) = error.clone()
             {
                 let anon_reg_sup = self.tcx().is_suitable_region(sup_r)?;
-                let (fn_return_span, is_dyn) =
-                    self.tcx().return_type_impl_or_dyn_trait(anon_reg_sup.def_id)?;
+                let fn_return = self.tcx().return_type_impl_or_dyn_trait(anon_reg_sup.def_id)?;
+                let is_dyn = matches!(fn_return.kind, TyKind::TraitObject(..));
+                let fn_return_span = fn_return.span;
                 if sub_r == &RegionKind::ReStatic {
                     let sp = var_origin.span();
                     let return_sp = sub_origin.span();
@@ -67,12 +69,58 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                             lifetime,
                         );
                         // FIXME: account for the need of parens in `&(dyn Trait + '_)`
-                        err.span_suggestion_verbose(
-                            fn_return_span.shrink_to_hi(),
-                            &msg,
-                            format!(" + {}", lifetime_name),
-                            Applicability::MaybeIncorrect,
-                        );
+                        match fn_return.kind {
+                            TyKind::Def(item_id, _) => {
+                                let item = self.tcx().hir().item(item_id.id);
+                                let opaque = if let ItemKind::OpaqueTy(opaque) = &item.kind {
+                                    opaque
+                                } else {
+                                    err.emit();
+                                    return Some(ErrorReported);
+                                };
+                                let (span, sugg) = opaque
+                                    .bounds
+                                    .iter()
+                                    .filter_map(|arg| match arg {
+                                        GenericBound::Outlives(Lifetime {
+                                            name: LifetimeName::Static,
+                                            span,
+                                            ..
+                                        }) => Some((*span, lifetime_name.clone())),
+                                        _ => None,
+                                    })
+                                    .next()
+                                    .unwrap_or_else(|| {
+                                        (
+                                            fn_return_span.shrink_to_hi(),
+                                            format!(" + {}", lifetime_name),
+                                        )
+                                    });
+
+                                err.span_suggestion_verbose(
+                                    span,
+                                    &msg,
+                                    sugg,
+                                    Applicability::MaybeIncorrect,
+                                );
+                            }
+                            TyKind::TraitObject(_, lt) => {
+                                let (span, sugg) = match lt.name {
+                                    LifetimeName::ImplicitObjectLifetimeDefault => (
+                                        fn_return_span.shrink_to_hi(),
+                                        format!(" + {}", lifetime_name),
+                                    ),
+                                    _ => (lt.span, lifetime_name),
+                                };
+                                err.span_suggestion_verbose(
+                                    span,
+                                    &msg,
+                                    sugg,
+                                    Applicability::MaybeIncorrect,
+                                );
+                            }
+                            _ => {}
+                        }
                     }
                     err.emit();
                     return Some(ErrorReported);
diff --git a/src/librustc_middle/ty/context.rs b/src/librustc_middle/ty/context.rs
index d5be3508d2d80..4770993d9cb07 100644
--- a/src/librustc_middle/ty/context.rs
+++ b/src/librustc_middle/ty/context.rs
@@ -1383,7 +1383,10 @@ impl<'tcx> TyCtxt<'tcx> {
         })
     }
 
-    pub fn return_type_impl_or_dyn_trait(&self, scope_def_id: DefId) -> Option<(Span, bool)> {
+    pub fn return_type_impl_or_dyn_trait(
+        &self,
+        scope_def_id: DefId,
+    ) -> Option<&'tcx hir::Ty<'tcx>> {
         let hir_id = self.hir().as_local_hir_id(scope_def_id.expect_local());
         let hir_output = match self.hir().get(hir_id) {
             Node::Item(hir::Item {
@@ -1429,15 +1432,17 @@ impl<'tcx> TyCtxt<'tcx> {
                 let output = self.erase_late_bound_regions(&sig.output());
                 if output.is_impl_trait() {
                     let fn_decl = self.hir().fn_decl_by_hir_id(hir_id).unwrap();
-                    Some((fn_decl.output.span(), false))
+                    if let hir::FnRetTy::Return(ty) = fn_decl.output {
+                        return Some(ty);
+                    }
                 } else {
                     let mut v = TraitObjectVisitor(vec![]);
                     rustc_hir::intravisit::walk_ty(&mut v, hir_output);
                     if v.0.len() == 1 {
-                        return Some((v.0[0], true));
+                        return Some(v.0[0]);
                     }
-                    None
                 }
+                None
             }
             _ => None,
         }
diff --git a/src/librustc_middle/ty/diagnostics.rs b/src/librustc_middle/ty/diagnostics.rs
index 2e9aa724ac5af..3ca506fe0d590 100644
--- a/src/librustc_middle/ty/diagnostics.rs
+++ b/src/librustc_middle/ty/diagnostics.rs
@@ -236,21 +236,21 @@ pub fn suggest_constraining_type_param(
     }
 }
 
-pub struct TraitObjectVisitor(pub Vec<rustc_span::Span>);
-impl<'v> hir::intravisit::Visitor<'v> for TraitObjectVisitor {
+pub struct TraitObjectVisitor<'tcx>(pub Vec<&'tcx hir::Ty<'tcx>>);
+impl<'v> hir::intravisit::Visitor<'v> for TraitObjectVisitor<'v> {
     type Map = rustc_hir::intravisit::ErasedMap<'v>;
 
     fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
         hir::intravisit::NestedVisitorMap::None
     }
 
-    fn visit_ty(&mut self, ty: &hir::Ty<'_>) {
+    fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) {
         if let hir::TyKind::TraitObject(
             _,
             hir::Lifetime { name: hir::LifetimeName::ImplicitObjectLifetimeDefault, .. },
         ) = ty.kind
         {
-            self.0.push(ty.span);
+            self.0.push(ty);
         }
     }
 }
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.nll.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.nll.stderr
index 1806d2607a3ac..ca9ca8a9debe2 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.nll.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.nll.stderr
@@ -26,7 +26,34 @@ LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                ^^^^^^^^^^^^^^
 
 error: lifetime may not live long enough
-  --> $DIR/must_outlive_least_region_or_bound.rs:12:69
+  --> $DIR/must_outlive_least_region_or_bound.rs:9:46
+   |
+LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
+   |               -                              ^ returning this value requires that `'1` must outlive `'static`
+   |               |
+   |               let's call the lifetime of this reference `'1`
+   |
+   = help: consider replacing `'1` with `'static`
+
+error: lifetime may not live long enough
+  --> $DIR/must_outlive_least_region_or_bound.rs:12:55
+   |
+LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
+   |              -- lifetime `'a` defined here            ^ returning this value requires that `'a` must outlive `'static`
+   |
+   = help: consider replacing `'a` with `'static`
+   = help: consider replacing `'a` with `'static`
+
+error[E0621]: explicit lifetime required in the type of `x`
+  --> $DIR/must_outlive_least_region_or_bound.rs:15:41
+   |
+LL | fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
+   |               ----                      ^ lifetime `'a` required
+   |               |
+   |               help: add explicit lifetime `'a` to the type of `x`: `&'a i32`
+
+error: lifetime may not live long enough
+  --> $DIR/must_outlive_least_region_or_bound.rs:33:69
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |               -- lifetime `'a` defined here                         ^ returning this value requires that `'a` must outlive `'static`
@@ -35,7 +62,7 @@ LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    = help: consider replacing `'a` with `'static`
 
 error: lifetime may not live long enough
-  --> $DIR/must_outlive_least_region_or_bound.rs:17:61
+  --> $DIR/must_outlive_least_region_or_bound.rs:38:61
    |
 LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32) {
    |                          --  -- lifetime `'b` defined here  ^^^^^^^^^^^^^^^^ opaque type requires that `'b` must outlive `'a`
@@ -45,13 +72,14 @@ LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32
    = help: consider adding the following bound: `'b: 'a`
 
 error[E0310]: the parameter type `T` may not live long enough
-  --> $DIR/must_outlive_least_region_or_bound.rs:22:51
+  --> $DIR/must_outlive_least_region_or_bound.rs:43:51
    |
 LL | fn ty_param_wont_outlive_static<T:Debug>(x: T) -> impl Debug + 'static {
    |                                                   ^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding an explicit lifetime bound `T: 'static`...
 
-error: aborting due to 5 previous errors
+error: aborting due to 8 previous errors
 
-For more information about this error, try `rustc --explain E0310`.
+Some errors have detailed explanations: E0310, E0621.
+For more information about an error, try `rustc --explain E0310`.
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs
index 00f3490991b52..beafe9258209d 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs
@@ -6,6 +6,27 @@ fn elided(x: &i32) -> impl Copy { x }
 fn explicit<'a>(x: &'a i32) -> impl Copy { x }
 //~^ ERROR cannot infer an appropriate lifetime
 
+fn elided2(x: &i32) -> impl Copy + 'static { x }
+//~^ ERROR cannot infer an appropriate lifetime
+
+fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
+//~^ ERROR cannot infer an appropriate lifetime
+
+fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
+//~^ ERROR explicit lifetime required in the type of `x`
+
+fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
+//~^ ERROR cannot infer an appropriate lifetime
+
+fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
+//~^ ERROR cannot infer an appropriate lifetime
+
+fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+//~^ ERROR explicit lifetime required in the type of `x`
+
+fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+//~^ ERROR cannot infer an appropriate lifetime
+
 trait LifetimeTrait<'a> {}
 impl<'a> LifetimeTrait<'a> for &'a i32 {}
 
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index d7dae6a08a7b9..525e271bea9c3 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -27,7 +27,43 @@ LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                          ^^^^
 
 error: cannot infer an appropriate lifetime
-  --> $DIR/must_outlive_least_region_or_bound.rs:12:69
+  --> $DIR/must_outlive_least_region_or_bound.rs:9:46
+   |
+LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
+   |               ----     -------------------   ^ ...and is captured here
+   |               |        |
+   |               |        ...is required to be `'static` by this...
+   |               data with this lifetime...
+   |
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 9:1
+   |
+LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
+   |                                    ^^
+
+error: cannot infer an appropriate lifetime
+  --> $DIR/must_outlive_least_region_or_bound.rs:12:55
+   |
+LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
+   |                     -------     -------------------   ^ ...and is captured here
+   |                     |           |
+   |                     |           ...is required to be `'static` by this...
+   |                     data with this lifetime...
+   |
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 12:14
+   |
+LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'a { x }
+   |                                             ^^
+
+error[E0621]: explicit lifetime required in the type of `x`
+  --> $DIR/must_outlive_least_region_or_bound.rs:15:24
+   |
+LL | fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
+   |               ----     ^^^^^^^^^^^^^^ lifetime `'a` required
+   |               |
+   |               help: add explicit lifetime `'a` to the type of `x`: `&'a i32`
+
+error: cannot infer an appropriate lifetime
+  --> $DIR/must_outlive_least_region_or_bound.rs:33:69
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |                      -------     --------------------------------   ^ ...and is captured here
@@ -35,13 +71,13 @@ LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |                      |           ...is required to be `'static` by this...
    |                      data with this lifetime...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 12:15
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 33:15
    |
-LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static + 'a { x }
-   |                                                                   ^^^^
+LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'a { x }
+   |                                                           ^^
 
 error[E0623]: lifetime mismatch
-  --> $DIR/must_outlive_least_region_or_bound.rs:17:61
+  --> $DIR/must_outlive_least_region_or_bound.rs:38:61
    |
 LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32) {
    |                                                 -------     ^^^^^^^^^^^^^^^^
@@ -50,14 +86,79 @@ LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32
    |                                                 this parameter and the return type are declared with different lifetimes...
 
 error[E0310]: the parameter type `T` may not live long enough
-  --> $DIR/must_outlive_least_region_or_bound.rs:22:51
+  --> $DIR/must_outlive_least_region_or_bound.rs:43:51
    |
 LL | fn ty_param_wont_outlive_static<T:Debug>(x: T) -> impl Debug + 'static {
    |                                 --                ^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
    |                                 |
    |                                 help: consider adding an explicit lifetime bound...: `T: 'static +`
 
-error: aborting due to 5 previous errors
+error: cannot infer an appropriate lifetime
+  --> $DIR/must_outlive_least_region_or_bound.rs:18:50
+   |
+LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
+   |               ----                      ---------^-
+   |               |                         |        |
+   |               |                         |        ...and is captured here
+   |               |                         ...is required to be `'static` by this...
+   |               data with this lifetime...
+   |
+help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 18:1
+   |
+LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
+   |                                      ^^^^
+
+error: cannot infer an appropriate lifetime
+  --> $DIR/must_outlive_least_region_or_bound.rs:21:59
+   |
+LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
+   |                     -------                      ---------^-
+   |                     |                            |        |
+   |                     |                            |        ...and is captured here
+   |                     |                            ...is required to be `'static` by this...
+   |                     data with this lifetime...
+   |
+help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 21:14
+   |
+LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
+   |                                               ^^^^
+
+error[E0621]: explicit lifetime required in the type of `x`
+  --> $DIR/must_outlive_least_region_or_bound.rs:24:51
+   |
+LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+   |               ----                                ^^^^^^^^^^^ lifetime `'static` required
+   |               |
+   |               help: add explicit lifetime `'static` to the type of `x`: `&'static i32`
+
+error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
+  --> $DIR/must_outlive_least_region_or_bound.rs:27:69
+   |
+LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+   |                                                                     ^
+   |
+note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 27:14...
+  --> $DIR/must_outlive_least_region_or_bound.rs:27:14
+   |
+LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+   |              ^^
+note: ...so that the expression is assignable
+  --> $DIR/must_outlive_least_region_or_bound.rs:27:69
+   |
+LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+   |                                                                     ^
+   = note: expected  `&i32`
+              found  `&'a i32`
+   = note: but, the lifetime must be valid for the static lifetime...
+note: ...so that the expression is assignable
+  --> $DIR/must_outlive_least_region_or_bound.rs:27:60
+   |
+LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+   |                                                            ^^^^^^^^^^^
+   = note: expected  `std::boxed::Box<(dyn std::fmt::Debug + 'static)>`
+              found  `std::boxed::Box<dyn std::fmt::Debug>`
+
+error: aborting due to 12 previous errors
 
-Some errors have detailed explanations: E0310, E0623.
+Some errors have detailed explanations: E0310, E0495, E0621, E0623.
 For more information about an error, try `rustc --explain E0310`.

From c91320f06b0b967b662f62a1c00447b9c87d4542 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Fri, 29 May 2020 18:05:20 -0700
Subject: [PATCH 08/25] When `'static` is explicit, suggest constraining
 argument with it

---
 .../infer/error_reporting/mod.rs              |   3 +-
 .../nice_region_error/static_impl_trait.rs    | 115 +++++++++++-------
 src/librustc_middle/ty/diagnostics.rs         |   5 +-
 .../must_outlive_least_region_or_bound.rs     |   2 +-
 .../must_outlive_least_region_or_bound.stderr |  75 +++++++-----
 src/test/ui/issues/issue-16922.stderr         |   2 +-
 ...ect-lifetime-default-from-box-error.stderr |   2 +-
 ...ion-object-lifetime-in-coercion.nll.stderr |  19 ++-
 .../region-object-lifetime-in-coercion.rs     |   5 +-
 .../region-object-lifetime-in-coercion.stderr |  61 +++++++---
 .../regions-close-object-into-object-2.stderr |  32 ++---
 .../regions-close-object-into-object-4.stderr |  32 ++---
 .../regions-proc-bound-capture.nll.stderr     |  11 ++
 .../ui/regions/regions-proc-bound-capture.rs  |   4 +-
 .../regions/regions-proc-bound-capture.stderr |  25 ++--
 .../dyn-trait-underscore.stderr               |   2 +-
 16 files changed, 237 insertions(+), 158 deletions(-)
 create mode 100644 src/test/ui/regions/regions-proc-bound-capture.nll.stderr

diff --git a/src/librustc_infer/infer/error_reporting/mod.rs b/src/librustc_infer/infer/error_reporting/mod.rs
index a59a91e3005aa..f7969fe779d33 100644
--- a/src/librustc_infer/infer/error_reporting/mod.rs
+++ b/src/librustc_infer/infer/error_reporting/mod.rs
@@ -2037,8 +2037,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             self.tcx.sess,
             var_origin.span(),
             E0495,
-            "cannot infer an appropriate lifetime{} \
-             due to conflicting requirements",
+            "cannot infer an appropriate lifetime{} due to conflicting requirements",
             var_description
         )
     }
diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index 88d6c23d51441..e24535bba5fdc 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -10,6 +10,7 @@ use rustc_middle::ty::RegionKind;
 impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
     /// Print the error message for lifetime errors when the return type is a static impl Trait.
     pub(super) fn try_report_static_impl_trait(&self) -> Option<ErrorReported> {
+        debug!("try_report_static_impl_trait(error={:?})", self.error);
         if let Some(ref error) = self.error {
             if let RegionResolutionError::SubSupConflict(
                 _,
@@ -18,19 +19,24 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                 sub_r,
                 sup_origin,
                 sup_r,
-            ) = error.clone()
+            ) = error
             {
+                debug!(
+                    "try_report_static_impl_trait(var={:?}, sub={:?} {:?} sup={:?} {:?})",
+                    var_origin, sub_origin, sub_r, sup_origin, sup_r
+                );
                 let anon_reg_sup = self.tcx().is_suitable_region(sup_r)?;
+                debug!("try_report_static_impl_trait: anon_reg_sup={:?}", anon_reg_sup);
                 let fn_return = self.tcx().return_type_impl_or_dyn_trait(anon_reg_sup.def_id)?;
-                let is_dyn = matches!(fn_return.kind, TyKind::TraitObject(..));
-                let fn_return_span = fn_return.span;
-                if sub_r == &RegionKind::ReStatic {
+                debug!("try_report_static_impl_trait: fn_return={:?}", fn_return);
+                if **sub_r == RegionKind::ReStatic {
                     let sp = var_origin.span();
                     let return_sp = sub_origin.span();
+                    let param_info = self.find_param_with_region(sup_r, sub_r)?;
                     let mut err =
                         self.tcx().sess.struct_span_err(sp, "cannot infer an appropriate lifetime");
-                    let param_info = self.find_param_with_region(sup_r, sub_r)?;
                     err.span_label(param_info.param_ty_span, "data with this lifetime...");
+                    debug!("try_report_static_impl_trait: param_info={:?}", param_info);
 
                     // We try to make the output have fewer overlapping spans if possible.
                     if (sp == sup_origin.span() || !return_sp.overlaps(sup_origin.span()))
@@ -60,14 +66,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                         if sup_r.has_name() { sup_r.to_string() } else { "'_".to_owned() };
                     // only apply this suggestion onto functions with
                     // explicit non-desugar'able return.
-                    if fn_return_span.desugaring_kind().is_none() {
-                        let msg = format!(
-                            "to permit non-static references in {} `{} Trait` value, you can add \
-                             an explicit bound for {}",
-                            if is_dyn { "a" } else { "an" },
-                            if is_dyn { "dyn" } else { "impl" },
-                            lifetime,
-                        );
+                    if fn_return.span.desugaring_kind().is_none() {
                         // FIXME: account for the need of parens in `&(dyn Trait + '_)`
                         match fn_return.kind {
                             TyKind::Def(item_id, _) => {
@@ -78,7 +77,8 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                     err.emit();
                                     return Some(ErrorReported);
                                 };
-                                let (span, sugg) = opaque
+
+                                if let Some(span) = opaque
                                     .bounds
                                     .iter()
                                     .filter_map(|arg| match arg {
@@ -86,38 +86,71 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                             name: LifetimeName::Static,
                                             span,
                                             ..
-                                        }) => Some((*span, lifetime_name.clone())),
+                                        }) => Some(*span),
                                         _ => None,
                                     })
                                     .next()
-                                    .unwrap_or_else(|| {
-                                        (
-                                            fn_return_span.shrink_to_hi(),
-                                            format!(" + {}", lifetime_name),
-                                        )
-                                    });
-
-                                err.span_suggestion_verbose(
-                                    span,
-                                    &msg,
-                                    sugg,
-                                    Applicability::MaybeIncorrect,
-                                );
-                            }
-                            TyKind::TraitObject(_, lt) => {
-                                let (span, sugg) = match lt.name {
-                                    LifetimeName::ImplicitObjectLifetimeDefault => (
-                                        fn_return_span.shrink_to_hi(),
+                                {
+                                    err.span_suggestion_verbose(
+                                        span,
+                                        "consider changing the `impl Trait`'s explicit \
+                                         `'static` bound",
+                                        lifetime_name,
+                                        Applicability::MaybeIncorrect,
+                                    );
+                                    err.span_suggestion_verbose(
+                                        param_info.param_ty_span,
+                                        "alternatively, set an explicit `'static` lifetime to \
+                                         this parameter",
+                                        param_info.param_ty.to_string(),
+                                        Applicability::MaybeIncorrect,
+                                    );
+                                } else {
+                                    err.span_suggestion_verbose(
+                                        fn_return.span.shrink_to_hi(),
+                                        &format!(
+                                            "to permit non-static references in an `impl Trait` \
+                                             value, you can add an explicit bound for {}",
+                                            lifetime,
+                                        ),
                                         format!(" + {}", lifetime_name),
-                                    ),
-                                    _ => (lt.span, lifetime_name),
+                                        Applicability::MaybeIncorrect,
+                                    );
                                 };
-                                err.span_suggestion_verbose(
-                                    span,
-                                    &msg,
-                                    sugg,
-                                    Applicability::MaybeIncorrect,
-                                );
+                            }
+                            TyKind::TraitObject(_, lt) => {
+                                match lt.name {
+                                    LifetimeName::ImplicitObjectLifetimeDefault => {
+                                        err.span_suggestion_verbose(
+                                            fn_return.span.shrink_to_hi(),
+                                            &format!(
+                                                "to permit non-static references in a trait object \
+                                                 value, you can add an explicit bound for {}",
+                                                lifetime,
+                                            ),
+                                            format!(" + {}", lifetime_name),
+                                            Applicability::MaybeIncorrect,
+                                        );
+                                    }
+                                    _ => {
+                                        err.span_suggestion_verbose(
+                                            lt.span,
+                                            "consider changing the trait object's explicit \
+                                             `'static` bound",
+                                            lifetime_name,
+                                            Applicability::MaybeIncorrect,
+                                        );
+                                        err.span_suggestion_verbose(
+                                            param_info.param_ty_span,
+                                            &format!(
+                                                "alternatively, set an explicit `'static` lifetime \
+                                                 in this parameter",
+                                            ),
+                                            param_info.param_ty.to_string(),
+                                            Applicability::MaybeIncorrect,
+                                        );
+                                    }
+                                }
                             }
                             _ => {}
                         }
diff --git a/src/librustc_middle/ty/diagnostics.rs b/src/librustc_middle/ty/diagnostics.rs
index 3ca506fe0d590..a2812e117ed39 100644
--- a/src/librustc_middle/ty/diagnostics.rs
+++ b/src/librustc_middle/ty/diagnostics.rs
@@ -247,7 +247,10 @@ impl<'v> hir::intravisit::Visitor<'v> for TraitObjectVisitor<'v> {
     fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) {
         if let hir::TyKind::TraitObject(
             _,
-            hir::Lifetime { name: hir::LifetimeName::ImplicitObjectLifetimeDefault, .. },
+            hir::Lifetime {
+                name: hir::LifetimeName::ImplicitObjectLifetimeDefault | hir::LifetimeName::Static,
+                ..
+            },
         ) = ty.kind
         {
             self.0.push(ty);
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs
index beafe9258209d..837244b022721 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs
@@ -22,7 +22,7 @@ fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
 //~^ ERROR cannot infer an appropriate lifetime
 
 fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-//~^ ERROR explicit lifetime required in the type of `x`
+//~^ ERROR cannot infer an appropriate lifetime
 
 fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
 //~^ ERROR cannot infer an appropriate lifetime
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index 525e271bea9c3..96d4a121c16af 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -35,10 +35,14 @@ LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
    |               |        ...is required to be `'static` by this...
    |               data with this lifetime...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 9:1
+help: consider changing the `impl Trait`'s explicit `'static` bound
    |
 LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
    |                                    ^^
+help: alternatively, set an explicit `'static` lifetime to this parameter
+   |
+LL | fn elided2(x: &'static i32) -> impl Copy + 'static { x }
+   |               ^^^^^^^^^^^^
 
 error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:12:55
@@ -49,10 +53,14 @@ LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
    |                     |           ...is required to be `'static` by this...
    |                     data with this lifetime...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 12:14
+help: consider changing the `impl Trait`'s explicit `'static` bound
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                             ^^
+help: alternatively, set an explicit `'static` lifetime to this parameter
+   |
+LL | fn explicit2<'a>(x: &'static i32) -> impl Copy + 'static { x }
+   |                     ^^^^^^^^^^^^
 
 error[E0621]: explicit lifetime required in the type of `x`
   --> $DIR/must_outlive_least_region_or_bound.rs:15:24
@@ -71,10 +79,14 @@ LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |                      |           ...is required to be `'static` by this...
    |                      data with this lifetime...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 33:15
+help: consider changing the `impl Trait`'s explicit `'static` bound
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'a { x }
    |                                                           ^^
+help: alternatively, set an explicit `'static` lifetime to this parameter
+   |
+LL | fn with_bound<'a>(x: &'static i32) -> impl LifetimeTrait<'a> + 'static { x }
+   |                      ^^^^^^^^^^^^
 
 error[E0623]: lifetime mismatch
   --> $DIR/must_outlive_least_region_or_bound.rs:38:61
@@ -103,7 +115,7 @@ LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
    |               |                         ...is required to be `'static` by this...
    |               data with this lifetime...
    |
-help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 18:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 18:1
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                      ^^^^
@@ -118,47 +130,48 @@ LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
    |                     |                            ...is required to be `'static` by this...
    |                     data with this lifetime...
    |
-help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 21:14
+help: to permit non-static references in a trait object value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 21:14
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                               ^^^^
 
-error[E0621]: explicit lifetime required in the type of `x`
-  --> $DIR/must_outlive_least_region_or_bound.rs:24:51
+error: cannot infer an appropriate lifetime
+  --> $DIR/must_outlive_least_region_or_bound.rs:24:60
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |               ----                                ^^^^^^^^^^^ lifetime `'static` required
-   |               |
-   |               help: add explicit lifetime `'static` to the type of `x`: `&'static i32`
-
-error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
-  --> $DIR/must_outlive_least_region_or_bound.rs:27:69
+   |               ----                                ---------^-
+   |               |                                   |        |
+   |               |                                   |        ...and is captured here
+   |               data with this lifetime...          ...is required to be `'static` by this...
    |
-LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |                                                                     ^
+help: consider changing the trait object's explicit `'static` bound
    |
-note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 27:14...
-  --> $DIR/must_outlive_least_region_or_bound.rs:27:14
+LL | fn elided4(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
+   |                                        ^^
+help: alternatively, set an explicit `'static` lifetime in this parameter
    |
-LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |              ^^
-note: ...so that the expression is assignable
+LL | fn elided4(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+   |               ^^^^^^^^^^^^
+
+error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:27:69
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |                                                                     ^
-   = note: expected  `&i32`
-              found  `&'a i32`
-   = note: but, the lifetime must be valid for the static lifetime...
-note: ...so that the expression is assignable
-  --> $DIR/must_outlive_least_region_or_bound.rs:27:60
+   |                     -------                                ---------^-
+   |                     |                                      |        |
+   |                     |                                      |        ...and is captured here
+   |                     data with this lifetime...             ...is required to be `'static` by this...
    |
-LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |                                                            ^^^^^^^^^^^
-   = note: expected  `std::boxed::Box<(dyn std::fmt::Debug + 'static)>`
-              found  `std::boxed::Box<dyn std::fmt::Debug>`
+help: consider changing the trait object's explicit `'static` bound
+   |
+LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
+   |                                                 ^^
+help: alternatively, set an explicit `'static` lifetime in this parameter
+   |
+LL | fn explicit4<'a>(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+   |                     ^^^^^^^^^^^^
 
 error: aborting due to 12 previous errors
 
-Some errors have detailed explanations: E0310, E0495, E0621, E0623.
+Some errors have detailed explanations: E0310, E0621, E0623.
 For more information about an error, try `rustc --explain E0310`.
diff --git a/src/test/ui/issues/issue-16922.stderr b/src/test/ui/issues/issue-16922.stderr
index 02d33aae023ff..038df47e1bd98 100644
--- a/src/test/ui/issues/issue-16922.stderr
+++ b/src/test/ui/issues/issue-16922.stderr
@@ -9,7 +9,7 @@ LL |     Box::new(value) as Box<dyn Any>
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 3:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 3:1
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
    |                                          ^^^^
diff --git a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
index 70a9bf22b8db3..555622c9d13c1 100644
--- a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
+++ b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
@@ -7,7 +7,7 @@ LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait> {
 LL |     ss.r
    |     ^^^^ ...is captured and required to be `'static` here
    |
-help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #2 defined on the function body at 14:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #2 defined on the function body at 14:1
    |
 LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait + '_> {
    |                                                   ^^^^
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.nll.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.nll.stderr
index bf02ba8eb9199..7e8f78067e08a 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.nll.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.nll.stderr
@@ -1,21 +1,21 @@
-error[E0621]: explicit lifetime required in the type of `v`
+error: lifetime may not live long enough
   --> $DIR/region-object-lifetime-in-coercion.rs:8:12
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- help: add explicit lifetime `'static` to the type of `v`: `&'static [u8]`
+   |         - let's call the lifetime of this reference `'1`
 LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
-   |            ^^^^^^^^^^^^^^^^^^^^^^ lifetime `'static` required
+   |            ^^^^^^^^^^^^^^^^^^^^^^ type annotation requires that `'1` must outlive `'static`
 
-error[E0621]: explicit lifetime required in the type of `v`
-  --> $DIR/region-object-lifetime-in-coercion.rs:14:5
+error: lifetime may not live long enough
+  --> $DIR/region-object-lifetime-in-coercion.rs:13:5
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- help: add explicit lifetime `'static` to the type of `v`: `&'static [u8]`
+   |         - let's call the lifetime of this reference `'1`
 LL |     Box::new(v)
-   |     ^^^^^^^^^^^ lifetime `'static` required
+   |     ^^^^^^^^^^^ returning this value requires that `'1` must outlive `'static`
 
 error: lifetime may not live long enough
-  --> $DIR/region-object-lifetime-in-coercion.rs:20:5
+  --> $DIR/region-object-lifetime-in-coercion.rs:19:5
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo> {
    |         - let's call the lifetime of this reference `'1`
@@ -24,7 +24,7 @@ LL |     Box::new(v)
    |     ^^^^^^^^^^^ returning this value requires that `'1` must outlive `'static`
 
 error: lifetime may not live long enough
-  --> $DIR/region-object-lifetime-in-coercion.rs:24:5
+  --> $DIR/region-object-lifetime-in-coercion.rs:23:5
    |
 LL | fn d<'a,'b>(v: &'a [u8]) -> Box<dyn Foo+'b> {
    |      -- -- lifetime `'b` defined here
@@ -37,4 +37,3 @@ LL |     Box::new(v)
 
 error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0621`.
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.rs b/src/test/ui/regions/region-object-lifetime-in-coercion.rs
index d56eaf77b6646..5d199149c39b8 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.rs
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.rs
@@ -5,13 +5,12 @@ trait Foo {}
 impl<'a> Foo for &'a [u8] {}
 
 fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
-    let x: Box<dyn Foo + 'static> = Box::new(v);
-    //~^ ERROR explicit lifetime required in the type of `v` [E0621]
+    let x: Box<dyn Foo + 'static> = Box::new(v); //~ ERROR cannot infer an appropriate lifetime
     x
 }
 
 fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
-    Box::new(v) //~ ERROR explicit lifetime required in the type of `v` [E0621]
+    Box::new(v) //~ ERROR cannot infer an appropriate lifetime
 }
 
 fn c(v: &[u8]) -> Box<dyn Foo> {
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
index 1462af44cb15a..673300cebc26c 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
@@ -1,21 +1,45 @@
-error[E0621]: explicit lifetime required in the type of `v`
-  --> $DIR/region-object-lifetime-in-coercion.rs:8:37
+error: cannot infer an appropriate lifetime
+  --> $DIR/region-object-lifetime-in-coercion.rs:8:46
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- help: add explicit lifetime `'static` to the type of `v`: `&'static [u8]`
+   |         ----- data with this lifetime...
 LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
-   |                                     ^^^^^^^^^^^ lifetime `'static` required
+   |                                     ---------^-
+   |                                     |        |
+   |                                     |        ...and is captured here
+   |                                     ...is required to be `'static` by this...
+   |
+help: consider changing the trait object's explicit `'static` bound
+   |
+LL | fn a(v: &[u8]) -> Box<dyn Foo + '_> {
+   |                                 ^^
+help: alternatively, set an explicit `'static` lifetime in this parameter
+   |
+LL | fn a(v: &'static [u8]) -> Box<dyn Foo + 'static> {
+   |         ^^^^^^^^^^^^^
 
-error[E0621]: explicit lifetime required in the type of `v`
-  --> $DIR/region-object-lifetime-in-coercion.rs:14:5
+error: cannot infer an appropriate lifetime
+  --> $DIR/region-object-lifetime-in-coercion.rs:13:14
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- help: add explicit lifetime `'static` to the type of `v`: `&'static [u8]`
+   |         ----- data with this lifetime...
 LL |     Box::new(v)
-   |     ^^^^^^^^^^^ lifetime `'static` required
+   |     ---------^-
+   |     |        |
+   |     |        ...and is captured here
+   |     ...is required to be `'static` by this...
+   |
+help: consider changing the trait object's explicit `'static` bound
+   |
+LL | fn b(v: &[u8]) -> Box<dyn Foo + '_> {
+   |                                 ^^
+help: alternatively, set an explicit `'static` lifetime in this parameter
+   |
+LL | fn b(v: &'static [u8]) -> Box<dyn Foo + 'static> {
+   |         ^^^^^^^^^^^^^
 
 error: cannot infer an appropriate lifetime
-  --> $DIR/region-object-lifetime-in-coercion.rs:20:14
+  --> $DIR/region-object-lifetime-in-coercion.rs:19:14
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo> {
    |         ----- data with this lifetime...
@@ -26,36 +50,36 @@ LL |     Box::new(v)
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 17:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 16:1
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo + '_> {
    |                               ^^^^
 
 error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
-  --> $DIR/region-object-lifetime-in-coercion.rs:24:14
+  --> $DIR/region-object-lifetime-in-coercion.rs:23:14
    |
 LL |     Box::new(v)
    |              ^
    |
-note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 23:6...
-  --> $DIR/region-object-lifetime-in-coercion.rs:23:6
+note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 22:6...
+  --> $DIR/region-object-lifetime-in-coercion.rs:22:6
    |
 LL | fn d<'a,'b>(v: &'a [u8]) -> Box<dyn Foo+'b> {
    |      ^^
 note: ...so that the expression is assignable
-  --> $DIR/region-object-lifetime-in-coercion.rs:24:14
+  --> $DIR/region-object-lifetime-in-coercion.rs:23:14
    |
 LL |     Box::new(v)
    |              ^
    = note: expected `&[u8]`
               found `&'a [u8]`
-note: but, the lifetime must be valid for the lifetime `'b` as defined on the function body at 23:9...
-  --> $DIR/region-object-lifetime-in-coercion.rs:23:9
+note: but, the lifetime must be valid for the lifetime `'b` as defined on the function body at 22:9...
+  --> $DIR/region-object-lifetime-in-coercion.rs:22:9
    |
 LL | fn d<'a,'b>(v: &'a [u8]) -> Box<dyn Foo+'b> {
    |         ^^
 note: ...so that the expression is assignable
-  --> $DIR/region-object-lifetime-in-coercion.rs:24:5
+  --> $DIR/region-object-lifetime-in-coercion.rs:23:5
    |
 LL |     Box::new(v)
    |     ^^^^^^^^^^^
@@ -64,5 +88,4 @@ LL |     Box::new(v)
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0495, E0621.
-For more information about an error, try `rustc --explain E0495`.
+For more information about this error, try `rustc --explain E0495`.
diff --git a/src/test/ui/regions/regions-close-object-into-object-2.stderr b/src/test/ui/regions/regions-close-object-into-object-2.stderr
index 147f7f3541816..982ed07232a80 100644
--- a/src/test/ui/regions/regions-close-object-into-object-2.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-2.stderr
@@ -1,28 +1,22 @@
-error[E0495]: cannot infer an appropriate lifetime for borrow expression due to conflicting requirements
+error: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-2.rs:10:11
    |
+LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
+   |                         ------------------ data with this lifetime...
 LL |     box B(&*v) as Box<dyn X>
-   |           ^^^
-   |
-note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 9:6...
-  --> $DIR/regions-close-object-into-object-2.rs:9:6
+   |     ------^^^---------------
+   |     |     |
+   |     |     ...and is captured here
+   |     ...is required to be `'static` by this...
    |
-LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
-   |      ^^
-note: ...so that the type `(dyn A<T> + 'a)` is not borrowed for too long
-  --> $DIR/regions-close-object-into-object-2.rs:10:11
+help: consider changing the trait object's explicit `'static` bound
    |
-LL |     box B(&*v) as Box<dyn X>
-   |           ^^^
-   = note: but, the lifetime must be valid for the static lifetime...
-note: ...so that the expression is assignable
-  --> $DIR/regions-close-object-into-object-2.rs:10:5
+LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'a> {
+   |                                                            ^^
+help: alternatively, set an explicit `'static` lifetime in this parameter
    |
-LL |     box B(&*v) as Box<dyn X>
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: expected `std::boxed::Box<(dyn X + 'static)>`
-              found `std::boxed::Box<dyn X>`
+LL | fn g<'a, T: 'static>(v: std::boxed::Box<(dyn A<T> + 'static)>) -> Box<dyn X + 'static> {
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0495`.
diff --git a/src/test/ui/regions/regions-close-object-into-object-4.stderr b/src/test/ui/regions/regions-close-object-into-object-4.stderr
index 6e7d6152cd09a..1b82098ee13c2 100644
--- a/src/test/ui/regions/regions-close-object-into-object-4.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-4.stderr
@@ -1,28 +1,22 @@
-error[E0495]: cannot infer an appropriate lifetime for borrow expression due to conflicting requirements
+error: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-4.rs:10:11
    |
+LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
+   |                   ---------------- data with this lifetime...
 LL |     box B(&*v) as Box<dyn X>
-   |           ^^^
-   |
-note: first, the lifetime cannot outlive the lifetime `'a` as defined on the function body at 9:6...
-  --> $DIR/regions-close-object-into-object-4.rs:9:6
+   |     ------^^^---------------
+   |     |     |
+   |     |     ...and is captured here
+   |     ...is required to be `'static` by this...
    |
-LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
-   |      ^^
-note: ...so that the type `(dyn A<U> + 'a)` is not borrowed for too long
-  --> $DIR/regions-close-object-into-object-4.rs:10:11
+help: consider changing the trait object's explicit `'static` bound
    |
-LL |     box B(&*v) as Box<dyn X>
-   |           ^^^
-   = note: but, the lifetime must be valid for the static lifetime...
-note: ...so that the expression is assignable
-  --> $DIR/regions-close-object-into-object-4.rs:10:5
+LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'a> {
+   |                                                    ^^
+help: alternatively, set an explicit `'static` lifetime in this parameter
    |
-LL |     box B(&*v) as Box<dyn X>
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: expected `std::boxed::Box<(dyn X + 'static)>`
-              found `std::boxed::Box<dyn X>`
+LL | fn i<'a, T, U>(v: std::boxed::Box<(dyn A<U> + 'static)>) -> Box<dyn X + 'static> {
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0495`.
diff --git a/src/test/ui/regions/regions-proc-bound-capture.nll.stderr b/src/test/ui/regions/regions-proc-bound-capture.nll.stderr
new file mode 100644
index 0000000000000..75890b8581537
--- /dev/null
+++ b/src/test/ui/regions/regions-proc-bound-capture.nll.stderr
@@ -0,0 +1,11 @@
+error: lifetime may not live long enough
+  --> $DIR/regions-proc-bound-capture.rs:9:5
+   |
+LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
+   |                   - let's call the lifetime of this reference `'1`
+LL |     // This is illegal, because the region bound on `proc` is 'static.
+LL |     Box::new(move || { *x })
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^ returning this value requires that `'1` must outlive `'static`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/regions/regions-proc-bound-capture.rs b/src/test/ui/regions/regions-proc-bound-capture.rs
index 0c903b7384992..8617c0e9da8f7 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.rs
+++ b/src/test/ui/regions/regions-proc-bound-capture.rs
@@ -4,9 +4,9 @@ fn borrowed_proc<'a>(x: &'a isize) -> Box<dyn FnMut()->(isize) + 'a> {
     Box::new(move|| { *x })
 }
 
-fn static_proc(x: &isize) -> Box<dyn FnMut()->(isize) + 'static> {
+fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
     // This is illegal, because the region bound on `proc` is 'static.
-    Box::new(move|| { *x }) //~ ERROR explicit lifetime required in the type of `x` [E0621]
+    Box::new(move || { *x }) //~ ERROR cannot infer an appropriate lifetime
 }
 
 fn main() { }
diff --git a/src/test/ui/regions/regions-proc-bound-capture.stderr b/src/test/ui/regions/regions-proc-bound-capture.stderr
index c53af34456ef3..e7bbfaababe8a 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.stderr
+++ b/src/test/ui/regions/regions-proc-bound-capture.stderr
@@ -1,12 +1,23 @@
-error[E0621]: explicit lifetime required in the type of `x`
-  --> $DIR/regions-proc-bound-capture.rs:9:5
+error: cannot infer an appropriate lifetime
+  --> $DIR/regions-proc-bound-capture.rs:9:14
    |
-LL | fn static_proc(x: &isize) -> Box<dyn FnMut()->(isize) + 'static> {
-   |                   ------ help: add explicit lifetime `'static` to the type of `x`: `&'static isize`
+LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
+   |                   ------ data with this lifetime...
 LL |     // This is illegal, because the region bound on `proc` is 'static.
-LL |     Box::new(move|| { *x })
-   |     ^^^^^^^^^^^^^^^^^^^^^^^ lifetime `'static` required
+LL |     Box::new(move || { *x })
+   |     ---------^^^^^^^^^^^^^^-
+   |     |        |
+   |     |        ...and is captured here
+   |     ...is required to be `'static` by this...
+   |
+help: consider changing the trait object's explicit `'static` bound
+   |
+LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + '_> {
+   |                                                           ^^
+help: alternatively, set an explicit `'static` lifetime in this parameter
+   |
+LL | fn static_proc(x: &'static isize) -> Box<dyn FnMut() -> (isize) + 'static> {
+   |                   ^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0621`.
diff --git a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
index 3577dd59289e5..4dc4aac6ceac4 100644
--- a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
+++ b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
@@ -7,7 +7,7 @@ LL |     //                      ^^^^^^^^^^^^^^^^^^^^^ bound *here* defaults to
 LL |     Box::new(items.iter())
    |     ---------------^^^^--- ...is captured and required to be `'static` here
    |
-help: to permit non-static references in a `dyn Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 6:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 6:1
    |
 LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T> + '_> {
    |                                                   ^^^^

From abf74b9e729463a18f5da1d79cecaf9f4fc07d17 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Fri, 29 May 2020 18:59:42 -0700
Subject: [PATCH 09/25] Reduce verbosity of suggestion message and mention
 lifetime in label

---
 .../nice_region_error/static_impl_trait.rs    | 87 ++++++++++---------
 .../ui/async-await/issues/issue-62097.stderr  |  2 +-
 .../must_outlive_least_region_or_bound.stderr | 38 ++++----
 .../static-return-lifetime-infered.stderr     |  8 +-
 src/test/ui/issues/issue-16922.stderr         |  4 +-
 ...ect-lifetime-default-from-box-error.stderr |  4 +-
 .../region-object-lifetime-in-coercion.stderr | 12 +--
 .../regions-close-object-into-object-2.stderr |  4 +-
 .../regions-close-object-into-object-4.stderr |  4 +-
 .../regions/regions-proc-bound-capture.stderr |  4 +-
 ...types_pin_lifetime_impl_trait-async.stderr |  2 +-
 ..._self_types_pin_lifetime_impl_trait.stderr |  4 +-
 .../missing-lifetimes-in-signature.stderr     |  4 +-
 .../dyn-trait-underscore.stderr               |  4 +-
 14 files changed, 95 insertions(+), 86 deletions(-)

diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index e24535bba5fdc..e9f165d309f8f 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -1,6 +1,5 @@
 //! Error Reporting for static impl Traits.
 
-use crate::infer::error_reporting::msg_span_from_free_region;
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
 use rustc_errors::{Applicability, ErrorReported};
@@ -33,9 +32,17 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                     let sp = var_origin.span();
                     let return_sp = sub_origin.span();
                     let param_info = self.find_param_with_region(sup_r, sub_r)?;
+                    let (lifetime_name, lifetime) = if sup_r.has_name() {
+                        (sup_r.to_string(), format!("lifetime `{}`", sup_r))
+                    } else {
+                        ("'_".to_owned(), "the anonymous lifetime `'_`".to_string())
+                    };
                     let mut err =
                         self.tcx().sess.struct_span_err(sp, "cannot infer an appropriate lifetime");
-                    err.span_label(param_info.param_ty_span, "data with this lifetime...");
+                    err.span_label(
+                        param_info.param_ty_span,
+                        &format!("this data with {}...", lifetime),
+                    );
                     debug!("try_report_static_impl_trait: param_info={:?}", param_info);
 
                     // We try to make the output have fewer overlapping spans if possible.
@@ -60,10 +67,6 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                         );
                     }
 
-                    let (lifetime, _) = msg_span_from_free_region(self.tcx(), sup_r);
-
-                    let lifetime_name =
-                        if sup_r.has_name() { sup_r.to_string() } else { "'_".to_owned() };
                     // only apply this suggestion onto functions with
                     // explicit non-desugar'able return.
                     if fn_return.span.desugaring_kind().is_none() {
@@ -93,8 +96,11 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                 {
                                     err.span_suggestion_verbose(
                                         span,
-                                        "consider changing the `impl Trait`'s explicit \
-                                         `'static` bound",
+                                        &format!(
+                                            "consider changing the `impl Trait`'s explicit \
+                                             `'static` bound to {}",
+                                            lifetime,
+                                        ),
                                         lifetime_name,
                                         Applicability::MaybeIncorrect,
                                     );
@@ -118,40 +124,41 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                     );
                                 };
                             }
-                            TyKind::TraitObject(_, lt) => {
-                                match lt.name {
-                                    LifetimeName::ImplicitObjectLifetimeDefault => {
-                                        err.span_suggestion_verbose(
-                                            fn_return.span.shrink_to_hi(),
-                                            &format!(
-                                                "to permit non-static references in a trait object \
-                                                 value, you can add an explicit bound for {}",
-                                                lifetime,
-                                            ),
-                                            format!(" + {}", lifetime_name),
-                                            Applicability::MaybeIncorrect,
-                                        );
-                                    }
-                                    _ => {
-                                        err.span_suggestion_verbose(
-                                            lt.span,
+                            TyKind::TraitObject(_, lt) => match lt.name {
+                                LifetimeName::ImplicitObjectLifetimeDefault => {
+                                    err.span_suggestion_verbose(
+                                        fn_return.span.shrink_to_hi(),
+                                        &format!(
+                                            "to permit non-static references in a trait object \
+                                             value, you can add an explicit bound for {}",
+                                            lifetime,
+                                        ),
+                                        format!(" + {}", lifetime_name),
+                                        Applicability::MaybeIncorrect,
+                                    );
+                                }
+                                _ => {
+                                    err.span_suggestion_verbose(
+                                        lt.span,
+                                        &format!(
                                             "consider changing the trait object's explicit \
-                                             `'static` bound",
-                                            lifetime_name,
-                                            Applicability::MaybeIncorrect,
-                                        );
-                                        err.span_suggestion_verbose(
-                                            param_info.param_ty_span,
-                                            &format!(
-                                                "alternatively, set an explicit `'static` lifetime \
-                                                 in this parameter",
-                                            ),
-                                            param_info.param_ty.to_string(),
-                                            Applicability::MaybeIncorrect,
-                                        );
-                                    }
+                                             `'static` bound to {}",
+                                            lifetime,
+                                        ),
+                                        lifetime_name,
+                                        Applicability::MaybeIncorrect,
+                                    );
+                                    err.span_suggestion_verbose(
+                                        param_info.param_ty_span,
+                                        &format!(
+                                            "alternatively, set an explicit `'static` lifetime \
+                                             in this parameter",
+                                        ),
+                                        param_info.param_ty.to_string(),
+                                        Applicability::MaybeIncorrect,
+                                    );
                                 }
-                            }
+                            },
                             _ => {}
                         }
                     }
diff --git a/src/test/ui/async-await/issues/issue-62097.stderr b/src/test/ui/async-await/issues/issue-62097.stderr
index af8fc2cd2ab45..fff43ae9f47bc 100644
--- a/src/test/ui/async-await/issues/issue-62097.stderr
+++ b/src/test/ui/async-await/issues/issue-62097.stderr
@@ -4,7 +4,7 @@ error: cannot infer an appropriate lifetime
 LL |     pub async fn run_dummy_fn(&self) {
    |                               ^^^^^
    |                               |
-   |                               data with this lifetime...
+   |                               this data with the anonymous lifetime `'_`...
    |                               ...is captured here...
 LL |         foo(|| self.bar()).await;
    |         --- ...and required to be `'static` by this
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index 96d4a121c16af..00b6ec38323c3 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -5,9 +5,9 @@ LL | fn elided(x: &i32) -> impl Copy { x }
    |              ----     ---------   ^ ...and is captured here
    |              |        |
    |              |        ...is required to be `'static` by this...
-   |              data with this lifetime...
+   |              this data with the anonymous lifetime `'_`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 3:1
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn elided(x: &i32) -> impl Copy + '_ { x }
    |                                 ^^^^
@@ -19,9 +19,9 @@ LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
    |                    -------     ---------   ^ ...and is captured here
    |                    |           |
    |                    |           ...is required to be `'static` by this...
-   |                    data with this lifetime...
+   |                    this data with lifetime `'a`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 6:13
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for lifetime `'a`
    |
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                          ^^^^
@@ -33,9 +33,9 @@ LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
    |               ----     -------------------   ^ ...and is captured here
    |               |        |
    |               |        ...is required to be `'static` by this...
-   |               data with this lifetime...
+   |               this data with the anonymous lifetime `'_`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound
+help: consider changing the `impl Trait`'s explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
    |                                    ^^
@@ -51,9 +51,9 @@ LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
    |                     -------     -------------------   ^ ...and is captured here
    |                     |           |
    |                     |           ...is required to be `'static` by this...
-   |                     data with this lifetime...
+   |                     this data with lifetime `'a`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound
+help: consider changing the `impl Trait`'s explicit `'static` bound to lifetime `'a`
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                             ^^
@@ -77,9 +77,9 @@ LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |                      -------     --------------------------------   ^ ...and is captured here
    |                      |           |
    |                      |           ...is required to be `'static` by this...
-   |                      data with this lifetime...
+   |                      this data with lifetime `'a`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound
+help: consider changing the `impl Trait`'s explicit `'static` bound to lifetime `'a`
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'a { x }
    |                                                           ^^
@@ -113,9 +113,9 @@ LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
    |               |                         |        |
    |               |                         |        ...and is captured here
    |               |                         ...is required to be `'static` by this...
-   |               data with this lifetime...
+   |               this data with the anonymous lifetime `'_`...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 18:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                      ^^^^
@@ -128,9 +128,9 @@ LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
    |                     |                            |        |
    |                     |                            |        ...and is captured here
    |                     |                            ...is required to be `'static` by this...
-   |                     data with this lifetime...
+   |                     this data with lifetime `'a`...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the lifetime `'a` as defined on the function body at 21:14
+help: to permit non-static references in a trait object value, you can add an explicit bound for lifetime `'a`
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                               ^^^^
@@ -142,9 +142,10 @@ LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |               ----                                ---------^-
    |               |                                   |        |
    |               |                                   |        ...and is captured here
-   |               data with this lifetime...          ...is required to be `'static` by this...
+   |               |                                   ...is required to be `'static` by this...
+   |               this data with the anonymous lifetime `'_`...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                        ^^
@@ -160,9 +161,10 @@ LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |                     -------                                ---------^-
    |                     |                                      |        |
    |                     |                                      |        ...and is captured here
-   |                     data with this lifetime...             ...is required to be `'static` by this...
+   |                     |                                      ...is required to be `'static` by this...
+   |                     this data with lifetime `'a`...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                                 ^^
diff --git a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
index 1c3a5979ee55b..67d4f60dff6f1 100644
--- a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
+++ b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
@@ -4,13 +4,13 @@ error: cannot infer an appropriate lifetime
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
    |                         -----     ----------------------- ...is required to be `'static` by this...
    |                         |
-   |                         data with this lifetime...
+   |                         this data with the anonymous lifetime `'_`...
 LL |         self.x.iter().map(|a| a.0)
    |         ------ ^^^^
    |         |
    |         ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the method body at 6:5
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
    |                                                           ^^^^
@@ -21,13 +21,13 @@ error: cannot infer an appropriate lifetime
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
    |                        --------     ----------------------- ...is required to be `'static` by this...
    |                        |
-   |                        data with this lifetime...
+   |                        this data with lifetime `'a`...
 LL |         self.x.iter().map(|a| a.0)
    |         ------ ^^^^
    |         |
    |         ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the lifetime `'a` as defined on the method body at 10:20
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for lifetime `'a`
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
    |                                                             ^^^^
diff --git a/src/test/ui/issues/issue-16922.stderr b/src/test/ui/issues/issue-16922.stderr
index 038df47e1bd98..c533a72dfc014 100644
--- a/src/test/ui/issues/issue-16922.stderr
+++ b/src/test/ui/issues/issue-16922.stderr
@@ -2,14 +2,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/issue-16922.rs:4:14
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any> {
-   |                       -- data with this lifetime...
+   |                       -- this data with the anonymous lifetime `'_`...
 LL |     Box::new(value) as Box<dyn Any>
    |     ---------^^^^^-
    |     |        |
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 3:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
    |                                          ^^^^
diff --git a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
index 555622c9d13c1..6edef8086b937 100644
--- a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
+++ b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
@@ -2,12 +2,12 @@ error: cannot infer an appropriate lifetime
   --> $DIR/object-lifetime-default-from-box-error.rs:18:5
    |
 LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait> {
-   |             --------------- data with this lifetime...
+   |             --------------- this data with the anonymous lifetime `'_`...
 ...
 LL |     ss.r
    |     ^^^^ ...is captured and required to be `'static` here
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #2 defined on the function body at 14:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait + '_> {
    |                                                   ^^^^
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
index 673300cebc26c..4b08c4bff2ebc 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
@@ -2,14 +2,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:8:46
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- data with this lifetime...
+   |         ----- this data with the anonymous lifetime `'_`...
 LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
    |                                     ---------^-
    |                                     |        |
    |                                     |        ...and is captured here
    |                                     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
@@ -22,14 +22,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:13:14
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- data with this lifetime...
+   |         ----- this data with the anonymous lifetime `'_`...
 LL |     Box::new(v)
    |     ---------^-
    |     |        |
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
@@ -42,7 +42,7 @@ error: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:19:14
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo> {
-   |         ----- data with this lifetime...
+   |         ----- this data with the anonymous lifetime `'_`...
 ...
 LL |     Box::new(v)
    |     ---------^-
@@ -50,7 +50,7 @@ LL |     Box::new(v)
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 16:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo + '_> {
    |                               ^^^^
diff --git a/src/test/ui/regions/regions-close-object-into-object-2.stderr b/src/test/ui/regions/regions-close-object-into-object-2.stderr
index 982ed07232a80..894be310fd14b 100644
--- a/src/test/ui/regions/regions-close-object-into-object-2.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-2.stderr
@@ -2,14 +2,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-2.rs:10:11
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
-   |                         ------------------ data with this lifetime...
+   |                         ------------------ this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
    |     ------^^^---------------
    |     |     |
    |     |     ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'a> {
    |                                                            ^^
diff --git a/src/test/ui/regions/regions-close-object-into-object-4.stderr b/src/test/ui/regions/regions-close-object-into-object-4.stderr
index 1b82098ee13c2..ce261d78c2909 100644
--- a/src/test/ui/regions/regions-close-object-into-object-4.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-4.stderr
@@ -2,14 +2,14 @@ error: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-4.rs:10:11
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
-   |                   ---------------- data with this lifetime...
+   |                   ---------------- this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
    |     ------^^^---------------
    |     |     |
    |     |     ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'a> {
    |                                                    ^^
diff --git a/src/test/ui/regions/regions-proc-bound-capture.stderr b/src/test/ui/regions/regions-proc-bound-capture.stderr
index e7bbfaababe8a..a0df1815247c3 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.stderr
+++ b/src/test/ui/regions/regions-proc-bound-capture.stderr
@@ -2,7 +2,7 @@ error: cannot infer an appropriate lifetime
   --> $DIR/regions-proc-bound-capture.rs:9:14
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
-   |                   ------ data with this lifetime...
+   |                   ------ this data with the anonymous lifetime `'_`...
 LL |     // This is illegal, because the region bound on `proc` is 'static.
 LL |     Box::new(move || { *x })
    |     ---------^^^^^^^^^^^^^^-
@@ -10,7 +10,7 @@ LL |     Box::new(move || { *x })
    |     |        ...and is captured here
    |     ...is required to be `'static` by this...
    |
-help: consider changing the trait object's explicit `'static` bound
+help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + '_> {
    |                                                           ^^
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
index 1aeabce5e8aaf..5520341b5b1c3 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
@@ -4,7 +4,7 @@ error: cannot infer an appropriate lifetime
 LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
    |                ^^^^  ----------     ---------- ...and required to be `'static` by this
    |                |     |
-   |                |     data with this lifetime...
+   |                |     this data with the anonymous lifetime `'_`...
    |                ...is captured here...
 
 error: aborting due to previous error
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
index 04c475be787b8..5374929f3a45f 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
@@ -5,9 +5,9 @@ LL |     fn f(self: Pin<&Self>) -> impl Clone { self }
    |                ----------     ----------   ^^^^ ...and is captured here
    |                |              |
    |                |              ...is required to be `'static` by this...
-   |                data with this lifetime...
+   |                this data with the anonymous lifetime `'_`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the method body at 6:5
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL |     fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
    |                                          ^^^^
diff --git a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
index 5cf170d566ca9..471f3cd14aa3e 100644
--- a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
+++ b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
@@ -12,14 +12,14 @@ error: cannot infer an appropriate lifetime
 LL |   fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce()
    |                            ------     ------------- ...is required to be `'static` by this...
    |                            |
-   |                            data with this lifetime...
+   |                            this data with the anonymous lifetime `'_`...
 ...
 LL | /     move || {
 LL | |         *dest = g.get();
 LL | |     }
    | |_____^ ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 15:1
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce() + '_
    |                                                   ^^^^
diff --git a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
index 4dc4aac6ceac4..5fd03f9770e5d 100644
--- a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
+++ b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
@@ -2,12 +2,12 @@ error: cannot infer an appropriate lifetime
   --> $DIR/dyn-trait-underscore.rs:8:20
    |
 LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T>> {
-   |                ---- data with this lifetime...
+   |                ---- this data with the anonymous lifetime `'_`...
 LL |     //                      ^^^^^^^^^^^^^^^^^^^^^ bound *here* defaults to `'static`
 LL |     Box::new(items.iter())
    |     ---------------^^^^--- ...is captured and required to be `'static` here
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime #1 defined on the function body at 6:1
+help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T> + '_> {
    |                                                   ^^^^

From 50c422e028dd7b66302eabb987fe1da482bee8fa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Fri, 29 May 2020 19:46:22 -0700
Subject: [PATCH 10/25] Move overlapping span to a note

---
 .../nice_region_error/static_impl_trait.rs    | 31 ++++++++++++-
 .../must_outlive_least_region_or_bound.stderr | 44 ++++++++++++-------
 src/test/ui/issues/issue-16922.stderr         | 10 +++--
 .../region-object-lifetime-in-coercion.stderr | 30 ++++++++-----
 .../regions-close-object-into-object-2.stderr | 10 +++--
 .../regions-close-object-into-object-4.stderr | 10 +++--
 .../regions/regions-proc-bound-capture.stderr | 10 +++--
 7 files changed, 99 insertions(+), 46 deletions(-)

diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index e9f165d309f8f..cc95441b68a03 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -53,7 +53,36 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
 
                         // Customize the spans and labels depending on their relative order so
                         // that split sentences flow correctly.
-                        if sup_origin.span().shrink_to_hi() <= return_sp.shrink_to_lo() {
+                        if sup_origin.span().overlaps(return_sp) && sp == sup_origin.span() {
+                            // Avoid the following:
+                            //
+                            // error: cannot infer an appropriate lifetime
+                            //   --> $DIR/must_outlive_least_region_or_bound.rs:18:50
+                            //    |
+                            // LL | fn foo(x: &i32) -> Box<dyn Debug> { Box::new(x) }
+                            //    |           ----                      ---------^-
+                            //    |           |                         |        |
+                            //    |           |                         |   ...and is captured here
+                            //    |           |           ...is required to be `'static` by this...
+                            //    |           this data with the anonymous lifetime `'_`...
+                            //
+                            // and instead show:
+                            //
+                            // error: cannot infer an appropriate lifetime
+                            //   --> $DIR/must_outlive_least_region_or_bound.rs:18:50
+                            //    |
+                            // LL | fn foo(x: &i32) -> Box<dyn Debug> { Box::new(x) }
+                            //    |           ----                               ^ ...is captured here with a `'static` requirement
+                            //    |           |
+                            //    |           this data with the anonymous lifetime `'_`...
+                            //    |
+                            // note: ...is required to be `'static` by this
+                            //    |
+                            // LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
+                            //    |                                         ^^^^^^^^^^^
+                            err.span_label(sup_origin.span(), "...is captured here...");
+                            err.span_note(return_sp, "...and required to be `'static` by this");
+                        } else if sup_origin.span() <= return_sp {
                             err.span_label(sup_origin.span(), "...is captured here...");
                             err.span_label(return_sp, "...and required to be `'static` by this");
                         } else {
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index 00b6ec38323c3..2da49379ea8c2 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -109,12 +109,15 @@ error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:18:50
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
-   |               ----                      ---------^-
-   |               |                         |        |
-   |               |                         |        ...and is captured here
-   |               |                         ...is required to be `'static` by this...
+   |               ----                               ^ ...is captured here...
+   |               |
    |               this data with the anonymous lifetime `'_`...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/must_outlive_least_region_or_bound.rs:18:41
+   |
+LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
+   |                                         ^^^^^^^^^^^
 help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
@@ -124,12 +127,15 @@ error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:21:59
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
-   |                     -------                      ---------^-
-   |                     |                            |        |
-   |                     |                            |        ...and is captured here
-   |                     |                            ...is required to be `'static` by this...
+   |                     -------                               ^ ...is captured here...
+   |                     |
    |                     this data with lifetime `'a`...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/must_outlive_least_region_or_bound.rs:21:50
+   |
+LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
+   |                                                  ^^^^^^^^^^^
 help: to permit non-static references in a trait object value, you can add an explicit bound for lifetime `'a`
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
@@ -139,12 +145,15 @@ error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:24:60
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |               ----                                ---------^-
-   |               |                                   |        |
-   |               |                                   |        ...and is captured here
-   |               |                                   ...is required to be `'static` by this...
+   |               ----                                         ^ ...is captured here...
+   |               |
    |               this data with the anonymous lifetime `'_`...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/must_outlive_least_region_or_bound.rs:24:51
+   |
+LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+   |                                                   ^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
@@ -158,12 +167,13 @@ error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:27:69
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |                     -------                                ---------^-
-   |                     |                                      |        |
-   |                     |                                      |        ...and is captured here
-   |                     |                                      ...is required to be `'static` by this...
-   |                     this data with lifetime `'a`...
+   |                     ------- this data with lifetime `'a`...         ^ ...is captured here...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/must_outlive_least_region_or_bound.rs:27:60
+   |
+LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
+   |                                                            ^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
diff --git a/src/test/ui/issues/issue-16922.stderr b/src/test/ui/issues/issue-16922.stderr
index c533a72dfc014..6c0b26a86b651 100644
--- a/src/test/ui/issues/issue-16922.stderr
+++ b/src/test/ui/issues/issue-16922.stderr
@@ -4,11 +4,13 @@ error: cannot infer an appropriate lifetime
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any> {
    |                       -- this data with the anonymous lifetime `'_`...
 LL |     Box::new(value) as Box<dyn Any>
-   |     ---------^^^^^-
-   |     |        |
-   |     |        ...and is captured here
-   |     ...is required to be `'static` by this...
+   |              ^^^^^ ...is captured here...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/issue-16922.rs:4:5
+   |
+LL |     Box::new(value) as Box<dyn Any>
+   |     ^^^^^^^^^^^^^^^
 help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
index 4b08c4bff2ebc..b333c314c57c9 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
@@ -4,11 +4,13 @@ error: cannot infer an appropriate lifetime
 LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
    |         ----- this data with the anonymous lifetime `'_`...
 LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
-   |                                     ---------^-
-   |                                     |        |
-   |                                     |        ...and is captured here
-   |                                     ...is required to be `'static` by this...
+   |                                              ^ ...is captured here...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/region-object-lifetime-in-coercion.rs:8:37
+   |
+LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
+   |                                     ^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + '_> {
@@ -24,11 +26,13 @@ error: cannot infer an appropriate lifetime
 LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
    |         ----- this data with the anonymous lifetime `'_`...
 LL |     Box::new(v)
-   |     ---------^-
-   |     |        |
-   |     |        ...and is captured here
-   |     ...is required to be `'static` by this...
+   |              ^ ...is captured here...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/region-object-lifetime-in-coercion.rs:13:5
+   |
+LL |     Box::new(v)
+   |     ^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + '_> {
@@ -45,11 +49,13 @@ LL | fn c(v: &[u8]) -> Box<dyn Foo> {
    |         ----- this data with the anonymous lifetime `'_`...
 ...
 LL |     Box::new(v)
-   |     ---------^-
-   |     |        |
-   |     |        ...and is captured here
-   |     ...is required to be `'static` by this...
+   |              ^ ...is captured here...
+   |
+note: ...and required to be `'static` by this
+  --> $DIR/region-object-lifetime-in-coercion.rs:19:5
    |
+LL |     Box::new(v)
+   |     ^^^^^^^^^^^
 help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo + '_> {
diff --git a/src/test/ui/regions/regions-close-object-into-object-2.stderr b/src/test/ui/regions/regions-close-object-into-object-2.stderr
index 894be310fd14b..3127ae65ace7d 100644
--- a/src/test/ui/regions/regions-close-object-into-object-2.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-2.stderr
@@ -4,11 +4,13 @@ error: cannot infer an appropriate lifetime
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
    |                         ------------------ this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
-   |     ------^^^---------------
-   |     |     |
-   |     |     ...and is captured here
-   |     ...is required to be `'static` by this...
+   |           ^^^ ...is captured here...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/regions-close-object-into-object-2.rs:10:5
+   |
+LL |     box B(&*v) as Box<dyn X>
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'a> {
diff --git a/src/test/ui/regions/regions-close-object-into-object-4.stderr b/src/test/ui/regions/regions-close-object-into-object-4.stderr
index ce261d78c2909..b18c61f137694 100644
--- a/src/test/ui/regions/regions-close-object-into-object-4.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-4.stderr
@@ -4,11 +4,13 @@ error: cannot infer an appropriate lifetime
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
    |                   ---------------- this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
-   |     ------^^^---------------
-   |     |     |
-   |     |     ...and is captured here
-   |     ...is required to be `'static` by this...
+   |           ^^^ ...is captured here...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/regions-close-object-into-object-4.rs:10:5
+   |
+LL |     box B(&*v) as Box<dyn X>
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'a> {
diff --git a/src/test/ui/regions/regions-proc-bound-capture.stderr b/src/test/ui/regions/regions-proc-bound-capture.stderr
index a0df1815247c3..5cb9506afd351 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.stderr
+++ b/src/test/ui/regions/regions-proc-bound-capture.stderr
@@ -5,11 +5,13 @@ LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
    |                   ------ this data with the anonymous lifetime `'_`...
 LL |     // This is illegal, because the region bound on `proc` is 'static.
 LL |     Box::new(move || { *x })
-   |     ---------^^^^^^^^^^^^^^-
-   |     |        |
-   |     |        ...and is captured here
-   |     ...is required to be `'static` by this...
+   |              ^^^^^^^^^^^^^^ ...is captured here...
    |
+note: ...and required to be `'static` by this
+  --> $DIR/regions-proc-bound-capture.rs:9:5
+   |
+LL |     Box::new(move || { *x })
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + '_> {

From 17951e21d4c690ad70e79a40d223a0d0984c0f35 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Sat, 30 May 2020 09:54:05 -0700
Subject: [PATCH 11/25] Tweak output for overlapping required/captured spans

---
 .../nice_region_error/static_impl_trait.rs    | 10 +++----
 .../must_outlive_least_region_or_bound.stderr | 28 +++----------------
 src/test/ui/issues/issue-16922.stderr         |  7 +----
 .../region-object-lifetime-in-coercion.stderr | 21 ++------------
 .../regions-close-object-into-object-2.stderr |  7 +----
 .../regions-close-object-into-object-4.stderr |  7 +----
 .../regions/regions-proc-bound-capture.stderr |  7 +----
 7 files changed, 15 insertions(+), 72 deletions(-)

diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index cc95441b68a03..253057536f133 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -76,12 +76,10 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                             //    |           |
                             //    |           this data with the anonymous lifetime `'_`...
                             //    |
-                            // note: ...is required to be `'static` by this
-                            //    |
-                            // LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
-                            //    |                                         ^^^^^^^^^^^
-                            err.span_label(sup_origin.span(), "...is captured here...");
-                            err.span_note(return_sp, "...and required to be `'static` by this");
+                            err.span_label(
+                                sup_origin.span(),
+                                "...is captured here with a `'static` requirement",
+                            );
                         } else if sup_origin.span() <= return_sp {
                             err.span_label(sup_origin.span(), "...is captured here...");
                             err.span_label(return_sp, "...and required to be `'static` by this");
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index 2da49379ea8c2..82e44cff9cc44 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -109,15 +109,10 @@ error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:18:50
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
-   |               ----                               ^ ...is captured here...
+   |               ----                               ^ ...is captured here with a `'static` requirement
    |               |
    |               this data with the anonymous lifetime `'_`...
    |
-note: ...and required to be `'static` by this
-  --> $DIR/must_outlive_least_region_or_bound.rs:18:41
-   |
-LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
-   |                                         ^^^^^^^^^^^
 help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
@@ -127,15 +122,10 @@ error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:21:59
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
-   |                     -------                               ^ ...is captured here...
+   |                     -------                               ^ ...is captured here with a `'static` requirement
    |                     |
    |                     this data with lifetime `'a`...
    |
-note: ...and required to be `'static` by this
-  --> $DIR/must_outlive_least_region_or_bound.rs:21:50
-   |
-LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
-   |                                                  ^^^^^^^^^^^
 help: to permit non-static references in a trait object value, you can add an explicit bound for lifetime `'a`
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
@@ -145,15 +135,10 @@ error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:24:60
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |               ----                                         ^ ...is captured here...
+   |               ----                                         ^ ...is captured here with a `'static` requirement
    |               |
    |               this data with the anonymous lifetime `'_`...
    |
-note: ...and required to be `'static` by this
-  --> $DIR/must_outlive_least_region_or_bound.rs:24:51
-   |
-LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |                                                   ^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
@@ -167,13 +152,8 @@ error: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:27:69
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |                     ------- this data with lifetime `'a`...         ^ ...is captured here...
+   |                     ------- this data with lifetime `'a`...         ^ ...is captured here with a `'static` requirement
    |
-note: ...and required to be `'static` by this
-  --> $DIR/must_outlive_least_region_or_bound.rs:27:60
-   |
-LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |                                                            ^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
diff --git a/src/test/ui/issues/issue-16922.stderr b/src/test/ui/issues/issue-16922.stderr
index 6c0b26a86b651..a254343cd1bb7 100644
--- a/src/test/ui/issues/issue-16922.stderr
+++ b/src/test/ui/issues/issue-16922.stderr
@@ -4,13 +4,8 @@ error: cannot infer an appropriate lifetime
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any> {
    |                       -- this data with the anonymous lifetime `'_`...
 LL |     Box::new(value) as Box<dyn Any>
-   |              ^^^^^ ...is captured here...
+   |              ^^^^^ ...is captured here with a `'static` requirement
    |
-note: ...and required to be `'static` by this
-  --> $DIR/issue-16922.rs:4:5
-   |
-LL |     Box::new(value) as Box<dyn Any>
-   |     ^^^^^^^^^^^^^^^
 help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
index b333c314c57c9..97d1f3579fcd8 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
@@ -4,13 +4,8 @@ error: cannot infer an appropriate lifetime
 LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
    |         ----- this data with the anonymous lifetime `'_`...
 LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
-   |                                              ^ ...is captured here...
+   |                                              ^ ...is captured here with a `'static` requirement
    |
-note: ...and required to be `'static` by this
-  --> $DIR/region-object-lifetime-in-coercion.rs:8:37
-   |
-LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
-   |                                     ^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + '_> {
@@ -26,13 +21,8 @@ error: cannot infer an appropriate lifetime
 LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
    |         ----- this data with the anonymous lifetime `'_`...
 LL |     Box::new(v)
-   |              ^ ...is captured here...
+   |              ^ ...is captured here with a `'static` requirement
    |
-note: ...and required to be `'static` by this
-  --> $DIR/region-object-lifetime-in-coercion.rs:13:5
-   |
-LL |     Box::new(v)
-   |     ^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + '_> {
@@ -49,13 +39,8 @@ LL | fn c(v: &[u8]) -> Box<dyn Foo> {
    |         ----- this data with the anonymous lifetime `'_`...
 ...
 LL |     Box::new(v)
-   |              ^ ...is captured here...
-   |
-note: ...and required to be `'static` by this
-  --> $DIR/region-object-lifetime-in-coercion.rs:19:5
+   |              ^ ...is captured here with a `'static` requirement
    |
-LL |     Box::new(v)
-   |     ^^^^^^^^^^^
 help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo + '_> {
diff --git a/src/test/ui/regions/regions-close-object-into-object-2.stderr b/src/test/ui/regions/regions-close-object-into-object-2.stderr
index 3127ae65ace7d..3d707f2d99941 100644
--- a/src/test/ui/regions/regions-close-object-into-object-2.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-2.stderr
@@ -4,13 +4,8 @@ error: cannot infer an appropriate lifetime
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
    |                         ------------------ this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
-   |           ^^^ ...is captured here...
+   |           ^^^ ...is captured here with a `'static` requirement
    |
-note: ...and required to be `'static` by this
-  --> $DIR/regions-close-object-into-object-2.rs:10:5
-   |
-LL |     box B(&*v) as Box<dyn X>
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'a> {
diff --git a/src/test/ui/regions/regions-close-object-into-object-4.stderr b/src/test/ui/regions/regions-close-object-into-object-4.stderr
index b18c61f137694..70282c8cbdb30 100644
--- a/src/test/ui/regions/regions-close-object-into-object-4.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-4.stderr
@@ -4,13 +4,8 @@ error: cannot infer an appropriate lifetime
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
    |                   ---------------- this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
-   |           ^^^ ...is captured here...
+   |           ^^^ ...is captured here with a `'static` requirement
    |
-note: ...and required to be `'static` by this
-  --> $DIR/regions-close-object-into-object-4.rs:10:5
-   |
-LL |     box B(&*v) as Box<dyn X>
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'a> {
diff --git a/src/test/ui/regions/regions-proc-bound-capture.stderr b/src/test/ui/regions/regions-proc-bound-capture.stderr
index 5cb9506afd351..8f93fad7fe9d8 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.stderr
+++ b/src/test/ui/regions/regions-proc-bound-capture.stderr
@@ -5,13 +5,8 @@ LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
    |                   ------ this data with the anonymous lifetime `'_`...
 LL |     // This is illegal, because the region bound on `proc` is 'static.
 LL |     Box::new(move || { *x })
-   |              ^^^^^^^^^^^^^^ ...is captured here...
+   |              ^^^^^^^^^^^^^^ ...is captured here with a `'static` requirement
    |
-note: ...and required to be `'static` by this
-  --> $DIR/regions-proc-bound-capture.rs:9:5
-   |
-LL |     Box::new(move || { *x })
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^
 help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + '_> {

From 19bb589410f2ab0ff14178992ef4b44fbe5e297b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Sat, 30 May 2020 10:15:58 -0700
Subject: [PATCH 12/25] Tweak wording and add error code

---
 .../nice_region_error/static_impl_trait.rs    | 35 +++++++------
 .../ui/async-await/issues/issue-62097.stderr  |  6 +--
 .../must_outlive_least_region_or_bound.stderr | 52 +++++++++----------
 .../static-return-lifetime-infered.stderr     | 12 ++---
 src/test/ui/issues/issue-16922.stderr         |  8 +--
 ...ect-lifetime-default-from-box-error.stderr |  8 +--
 .../region-object-lifetime-in-coercion.stderr | 24 ++++-----
 .../regions-close-object-into-object-2.stderr |  4 +-
 .../regions-close-object-into-object-4.stderr |  4 +-
 .../regions/regions-proc-bound-capture.stderr |  8 +--
 ...types_pin_lifetime_impl_trait-async.stderr |  6 +--
 ..._self_types_pin_lifetime_impl_trait.stderr |  8 +--
 .../missing-lifetimes-in-signature.stderr     |  8 +--
 .../dyn-trait-underscore.stderr               |  8 +--
 14 files changed, 97 insertions(+), 94 deletions(-)

diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index 253057536f133..4e16e8c2c5717 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -2,7 +2,7 @@
 
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
-use rustc_errors::{Applicability, ErrorReported};
+use rustc_errors::{struct_span_err, Applicability, ErrorReported};
 use rustc_hir::{GenericBound, ItemKind, Lifetime, LifetimeName, TyKind};
 use rustc_middle::ty::RegionKind;
 
@@ -35,10 +35,14 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                     let (lifetime_name, lifetime) = if sup_r.has_name() {
                         (sup_r.to_string(), format!("lifetime `{}`", sup_r))
                     } else {
-                        ("'_".to_owned(), "the anonymous lifetime `'_`".to_string())
+                        ("'_".to_owned(), "an anonymous lifetime `'_`".to_string())
                     };
-                    let mut err =
-                        self.tcx().sess.struct_span_err(sp, "cannot infer an appropriate lifetime");
+                    let mut err = struct_span_err!(
+                        self.tcx().sess,
+                        sp,
+                        E0758,
+                        "cannot infer an appropriate lifetime"
+                    );
                     err.span_label(
                         param_info.param_ty_span,
                         &format!("this data with {}...", lifetime),
@@ -61,10 +65,6 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                             //    |
                             // LL | fn foo(x: &i32) -> Box<dyn Debug> { Box::new(x) }
                             //    |           ----                      ---------^-
-                            //    |           |                         |        |
-                            //    |           |                         |   ...and is captured here
-                            //    |           |           ...is required to be `'static` by this...
-                            //    |           this data with the anonymous lifetime `'_`...
                             //
                             // and instead show:
                             //
@@ -72,25 +72,28 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                             //   --> $DIR/must_outlive_least_region_or_bound.rs:18:50
                             //    |
                             // LL | fn foo(x: &i32) -> Box<dyn Debug> { Box::new(x) }
-                            //    |           ----                               ^ ...is captured here with a `'static` requirement
-                            //    |           |
-                            //    |           this data with the anonymous lifetime `'_`...
-                            //    |
+                            //    |           ----                               ^
                             err.span_label(
                                 sup_origin.span(),
-                                "...is captured here with a `'static` requirement",
+                                "...is captured here requiring it to live as long as `'static`",
                             );
                         } else if sup_origin.span() <= return_sp {
                             err.span_label(sup_origin.span(), "...is captured here...");
-                            err.span_label(return_sp, "...and required to be `'static` by this");
+                            err.span_label(
+                                return_sp,
+                                "...and required to live as long as `'static` by this",
+                            );
                         } else {
-                            err.span_label(return_sp, "...is required to be `'static` by this...");
+                            err.span_label(
+                                return_sp,
+                                "...is required to live as long as `'static` by this...",
+                            );
                             err.span_label(sup_origin.span(), "...and is captured here");
                         }
                     } else {
                         err.span_label(
                             return_sp,
-                            "...is captured and required to be `'static` here",
+                            "...is captured and required live as long as `'static` here",
                         );
                     }
 
diff --git a/src/test/ui/async-await/issues/issue-62097.stderr b/src/test/ui/async-await/issues/issue-62097.stderr
index fff43ae9f47bc..558d89f928945 100644
--- a/src/test/ui/async-await/issues/issue-62097.stderr
+++ b/src/test/ui/async-await/issues/issue-62097.stderr
@@ -1,13 +1,13 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/issue-62097.rs:12:31
    |
 LL |     pub async fn run_dummy_fn(&self) {
    |                               ^^^^^
    |                               |
-   |                               this data with the anonymous lifetime `'_`...
+   |                               this data with an anonymous lifetime `'_`...
    |                               ...is captured here...
 LL |         foo(|| self.bar()).await;
-   |         --- ...and required to be `'static` by this
+   |         --- ...and required to live as long as `'static` by this
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index 82e44cff9cc44..eff56ddc440d4 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -1,24 +1,24 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:3:35
    |
 LL | fn elided(x: &i32) -> impl Copy { x }
    |              ----     ---------   ^ ...and is captured here
    |              |        |
-   |              |        ...is required to be `'static` by this...
-   |              this data with the anonymous lifetime `'_`...
+   |              |        ...is required to live as long as `'static` by this...
+   |              this data with an anonymous lifetime `'_`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for an anonymous lifetime `'_`
    |
 LL | fn elided(x: &i32) -> impl Copy + '_ { x }
    |                                 ^^^^
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:6:44
    |
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
    |                    -------     ---------   ^ ...and is captured here
    |                    |           |
-   |                    |           ...is required to be `'static` by this...
+   |                    |           ...is required to live as long as `'static` by this...
    |                    this data with lifetime `'a`...
    |
 help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for lifetime `'a`
@@ -26,16 +26,16 @@ help: to permit non-static references in an `impl Trait` value, you can add an e
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                          ^^^^
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:9:46
    |
 LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
    |               ----     -------------------   ^ ...and is captured here
    |               |        |
-   |               |        ...is required to be `'static` by this...
-   |               this data with the anonymous lifetime `'_`...
+   |               |        ...is required to live as long as `'static` by this...
+   |               this data with an anonymous lifetime `'_`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound to the anonymous lifetime `'_`
+help: consider changing the `impl Trait`'s explicit `'static` bound to an anonymous lifetime `'_`
    |
 LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
    |                                    ^^
@@ -44,13 +44,13 @@ help: alternatively, set an explicit `'static` lifetime to this parameter
 LL | fn elided2(x: &'static i32) -> impl Copy + 'static { x }
    |               ^^^^^^^^^^^^
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:12:55
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
    |                     -------     -------------------   ^ ...and is captured here
    |                     |           |
-   |                     |           ...is required to be `'static` by this...
+   |                     |           ...is required to live as long as `'static` by this...
    |                     this data with lifetime `'a`...
    |
 help: consider changing the `impl Trait`'s explicit `'static` bound to lifetime `'a`
@@ -70,13 +70,13 @@ LL | fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
    |               |
    |               help: add explicit lifetime `'a` to the type of `x`: `&'a i32`
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:33:69
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |                      -------     --------------------------------   ^ ...and is captured here
    |                      |           |
-   |                      |           ...is required to be `'static` by this...
+   |                      |           ...is required to live as long as `'static` by this...
    |                      this data with lifetime `'a`...
    |
 help: consider changing the `impl Trait`'s explicit `'static` bound to lifetime `'a`
@@ -105,24 +105,24 @@ LL | fn ty_param_wont_outlive_static<T:Debug>(x: T) -> impl Debug + 'static {
    |                                 |
    |                                 help: consider adding an explicit lifetime bound...: `T: 'static +`
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:18:50
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
-   |               ----                               ^ ...is captured here with a `'static` requirement
+   |               ----                               ^ ...is captured here requiring it to live as long as `'static`
    |               |
-   |               this data with the anonymous lifetime `'_`...
+   |               this data with an anonymous lifetime `'_`...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
+help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                      ^^^^
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:21:59
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
-   |                     -------                               ^ ...is captured here with a `'static` requirement
+   |                     -------                               ^ ...is captured here requiring it to live as long as `'static`
    |                     |
    |                     this data with lifetime `'a`...
    |
@@ -131,15 +131,15 @@ help: to permit non-static references in a trait object value, you can add an ex
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                               ^^^^
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:24:60
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |               ----                                         ^ ...is captured here with a `'static` requirement
+   |               ----                                         ^ ...is captured here requiring it to live as long as `'static`
    |               |
-   |               this data with the anonymous lifetime `'_`...
+   |               this data with an anonymous lifetime `'_`...
    |
-help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
+help: consider changing the trait object's explicit `'static` bound to an anonymous lifetime `'_`
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                        ^^
@@ -148,11 +148,11 @@ help: alternatively, set an explicit `'static` lifetime in this parameter
 LL | fn elided4(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |               ^^^^^^^^^^^^
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:27:69
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |                     ------- this data with lifetime `'a`...         ^ ...is captured here with a `'static` requirement
+   |                     ------- this data with lifetime `'a`...         ^ ...is captured here requiring it to live as long as `'static`
    |
 help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
diff --git a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
index 67d4f60dff6f1..a48580ee2d2fc 100644
--- a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
+++ b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
@@ -1,25 +1,25 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/static-return-lifetime-infered.rs:7:16
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
-   |                         -----     ----------------------- ...is required to be `'static` by this...
+   |                         -----     ----------------------- ...is required to live as long as `'static` by this...
    |                         |
-   |                         this data with the anonymous lifetime `'_`...
+   |                         this data with an anonymous lifetime `'_`...
 LL |         self.x.iter().map(|a| a.0)
    |         ------ ^^^^
    |         |
    |         ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for an anonymous lifetime `'_`
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
    |                                                           ^^^^
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/static-return-lifetime-infered.rs:11:16
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
-   |                        --------     ----------------------- ...is required to be `'static` by this...
+   |                        --------     ----------------------- ...is required to live as long as `'static` by this...
    |                        |
    |                        this data with lifetime `'a`...
 LL |         self.x.iter().map(|a| a.0)
diff --git a/src/test/ui/issues/issue-16922.stderr b/src/test/ui/issues/issue-16922.stderr
index a254343cd1bb7..53fd658800a7a 100644
--- a/src/test/ui/issues/issue-16922.stderr
+++ b/src/test/ui/issues/issue-16922.stderr
@@ -1,12 +1,12 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/issue-16922.rs:4:14
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any> {
-   |                       -- this data with the anonymous lifetime `'_`...
+   |                       -- this data with an anonymous lifetime `'_`...
 LL |     Box::new(value) as Box<dyn Any>
-   |              ^^^^^ ...is captured here with a `'static` requirement
+   |              ^^^^^ ...is captured here requiring it to live as long as `'static`
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
+help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
    |                                          ^^^^
diff --git a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
index 6edef8086b937..04a06104faf99 100644
--- a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
+++ b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
@@ -1,13 +1,13 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/object-lifetime-default-from-box-error.rs:18:5
    |
 LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait> {
-   |             --------------- this data with the anonymous lifetime `'_`...
+   |             --------------- this data with an anonymous lifetime `'_`...
 ...
 LL |     ss.r
-   |     ^^^^ ...is captured and required to be `'static` here
+   |     ^^^^ ...is captured and required live as long as `'static` here
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
+help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
    |
 LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait + '_> {
    |                                                   ^^^^
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
index 97d1f3579fcd8..34cf131319a1c 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
@@ -1,12 +1,12 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:8:46
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- this data with the anonymous lifetime `'_`...
+   |         ----- this data with an anonymous lifetime `'_`...
 LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
-   |                                              ^ ...is captured here with a `'static` requirement
+   |                                              ^ ...is captured here requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
+help: consider changing the trait object's explicit `'static` bound to an anonymous lifetime `'_`
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
@@ -15,15 +15,15 @@ help: alternatively, set an explicit `'static` lifetime in this parameter
 LL | fn a(v: &'static [u8]) -> Box<dyn Foo + 'static> {
    |         ^^^^^^^^^^^^^
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:13:14
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
-   |         ----- this data with the anonymous lifetime `'_`...
+   |         ----- this data with an anonymous lifetime `'_`...
 LL |     Box::new(v)
-   |              ^ ...is captured here with a `'static` requirement
+   |              ^ ...is captured here requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
+help: consider changing the trait object's explicit `'static` bound to an anonymous lifetime `'_`
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
@@ -32,16 +32,16 @@ help: alternatively, set an explicit `'static` lifetime in this parameter
 LL | fn b(v: &'static [u8]) -> Box<dyn Foo + 'static> {
    |         ^^^^^^^^^^^^^
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:19:14
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo> {
-   |         ----- this data with the anonymous lifetime `'_`...
+   |         ----- this data with an anonymous lifetime `'_`...
 ...
 LL |     Box::new(v)
-   |              ^ ...is captured here with a `'static` requirement
+   |              ^ ...is captured here requiring it to live as long as `'static`
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
+help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo + '_> {
    |                               ^^^^
diff --git a/src/test/ui/regions/regions-close-object-into-object-2.stderr b/src/test/ui/regions/regions-close-object-into-object-2.stderr
index 3d707f2d99941..be47ef589af8c 100644
--- a/src/test/ui/regions/regions-close-object-into-object-2.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-2.stderr
@@ -1,10 +1,10 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-2.rs:10:11
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
    |                         ------------------ this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
-   |           ^^^ ...is captured here with a `'static` requirement
+   |           ^^^ ...is captured here requiring it to live as long as `'static`
    |
 help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
diff --git a/src/test/ui/regions/regions-close-object-into-object-4.stderr b/src/test/ui/regions/regions-close-object-into-object-4.stderr
index 70282c8cbdb30..1b099c7d8bdf0 100644
--- a/src/test/ui/regions/regions-close-object-into-object-4.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-4.stderr
@@ -1,10 +1,10 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-4.rs:10:11
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
    |                   ---------------- this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
-   |           ^^^ ...is captured here with a `'static` requirement
+   |           ^^^ ...is captured here requiring it to live as long as `'static`
    |
 help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
    |
diff --git a/src/test/ui/regions/regions-proc-bound-capture.stderr b/src/test/ui/regions/regions-proc-bound-capture.stderr
index 8f93fad7fe9d8..e8baf44bd10aa 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.stderr
+++ b/src/test/ui/regions/regions-proc-bound-capture.stderr
@@ -1,13 +1,13 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/regions-proc-bound-capture.rs:9:14
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
-   |                   ------ this data with the anonymous lifetime `'_`...
+   |                   ------ this data with an anonymous lifetime `'_`...
 LL |     // This is illegal, because the region bound on `proc` is 'static.
 LL |     Box::new(move || { *x })
-   |              ^^^^^^^^^^^^^^ ...is captured here with a `'static` requirement
+   |              ^^^^^^^^^^^^^^ ...is captured here requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to the anonymous lifetime `'_`
+help: consider changing the trait object's explicit `'static` bound to an anonymous lifetime `'_`
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + '_> {
    |                                                           ^^
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
index 5520341b5b1c3..92e1473a5da73 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
@@ -1,10 +1,10 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait-async.rs:8:16
    |
 LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
-   |                ^^^^  ----------     ---------- ...and required to be `'static` by this
+   |                ^^^^  ----------     ---------- ...and required to live as long as `'static` by this
    |                |     |
-   |                |     this data with the anonymous lifetime `'_`...
+   |                |     this data with an anonymous lifetime `'_`...
    |                ...is captured here...
 
 error: aborting due to previous error
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
index 5374929f3a45f..6721d41bb73c9 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
@@ -1,13 +1,13 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait.rs:6:44
    |
 LL |     fn f(self: Pin<&Self>) -> impl Clone { self }
    |                ----------     ----------   ^^^^ ...and is captured here
    |                |              |
-   |                |              ...is required to be `'static` by this...
-   |                this data with the anonymous lifetime `'_`...
+   |                |              ...is required to live as long as `'static` by this...
+   |                this data with an anonymous lifetime `'_`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for an anonymous lifetime `'_`
    |
 LL |     fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
    |                                          ^^^^
diff --git a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
index 471f3cd14aa3e..ba56255af5b0c 100644
--- a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
+++ b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
@@ -6,20 +6,20 @@ LL | fn baz<G: 'a, T>(g: G, dest: &mut T) -> impl FnOnce() + '_
    |        |
    |        help: consider introducing lifetime `'a` here: `'a,`
 
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/missing-lifetimes-in-signature.rs:19:5
    |
 LL |   fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce()
-   |                            ------     ------------- ...is required to be `'static` by this...
+   |                            ------     ------------- ...is required to live as long as `'static` by this...
    |                            |
-   |                            this data with the anonymous lifetime `'_`...
+   |                            this data with an anonymous lifetime `'_`...
 ...
 LL | /     move || {
 LL | |         *dest = g.get();
 LL | |     }
    | |_____^ ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for the anonymous lifetime `'_`
+help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for an anonymous lifetime `'_`
    |
 LL | fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce() + '_
    |                                                   ^^^^
diff --git a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
index 5fd03f9770e5d..20d3640d4118e 100644
--- a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
+++ b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
@@ -1,13 +1,13 @@
-error: cannot infer an appropriate lifetime
+error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/dyn-trait-underscore.rs:8:20
    |
 LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T>> {
-   |                ---- this data with the anonymous lifetime `'_`...
+   |                ---- this data with an anonymous lifetime `'_`...
 LL |     //                      ^^^^^^^^^^^^^^^^^^^^^ bound *here* defaults to `'static`
 LL |     Box::new(items.iter())
-   |     ---------------^^^^--- ...is captured and required to be `'static` here
+   |     ---------------^^^^--- ...is captured and required live as long as `'static` here
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for the anonymous lifetime `'_`
+help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
    |
 LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T> + '_> {
    |                                                   ^^^^

From 3cfecdee0d677e0982cd160991130a997ffc619e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Mon, 1 Jun 2020 16:15:10 -0700
Subject: [PATCH 13/25] review comments: wording

---
 .../nice_region_error/static_impl_trait.rs    | 58 ++++++++++---------
 .../ui/async-await/issues/issue-62097.stderr  |  2 +-
 .../must_outlive_least_region_or_bound.stderr | 46 +++++++--------
 .../static-return-lifetime-infered.stderr     |  8 +--
 src/test/ui/issues/issue-16922.stderr         |  4 +-
 ...ect-lifetime-default-from-box-error.stderr |  2 +-
 .../region-object-lifetime-in-coercion.stderr | 16 ++---
 .../regions-close-object-into-object-2.stderr |  6 +-
 .../regions-close-object-into-object-4.stderr |  6 +-
 .../regions/regions-proc-bound-capture.stderr |  6 +-
 ...types_pin_lifetime_impl_trait-async.stderr |  2 +-
 ..._self_types_pin_lifetime_impl_trait.stderr |  4 +-
 .../missing-lifetimes-in-signature.stderr     |  4 +-
 .../dyn-trait-underscore.stderr               |  2 +-
 14 files changed, 85 insertions(+), 81 deletions(-)

diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index 4e16e8c2c5717..86f310eb71d76 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -75,18 +75,18 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                             //    |           ----                               ^
                             err.span_label(
                                 sup_origin.span(),
-                                "...is captured here requiring it to live as long as `'static`",
+                                "...is captured here, requiring it to live as long as `'static`",
                             );
                         } else if sup_origin.span() <= return_sp {
                             err.span_label(sup_origin.span(), "...is captured here...");
                             err.span_label(
                                 return_sp,
-                                "...and required to live as long as `'static` by this",
+                                "...and is required to live as long as `'static` here",
                             );
                         } else {
                             err.span_label(
                                 return_sp,
-                                "...is required to live as long as `'static` by this...",
+                                "...is required to live as long as `'static` here...",
                             );
                             err.span_label(sup_origin.span(), "...and is captured here");
                         }
@@ -101,6 +101,20 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                     // explicit non-desugar'able return.
                     if fn_return.span.desugaring_kind().is_none() {
                         // FIXME: account for the need of parens in `&(dyn Trait + '_)`
+
+                        let consider = "consider changing the";
+                        let declare = "to declare that the";
+                        let arg = match param_info.param.pat.simple_ident() {
+                            Some(simple_ident) => format!("argument `{}`", simple_ident),
+                            None => "the argument".to_string(),
+                        };
+                        let explicit =
+                            format!("you can add an explicit `{}` lifetime bound", lifetime_name);
+                        let explicit_static = format!("explicit `'static` bound to {}", arg);
+                        let captures = format!("captures data from {}", arg);
+                        let add_static_bound =
+                            "alternatively, add an explicit `'static` bound to this reference";
+                        let plus_lt = format!(" + {}", lifetime_name);
                         match fn_return.kind {
                             TyKind::Def(item_id, _) => {
                                 let item = self.tcx().hir().item(item_id.id);
@@ -126,18 +140,13 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                 {
                                     err.span_suggestion_verbose(
                                         span,
-                                        &format!(
-                                            "consider changing the `impl Trait`'s explicit \
-                                             `'static` bound to {}",
-                                            lifetime,
-                                        ),
+                                        &format!("{} `impl Trait`'s {}", consider, explicit_static),
                                         lifetime_name,
                                         Applicability::MaybeIncorrect,
                                     );
                                     err.span_suggestion_verbose(
                                         param_info.param_ty_span,
-                                        "alternatively, set an explicit `'static` lifetime to \
-                                         this parameter",
+                                        add_static_bound,
                                         param_info.param_ty.to_string(),
                                         Applicability::MaybeIncorrect,
                                     );
@@ -145,11 +154,12 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                     err.span_suggestion_verbose(
                                         fn_return.span.shrink_to_hi(),
                                         &format!(
-                                            "to permit non-static references in an `impl Trait` \
-                                             value, you can add an explicit bound for {}",
-                                            lifetime,
+                                            "{declare} `impl Trait` {captures}, {explicit}",
+                                            declare = declare,
+                                            captures = captures,
+                                            explicit = explicit,
                                         ),
-                                        format!(" + {}", lifetime_name),
+                                        plus_lt,
                                         Applicability::MaybeIncorrect,
                                     );
                                 };
@@ -159,31 +169,25 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                     err.span_suggestion_verbose(
                                         fn_return.span.shrink_to_hi(),
                                         &format!(
-                                            "to permit non-static references in a trait object \
-                                             value, you can add an explicit bound for {}",
-                                            lifetime,
+                                            "{declare} trait object {captures}, {explicit}",
+                                            declare = declare,
+                                            captures = captures,
+                                            explicit = explicit,
                                         ),
-                                        format!(" + {}", lifetime_name),
+                                        plus_lt,
                                         Applicability::MaybeIncorrect,
                                     );
                                 }
                                 _ => {
                                     err.span_suggestion_verbose(
                                         lt.span,
-                                        &format!(
-                                            "consider changing the trait object's explicit \
-                                             `'static` bound to {}",
-                                            lifetime,
-                                        ),
+                                        &format!("{} trait object's {}", consider, explicit_static),
                                         lifetime_name,
                                         Applicability::MaybeIncorrect,
                                     );
                                     err.span_suggestion_verbose(
                                         param_info.param_ty_span,
-                                        &format!(
-                                            "alternatively, set an explicit `'static` lifetime \
-                                             in this parameter",
-                                        ),
+                                        add_static_bound,
                                         param_info.param_ty.to_string(),
                                         Applicability::MaybeIncorrect,
                                     );
diff --git a/src/test/ui/async-await/issues/issue-62097.stderr b/src/test/ui/async-await/issues/issue-62097.stderr
index 558d89f928945..e9f155c6ced31 100644
--- a/src/test/ui/async-await/issues/issue-62097.stderr
+++ b/src/test/ui/async-await/issues/issue-62097.stderr
@@ -7,7 +7,7 @@ LL |     pub async fn run_dummy_fn(&self) {
    |                               this data with an anonymous lifetime `'_`...
    |                               ...is captured here...
 LL |         foo(|| self.bar()).await;
-   |         --- ...and required to live as long as `'static` by this
+   |         --- ...and is required to live as long as `'static` here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index eff56ddc440d4..a9fa0e93fed61 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -4,10 +4,10 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn elided(x: &i32) -> impl Copy { x }
    |              ----     ---------   ^ ...and is captured here
    |              |        |
-   |              |        ...is required to live as long as `'static` by this...
+   |              |        ...is required to live as long as `'static` here...
    |              this data with an anonymous lifetime `'_`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for an anonymous lifetime `'_`
+help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'_` lifetime bound
    |
 LL | fn elided(x: &i32) -> impl Copy + '_ { x }
    |                                 ^^^^
@@ -18,10 +18,10 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
    |                    -------     ---------   ^ ...and is captured here
    |                    |           |
-   |                    |           ...is required to live as long as `'static` by this...
+   |                    |           ...is required to live as long as `'static` here...
    |                    this data with lifetime `'a`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for lifetime `'a`
+help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'a` lifetime bound
    |
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                          ^^^^
@@ -32,14 +32,14 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
    |               ----     -------------------   ^ ...and is captured here
    |               |        |
-   |               |        ...is required to live as long as `'static` by this...
+   |               |        ...is required to live as long as `'static` here...
    |               this data with an anonymous lifetime `'_`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound to an anonymous lifetime `'_`
+help: consider changing the `impl Trait`'s explicit `'static` bound to argument `x`
    |
 LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
    |                                    ^^
-help: alternatively, set an explicit `'static` lifetime to this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn elided2(x: &'static i32) -> impl Copy + 'static { x }
    |               ^^^^^^^^^^^^
@@ -50,14 +50,14 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
    |                     -------     -------------------   ^ ...and is captured here
    |                     |           |
-   |                     |           ...is required to live as long as `'static` by this...
+   |                     |           ...is required to live as long as `'static` here...
    |                     this data with lifetime `'a`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound to lifetime `'a`
+help: consider changing the `impl Trait`'s explicit `'static` bound to argument `x`
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                             ^^
-help: alternatively, set an explicit `'static` lifetime to this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn explicit2<'a>(x: &'static i32) -> impl Copy + 'static { x }
    |                     ^^^^^^^^^^^^
@@ -76,14 +76,14 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |                      -------     --------------------------------   ^ ...and is captured here
    |                      |           |
-   |                      |           ...is required to live as long as `'static` by this...
+   |                      |           ...is required to live as long as `'static` here...
    |                      this data with lifetime `'a`...
    |
-help: consider changing the `impl Trait`'s explicit `'static` bound to lifetime `'a`
+help: consider changing the `impl Trait`'s explicit `'static` bound to argument `x`
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'a { x }
    |                                                           ^^
-help: alternatively, set an explicit `'static` lifetime to this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn with_bound<'a>(x: &'static i32) -> impl LifetimeTrait<'a> + 'static { x }
    |                      ^^^^^^^^^^^^
@@ -109,11 +109,11 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:18:50
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
-   |               ----                               ^ ...is captured here requiring it to live as long as `'static`
+   |               ----                               ^ ...is captured here, requiring it to live as long as `'static`
    |               |
    |               this data with an anonymous lifetime `'_`...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
+help: to declare that the trait object captures data from argument `x`, you can add an explicit `'_` lifetime bound
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                      ^^^^
@@ -122,11 +122,11 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:21:59
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
-   |                     -------                               ^ ...is captured here requiring it to live as long as `'static`
+   |                     -------                               ^ ...is captured here, requiring it to live as long as `'static`
    |                     |
    |                     this data with lifetime `'a`...
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for lifetime `'a`
+help: to declare that the trait object captures data from argument `x`, you can add an explicit `'a` lifetime bound
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                               ^^^^
@@ -135,15 +135,15 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:24:60
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |               ----                                         ^ ...is captured here requiring it to live as long as `'static`
+   |               ----                                         ^ ...is captured here, requiring it to live as long as `'static`
    |               |
    |               this data with an anonymous lifetime `'_`...
    |
-help: consider changing the trait object's explicit `'static` bound to an anonymous lifetime `'_`
+help: consider changing the trait object's explicit `'static` bound to argument `x`
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                        ^^
-help: alternatively, set an explicit `'static` lifetime in this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn elided4(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |               ^^^^^^^^^^^^
@@ -152,13 +152,13 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:27:69
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
-   |                     ------- this data with lifetime `'a`...         ^ ...is captured here requiring it to live as long as `'static`
+   |                     ------- this data with lifetime `'a`...         ^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
+help: consider changing the trait object's explicit `'static` bound to argument `x`
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                                 ^^
-help: alternatively, set an explicit `'static` lifetime in this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn explicit4<'a>(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |                     ^^^^^^^^^^^^
diff --git a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
index a48580ee2d2fc..6681eaa909ee0 100644
--- a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
+++ b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
@@ -2,7 +2,7 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/static-return-lifetime-infered.rs:7:16
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
-   |                         -----     ----------------------- ...is required to live as long as `'static` by this...
+   |                         -----     ----------------------- ...is required to live as long as `'static` here...
    |                         |
    |                         this data with an anonymous lifetime `'_`...
 LL |         self.x.iter().map(|a| a.0)
@@ -10,7 +10,7 @@ LL |         self.x.iter().map(|a| a.0)
    |         |
    |         ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for an anonymous lifetime `'_`
+help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'_` lifetime bound
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
    |                                                           ^^^^
@@ -19,7 +19,7 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/static-return-lifetime-infered.rs:11:16
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
-   |                        --------     ----------------------- ...is required to live as long as `'static` by this...
+   |                        --------     ----------------------- ...is required to live as long as `'static` here...
    |                        |
    |                        this data with lifetime `'a`...
 LL |         self.x.iter().map(|a| a.0)
@@ -27,7 +27,7 @@ LL |         self.x.iter().map(|a| a.0)
    |         |
    |         ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for lifetime `'a`
+help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'a` lifetime bound
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
    |                                                             ^^^^
diff --git a/src/test/ui/issues/issue-16922.stderr b/src/test/ui/issues/issue-16922.stderr
index 53fd658800a7a..95f46bd7f3eb6 100644
--- a/src/test/ui/issues/issue-16922.stderr
+++ b/src/test/ui/issues/issue-16922.stderr
@@ -4,9 +4,9 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any> {
    |                       -- this data with an anonymous lifetime `'_`...
 LL |     Box::new(value) as Box<dyn Any>
-   |              ^^^^^ ...is captured here requiring it to live as long as `'static`
+   |              ^^^^^ ...is captured here, requiring it to live as long as `'static`
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
+help: to declare that the trait object captures data from argument `value`, you can add an explicit `'_` lifetime bound
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
    |                                          ^^^^
diff --git a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
index 04a06104faf99..e585db262f2d8 100644
--- a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
+++ b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
@@ -7,7 +7,7 @@ LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait> {
 LL |     ss.r
    |     ^^^^ ...is captured and required live as long as `'static` here
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
+help: to declare that the trait object captures data from argument `ss`, you can add an explicit `'_` lifetime bound
    |
 LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait + '_> {
    |                                                   ^^^^
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
index 34cf131319a1c..8d048d90cb345 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
@@ -4,13 +4,13 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
    |         ----- this data with an anonymous lifetime `'_`...
 LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
-   |                                              ^ ...is captured here requiring it to live as long as `'static`
+   |                                              ^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to an anonymous lifetime `'_`
+help: consider changing the trait object's explicit `'static` bound to argument `v`
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
-help: alternatively, set an explicit `'static` lifetime in this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn a(v: &'static [u8]) -> Box<dyn Foo + 'static> {
    |         ^^^^^^^^^^^^^
@@ -21,13 +21,13 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
    |         ----- this data with an anonymous lifetime `'_`...
 LL |     Box::new(v)
-   |              ^ ...is captured here requiring it to live as long as `'static`
+   |              ^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to an anonymous lifetime `'_`
+help: consider changing the trait object's explicit `'static` bound to argument `v`
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
-help: alternatively, set an explicit `'static` lifetime in this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn b(v: &'static [u8]) -> Box<dyn Foo + 'static> {
    |         ^^^^^^^^^^^^^
@@ -39,9 +39,9 @@ LL | fn c(v: &[u8]) -> Box<dyn Foo> {
    |         ----- this data with an anonymous lifetime `'_`...
 ...
 LL |     Box::new(v)
-   |              ^ ...is captured here requiring it to live as long as `'static`
+   |              ^ ...is captured here, requiring it to live as long as `'static`
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
+help: to declare that the trait object captures data from argument `v`, you can add an explicit `'_` lifetime bound
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo + '_> {
    |                               ^^^^
diff --git a/src/test/ui/regions/regions-close-object-into-object-2.stderr b/src/test/ui/regions/regions-close-object-into-object-2.stderr
index be47ef589af8c..5dfe384112b2a 100644
--- a/src/test/ui/regions/regions-close-object-into-object-2.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-2.stderr
@@ -4,13 +4,13 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
    |                         ------------------ this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
-   |           ^^^ ...is captured here requiring it to live as long as `'static`
+   |           ^^^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
+help: consider changing the trait object's explicit `'static` bound to argument `v`
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'a> {
    |                                                            ^^
-help: alternatively, set an explicit `'static` lifetime in this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn g<'a, T: 'static>(v: std::boxed::Box<(dyn A<T> + 'static)>) -> Box<dyn X + 'static> {
    |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/regions/regions-close-object-into-object-4.stderr b/src/test/ui/regions/regions-close-object-into-object-4.stderr
index 1b099c7d8bdf0..4d23118ba06f0 100644
--- a/src/test/ui/regions/regions-close-object-into-object-4.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-4.stderr
@@ -4,13 +4,13 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
    |                   ---------------- this data with lifetime `'a`...
 LL |     box B(&*v) as Box<dyn X>
-   |           ^^^ ...is captured here requiring it to live as long as `'static`
+   |           ^^^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to lifetime `'a`
+help: consider changing the trait object's explicit `'static` bound to argument `v`
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'a> {
    |                                                    ^^
-help: alternatively, set an explicit `'static` lifetime in this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn i<'a, T, U>(v: std::boxed::Box<(dyn A<U> + 'static)>) -> Box<dyn X + 'static> {
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/src/test/ui/regions/regions-proc-bound-capture.stderr b/src/test/ui/regions/regions-proc-bound-capture.stderr
index e8baf44bd10aa..e36f77ec1da96 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.stderr
+++ b/src/test/ui/regions/regions-proc-bound-capture.stderr
@@ -5,13 +5,13 @@ LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
    |                   ------ this data with an anonymous lifetime `'_`...
 LL |     // This is illegal, because the region bound on `proc` is 'static.
 LL |     Box::new(move || { *x })
-   |              ^^^^^^^^^^^^^^ ...is captured here requiring it to live as long as `'static`
+   |              ^^^^^^^^^^^^^^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to an anonymous lifetime `'_`
+help: consider changing the trait object's explicit `'static` bound to argument `x`
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + '_> {
    |                                                           ^^
-help: alternatively, set an explicit `'static` lifetime in this parameter
+help: alternatively, add an explicit `'static` bound to this reference
    |
 LL | fn static_proc(x: &'static isize) -> Box<dyn FnMut() -> (isize) + 'static> {
    |                   ^^^^^^^^^^^^^^
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
index 92e1473a5da73..365e38515b12c 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
@@ -2,7 +2,7 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait-async.rs:8:16
    |
 LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
-   |                ^^^^  ----------     ---------- ...and required to live as long as `'static` by this
+   |                ^^^^  ----------     ---------- ...and is required to live as long as `'static` here
    |                |     |
    |                |     this data with an anonymous lifetime `'_`...
    |                ...is captured here...
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
index 6721d41bb73c9..bd3f3efad82f2 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
@@ -4,10 +4,10 @@ error[E0758]: cannot infer an appropriate lifetime
 LL |     fn f(self: Pin<&Self>) -> impl Clone { self }
    |                ----------     ----------   ^^^^ ...and is captured here
    |                |              |
-   |                |              ...is required to live as long as `'static` by this...
+   |                |              ...is required to live as long as `'static` here...
    |                this data with an anonymous lifetime `'_`...
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for an anonymous lifetime `'_`
+help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'_` lifetime bound
    |
 LL |     fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
    |                                          ^^^^
diff --git a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
index ba56255af5b0c..d96a5f961bdb8 100644
--- a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
+++ b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
@@ -10,7 +10,7 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/missing-lifetimes-in-signature.rs:19:5
    |
 LL |   fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce()
-   |                            ------     ------------- ...is required to live as long as `'static` by this...
+   |                            ------     ------------- ...is required to live as long as `'static` here...
    |                            |
    |                            this data with an anonymous lifetime `'_`...
 ...
@@ -19,7 +19,7 @@ LL | |         *dest = g.get();
 LL | |     }
    | |_____^ ...and is captured here
    |
-help: to permit non-static references in an `impl Trait` value, you can add an explicit bound for an anonymous lifetime `'_`
+help: to declare that the `impl Trait` captures data from argument `dest`, you can add an explicit `'_` lifetime bound
    |
 LL | fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce() + '_
    |                                                   ^^^^
diff --git a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
index 20d3640d4118e..7c649f9c08d64 100644
--- a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
+++ b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
@@ -7,7 +7,7 @@ LL |     //                      ^^^^^^^^^^^^^^^^^^^^^ bound *here* defaults to
 LL |     Box::new(items.iter())
    |     ---------------^^^^--- ...is captured and required live as long as `'static` here
    |
-help: to permit non-static references in a trait object value, you can add an explicit bound for an anonymous lifetime `'_`
+help: to declare that the trait object captures data from argument `items`, you can add an explicit `'_` lifetime bound
    |
 LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T> + '_> {
    |                                                   ^^^^

From bdfb9b18ab7ba6c4fc27c79dde62d678c25f3b38 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Mon, 1 Jun 2020 17:51:12 -0700
Subject: [PATCH 14/25] Use note for requirement source span

---
 .../nice_region_error/static_impl_trait.rs    | 10 +---
 .../ui/async-await/issues/issue-62097.stderr  |  6 ++-
 .../must_outlive_least_region_or_bound.stderr | 50 +++++++++++++------
 .../static-return-lifetime-infered.stderr     | 22 +++++---
 ...types_pin_lifetime_impl_trait-async.stderr | 11 ++--
 ..._self_types_pin_lifetime_impl_trait.stderr | 10 ++--
 .../missing-lifetimes-in-signature.stderr     | 11 ++--
 7 files changed, 77 insertions(+), 43 deletions(-)

diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index 86f310eb71d76..74267a8dec059 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -77,18 +77,12 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                                 sup_origin.span(),
                                 "...is captured here, requiring it to live as long as `'static`",
                             );
-                        } else if sup_origin.span() <= return_sp {
+                        } else {
                             err.span_label(sup_origin.span(), "...is captured here...");
-                            err.span_label(
+                            err.span_note(
                                 return_sp,
                                 "...and is required to live as long as `'static` here",
                             );
-                        } else {
-                            err.span_label(
-                                return_sp,
-                                "...is required to live as long as `'static` here...",
-                            );
-                            err.span_label(sup_origin.span(), "...and is captured here");
                         }
                     } else {
                         err.span_label(
diff --git a/src/test/ui/async-await/issues/issue-62097.stderr b/src/test/ui/async-await/issues/issue-62097.stderr
index e9f155c6ced31..ff7007dd30b1b 100644
--- a/src/test/ui/async-await/issues/issue-62097.stderr
+++ b/src/test/ui/async-await/issues/issue-62097.stderr
@@ -6,8 +6,12 @@ LL |     pub async fn run_dummy_fn(&self) {
    |                               |
    |                               this data with an anonymous lifetime `'_`...
    |                               ...is captured here...
+   |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/issue-62097.rs:13:9
+   |
 LL |         foo(|| self.bar()).await;
-   |         --- ...and is required to live as long as `'static` here
+   |         ^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index a9fa0e93fed61..698464b4971a7 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -2,11 +2,15 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:3:35
    |
 LL | fn elided(x: &i32) -> impl Copy { x }
-   |              ----     ---------   ^ ...and is captured here
-   |              |        |
-   |              |        ...is required to live as long as `'static` here...
+   |              ----                 ^ ...is captured here...
+   |              |
    |              this data with an anonymous lifetime `'_`...
    |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/must_outlive_least_region_or_bound.rs:3:23
+   |
+LL | fn elided(x: &i32) -> impl Copy { x }
+   |                       ^^^^^^^^^
 help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'_` lifetime bound
    |
 LL | fn elided(x: &i32) -> impl Copy + '_ { x }
@@ -16,11 +20,15 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:6:44
    |
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
-   |                    -------     ---------   ^ ...and is captured here
-   |                    |           |
-   |                    |           ...is required to live as long as `'static` here...
+   |                    -------                 ^ ...is captured here...
+   |                    |
    |                    this data with lifetime `'a`...
    |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/must_outlive_least_region_or_bound.rs:6:32
+   |
+LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
+   |                                ^^^^^^^^^
 help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'a` lifetime bound
    |
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
@@ -30,11 +38,15 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:9:46
    |
 LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
-   |               ----     -------------------   ^ ...and is captured here
-   |               |        |
-   |               |        ...is required to live as long as `'static` here...
+   |               ----                           ^ ...is captured here...
+   |               |
    |               this data with an anonymous lifetime `'_`...
    |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/must_outlive_least_region_or_bound.rs:9:24
+   |
+LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
+   |                        ^^^^^^^^^^^^^^^^^^^
 help: consider changing the `impl Trait`'s explicit `'static` bound to argument `x`
    |
 LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
@@ -48,11 +60,15 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:12:55
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
-   |                     -------     -------------------   ^ ...and is captured here
-   |                     |           |
-   |                     |           ...is required to live as long as `'static` here...
+   |                     -------                           ^ ...is captured here...
+   |                     |
    |                     this data with lifetime `'a`...
    |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/must_outlive_least_region_or_bound.rs:12:33
+   |
+LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
+   |                                 ^^^^^^^^^^^^^^^^^^^
 help: consider changing the `impl Trait`'s explicit `'static` bound to argument `x`
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'a { x }
@@ -74,11 +90,13 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:33:69
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
-   |                      -------     --------------------------------   ^ ...and is captured here
-   |                      |           |
-   |                      |           ...is required to live as long as `'static` here...
-   |                      this data with lifetime `'a`...
+   |                      ------- this data with lifetime `'a`...        ^ ...is captured here...
+   |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/must_outlive_least_region_or_bound.rs:33:34
    |
+LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
+   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 help: consider changing the `impl Trait`'s explicit `'static` bound to argument `x`
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'a { x }
diff --git a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
index 6681eaa909ee0..bcc46785c5918 100644
--- a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
+++ b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
@@ -2,14 +2,17 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/static-return-lifetime-infered.rs:7:16
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
-   |                         -----     ----------------------- ...is required to live as long as `'static` here...
-   |                         |
-   |                         this data with an anonymous lifetime `'_`...
+   |                         ----- this data with an anonymous lifetime `'_`...
 LL |         self.x.iter().map(|a| a.0)
    |         ------ ^^^^
    |         |
-   |         ...and is captured here
+   |         ...is captured here...
    |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/static-return-lifetime-infered.rs:6:35
+   |
+LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
+   |                                   ^^^^^^^^^^^^^^^^^^^^^^^
 help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'_` lifetime bound
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
@@ -19,14 +22,17 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/static-return-lifetime-infered.rs:11:16
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
-   |                        --------     ----------------------- ...is required to live as long as `'static` here...
-   |                        |
-   |                        this data with lifetime `'a`...
+   |                        -------- this data with lifetime `'a`...
 LL |         self.x.iter().map(|a| a.0)
    |         ------ ^^^^
    |         |
-   |         ...and is captured here
+   |         ...is captured here...
    |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/static-return-lifetime-infered.rs:10:37
+   |
+LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
+   |                                     ^^^^^^^^^^^^^^^^^^^^^^^
 help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'a` lifetime bound
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
index 365e38515b12c..2ffbf6e08158e 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
@@ -2,10 +2,15 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait-async.rs:8:16
    |
 LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
-   |                ^^^^  ----------     ---------- ...and is required to live as long as `'static` here
-   |                |     |
-   |                |     this data with an anonymous lifetime `'_`...
+   |                ^^^^  ---------- this data with an anonymous lifetime `'_`...
+   |                |
    |                ...is captured here...
+   |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait-async.rs:8:37
+   |
+LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
+   |                                     ^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
index bd3f3efad82f2..2da7bcf543d66 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
@@ -2,11 +2,15 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait.rs:6:44
    |
 LL |     fn f(self: Pin<&Self>) -> impl Clone { self }
-   |                ----------     ----------   ^^^^ ...and is captured here
-   |                |              |
-   |                |              ...is required to live as long as `'static` here...
+   |                ----------                  ^^^^ ...is captured here...
+   |                |
    |                this data with an anonymous lifetime `'_`...
    |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait.rs:6:31
+   |
+LL |     fn f(self: Pin<&Self>) -> impl Clone { self }
+   |                               ^^^^^^^^^^
 help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'_` lifetime bound
    |
 LL |     fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
diff --git a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
index d96a5f961bdb8..95d905af05089 100644
--- a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
+++ b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
@@ -10,15 +10,18 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/missing-lifetimes-in-signature.rs:19:5
    |
 LL |   fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce()
-   |                            ------     ------------- ...is required to live as long as `'static` here...
-   |                            |
-   |                            this data with an anonymous lifetime `'_`...
+   |                            ------ this data with an anonymous lifetime `'_`...
 ...
 LL | /     move || {
 LL | |         *dest = g.get();
 LL | |     }
-   | |_____^ ...and is captured here
+   | |_____^ ...is captured here...
    |
+note: ...and is required to live as long as `'static` here
+  --> $DIR/missing-lifetimes-in-signature.rs:15:37
+   |
+LL | fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce()
+   |                                     ^^^^^^^^^^^^^
 help: to declare that the `impl Trait` captures data from argument `dest`, you can add an explicit `'_` lifetime bound
    |
 LL | fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce() + '_

From 215de3b3c5105982978582861b95b0b449dbff94 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Tue, 2 Jun 2020 10:47:58 -0700
Subject: [PATCH 15/25] Register new eror code

---
 src/test/ui/async-await/issues/issue-62097.stderr              | 1 +
 .../ui/impl-trait/must_outlive_least_region_or_bound.stderr    | 2 +-
 src/test/ui/impl-trait/static-return-lifetime-infered.stderr   | 1 +
 src/test/ui/issues/issue-16922.stderr                          | 1 +
 .../object-lifetime-default-from-box-error.stderr              | 3 ++-
 src/test/ui/regions/region-object-lifetime-in-coercion.stderr  | 3 ++-
 src/test/ui/regions/regions-close-object-into-object-2.stderr  | 1 +
 src/test/ui/regions/regions-close-object-into-object-4.stderr  | 1 +
 src/test/ui/regions/regions-proc-bound-capture.stderr          | 1 +
 .../arbitrary_self_types_pin_lifetime_impl_trait-async.stderr  | 1 +
 .../self/arbitrary_self_types_pin_lifetime_impl_trait.stderr   | 1 +
 .../lifetimes/missing-lifetimes-in-signature.stderr            | 2 +-
 src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr    | 1 +
 13 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/test/ui/async-await/issues/issue-62097.stderr b/src/test/ui/async-await/issues/issue-62097.stderr
index ff7007dd30b1b..b3754cce40833 100644
--- a/src/test/ui/async-await/issues/issue-62097.stderr
+++ b/src/test/ui/async-await/issues/issue-62097.stderr
@@ -15,3 +15,4 @@ LL |         foo(|| self.bar()).await;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0758`.
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index 698464b4971a7..5ab450a85d9e1 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -183,5 +183,5 @@ LL | fn explicit4<'a>(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x)
 
 error: aborting due to 12 previous errors
 
-Some errors have detailed explanations: E0310, E0621, E0623.
+Some errors have detailed explanations: E0310, E0621, E0623, E0758.
 For more information about an error, try `rustc --explain E0310`.
diff --git a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
index bcc46785c5918..90aada01d9917 100644
--- a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
+++ b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
@@ -40,3 +40,4 @@ LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0758`.
diff --git a/src/test/ui/issues/issue-16922.stderr b/src/test/ui/issues/issue-16922.stderr
index 95f46bd7f3eb6..ec80f6569f5ac 100644
--- a/src/test/ui/issues/issue-16922.stderr
+++ b/src/test/ui/issues/issue-16922.stderr
@@ -13,3 +13,4 @@ LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0758`.
diff --git a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
index e585db262f2d8..ac7502e004c44 100644
--- a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
+++ b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
@@ -23,4 +23,5 @@ LL |     ss.r = b;
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0621`.
+Some errors have detailed explanations: E0621, E0758.
+For more information about an error, try `rustc --explain E0621`.
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
index 8d048d90cb345..fe191e9b69565 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
@@ -79,4 +79,5 @@ LL |     Box::new(v)
 
 error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0495`.
+Some errors have detailed explanations: E0495, E0758.
+For more information about an error, try `rustc --explain E0495`.
diff --git a/src/test/ui/regions/regions-close-object-into-object-2.stderr b/src/test/ui/regions/regions-close-object-into-object-2.stderr
index 5dfe384112b2a..2ea970afcede2 100644
--- a/src/test/ui/regions/regions-close-object-into-object-2.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-2.stderr
@@ -17,3 +17,4 @@ LL | fn g<'a, T: 'static>(v: std::boxed::Box<(dyn A<T> + 'static)>) -> Box<dyn X
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0758`.
diff --git a/src/test/ui/regions/regions-close-object-into-object-4.stderr b/src/test/ui/regions/regions-close-object-into-object-4.stderr
index 4d23118ba06f0..493b7a1df9920 100644
--- a/src/test/ui/regions/regions-close-object-into-object-4.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-4.stderr
@@ -17,3 +17,4 @@ LL | fn i<'a, T, U>(v: std::boxed::Box<(dyn A<U> + 'static)>) -> Box<dyn X + 'st
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0758`.
diff --git a/src/test/ui/regions/regions-proc-bound-capture.stderr b/src/test/ui/regions/regions-proc-bound-capture.stderr
index e36f77ec1da96..c10b9850a4e99 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.stderr
+++ b/src/test/ui/regions/regions-proc-bound-capture.stderr
@@ -18,3 +18,4 @@ LL | fn static_proc(x: &'static isize) -> Box<dyn FnMut() -> (isize) + 'static>
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0758`.
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
index 2ffbf6e08158e..69022607bd19e 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
@@ -14,3 +14,4 @@ LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0758`.
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
index 2da7bcf543d66..c37eb2d136ef1 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
@@ -18,3 +18,4 @@ LL |     fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0758`.
diff --git a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
index 95d905af05089..7e8ab1bfe1633 100644
--- a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
+++ b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
@@ -125,5 +125,5 @@ LL | fn bak<'a, G, T>(g: G, dest: &'a mut T) -> impl FnOnce() + 'a
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0261, E0309, E0621.
+Some errors have detailed explanations: E0261, E0309, E0621, E0758.
 For more information about an error, try `rustc --explain E0261`.
diff --git a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
index 7c649f9c08d64..e768d7c8ab99f 100644
--- a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
+++ b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
@@ -14,3 +14,4 @@ LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T> + '_> {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0758`.

From 187e1050a2d0ffd822e2ccc0baf8df9679bbde20 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Tue, 2 Jun 2020 16:05:48 -0700
Subject: [PATCH 16/25] small tweaks

---
 .../nice_region_error/static_impl_trait.rs    | 20 +++++++++++++------
 .../ui/async-await/issues/issue-62097.stderr  |  6 +-----
 .../must_outlive_least_region_or_bound.stderr | 10 +++++-----
 ...ect-lifetime-default-from-box-error.stderr |  2 +-
 .../region-object-lifetime-in-coercion.stderr |  4 ++--
 .../regions-close-object-into-object-2.stderr |  2 +-
 .../regions-close-object-into-object-4.stderr |  2 +-
 .../regions/regions-proc-bound-capture.stderr |  2 +-
 ...types_pin_lifetime_impl_trait-async.stderr | 11 +++-------
 .../dyn-trait-underscore.stderr               |  2 +-
 10 files changed, 30 insertions(+), 31 deletions(-)

diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index 74267a8dec059..5ad76e3964038 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -79,15 +79,22 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                             );
                         } else {
                             err.span_label(sup_origin.span(), "...is captured here...");
-                            err.span_note(
-                                return_sp,
-                                "...and is required to live as long as `'static` here",
-                            );
+                            if return_sp < sup_origin.span() {
+                                err.span_note(
+                                    return_sp,
+                                    "...and is required to live as long as `'static` here",
+                                );
+                            } else {
+                                err.span_label(
+                                    return_sp,
+                                    "...and is required to live as long as `'static` here",
+                                );
+                            }
                         }
                     } else {
                         err.span_label(
                             return_sp,
-                            "...is captured and required live as long as `'static` here",
+                            "...is captured and required to live as long as `'static` here",
                         );
                     }
 
@@ -104,7 +111,8 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                         };
                         let explicit =
                             format!("you can add an explicit `{}` lifetime bound", lifetime_name);
-                        let explicit_static = format!("explicit `'static` bound to {}", arg);
+                        let explicit_static =
+                            format!("explicit `'static` bound to the lifetime of {}", arg);
                         let captures = format!("captures data from {}", arg);
                         let add_static_bound =
                             "alternatively, add an explicit `'static` bound to this reference";
diff --git a/src/test/ui/async-await/issues/issue-62097.stderr b/src/test/ui/async-await/issues/issue-62097.stderr
index b3754cce40833..aa443b9d2fc16 100644
--- a/src/test/ui/async-await/issues/issue-62097.stderr
+++ b/src/test/ui/async-await/issues/issue-62097.stderr
@@ -6,12 +6,8 @@ LL |     pub async fn run_dummy_fn(&self) {
    |                               |
    |                               this data with an anonymous lifetime `'_`...
    |                               ...is captured here...
-   |
-note: ...and is required to live as long as `'static` here
-  --> $DIR/issue-62097.rs:13:9
-   |
 LL |         foo(|| self.bar()).await;
-   |         ^^^
+   |         --- ...and is required to live as long as `'static` here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index 5ab450a85d9e1..baed43783a13c 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -47,7 +47,7 @@ note: ...and is required to live as long as `'static` here
    |
 LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
    |                        ^^^^^^^^^^^^^^^^^^^
-help: consider changing the `impl Trait`'s explicit `'static` bound to argument `x`
+help: consider changing the `impl Trait`'s explicit `'static` bound to the lifetime of argument `x`
    |
 LL | fn elided2(x: &i32) -> impl Copy + '_ { x }
    |                                    ^^
@@ -69,7 +69,7 @@ note: ...and is required to live as long as `'static` here
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
    |                                 ^^^^^^^^^^^^^^^^^^^
-help: consider changing the `impl Trait`'s explicit `'static` bound to argument `x`
+help: consider changing the `impl Trait`'s explicit `'static` bound to the lifetime of argument `x`
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                             ^^
@@ -97,7 +97,7 @@ note: ...and is required to live as long as `'static` here
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
    |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-help: consider changing the `impl Trait`'s explicit `'static` bound to argument `x`
+help: consider changing the `impl Trait`'s explicit `'static` bound to the lifetime of argument `x`
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'a { x }
    |                                                           ^^
@@ -157,7 +157,7 @@ LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |               |
    |               this data with an anonymous lifetime `'_`...
    |
-help: consider changing the trait object's explicit `'static` bound to argument `x`
+help: consider changing the trait object's explicit `'static` bound to the lifetime of argument `x`
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                        ^^
@@ -172,7 +172,7 @@ error[E0758]: cannot infer an appropriate lifetime
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |                     ------- this data with lifetime `'a`...         ^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to argument `x`
+help: consider changing the trait object's explicit `'static` bound to the lifetime of argument `x`
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                                 ^^
diff --git a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
index ac7502e004c44..d461001adead9 100644
--- a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
+++ b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
@@ -5,7 +5,7 @@ LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait> {
    |             --------------- this data with an anonymous lifetime `'_`...
 ...
 LL |     ss.r
-   |     ^^^^ ...is captured and required live as long as `'static` here
+   |     ^^^^ ...is captured and required to live as long as `'static` here
    |
 help: to declare that the trait object captures data from argument `ss`, you can add an explicit `'_` lifetime bound
    |
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
index fe191e9b69565..c684373c67e9d 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
@@ -6,7 +6,7 @@ LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
 LL |     let x: Box<dyn Foo + 'static> = Box::new(v);
    |                                              ^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to argument `v`
+help: consider changing the trait object's explicit `'static` bound to the lifetime of argument `v`
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
@@ -23,7 +23,7 @@ LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
 LL |     Box::new(v)
    |              ^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to argument `v`
+help: consider changing the trait object's explicit `'static` bound to the lifetime of argument `v`
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + '_> {
    |                                 ^^
diff --git a/src/test/ui/regions/regions-close-object-into-object-2.stderr b/src/test/ui/regions/regions-close-object-into-object-2.stderr
index 2ea970afcede2..c4ba395179831 100644
--- a/src/test/ui/regions/regions-close-object-into-object-2.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-2.stderr
@@ -6,7 +6,7 @@ LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
 LL |     box B(&*v) as Box<dyn X>
    |           ^^^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to argument `v`
+help: consider changing the trait object's explicit `'static` bound to the lifetime of argument `v`
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'a> {
    |                                                            ^^
diff --git a/src/test/ui/regions/regions-close-object-into-object-4.stderr b/src/test/ui/regions/regions-close-object-into-object-4.stderr
index 493b7a1df9920..e45930bd95710 100644
--- a/src/test/ui/regions/regions-close-object-into-object-4.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-4.stderr
@@ -6,7 +6,7 @@ LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
 LL |     box B(&*v) as Box<dyn X>
    |           ^^^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to argument `v`
+help: consider changing the trait object's explicit `'static` bound to the lifetime of argument `v`
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'a> {
    |                                                    ^^
diff --git a/src/test/ui/regions/regions-proc-bound-capture.stderr b/src/test/ui/regions/regions-proc-bound-capture.stderr
index c10b9850a4e99..69c7256364d70 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.stderr
+++ b/src/test/ui/regions/regions-proc-bound-capture.stderr
@@ -7,7 +7,7 @@ LL |     // This is illegal, because the region bound on `proc` is 'static.
 LL |     Box::new(move || { *x })
    |              ^^^^^^^^^^^^^^ ...is captured here, requiring it to live as long as `'static`
    |
-help: consider changing the trait object's explicit `'static` bound to argument `x`
+help: consider changing the trait object's explicit `'static` bound to the lifetime of argument `x`
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + '_> {
    |                                                           ^^
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
index 69022607bd19e..9b04069136be2 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
@@ -2,15 +2,10 @@ error[E0758]: cannot infer an appropriate lifetime
   --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait-async.rs:8:16
    |
 LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
-   |                ^^^^  ---------- this data with an anonymous lifetime `'_`...
-   |                |
+   |                ^^^^  ----------     ---------- ...and is required to live as long as `'static` here
+   |                |     |
+   |                |     this data with an anonymous lifetime `'_`...
    |                ...is captured here...
-   |
-note: ...and is required to live as long as `'static` here
-  --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait-async.rs:8:37
-   |
-LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
-   |                                     ^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
index e768d7c8ab99f..fc4c801949512 100644
--- a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
+++ b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
@@ -5,7 +5,7 @@ LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T>> {
    |                ---- this data with an anonymous lifetime `'_`...
 LL |     //                      ^^^^^^^^^^^^^^^^^^^^^ bound *here* defaults to `'static`
 LL |     Box::new(items.iter())
-   |     ---------------^^^^--- ...is captured and required live as long as `'static` here
+   |     ---------------^^^^--- ...is captured and required to live as long as `'static` here
    |
 help: to declare that the trait object captures data from argument `items`, you can add an explicit `'_` lifetime bound
    |

From 6145918c83d10e9679805b8feff0286ce9e58afc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Wed, 3 Jun 2020 11:34:04 -0700
Subject: [PATCH 17/25] Change E0758 to E0759 to avoid conflict with #72912

---
 src/librustc_error_codes/error_codes.rs       |  1 +
 src/librustc_error_codes/error_codes/E0759.md | 67 +++++++++++++++++++
 .../nice_region_error/static_impl_trait.rs    |  2 +-
 .../ui/async-await/issues/issue-62097.stderr  |  4 +-
 .../must_outlive_least_region_or_bound.stderr | 20 +++---
 .../static-return-lifetime-infered.stderr     |  6 +-
 src/test/ui/issues/issue-16922.stderr         |  4 +-
 ...ect-lifetime-default-from-box-error.stderr |  4 +-
 .../region-object-lifetime-in-coercion.stderr |  8 +--
 .../regions-close-object-into-object-2.stderr |  4 +-
 .../regions-close-object-into-object-4.stderr |  4 +-
 .../regions/regions-proc-bound-capture.stderr |  4 +-
 ...types_pin_lifetime_impl_trait-async.stderr |  4 +-
 ..._self_types_pin_lifetime_impl_trait.stderr |  4 +-
 .../missing-lifetimes-in-signature.stderr     |  4 +-
 .../dyn-trait-underscore.stderr               |  4 +-
 16 files changed, 106 insertions(+), 38 deletions(-)
 create mode 100644 src/librustc_error_codes/error_codes/E0759.md

diff --git a/src/librustc_error_codes/error_codes.rs b/src/librustc_error_codes/error_codes.rs
index 760b4d7ba00a3..2e3ba13f37911 100644
--- a/src/librustc_error_codes/error_codes.rs
+++ b/src/librustc_error_codes/error_codes.rs
@@ -438,6 +438,7 @@ E0752: include_str!("./error_codes/E0752.md"),
 E0753: include_str!("./error_codes/E0753.md"),
 E0754: include_str!("./error_codes/E0754.md"),
 E0758: include_str!("./error_codes/E0758.md"),
+E0759: include_str!("./error_codes/E0759.md"),
 E0760: include_str!("./error_codes/E0760.md"),
 ;
 //  E0006, // merged with E0005
diff --git a/src/librustc_error_codes/error_codes/E0759.md b/src/librustc_error_codes/error_codes/E0759.md
new file mode 100644
index 0000000000000..a74759bdf634b
--- /dev/null
+++ b/src/librustc_error_codes/error_codes/E0759.md
@@ -0,0 +1,67 @@
+A `'static` requirement in a return type involving a trait is not fulfilled.
+
+Erroneous code examples:
+
+```compile_fail,E0759
+use std::fmt::Debug;
+
+fn foo(x: &i32) -> impl Debug {
+    x
+}
+```
+
+```compile_fail,E0759
+# use std::fmt::Debug;
+fn bar(x: &i32) -> Box<dyn Debug> {
+    Box::new(x)
+}
+```
+
+These examples have the same semantics as the following:
+
+```compile_fail,E0759
+# use std::fmt::Debug;
+fn foo(x: &i32) -> impl Debug + 'static {
+    x
+}
+```
+
+```compile_fail,E0759
+# use std::fmt::Debug;
+fn bar(x: &i32) -> Box<dyn Debug + 'static> {
+    Box::new(x)
+}
+```
+
+Both [`dyn Trait`] and [`impl Trait`] in return types have a an implicit
+`'static` requirement, meaning that the value implementing them that is being
+returned has to be either a `'static` borrow or an owned value.
+
+In order to change the requirement from `'static` to be a lifetime derived from
+its arguments, you can add an explicit bound, either to an anonymous lifetime
+`'_` or some appropriate named lifetime.
+
+```
+# use std::fmt::Debug;
+fn foo(x: &i32) -> impl Debug + '_ {
+    x
+}
+fn bar(x: &i32) -> Box<dyn Debug + '_> {
+    Box::new(x)
+}
+```
+
+These are equivalent to the following explicit lifetime annotations:
+
+```
+# use std::fmt::Debug;
+fn foo<'a>(x: &'a i32) -> impl Debug + 'a {
+    x
+}
+fn bar<'a>(x: &'a i32) -> Box<dyn Debug + 'a> {
+    Box::new(x)
+}
+```
+
+[`dyn Trait`]: https://doc.rust-lang.org/book/ch17-02-trait-objects.html#using-trait-objects-that-allow-for-values-of-different-types
+[`impl Trait`]: https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits
diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
index 5ad76e3964038..853a414290704 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
@@ -40,7 +40,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                     let mut err = struct_span_err!(
                         self.tcx().sess,
                         sp,
-                        E0758,
+                        E0759,
                         "cannot infer an appropriate lifetime"
                     );
                     err.span_label(
diff --git a/src/test/ui/async-await/issues/issue-62097.stderr b/src/test/ui/async-await/issues/issue-62097.stderr
index aa443b9d2fc16..0f58b158904db 100644
--- a/src/test/ui/async-await/issues/issue-62097.stderr
+++ b/src/test/ui/async-await/issues/issue-62097.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/issue-62097.rs:12:31
    |
 LL |     pub async fn run_dummy_fn(&self) {
@@ -11,4 +11,4 @@ LL |         foo(|| self.bar()).await;
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0758`.
+For more information about this error, try `rustc --explain E0759`.
diff --git a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
index baed43783a13c..e1fa4f02b6fcf 100644
--- a/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
+++ b/src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:3:35
    |
 LL | fn elided(x: &i32) -> impl Copy { x }
@@ -16,7 +16,7 @@ help: to declare that the `impl Trait` captures data from argument `x`, you can
 LL | fn elided(x: &i32) -> impl Copy + '_ { x }
    |                                 ^^^^
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:6:44
    |
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy { x }
@@ -34,7 +34,7 @@ help: to declare that the `impl Trait` captures data from argument `x`, you can
 LL | fn explicit<'a>(x: &'a i32) -> impl Copy + 'a { x }
    |                                          ^^^^
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:9:46
    |
 LL | fn elided2(x: &i32) -> impl Copy + 'static { x }
@@ -56,7 +56,7 @@ help: alternatively, add an explicit `'static` bound to this reference
 LL | fn elided2(x: &'static i32) -> impl Copy + 'static { x }
    |               ^^^^^^^^^^^^
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:12:55
    |
 LL | fn explicit2<'a>(x: &'a i32) -> impl Copy + 'static { x }
@@ -86,7 +86,7 @@ LL | fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
    |               |
    |               help: add explicit lifetime `'a` to the type of `x`: `&'a i32`
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:33:69
    |
 LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
@@ -123,7 +123,7 @@ LL | fn ty_param_wont_outlive_static<T:Debug>(x: T) -> impl Debug + 'static {
    |                                 |
    |                                 help: consider adding an explicit lifetime bound...: `T: 'static +`
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:18:50
    |
 LL | fn elided3(x: &i32) -> Box<dyn Debug> { Box::new(x) }
@@ -136,7 +136,7 @@ help: to declare that the trait object captures data from argument `x`, you can
 LL | fn elided3(x: &i32) -> Box<dyn Debug + '_> { Box::new(x) }
    |                                      ^^^^
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:21:59
    |
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug> { Box::new(x) }
@@ -149,7 +149,7 @@ help: to declare that the trait object captures data from argument `x`, you can
 LL | fn explicit3<'a>(x: &'a i32) -> Box<dyn Debug + 'a> { Box::new(x) }
    |                                               ^^^^
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:24:60
    |
 LL | fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
@@ -166,7 +166,7 @@ help: alternatively, add an explicit `'static` bound to this reference
 LL | fn elided4(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x) }
    |               ^^^^^^^^^^^^
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/must_outlive_least_region_or_bound.rs:27:69
    |
 LL | fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
@@ -183,5 +183,5 @@ LL | fn explicit4<'a>(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x)
 
 error: aborting due to 12 previous errors
 
-Some errors have detailed explanations: E0310, E0621, E0623, E0758.
+Some errors have detailed explanations: E0310, E0621, E0623, E0759.
 For more information about an error, try `rustc --explain E0310`.
diff --git a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
index 90aada01d9917..df0db6e4fc6df 100644
--- a/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
+++ b/src/test/ui/impl-trait/static-return-lifetime-infered.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/static-return-lifetime-infered.rs:7:16
    |
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> {
@@ -18,7 +18,7 @@ help: to declare that the `impl Trait` captures data from argument `self`, you c
 LL |     fn iter_values_anon(&self) -> impl Iterator<Item=u32> + '_ {
    |                                                           ^^^^
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/static-return-lifetime-infered.rs:11:16
    |
 LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> {
@@ -40,4 +40,4 @@ LL |     fn iter_values<'a>(&'a self) -> impl Iterator<Item=u32> + 'a {
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0758`.
+For more information about this error, try `rustc --explain E0759`.
diff --git a/src/test/ui/issues/issue-16922.stderr b/src/test/ui/issues/issue-16922.stderr
index ec80f6569f5ac..919594fc9af4b 100644
--- a/src/test/ui/issues/issue-16922.stderr
+++ b/src/test/ui/issues/issue-16922.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/issue-16922.rs:4:14
    |
 LL | fn foo<T: Any>(value: &T) -> Box<dyn Any> {
@@ -13,4 +13,4 @@ LL | fn foo<T: Any>(value: &T) -> Box<dyn Any + '_> {
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0758`.
+For more information about this error, try `rustc --explain E0759`.
diff --git a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
index d461001adead9..1b1e0d9610724 100644
--- a/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
+++ b/src/test/ui/object-lifetime/object-lifetime-default-from-box-error.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/object-lifetime-default-from-box-error.rs:18:5
    |
 LL | fn load(ss: &mut SomeStruct) -> Box<dyn SomeTrait> {
@@ -23,5 +23,5 @@ LL |     ss.r = b;
 
 error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0621, E0758.
+Some errors have detailed explanations: E0621, E0759.
 For more information about an error, try `rustc --explain E0621`.
diff --git a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
index c684373c67e9d..7f5a3a47976c7 100644
--- a/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
+++ b/src/test/ui/regions/region-object-lifetime-in-coercion.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:8:46
    |
 LL | fn a(v: &[u8]) -> Box<dyn Foo + 'static> {
@@ -15,7 +15,7 @@ help: alternatively, add an explicit `'static` bound to this reference
 LL | fn a(v: &'static [u8]) -> Box<dyn Foo + 'static> {
    |         ^^^^^^^^^^^^^
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:13:14
    |
 LL | fn b(v: &[u8]) -> Box<dyn Foo + 'static> {
@@ -32,7 +32,7 @@ help: alternatively, add an explicit `'static` bound to this reference
 LL | fn b(v: &'static [u8]) -> Box<dyn Foo + 'static> {
    |         ^^^^^^^^^^^^^
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/region-object-lifetime-in-coercion.rs:19:14
    |
 LL | fn c(v: &[u8]) -> Box<dyn Foo> {
@@ -79,5 +79,5 @@ LL |     Box::new(v)
 
 error: aborting due to 4 previous errors
 
-Some errors have detailed explanations: E0495, E0758.
+Some errors have detailed explanations: E0495, E0759.
 For more information about an error, try `rustc --explain E0495`.
diff --git a/src/test/ui/regions/regions-close-object-into-object-2.stderr b/src/test/ui/regions/regions-close-object-into-object-2.stderr
index c4ba395179831..114e4052aae09 100644
--- a/src/test/ui/regions/regions-close-object-into-object-2.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-2.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-2.rs:10:11
    |
 LL | fn g<'a, T: 'static>(v: Box<dyn A<T> + 'a>) -> Box<dyn X + 'static> {
@@ -17,4 +17,4 @@ LL | fn g<'a, T: 'static>(v: std::boxed::Box<(dyn A<T> + 'static)>) -> Box<dyn X
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0758`.
+For more information about this error, try `rustc --explain E0759`.
diff --git a/src/test/ui/regions/regions-close-object-into-object-4.stderr b/src/test/ui/regions/regions-close-object-into-object-4.stderr
index e45930bd95710..850d81940791f 100644
--- a/src/test/ui/regions/regions-close-object-into-object-4.stderr
+++ b/src/test/ui/regions/regions-close-object-into-object-4.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/regions-close-object-into-object-4.rs:10:11
    |
 LL | fn i<'a, T, U>(v: Box<dyn A<U>+'a>) -> Box<dyn X + 'static> {
@@ -17,4 +17,4 @@ LL | fn i<'a, T, U>(v: std::boxed::Box<(dyn A<U> + 'static)>) -> Box<dyn X + 'st
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0758`.
+For more information about this error, try `rustc --explain E0759`.
diff --git a/src/test/ui/regions/regions-proc-bound-capture.stderr b/src/test/ui/regions/regions-proc-bound-capture.stderr
index 69c7256364d70..67eee3bb6e281 100644
--- a/src/test/ui/regions/regions-proc-bound-capture.stderr
+++ b/src/test/ui/regions/regions-proc-bound-capture.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/regions-proc-bound-capture.rs:9:14
    |
 LL | fn static_proc(x: &isize) -> Box<dyn FnMut() -> (isize) + 'static> {
@@ -18,4 +18,4 @@ LL | fn static_proc(x: &'static isize) -> Box<dyn FnMut() -> (isize) + 'static>
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0758`.
+For more information about this error, try `rustc --explain E0759`.
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
index 9b04069136be2..88bd990b1e81b 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait-async.rs:8:16
    |
 LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
@@ -9,4 +9,4 @@ LL |     async fn f(self: Pin<&Self>) -> impl Clone { self }
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0758`.
+For more information about this error, try `rustc --explain E0759`.
diff --git a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
index c37eb2d136ef1..2e10ab3d3f9b8 100644
--- a/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
+++ b/src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/arbitrary_self_types_pin_lifetime_impl_trait.rs:6:44
    |
 LL |     fn f(self: Pin<&Self>) -> impl Clone { self }
@@ -18,4 +18,4 @@ LL |     fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0758`.
+For more information about this error, try `rustc --explain E0759`.
diff --git a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
index 7e8ab1bfe1633..9ab060328537b 100644
--- a/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
+++ b/src/test/ui/suggestions/lifetimes/missing-lifetimes-in-signature.stderr
@@ -6,7 +6,7 @@ LL | fn baz<G: 'a, T>(g: G, dest: &mut T) -> impl FnOnce() + '_
    |        |
    |        help: consider introducing lifetime `'a` here: `'a,`
 
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/missing-lifetimes-in-signature.rs:19:5
    |
 LL |   fn foo<G, T>(g: G, dest: &mut T) -> impl FnOnce()
@@ -125,5 +125,5 @@ LL | fn bak<'a, G, T>(g: G, dest: &'a mut T) -> impl FnOnce() + 'a
 
 error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0261, E0309, E0621, E0758.
+Some errors have detailed explanations: E0261, E0309, E0621, E0759.
 For more information about an error, try `rustc --explain E0261`.
diff --git a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
index fc4c801949512..dda5de431d309 100644
--- a/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
+++ b/src/test/ui/underscore-lifetime/dyn-trait-underscore.stderr
@@ -1,4 +1,4 @@
-error[E0758]: cannot infer an appropriate lifetime
+error[E0759]: cannot infer an appropriate lifetime
   --> $DIR/dyn-trait-underscore.rs:8:20
    |
 LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T>> {
@@ -14,4 +14,4 @@ LL | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item=&T> + '_> {
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0758`.
+For more information about this error, try `rustc --explain E0759`.

From c29b3fa1484c625bd34cb4d94fc76f36c6233447 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Fri, 29 May 2020 09:24:59 -0700
Subject: [PATCH 18/25] On recursive ADT, provide indirection structured
 suggestion

---
 src/librustc_errors/diagnostic.rs             | 23 +++++++
 src/librustc_errors/diagnostic_builder.rs     | 13 ++++
 src/librustc_middle/ty/util.rs                | 10 ++-
 .../traits/error_reporting/mod.rs             | 66 +++++++++++++++----
 src/librustc_typeck/check/mod.rs              |  6 +-
 .../infinite-tag-type-recursion.stderr        |  9 ++-
 src/test/ui/issues/issue-17431-1.stderr       | 11 +++-
 src/test/ui/issues/issue-17431-2.stderr       | 22 +++++--
 src/test/ui/issues/issue-17431-3.stderr       | 11 +++-
 src/test/ui/issues/issue-17431-4.stderr       | 11 +++-
 src/test/ui/issues/issue-17431-5.stderr       | 11 +++-
 src/test/ui/issues/issue-17431-6.stderr       |  9 ++-
 src/test/ui/issues/issue-17431-7.stderr       |  9 ++-
 src/test/ui/issues/issue-2718-a.stderr        |  9 ++-
 src/test/ui/issues/issue-3008-1.stderr        |  9 ++-
 src/test/ui/issues/issue-3008-2.stderr        | 11 +++-
 src/test/ui/issues/issue-3008-3.stderr        |  9 ++-
 src/test/ui/issues/issue-32326.stderr         |  5 +-
 src/test/ui/issues/issue-3779.stderr          | 11 +++-
 src/test/ui/issues/issue-57271.stderr         | 18 ++++-
 src/test/ui/recursion/recursive-enum.stderr   |  9 ++-
 src/test/ui/sized-cycle-note.stderr           | 22 +++++--
 src/test/ui/span/E0072.stderr                 | 11 +++-
 src/test/ui/span/multiline-span-E0072.stderr  | 11 +++-
 src/test/ui/span/recursive-type-field.stderr  | 23 ++++---
 src/test/ui/type/type-recursive.stderr        | 11 +++-
 .../ui/union/union-nonrepresentable.stderr    | 11 +++-
 27 files changed, 315 insertions(+), 66 deletions(-)

diff --git a/src/librustc_errors/diagnostic.rs b/src/librustc_errors/diagnostic.rs
index cff83c3d5cda2..acaa26c6ad2fc 100644
--- a/src/librustc_errors/diagnostic.rs
+++ b/src/librustc_errors/diagnostic.rs
@@ -296,6 +296,29 @@ impl Diagnostic {
         self
     }
 
+    pub fn multipart_suggestions(
+        &mut self,
+        msg: &str,
+        suggestions: Vec<Vec<(Span, String)>>,
+        applicability: Applicability,
+    ) -> &mut Self {
+        self.suggestions.push(CodeSuggestion {
+            substitutions: suggestions
+                .into_iter()
+                .map(|suggestion| Substitution {
+                    parts: suggestion
+                        .into_iter()
+                        .map(|(span, snippet)| SubstitutionPart { snippet, span })
+                        .collect(),
+                })
+                .collect(),
+            msg: msg.to_owned(),
+            style: SuggestionStyle::ShowCode,
+            applicability,
+        });
+        self
+    }
+
     /// Prints out a message with for a multipart suggestion without showing the suggested code.
     ///
     /// This is intended to be used for suggestions that are obvious in what the changes need to
diff --git a/src/librustc_errors/diagnostic_builder.rs b/src/librustc_errors/diagnostic_builder.rs
index 2dbd9f4e52fad..22bf8fe34aa15 100644
--- a/src/librustc_errors/diagnostic_builder.rs
+++ b/src/librustc_errors/diagnostic_builder.rs
@@ -260,6 +260,19 @@ impl<'a> DiagnosticBuilder<'a> {
         self
     }
 
+    pub fn multipart_suggestions(
+        &mut self,
+        msg: &str,
+        suggestions: Vec<Vec<(Span, String)>>,
+        applicability: Applicability,
+    ) -> &mut Self {
+        if !self.0.allow_suggestions {
+            return self;
+        }
+        self.0.diagnostic.multipart_suggestions(msg, suggestions, applicability);
+        self
+    }
+
     pub fn tool_only_multipart_suggestion(
         &mut self,
         msg: &str,
diff --git a/src/librustc_middle/ty/util.rs b/src/librustc_middle/ty/util.rs
index c2b794ca4bdd9..5cdfa6f90128d 100644
--- a/src/librustc_middle/ty/util.rs
+++ b/src/librustc_middle/ty/util.rs
@@ -827,7 +827,15 @@ impl<'tcx> ty::TyS<'tcx> {
                     // Find non representable fields with their spans
                     fold_repr(def.all_fields().map(|field| {
                         let ty = field.ty(tcx, substs);
-                        let span = tcx.hir().span_if_local(field.did).unwrap_or(sp);
+                        let span = match field
+                            .did
+                            .as_local()
+                            .map(|id| tcx.hir().as_local_hir_id(id))
+                            .and_then(|id| tcx.hir().find(id))
+                        {
+                            Some(hir::Node::Field(field)) => field.ty.span,
+                            _ => sp,
+                        };
                         match is_type_structurally_recursive(
                             tcx,
                             span,
diff --git a/src/librustc_trait_selection/traits/error_reporting/mod.rs b/src/librustc_trait_selection/traits/error_reporting/mod.rs
index 1b72a4bf84f19..3457f7b4580c5 100644
--- a/src/librustc_trait_selection/traits/error_reporting/mod.rs
+++ b/src/librustc_trait_selection/traits/error_reporting/mod.rs
@@ -1747,24 +1747,62 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
 pub fn recursive_type_with_infinite_size_error(
     tcx: TyCtxt<'tcx>,
     type_def_id: DefId,
-) -> DiagnosticBuilder<'tcx> {
+    spans: Vec<Span>,
+) {
     assert!(type_def_id.is_local());
     let span = tcx.hir().span_if_local(type_def_id).unwrap();
     let span = tcx.sess.source_map().guess_head_span(span);
-    let mut err = struct_span_err!(
-        tcx.sess,
-        span,
-        E0072,
-        "recursive type `{}` has infinite size",
-        tcx.def_path_str(type_def_id)
-    );
+    let path = tcx.def_path_str(type_def_id);
+    let mut err =
+        struct_span_err!(tcx.sess, span, E0072, "recursive type `{}` has infinite size", path);
     err.span_label(span, "recursive type has infinite size");
-    err.help(&format!(
-        "insert indirection (e.g., a `Box`, `Rc`, or `&`) \
-                           at some point to make `{}` representable",
-        tcx.def_path_str(type_def_id)
-    ));
-    err
+    for &span in &spans {
+        err.span_label(span, "recursive without indirection");
+    }
+    let short_msg = format!("insert some indirection to make `{}` representable", path);
+    let msg = format!(
+        "insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `{}` representable",
+        path,
+    );
+    match &spans[..] {
+        [span] => {
+            err.multipart_suggestions(
+                &short_msg,
+                vec![
+                    vec![
+                        (span.shrink_to_lo(), "Box<".to_string()),
+                        (span.shrink_to_hi(), ">".to_string()),
+                    ],
+                    vec![
+                        (span.shrink_to_lo(), "Rc<".to_string()),
+                        (span.shrink_to_hi(), ">".to_string()),
+                    ],
+                    vec![(span.shrink_to_lo(), "&".to_string())],
+                ],
+                Applicability::HasPlaceholders,
+            );
+        }
+        _ if spans.len() <= 4 => {
+            err.multipart_suggestion(
+                &msg,
+                spans
+                    .iter()
+                    .flat_map(|&span| {
+                        vec![
+                            (span.shrink_to_lo(), "Box<".to_string()),
+                            (span.shrink_to_hi(), ">".to_string()),
+                        ]
+                        .into_iter()
+                    })
+                    .collect(),
+                Applicability::HasPlaceholders,
+            );
+        }
+        _ => {
+            err.help(&msg);
+        }
+    }
+    err.emit();
 }
 
 /// Summarizes information
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index f2aeed4f1e465..1e8a149d7d9ec 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -2390,11 +2390,7 @@ fn check_representable(tcx: TyCtxt<'_>, sp: Span, item_def_id: LocalDefId) -> bo
     // caught by case 1.
     match rty.is_representable(tcx, sp) {
         Representability::SelfRecursive(spans) => {
-            let mut err = recursive_type_with_infinite_size_error(tcx, item_def_id.to_def_id());
-            for span in spans {
-                err.span_label(span, "recursive without indirection");
-            }
-            err.emit();
+            recursive_type_with_infinite_size_error(tcx, item_def_id.to_def_id(), spans);
             return false;
         }
         Representability::Representable | Representability::ContainsRecursive => (),
diff --git a/src/test/ui/infinite/infinite-tag-type-recursion.stderr b/src/test/ui/infinite/infinite-tag-type-recursion.stderr
index 11f82b842ba6f..b6a4d8f4cf563 100644
--- a/src/test/ui/infinite/infinite-tag-type-recursion.stderr
+++ b/src/test/ui/infinite/infinite-tag-type-recursion.stderr
@@ -6,7 +6,14 @@ LL | enum MList { Cons(isize, MList), Nil }
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `MList` representable
+help: insert some indirection to make `MList` representable
+   |
+LL | enum MList { Cons(isize, Box<MList>), Nil }
+   |                          ^^^^     ^
+LL | enum MList { Cons(isize, Rc<MList>), Nil }
+   |                          ^^^     ^
+LL | enum MList { Cons(isize, &MList), Nil }
+   |                          ^
 
 error[E0391]: cycle detected when computing drop-check constraints for `MList`
   --> $DIR/infinite-tag-type-recursion.rs:1:1
diff --git a/src/test/ui/issues/issue-17431-1.stderr b/src/test/ui/issues/issue-17431-1.stderr
index eb5a1366e8953..8d44154650e04 100644
--- a/src/test/ui/issues/issue-17431-1.stderr
+++ b/src/test/ui/issues/issue-17431-1.stderr
@@ -2,11 +2,18 @@ error[E0072]: recursive type `Foo` has infinite size
   --> $DIR/issue-17431-1.rs:1:1
    |
 LL | struct Foo { foo: Option<Option<Foo>> }
-   | ^^^^^^^^^^   ------------------------ recursive without indirection
+   | ^^^^^^^^^^        ------------------- recursive without indirection
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Foo` representable
+help: insert some indirection to make `Foo` representable
+   |
+LL | struct Foo { foo: Box<Option<Option<Foo>>> }
+   |                   ^^^^                   ^
+LL | struct Foo { foo: Rc<Option<Option<Foo>>> }
+   |                   ^^^                   ^
+LL | struct Foo { foo: &Option<Option<Foo>> }
+   |                   ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-2.stderr b/src/test/ui/issues/issue-17431-2.stderr
index 3a7b0e9ce7997..b06184e84da28 100644
--- a/src/test/ui/issues/issue-17431-2.stderr
+++ b/src/test/ui/issues/issue-17431-2.stderr
@@ -2,21 +2,35 @@ error[E0072]: recursive type `Baz` has infinite size
   --> $DIR/issue-17431-2.rs:1:1
    |
 LL | struct Baz { q: Option<Foo> }
-   | ^^^^^^^^^^   -------------- recursive without indirection
+   | ^^^^^^^^^^      ----------- recursive without indirection
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Baz` representable
+help: insert some indirection to make `Baz` representable
+   |
+LL | struct Baz { q: Box<Option<Foo>> }
+   |                 ^^^^           ^
+LL | struct Baz { q: Rc<Option<Foo>> }
+   |                 ^^^           ^
+LL | struct Baz { q: &Option<Foo> }
+   |                 ^
 
 error[E0072]: recursive type `Foo` has infinite size
   --> $DIR/issue-17431-2.rs:4:1
    |
 LL | struct Foo { q: Option<Baz> }
-   | ^^^^^^^^^^   -------------- recursive without indirection
+   | ^^^^^^^^^^      ----------- recursive without indirection
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Foo` representable
+help: insert some indirection to make `Foo` representable
+   |
+LL | struct Foo { q: Box<Option<Baz>> }
+   |                 ^^^^           ^
+LL | struct Foo { q: Rc<Option<Baz>> }
+   |                 ^^^           ^
+LL | struct Foo { q: &Option<Baz> }
+   |                 ^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/issues/issue-17431-3.stderr b/src/test/ui/issues/issue-17431-3.stderr
index 675a2e2714209..f32bd70fd6d94 100644
--- a/src/test/ui/issues/issue-17431-3.stderr
+++ b/src/test/ui/issues/issue-17431-3.stderr
@@ -2,11 +2,18 @@ error[E0072]: recursive type `Foo` has infinite size
   --> $DIR/issue-17431-3.rs:3:1
    |
 LL | struct Foo { foo: Mutex<Option<Foo>> }
-   | ^^^^^^^^^^   ----------------------- recursive without indirection
+   | ^^^^^^^^^^        ------------------ recursive without indirection
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Foo` representable
+help: insert some indirection to make `Foo` representable
+   |
+LL | struct Foo { foo: Box<Mutex<Option<Foo>>> }
+   |                   ^^^^                  ^
+LL | struct Foo { foo: Rc<Mutex<Option<Foo>>> }
+   |                   ^^^                  ^
+LL | struct Foo { foo: &Mutex<Option<Foo>> }
+   |                   ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-4.stderr b/src/test/ui/issues/issue-17431-4.stderr
index aff9071095ca0..372c5e975c844 100644
--- a/src/test/ui/issues/issue-17431-4.stderr
+++ b/src/test/ui/issues/issue-17431-4.stderr
@@ -2,11 +2,18 @@ error[E0072]: recursive type `Foo` has infinite size
   --> $DIR/issue-17431-4.rs:3:1
    |
 LL | struct Foo<T> { foo: Option<Option<Foo<T>>>, marker: marker::PhantomData<T> }
-   | ^^^^^^^^^^^^^   --------------------------- recursive without indirection
+   | ^^^^^^^^^^^^^        ---------------------- recursive without indirection
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Foo` representable
+help: insert some indirection to make `Foo` representable
+   |
+LL | struct Foo<T> { foo: Box<Option<Option<Foo<T>>>>, marker: marker::PhantomData<T> }
+   |                      ^^^^                      ^
+LL | struct Foo<T> { foo: Rc<Option<Option<Foo<T>>>>, marker: marker::PhantomData<T> }
+   |                      ^^^                      ^
+LL | struct Foo<T> { foo: &Option<Option<Foo<T>>>, marker: marker::PhantomData<T> }
+   |                      ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-5.stderr b/src/test/ui/issues/issue-17431-5.stderr
index 537f9f34f55ca..01b850ac33694 100644
--- a/src/test/ui/issues/issue-17431-5.stderr
+++ b/src/test/ui/issues/issue-17431-5.stderr
@@ -2,11 +2,18 @@ error[E0072]: recursive type `Bar` has infinite size
   --> $DIR/issue-17431-5.rs:5:1
    |
 LL | struct Bar<T> { x: Bar<Foo> , marker: marker::PhantomData<T> }
-   | ^^^^^^^^^^^^^   ----------- recursive without indirection
+   | ^^^^^^^^^^^^^      -------- recursive without indirection
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Bar` representable
+help: insert some indirection to make `Bar` representable
+   |
+LL | struct Bar<T> { x: Box<Bar<Foo>> , marker: marker::PhantomData<T> }
+   |                    ^^^^        ^
+LL | struct Bar<T> { x: Rc<Bar<Foo>> , marker: marker::PhantomData<T> }
+   |                    ^^^        ^
+LL | struct Bar<T> { x: &Bar<Foo> , marker: marker::PhantomData<T> }
+   |                    ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-6.stderr b/src/test/ui/issues/issue-17431-6.stderr
index cb2dab9501488..ce6c2db07fb6d 100644
--- a/src/test/ui/issues/issue-17431-6.stderr
+++ b/src/test/ui/issues/issue-17431-6.stderr
@@ -6,7 +6,14 @@ LL | enum Foo { X(Mutex<Option<Foo>>) }
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Foo` representable
+help: insert some indirection to make `Foo` representable
+   |
+LL | enum Foo { X(Box<Mutex<Option<Foo>>>) }
+   |              ^^^^                  ^
+LL | enum Foo { X(Rc<Mutex<Option<Foo>>>) }
+   |              ^^^                  ^
+LL | enum Foo { X(&Mutex<Option<Foo>>) }
+   |              ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-7.stderr b/src/test/ui/issues/issue-17431-7.stderr
index de70851da4b5f..4fb563ba502f2 100644
--- a/src/test/ui/issues/issue-17431-7.stderr
+++ b/src/test/ui/issues/issue-17431-7.stderr
@@ -6,7 +6,14 @@ LL | enum Foo { Voo(Option<Option<Foo>>) }
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Foo` representable
+help: insert some indirection to make `Foo` representable
+   |
+LL | enum Foo { Voo(Box<Option<Option<Foo>>>) }
+   |                ^^^^                   ^
+LL | enum Foo { Voo(Rc<Option<Option<Foo>>>) }
+   |                ^^^                   ^
+LL | enum Foo { Voo(&Option<Option<Foo>>) }
+   |                ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-2718-a.stderr b/src/test/ui/issues/issue-2718-a.stderr
index 0f52c79192843..48b7a61e059ea 100644
--- a/src/test/ui/issues/issue-2718-a.stderr
+++ b/src/test/ui/issues/issue-2718-a.stderr
@@ -7,7 +7,14 @@ LL |     pub struct Pong(SendPacket<Ping>);
    |     |               recursive without indirection
    |     recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `pingpong::Pong` representable
+help: insert some indirection to make `pingpong::Pong` representable
+   |
+LL |     pub struct Pong(Box<SendPacket<Ping>>);
+   |                     ^^^^                ^
+LL |     pub struct Pong(Rc<SendPacket<Ping>>);
+   |                     ^^^                ^
+LL |     pub struct Pong(&SendPacket<Ping>);
+   |                     ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-3008-1.stderr b/src/test/ui/issues/issue-3008-1.stderr
index f12274134ee05..d1173a4b3334c 100644
--- a/src/test/ui/issues/issue-3008-1.stderr
+++ b/src/test/ui/issues/issue-3008-1.stderr
@@ -7,7 +7,14 @@ LL | enum Bar {
 LL |     BarSome(Bar)
    |             --- recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Bar` representable
+help: insert some indirection to make `Bar` representable
+   |
+LL |     BarSome(Box<Bar>)
+   |             ^^^^   ^
+LL |     BarSome(Rc<Bar>)
+   |             ^^^   ^
+LL |     BarSome(&Bar)
+   |             ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-3008-2.stderr b/src/test/ui/issues/issue-3008-2.stderr
index acc15f4b57c73..4fd60639b21a8 100644
--- a/src/test/ui/issues/issue-3008-2.stderr
+++ b/src/test/ui/issues/issue-3008-2.stderr
@@ -2,11 +2,18 @@ error[E0072]: recursive type `Bar` has infinite size
   --> $DIR/issue-3008-2.rs:2:1
    |
 LL | struct Bar { x: Bar }
-   | ^^^^^^^^^^   ------ recursive without indirection
+   | ^^^^^^^^^^      --- recursive without indirection
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Bar` representable
+help: insert some indirection to make `Bar` representable
+   |
+LL | struct Bar { x: Box<Bar> }
+   |                 ^^^^   ^
+LL | struct Bar { x: Rc<Bar> }
+   |                 ^^^   ^
+LL | struct Bar { x: &Bar }
+   |                 ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-3008-3.stderr b/src/test/ui/issues/issue-3008-3.stderr
index d08a3d9708db3..e6efad9188300 100644
--- a/src/test/ui/issues/issue-3008-3.stderr
+++ b/src/test/ui/issues/issue-3008-3.stderr
@@ -6,7 +6,14 @@ LL | enum E2<T> { V2(E2<E1>, marker::PhantomData<T>), }
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `E2` representable
+help: insert some indirection to make `E2` representable
+   |
+LL | enum E2<T> { V2(Box<E2<E1>>, marker::PhantomData<T>), }
+   |                 ^^^^      ^
+LL | enum E2<T> { V2(Rc<E2<E1>>, marker::PhantomData<T>), }
+   |                 ^^^      ^
+LL | enum E2<T> { V2(&E2<E1>, marker::PhantomData<T>), }
+   |                 ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-32326.stderr b/src/test/ui/issues/issue-32326.stderr
index 5967627e51a4b..0f3d3690b732e 100644
--- a/src/test/ui/issues/issue-32326.stderr
+++ b/src/test/ui/issues/issue-32326.stderr
@@ -8,7 +8,10 @@ LL |     Plus(Expr, Expr),
    |          |
    |          recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Expr` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Expr` representable
+   |
+LL |     Plus(Box<Expr>, Box<Expr>),
+   |          ^^^^    ^  ^^^^    ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-3779.stderr b/src/test/ui/issues/issue-3779.stderr
index ba1e842c610ba..9b50ddec12a44 100644
--- a/src/test/ui/issues/issue-3779.stderr
+++ b/src/test/ui/issues/issue-3779.stderr
@@ -5,9 +5,16 @@ LL | struct S {
    | ^^^^^^^^ recursive type has infinite size
 LL |
 LL |     element: Option<S>
-   |     ------------------ recursive without indirection
+   |              --------- recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `S` representable
+help: insert some indirection to make `S` representable
+   |
+LL |     element: Box<Option<S>>
+   |              ^^^^         ^
+LL |     element: Rc<Option<S>>
+   |              ^^^         ^
+LL |     element: &Option<S>
+   |              ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-57271.stderr b/src/test/ui/issues/issue-57271.stderr
index 4f164624f7a53..a6fe83a9b5636 100644
--- a/src/test/ui/issues/issue-57271.stderr
+++ b/src/test/ui/issues/issue-57271.stderr
@@ -7,7 +7,14 @@ LL |     Class(ClassTypeSignature),
 LL |     Array(TypeSignature),
    |           ------------- recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `ObjectType` representable
+help: insert some indirection to make `ObjectType` representable
+   |
+LL |     Array(Box<TypeSignature>),
+   |           ^^^^             ^
+LL |     Array(Rc<TypeSignature>),
+   |           ^^^             ^
+LL |     Array(&TypeSignature),
+   |           ^
 
 error[E0072]: recursive type `TypeSignature` has infinite size
   --> $DIR/issue-57271.rs:19:1
@@ -18,7 +25,14 @@ LL |     Base(BaseType),
 LL |     Object(ObjectType),
    |            ---------- recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `TypeSignature` representable
+help: insert some indirection to make `TypeSignature` representable
+   |
+LL |     Object(Box<ObjectType>),
+   |            ^^^^          ^
+LL |     Object(Rc<ObjectType>),
+   |            ^^^          ^
+LL |     Object(&ObjectType),
+   |            ^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/recursion/recursive-enum.stderr b/src/test/ui/recursion/recursive-enum.stderr
index e4674b57a6d21..c68badd458bce 100644
--- a/src/test/ui/recursion/recursive-enum.stderr
+++ b/src/test/ui/recursion/recursive-enum.stderr
@@ -6,7 +6,14 @@ LL | enum List<T> { Cons(T, List<T>), Nil }
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `List` representable
+help: insert some indirection to make `List` representable
+   |
+LL | enum List<T> { Cons(T, Box<List<T>>), Nil }
+   |                        ^^^^       ^
+LL | enum List<T> { Cons(T, Rc<List<T>>), Nil }
+   |                        ^^^       ^
+LL | enum List<T> { Cons(T, &List<T>), Nil }
+   |                        ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/sized-cycle-note.stderr b/src/test/ui/sized-cycle-note.stderr
index 95bdc34942645..99d8cfd0a05c9 100644
--- a/src/test/ui/sized-cycle-note.stderr
+++ b/src/test/ui/sized-cycle-note.stderr
@@ -2,21 +2,35 @@ error[E0072]: recursive type `Baz` has infinite size
   --> $DIR/sized-cycle-note.rs:9:1
    |
 LL | struct Baz { q: Option<Foo> }
-   | ^^^^^^^^^^   -------------- recursive without indirection
+   | ^^^^^^^^^^      ----------- recursive without indirection
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Baz` representable
+help: insert some indirection to make `Baz` representable
+   |
+LL | struct Baz { q: Box<Option<Foo>> }
+   |                 ^^^^           ^
+LL | struct Baz { q: Rc<Option<Foo>> }
+   |                 ^^^           ^
+LL | struct Baz { q: &Option<Foo> }
+   |                 ^
 
 error[E0072]: recursive type `Foo` has infinite size
   --> $DIR/sized-cycle-note.rs:11:1
    |
 LL | struct Foo { q: Option<Baz> }
-   | ^^^^^^^^^^   -------------- recursive without indirection
+   | ^^^^^^^^^^      ----------- recursive without indirection
    | |
    | recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Foo` representable
+help: insert some indirection to make `Foo` representable
+   |
+LL | struct Foo { q: Box<Option<Baz>> }
+   |                 ^^^^           ^
+LL | struct Foo { q: Rc<Option<Baz>> }
+   |                 ^^^           ^
+LL | struct Foo { q: &Option<Baz> }
+   |                 ^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/span/E0072.stderr b/src/test/ui/span/E0072.stderr
index d4a5e7400d2a4..855e4facb7b8c 100644
--- a/src/test/ui/span/E0072.stderr
+++ b/src/test/ui/span/E0072.stderr
@@ -5,9 +5,16 @@ LL | struct ListNode {
    | ^^^^^^^^^^^^^^^ recursive type has infinite size
 LL |     head: u8,
 LL |     tail: Option<ListNode>,
-   |     ---------------------- recursive without indirection
+   |           ---------------- recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `ListNode` representable
+help: insert some indirection to make `ListNode` representable
+   |
+LL |     tail: Box<Option<ListNode>>,
+   |           ^^^^                ^
+LL |     tail: Rc<Option<ListNode>>,
+   |           ^^^                ^
+LL |     tail: &Option<ListNode>,
+   |           ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/multiline-span-E0072.stderr b/src/test/ui/span/multiline-span-E0072.stderr
index dd322fe833b49..260c2157e96b7 100644
--- a/src/test/ui/span/multiline-span-E0072.stderr
+++ b/src/test/ui/span/multiline-span-E0072.stderr
@@ -6,11 +6,18 @@ LL | | ListNode
 LL | | {
 LL | |     head: u8,
 LL | |     tail: Option<ListNode>,
-   | |     ---------------------- recursive without indirection
+   | |           ---------------- recursive without indirection
 LL | | }
    | |_^ recursive type has infinite size
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `ListNode` representable
+help: insert some indirection to make `ListNode` representable
+   |
+LL |     tail: Box<Option<ListNode>>,
+   |           ^^^^                ^
+LL |     tail: Rc<Option<ListNode>>,
+   |           ^^^                ^
+LL |     tail: &Option<ListNode>,
+   |           ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/recursive-type-field.stderr b/src/test/ui/span/recursive-type-field.stderr
index d240872647e50..c1a3270d0a567 100644
--- a/src/test/ui/span/recursive-type-field.stderr
+++ b/src/test/ui/span/recursive-type-field.stderr
@@ -4,9 +4,16 @@ error[E0072]: recursive type `Foo` has infinite size
 LL | struct Foo<'a> {
    | ^^^^^^^^^^^^^^ recursive type has infinite size
 LL |     bar: Bar<'a>,
-   |     ------------ recursive without indirection
+   |          ------- recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Foo` representable
+help: insert some indirection to make `Foo` representable
+   |
+LL |     bar: Box<Bar<'a>>,
+   |          ^^^^       ^
+LL |     bar: Rc<Bar<'a>>,
+   |          ^^^       ^
+LL |     bar: &Bar<'a>,
+   |          ^
 
 error[E0072]: recursive type `Bar` has infinite size
   --> $DIR/recursive-type-field.rs:8:1
@@ -14,18 +21,18 @@ error[E0072]: recursive type `Bar` has infinite size
 LL | struct Bar<'a> {
    | ^^^^^^^^^^^^^^ recursive type has infinite size
 LL |     y: (Foo<'a>, Foo<'a>),
-   |     --------------------- recursive without indirection
+   |        ------------------ recursive without indirection
 LL |     z: Option<Bar<'a>>,
-   |     ------------------ recursive without indirection
+   |        --------------- recursive without indirection
 ...
 LL |     d: [Bar<'a>; 1],
-   |     --------------- recursive without indirection
+   |        ------------ recursive without indirection
 LL |     e: Foo<'a>,
-   |     ---------- recursive without indirection
+   |        ------- recursive without indirection
 LL |     x: Bar<'a>,
-   |     ---------- recursive without indirection
+   |        ------- recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Bar` representable
+   = help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Bar` representable
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/type/type-recursive.stderr b/src/test/ui/type/type-recursive.stderr
index 72bf372e561d6..b98a6eac49e04 100644
--- a/src/test/ui/type/type-recursive.stderr
+++ b/src/test/ui/type/type-recursive.stderr
@@ -5,9 +5,16 @@ LL | struct T1 {
    | ^^^^^^^^^ recursive type has infinite size
 LL |     foo: isize,
 LL |     foolish: T1
-   |     ----------- recursive without indirection
+   |              -- recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `T1` representable
+help: insert some indirection to make `T1` representable
+   |
+LL |     foolish: Box<T1>
+   |              ^^^^  ^
+LL |     foolish: Rc<T1>
+   |              ^^^  ^
+LL |     foolish: &T1
+   |              ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/union/union-nonrepresentable.stderr b/src/test/ui/union/union-nonrepresentable.stderr
index 746c1033ea348..70863a549ad25 100644
--- a/src/test/ui/union/union-nonrepresentable.stderr
+++ b/src/test/ui/union/union-nonrepresentable.stderr
@@ -5,9 +5,16 @@ LL | union U {
    | ^^^^^^^ recursive type has infinite size
 LL |     a: u8,
 LL |     b: U,
-   |     ---- recursive without indirection
+   |        - recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `U` representable
+help: insert some indirection to make `U` representable
+   |
+LL |     b: Box<U>,
+   |        ^^^^ ^
+LL |     b: Rc<U>,
+   |        ^^^ ^
+LL |     b: &U,
+   |        ^
 
 error: aborting due to previous error
 

From 7cde07e5cc5cfc1665dd64e4c06482c2f10b693a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Sat, 30 May 2020 19:58:49 -0700
Subject: [PATCH 19/25] review comments: only suggest one substitution

---
 .../traits/error_reporting/mod.rs             | 49 ++++++-------------
 .../infinite-tag-type-recursion.stderr        |  6 +--
 src/test/ui/issues/issue-17431-1.stderr       |  6 +--
 src/test/ui/issues/issue-17431-2.stderr       | 12 +----
 src/test/ui/issues/issue-17431-3.stderr       |  6 +--
 src/test/ui/issues/issue-17431-4.stderr       |  6 +--
 src/test/ui/issues/issue-17431-5.stderr       |  6 +--
 src/test/ui/issues/issue-17431-6.stderr       |  6 +--
 src/test/ui/issues/issue-17431-7.stderr       |  6 +--
 src/test/ui/issues/issue-2718-a.stderr        |  6 +--
 src/test/ui/issues/issue-3008-1.stderr        |  6 +--
 src/test/ui/issues/issue-3008-2.stderr        |  6 +--
 src/test/ui/issues/issue-3008-3.stderr        |  6 +--
 src/test/ui/issues/issue-3779.stderr          |  6 +--
 src/test/ui/issues/issue-57271.stderr         | 12 +----
 src/test/ui/recursion/recursive-enum.stderr   |  6 +--
 src/test/ui/sized-cycle-note.stderr           | 12 +----
 src/test/ui/span/E0072.stderr                 |  6 +--
 src/test/ui/span/multiline-span-E0072.stderr  |  6 +--
 src/test/ui/span/recursive-type-field.stderr  |  6 +--
 src/test/ui/type/type-recursive.stderr        |  6 +--
 .../ui/union/union-nonrepresentable.stderr    |  6 +--
 22 files changed, 38 insertions(+), 155 deletions(-)

diff --git a/src/librustc_trait_selection/traits/error_reporting/mod.rs b/src/librustc_trait_selection/traits/error_reporting/mod.rs
index 3457f7b4580c5..d31e04cffd55f 100644
--- a/src/librustc_trait_selection/traits/error_reporting/mod.rs
+++ b/src/librustc_trait_selection/traits/error_reporting/mod.rs
@@ -1759,48 +1759,27 @@ pub fn recursive_type_with_infinite_size_error(
     for &span in &spans {
         err.span_label(span, "recursive without indirection");
     }
-    let short_msg = format!("insert some indirection to make `{}` representable", path);
     let msg = format!(
         "insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `{}` representable",
         path,
     );
-    match &spans[..] {
-        [span] => {
-            err.multipart_suggestions(
-                &short_msg,
-                vec![
+    if spans.len() <= 4 {
+        err.multipart_suggestion(
+            &msg,
+            spans
+                .iter()
+                .flat_map(|&span| {
                     vec![
                         (span.shrink_to_lo(), "Box<".to_string()),
                         (span.shrink_to_hi(), ">".to_string()),
-                    ],
-                    vec![
-                        (span.shrink_to_lo(), "Rc<".to_string()),
-                        (span.shrink_to_hi(), ">".to_string()),
-                    ],
-                    vec![(span.shrink_to_lo(), "&".to_string())],
-                ],
-                Applicability::HasPlaceholders,
-            );
-        }
-        _ if spans.len() <= 4 => {
-            err.multipart_suggestion(
-                &msg,
-                spans
-                    .iter()
-                    .flat_map(|&span| {
-                        vec![
-                            (span.shrink_to_lo(), "Box<".to_string()),
-                            (span.shrink_to_hi(), ">".to_string()),
-                        ]
-                        .into_iter()
-                    })
-                    .collect(),
-                Applicability::HasPlaceholders,
-            );
-        }
-        _ => {
-            err.help(&msg);
-        }
+                    ]
+                    .into_iter()
+                })
+                .collect(),
+            Applicability::HasPlaceholders,
+        );
+    } else {
+        err.help(&msg);
     }
     err.emit();
 }
diff --git a/src/test/ui/infinite/infinite-tag-type-recursion.stderr b/src/test/ui/infinite/infinite-tag-type-recursion.stderr
index b6a4d8f4cf563..6d1df4fda2eb0 100644
--- a/src/test/ui/infinite/infinite-tag-type-recursion.stderr
+++ b/src/test/ui/infinite/infinite-tag-type-recursion.stderr
@@ -6,14 +6,10 @@ LL | enum MList { Cons(isize, MList), Nil }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `MList` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `MList` representable
    |
 LL | enum MList { Cons(isize, Box<MList>), Nil }
    |                          ^^^^     ^
-LL | enum MList { Cons(isize, Rc<MList>), Nil }
-   |                          ^^^     ^
-LL | enum MList { Cons(isize, &MList), Nil }
-   |                          ^
 
 error[E0391]: cycle detected when computing drop-check constraints for `MList`
   --> $DIR/infinite-tag-type-recursion.rs:1:1
diff --git a/src/test/ui/issues/issue-17431-1.stderr b/src/test/ui/issues/issue-17431-1.stderr
index 8d44154650e04..58d087ca1998b 100644
--- a/src/test/ui/issues/issue-17431-1.stderr
+++ b/src/test/ui/issues/issue-17431-1.stderr
@@ -6,14 +6,10 @@ LL | struct Foo { foo: Option<Option<Foo>> }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Foo` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable
    |
 LL | struct Foo { foo: Box<Option<Option<Foo>>> }
    |                   ^^^^                   ^
-LL | struct Foo { foo: Rc<Option<Option<Foo>>> }
-   |                   ^^^                   ^
-LL | struct Foo { foo: &Option<Option<Foo>> }
-   |                   ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-2.stderr b/src/test/ui/issues/issue-17431-2.stderr
index b06184e84da28..eba4bf6d1d5ea 100644
--- a/src/test/ui/issues/issue-17431-2.stderr
+++ b/src/test/ui/issues/issue-17431-2.stderr
@@ -6,14 +6,10 @@ LL | struct Baz { q: Option<Foo> }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Baz` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Baz` representable
    |
 LL | struct Baz { q: Box<Option<Foo>> }
    |                 ^^^^           ^
-LL | struct Baz { q: Rc<Option<Foo>> }
-   |                 ^^^           ^
-LL | struct Baz { q: &Option<Foo> }
-   |                 ^
 
 error[E0072]: recursive type `Foo` has infinite size
   --> $DIR/issue-17431-2.rs:4:1
@@ -23,14 +19,10 @@ LL | struct Foo { q: Option<Baz> }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Foo` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable
    |
 LL | struct Foo { q: Box<Option<Baz>> }
    |                 ^^^^           ^
-LL | struct Foo { q: Rc<Option<Baz>> }
-   |                 ^^^           ^
-LL | struct Foo { q: &Option<Baz> }
-   |                 ^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/issues/issue-17431-3.stderr b/src/test/ui/issues/issue-17431-3.stderr
index f32bd70fd6d94..f6b15d0528ae8 100644
--- a/src/test/ui/issues/issue-17431-3.stderr
+++ b/src/test/ui/issues/issue-17431-3.stderr
@@ -6,14 +6,10 @@ LL | struct Foo { foo: Mutex<Option<Foo>> }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Foo` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable
    |
 LL | struct Foo { foo: Box<Mutex<Option<Foo>>> }
    |                   ^^^^                  ^
-LL | struct Foo { foo: Rc<Mutex<Option<Foo>>> }
-   |                   ^^^                  ^
-LL | struct Foo { foo: &Mutex<Option<Foo>> }
-   |                   ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-4.stderr b/src/test/ui/issues/issue-17431-4.stderr
index 372c5e975c844..aa709e1ad5183 100644
--- a/src/test/ui/issues/issue-17431-4.stderr
+++ b/src/test/ui/issues/issue-17431-4.stderr
@@ -6,14 +6,10 @@ LL | struct Foo<T> { foo: Option<Option<Foo<T>>>, marker: marker::PhantomData<T>
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Foo` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable
    |
 LL | struct Foo<T> { foo: Box<Option<Option<Foo<T>>>>, marker: marker::PhantomData<T> }
    |                      ^^^^                      ^
-LL | struct Foo<T> { foo: Rc<Option<Option<Foo<T>>>>, marker: marker::PhantomData<T> }
-   |                      ^^^                      ^
-LL | struct Foo<T> { foo: &Option<Option<Foo<T>>>, marker: marker::PhantomData<T> }
-   |                      ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-5.stderr b/src/test/ui/issues/issue-17431-5.stderr
index 01b850ac33694..1558cffb036b3 100644
--- a/src/test/ui/issues/issue-17431-5.stderr
+++ b/src/test/ui/issues/issue-17431-5.stderr
@@ -6,14 +6,10 @@ LL | struct Bar<T> { x: Bar<Foo> , marker: marker::PhantomData<T> }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Bar` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Bar` representable
    |
 LL | struct Bar<T> { x: Box<Bar<Foo>> , marker: marker::PhantomData<T> }
    |                    ^^^^        ^
-LL | struct Bar<T> { x: Rc<Bar<Foo>> , marker: marker::PhantomData<T> }
-   |                    ^^^        ^
-LL | struct Bar<T> { x: &Bar<Foo> , marker: marker::PhantomData<T> }
-   |                    ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-6.stderr b/src/test/ui/issues/issue-17431-6.stderr
index ce6c2db07fb6d..f2aa2a79c8200 100644
--- a/src/test/ui/issues/issue-17431-6.stderr
+++ b/src/test/ui/issues/issue-17431-6.stderr
@@ -6,14 +6,10 @@ LL | enum Foo { X(Mutex<Option<Foo>>) }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Foo` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable
    |
 LL | enum Foo { X(Box<Mutex<Option<Foo>>>) }
    |              ^^^^                  ^
-LL | enum Foo { X(Rc<Mutex<Option<Foo>>>) }
-   |              ^^^                  ^
-LL | enum Foo { X(&Mutex<Option<Foo>>) }
-   |              ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-17431-7.stderr b/src/test/ui/issues/issue-17431-7.stderr
index 4fb563ba502f2..684c3089e85ec 100644
--- a/src/test/ui/issues/issue-17431-7.stderr
+++ b/src/test/ui/issues/issue-17431-7.stderr
@@ -6,14 +6,10 @@ LL | enum Foo { Voo(Option<Option<Foo>>) }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Foo` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable
    |
 LL | enum Foo { Voo(Box<Option<Option<Foo>>>) }
    |                ^^^^                   ^
-LL | enum Foo { Voo(Rc<Option<Option<Foo>>>) }
-   |                ^^^                   ^
-LL | enum Foo { Voo(&Option<Option<Foo>>) }
-   |                ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-2718-a.stderr b/src/test/ui/issues/issue-2718-a.stderr
index 48b7a61e059ea..d152ffde4e57d 100644
--- a/src/test/ui/issues/issue-2718-a.stderr
+++ b/src/test/ui/issues/issue-2718-a.stderr
@@ -7,14 +7,10 @@ LL |     pub struct Pong(SendPacket<Ping>);
    |     |               recursive without indirection
    |     recursive type has infinite size
    |
-help: insert some indirection to make `pingpong::Pong` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `pingpong::Pong` representable
    |
 LL |     pub struct Pong(Box<SendPacket<Ping>>);
    |                     ^^^^                ^
-LL |     pub struct Pong(Rc<SendPacket<Ping>>);
-   |                     ^^^                ^
-LL |     pub struct Pong(&SendPacket<Ping>);
-   |                     ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-3008-1.stderr b/src/test/ui/issues/issue-3008-1.stderr
index d1173a4b3334c..87ee36df21696 100644
--- a/src/test/ui/issues/issue-3008-1.stderr
+++ b/src/test/ui/issues/issue-3008-1.stderr
@@ -7,14 +7,10 @@ LL | enum Bar {
 LL |     BarSome(Bar)
    |             --- recursive without indirection
    |
-help: insert some indirection to make `Bar` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Bar` representable
    |
 LL |     BarSome(Box<Bar>)
    |             ^^^^   ^
-LL |     BarSome(Rc<Bar>)
-   |             ^^^   ^
-LL |     BarSome(&Bar)
-   |             ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-3008-2.stderr b/src/test/ui/issues/issue-3008-2.stderr
index 4fd60639b21a8..369a19d37e6f6 100644
--- a/src/test/ui/issues/issue-3008-2.stderr
+++ b/src/test/ui/issues/issue-3008-2.stderr
@@ -6,14 +6,10 @@ LL | struct Bar { x: Bar }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Bar` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Bar` representable
    |
 LL | struct Bar { x: Box<Bar> }
    |                 ^^^^   ^
-LL | struct Bar { x: Rc<Bar> }
-   |                 ^^^   ^
-LL | struct Bar { x: &Bar }
-   |                 ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-3008-3.stderr b/src/test/ui/issues/issue-3008-3.stderr
index e6efad9188300..0b162eff94a7c 100644
--- a/src/test/ui/issues/issue-3008-3.stderr
+++ b/src/test/ui/issues/issue-3008-3.stderr
@@ -6,14 +6,10 @@ LL | enum E2<T> { V2(E2<E1>, marker::PhantomData<T>), }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `E2` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `E2` representable
    |
 LL | enum E2<T> { V2(Box<E2<E1>>, marker::PhantomData<T>), }
    |                 ^^^^      ^
-LL | enum E2<T> { V2(Rc<E2<E1>>, marker::PhantomData<T>), }
-   |                 ^^^      ^
-LL | enum E2<T> { V2(&E2<E1>, marker::PhantomData<T>), }
-   |                 ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-3779.stderr b/src/test/ui/issues/issue-3779.stderr
index 9b50ddec12a44..7b17e91421660 100644
--- a/src/test/ui/issues/issue-3779.stderr
+++ b/src/test/ui/issues/issue-3779.stderr
@@ -7,14 +7,10 @@ LL |
 LL |     element: Option<S>
    |              --------- recursive without indirection
    |
-help: insert some indirection to make `S` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `S` representable
    |
 LL |     element: Box<Option<S>>
    |              ^^^^         ^
-LL |     element: Rc<Option<S>>
-   |              ^^^         ^
-LL |     element: &Option<S>
-   |              ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-57271.stderr b/src/test/ui/issues/issue-57271.stderr
index a6fe83a9b5636..b7c799e163cee 100644
--- a/src/test/ui/issues/issue-57271.stderr
+++ b/src/test/ui/issues/issue-57271.stderr
@@ -7,14 +7,10 @@ LL |     Class(ClassTypeSignature),
 LL |     Array(TypeSignature),
    |           ------------- recursive without indirection
    |
-help: insert some indirection to make `ObjectType` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `ObjectType` representable
    |
 LL |     Array(Box<TypeSignature>),
    |           ^^^^             ^
-LL |     Array(Rc<TypeSignature>),
-   |           ^^^             ^
-LL |     Array(&TypeSignature),
-   |           ^
 
 error[E0072]: recursive type `TypeSignature` has infinite size
   --> $DIR/issue-57271.rs:19:1
@@ -25,14 +21,10 @@ LL |     Base(BaseType),
 LL |     Object(ObjectType),
    |            ---------- recursive without indirection
    |
-help: insert some indirection to make `TypeSignature` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `TypeSignature` representable
    |
 LL |     Object(Box<ObjectType>),
    |            ^^^^          ^
-LL |     Object(Rc<ObjectType>),
-   |            ^^^          ^
-LL |     Object(&ObjectType),
-   |            ^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/recursion/recursive-enum.stderr b/src/test/ui/recursion/recursive-enum.stderr
index c68badd458bce..ab4709d8e709e 100644
--- a/src/test/ui/recursion/recursive-enum.stderr
+++ b/src/test/ui/recursion/recursive-enum.stderr
@@ -6,14 +6,10 @@ LL | enum List<T> { Cons(T, List<T>), Nil }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `List` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `List` representable
    |
 LL | enum List<T> { Cons(T, Box<List<T>>), Nil }
    |                        ^^^^       ^
-LL | enum List<T> { Cons(T, Rc<List<T>>), Nil }
-   |                        ^^^       ^
-LL | enum List<T> { Cons(T, &List<T>), Nil }
-   |                        ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/sized-cycle-note.stderr b/src/test/ui/sized-cycle-note.stderr
index 99d8cfd0a05c9..45062c2ea6c72 100644
--- a/src/test/ui/sized-cycle-note.stderr
+++ b/src/test/ui/sized-cycle-note.stderr
@@ -6,14 +6,10 @@ LL | struct Baz { q: Option<Foo> }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Baz` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Baz` representable
    |
 LL | struct Baz { q: Box<Option<Foo>> }
    |                 ^^^^           ^
-LL | struct Baz { q: Rc<Option<Foo>> }
-   |                 ^^^           ^
-LL | struct Baz { q: &Option<Foo> }
-   |                 ^
 
 error[E0072]: recursive type `Foo` has infinite size
   --> $DIR/sized-cycle-note.rs:11:1
@@ -23,14 +19,10 @@ LL | struct Foo { q: Option<Baz> }
    | |
    | recursive type has infinite size
    |
-help: insert some indirection to make `Foo` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable
    |
 LL | struct Foo { q: Box<Option<Baz>> }
    |                 ^^^^           ^
-LL | struct Foo { q: Rc<Option<Baz>> }
-   |                 ^^^           ^
-LL | struct Foo { q: &Option<Baz> }
-   |                 ^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/span/E0072.stderr b/src/test/ui/span/E0072.stderr
index 855e4facb7b8c..06493f05142e6 100644
--- a/src/test/ui/span/E0072.stderr
+++ b/src/test/ui/span/E0072.stderr
@@ -7,14 +7,10 @@ LL |     head: u8,
 LL |     tail: Option<ListNode>,
    |           ---------------- recursive without indirection
    |
-help: insert some indirection to make `ListNode` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `ListNode` representable
    |
 LL |     tail: Box<Option<ListNode>>,
    |           ^^^^                ^
-LL |     tail: Rc<Option<ListNode>>,
-   |           ^^^                ^
-LL |     tail: &Option<ListNode>,
-   |           ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/multiline-span-E0072.stderr b/src/test/ui/span/multiline-span-E0072.stderr
index 260c2157e96b7..55128347f7404 100644
--- a/src/test/ui/span/multiline-span-E0072.stderr
+++ b/src/test/ui/span/multiline-span-E0072.stderr
@@ -10,14 +10,10 @@ LL | |     tail: Option<ListNode>,
 LL | | }
    | |_^ recursive type has infinite size
    |
-help: insert some indirection to make `ListNode` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `ListNode` representable
    |
 LL |     tail: Box<Option<ListNode>>,
    |           ^^^^                ^
-LL |     tail: Rc<Option<ListNode>>,
-   |           ^^^                ^
-LL |     tail: &Option<ListNode>,
-   |           ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/recursive-type-field.stderr b/src/test/ui/span/recursive-type-field.stderr
index c1a3270d0a567..fb1d98b58dfbe 100644
--- a/src/test/ui/span/recursive-type-field.stderr
+++ b/src/test/ui/span/recursive-type-field.stderr
@@ -6,14 +6,10 @@ LL | struct Foo<'a> {
 LL |     bar: Bar<'a>,
    |          ------- recursive without indirection
    |
-help: insert some indirection to make `Foo` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `Foo` representable
    |
 LL |     bar: Box<Bar<'a>>,
    |          ^^^^       ^
-LL |     bar: Rc<Bar<'a>>,
-   |          ^^^       ^
-LL |     bar: &Bar<'a>,
-   |          ^
 
 error[E0072]: recursive type `Bar` has infinite size
   --> $DIR/recursive-type-field.rs:8:1
diff --git a/src/test/ui/type/type-recursive.stderr b/src/test/ui/type/type-recursive.stderr
index b98a6eac49e04..d6d32cc5d6f39 100644
--- a/src/test/ui/type/type-recursive.stderr
+++ b/src/test/ui/type/type-recursive.stderr
@@ -7,14 +7,10 @@ LL |     foo: isize,
 LL |     foolish: T1
    |              -- recursive without indirection
    |
-help: insert some indirection to make `T1` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `T1` representable
    |
 LL |     foolish: Box<T1>
    |              ^^^^  ^
-LL |     foolish: Rc<T1>
-   |              ^^^  ^
-LL |     foolish: &T1
-   |              ^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/union/union-nonrepresentable.stderr b/src/test/ui/union/union-nonrepresentable.stderr
index 70863a549ad25..c54d04de12c50 100644
--- a/src/test/ui/union/union-nonrepresentable.stderr
+++ b/src/test/ui/union/union-nonrepresentable.stderr
@@ -7,14 +7,10 @@ LL |     a: u8,
 LL |     b: U,
    |        - recursive without indirection
    |
-help: insert some indirection to make `U` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `U` representable
    |
 LL |     b: Box<U>,
    |        ^^^^ ^
-LL |     b: Rc<U>,
-   |        ^^^ ^
-LL |     b: &U,
-   |        ^
 
 error: aborting due to previous error
 

From 03552ec3fa4828329874a17d1b8966a0c03809d8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Wed, 10 Jun 2020 14:54:27 -0700
Subject: [PATCH 20/25] fix rebase

---
 src/test/ui/issues/issue-72554.stderr | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/test/ui/issues/issue-72554.stderr b/src/test/ui/issues/issue-72554.stderr
index 9db65f4a2ee8f..9de94c393a711 100644
--- a/src/test/ui/issues/issue-72554.stderr
+++ b/src/test/ui/issues/issue-72554.stderr
@@ -6,7 +6,10 @@ LL | pub enum ElemDerived {
 LL |     A(ElemDerived)
    |       ----------- recursive without indirection
    |
-   = help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `ElemDerived` representable
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to make `ElemDerived` representable
+   |
+LL |     A(Box<ElemDerived>)
+   |       ^^^^           ^
 
 error: aborting due to previous error
 

From 57b54c49281df9559cae4a685c0d38d62a3ee500 Mon Sep 17 00:00:00 2001
From: Eric Huss <eric@huss.org>
Date: Thu, 11 Jun 2020 18:28:13 -0700
Subject: [PATCH 21/25] Use the built cargo for cargotest.

---
 src/bootstrap/test.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index 163132f563425..aeabb227cf5e9 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -154,6 +154,7 @@ impl Step for Cargotest {
     fn run(self, builder: &Builder<'_>) {
         let compiler = builder.compiler(self.stage, self.host);
         builder.ensure(compile::Rustc { compiler, target: compiler.host });
+        let cargo = builder.ensure(tool::Cargo { compiler, target: compiler.host });
 
         // Note that this is a short, cryptic, and not scoped directory name. This
         // is currently to minimize the length of path on Windows where we otherwise
@@ -165,7 +166,7 @@ impl Step for Cargotest {
         let mut cmd = builder.tool_cmd(Tool::CargoTest);
         try_run(
             builder,
-            cmd.arg(&builder.initial_cargo)
+            cmd.arg(&cargo)
                 .arg(&out_dir)
                 .env("RUSTC", builder.rustc(compiler))
                 .env("RUSTDOC", builder.rustdoc(compiler)),

From b4bd180e5e330c6b3019c0d9d0ad676f07885258 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Fri, 12 Jun 2020 12:35:37 +0200
Subject: [PATCH 22/25] fix caller_location intrinsic for Miri

---
 src/librustc_mir/interpret/eval_context.rs    | 11 ++------
 .../interpret/intrinsics/caller_location.rs   | 25 ++++++++++++-------
 2 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs
index 6497e211de316..b44152a5188a8 100644
--- a/src/librustc_mir/interpret/eval_context.rs
+++ b/src/librustc_mir/interpret/eval_context.rs
@@ -171,15 +171,8 @@ impl<'mir, 'tcx, Tag> Frame<'mir, 'tcx, Tag> {
 
 impl<'mir, 'tcx, Tag, Extra> Frame<'mir, 'tcx, Tag, Extra> {
     /// Return the `SourceInfo` of the current instruction.
-    pub fn current_source_info(&self) -> Option<mir::SourceInfo> {
-        self.loc.map(|loc| {
-            let block = &self.body.basic_blocks()[loc.block];
-            if loc.statement_index < block.statements.len() {
-                block.statements[loc.statement_index].source_info
-            } else {
-                block.terminator().source_info
-            }
-        })
+    pub fn current_source_info(&self) -> Option<&mir::SourceInfo> {
+        self.loc.map(|loc| self.body.source_info(loc))
     }
 }
 
diff --git a/src/librustc_mir/interpret/intrinsics/caller_location.rs b/src/librustc_mir/interpret/intrinsics/caller_location.rs
index ddeed92f85124..9adef8c43c7c8 100644
--- a/src/librustc_mir/interpret/intrinsics/caller_location.rs
+++ b/src/librustc_mir/interpret/intrinsics/caller_location.rs
@@ -29,18 +29,25 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             })
             // Assert that there is always such a frame.
             .unwrap();
+        // Assert that the frame we look at is actually executing code currently
+        // (`current_source_info` is None when we are unwinding and the frame does
+        // not require cleanup).
         let loc = frame.loc.unwrap();
+        // If this is a `Call` terminator, use the `fn_span` instead.
         let block = &frame.body.basic_blocks()[loc.block];
-        assert_eq!(block.statements.len(), loc.statement_index);
-        debug!(
-            "find_closest_untracked_caller_location:: got terminator {:?} ({:?})",
-            block.terminator(),
-            block.terminator().kind
-        );
-        if let TerminatorKind::Call { fn_span, .. } = block.terminator().kind {
-            return fn_span;
+        if loc.statement_index == block.statements.len() {
+            debug!(
+                "find_closest_untracked_caller_location:: got terminator {:?} ({:?})",
+                block.terminator(),
+                block.terminator().kind
+            );
+            if let TerminatorKind::Call { fn_span, .. } = block.terminator().kind {
+                return fn_span;
+            }
         }
-        unreachable!();
+        // This is a different terminator (such as `Drop`) or not a terminator at all
+        // (such as `box`). Use the normal span.
+        frame.body.source_info(loc).span
     }
 
     /// Allocate a `const core::panic::Location` with the provided filename and line/column numbers.

From bd4bd59ad7946f0717f1babb38a971b608fe4f3b Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Wed, 13 May 2020 13:40:22 -0700
Subject: [PATCH 23/25] Helper method for whether type has structural equality

This helper method works for all types, falling back to a query for
`TyKind::Adt`s to determine whether the implement the
`{Partial,}StructuralEq` traits.
---
 src/librustc_middle/query/mod.rs              | 11 ++++
 src/librustc_middle/ty/util.rs                | 51 +++++++++++++++++++
 .../transform/check_consts/qualifs.rs         |  6 +--
 .../hair/pattern/const_to_pat.rs              |  2 +-
 src/librustc_trait_selection/traits/mod.rs    |  1 +
 .../traits/structural_match.rs                | 32 +++++++-----
 6 files changed, 85 insertions(+), 18 deletions(-)

diff --git a/src/librustc_middle/query/mod.rs b/src/librustc_middle/query/mod.rs
index 4d7e7882e426c..be15e6c576f69 100644
--- a/src/librustc_middle/query/mod.rs
+++ b/src/librustc_middle/query/mod.rs
@@ -789,6 +789,17 @@ rustc_queries! {
             desc { "computing whether `{}` needs drop", env.value }
         }
 
+        /// Query backing `TyS::is_structural_eq_shallow`.
+        ///
+        /// This is only correct for ADTs. Call `is_structural_eq_shallow` to handle all types
+        /// correctly.
+        query has_structural_eq_impls(ty: Ty<'tcx>) -> bool {
+            desc {
+                "computing whether `{:?}` implements `PartialStructuralEq` and `StructuralEq`",
+                ty
+            }
+        }
+
         /// A list of types where the ADT requires drop if and only if any of
         /// those types require drop. If the ADT is known to always need drop
         /// then `Err(AlwaysRequiresDrop)` is returned.
diff --git a/src/librustc_middle/ty/util.rs b/src/librustc_middle/ty/util.rs
index c2b794ca4bdd9..252a11129beda 100644
--- a/src/librustc_middle/ty/util.rs
+++ b/src/librustc_middle/ty/util.rs
@@ -778,6 +778,57 @@ impl<'tcx> ty::TyS<'tcx> {
         }
     }
 
+    /// Returns `true` if equality for this type is both total and structural.
+    ///
+    /// Total equality for a type is indicated by an `Eq` impl for that type.
+    ///
+    /// Primitive types (`u32`, `str`) have structural equality by definition. For composite data
+    /// types, equality for the type as a whole is structural when it is the same as equality
+    /// between all components (fields, array elements, etc.) of that type. For ADTs, structural
+    /// equality is indicated by an implementation of `PartialStructuralEq` and `StructuralEq` for
+    /// that type.
+    ///
+    /// This function is "shallow" because it may return `true` for a composite type whose fields
+    /// are not `StructuralEq`. For example, `[T; 4]` has structural equality regardless of `T`
+    /// because equality for arrays is determined by the equality of each array element. If you
+    /// want to know whether a given call to `PartialEq::eq` will proceed structurally all the way
+    /// down, you will need to use a type visitor.
+    #[inline]
+    pub fn is_structural_eq_shallow(&'tcx self, tcx: TyCtxt<'tcx>) -> bool {
+        match self.kind {
+            // Look for an impl of both `PartialStructuralEq` and `StructuralEq`.
+            Adt(..) => tcx.has_structural_eq_impls(self),
+
+            // Primitive types that satisfy `Eq`.
+            Bool | Char | Int(_) | Uint(_) | Str | Never => true,
+
+            // Composite types that satisfy `Eq` when all of their fields do.
+            //
+            // Because this function is "shallow", we return `true` for these composites regardless
+            // of the type(s) contained within.
+            Ref(..) | Array(..) | Slice(_) | Tuple(..) => true,
+
+            // Raw pointers use bitwise comparison.
+            RawPtr(_) | FnPtr(_) => true,
+
+            // Floating point numbers are not `Eq`.
+            Float(_) => false,
+
+            // Conservatively return `false` for all others...
+
+            // Anonymous function types
+            FnDef(..) | Closure(..) | Dynamic(..) | Generator(..) => false,
+
+            // Generic or inferred types
+            //
+            // FIXME(ecstaticmorse): Maybe we should `bug` here? This should probably only be
+            // called for known, fully-monomorphized types.
+            Projection(_) | Opaque(..) | Param(_) | Bound(..) | Placeholder(_) | Infer(_) => false,
+
+            Foreign(_) | GeneratorWitness(..) | Error => false,
+        }
+    }
+
     pub fn same_type(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
         match (&a.kind, &b.kind) {
             (&Adt(did_a, substs_a), &Adt(did_b, substs_b)) => {
diff --git a/src/librustc_mir/transform/check_consts/qualifs.rs b/src/librustc_mir/transform/check_consts/qualifs.rs
index 5d604d8e3d716..936c1a84e142e 100644
--- a/src/librustc_mir/transform/check_consts/qualifs.rs
+++ b/src/librustc_mir/transform/check_consts/qualifs.rs
@@ -2,7 +2,6 @@
 //!
 //! See the `Qualif` trait for more info.
 
-use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, subst::SubstsRef, AdtDef, Ty};
 use rustc_span::DUMMY_SP;
@@ -137,10 +136,7 @@ impl Qualif for CustomEq {
         substs: SubstsRef<'tcx>,
     ) -> bool {
         let ty = cx.tcx.mk_ty(ty::Adt(adt, substs));
-        let id = cx.tcx.hir().local_def_id_to_hir_id(cx.def_id.as_local().unwrap());
-        cx.tcx
-            .infer_ctxt()
-            .enter(|infcx| !traits::type_marked_structural(id, cx.body.span, &infcx, ty))
+        !ty.is_structural_eq_shallow(cx.tcx)
     }
 }
 
diff --git a/src/librustc_mir_build/hair/pattern/const_to_pat.rs b/src/librustc_mir_build/hair/pattern/const_to_pat.rs
index 9e3f75fdc078c..46b687d76e504 100644
--- a/src/librustc_mir_build/hair/pattern/const_to_pat.rs
+++ b/src/librustc_mir_build/hair/pattern/const_to_pat.rs
@@ -80,7 +80,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
     }
 
     fn type_marked_structural(&self, ty: Ty<'tcx>) -> bool {
-        traits::type_marked_structural(self.id, self.span, &self.infcx, ty)
+        ty.is_structural_eq_shallow(self.infcx.tcx)
     }
 
     fn to_pat(
diff --git a/src/librustc_trait_selection/traits/mod.rs b/src/librustc_trait_selection/traits/mod.rs
index 6abea18ee296c..225bbfeb262fd 100644
--- a/src/librustc_trait_selection/traits/mod.rs
+++ b/src/librustc_trait_selection/traits/mod.rs
@@ -553,6 +553,7 @@ fn type_implements_trait<'tcx>(
 
 pub fn provide(providers: &mut ty::query::Providers<'_>) {
     object_safety::provide(providers);
+    structural_match::provide(providers);
     *providers = ty::query::Providers {
         specialization_graph_of: specialize::specialization_graph_provider,
         specializes: specialize::specializes,
diff --git a/src/librustc_trait_selection/traits/structural_match.rs b/src/librustc_trait_selection/traits/structural_match.rs
index 87ff667b6a09a..d01163a29d5ba 100644
--- a/src/librustc_trait_selection/traits/structural_match.rs
+++ b/src/librustc_trait_selection/traits/structural_match.rs
@@ -1,10 +1,11 @@
 use crate::infer::{InferCtxt, TyCtxtInferExt};
 use crate::traits::ObligationCause;
-use crate::traits::{self, ConstPatternStructural, TraitEngine};
+use crate::traits::{self, TraitEngine};
 
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
 use rustc_hir::lang_items::{StructuralPeqTraitLangItem, StructuralTeqTraitLangItem};
+use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt, TypeFoldable, TypeVisitor};
 use rustc_span::Span;
 
@@ -45,14 +46,14 @@ pub enum NonStructuralMatchTy<'tcx> {
 /// that arose when the requirement was not enforced completely, see
 /// Rust RFC 1445, rust-lang/rust#61188, and rust-lang/rust#62307.
 pub fn search_for_structural_match_violation<'tcx>(
-    id: hir::HirId,
+    _id: hir::HirId,
     span: Span,
     tcx: TyCtxt<'tcx>,
     ty: Ty<'tcx>,
 ) -> Option<NonStructuralMatchTy<'tcx>> {
     // FIXME: we should instead pass in an `infcx` from the outside.
     tcx.infer_ctxt().enter(|infcx| {
-        let mut search = Search { id, span, infcx, found: None, seen: FxHashSet::default() };
+        let mut search = Search { infcx, span, found: None, seen: FxHashSet::default() };
         ty.visit_with(&mut search);
         search.found
     })
@@ -66,26 +67,25 @@ pub fn search_for_structural_match_violation<'tcx>(
 /// Note that this does *not* recursively check if the substructure of `adt_ty`
 /// implements the traits.
 pub fn type_marked_structural(
-    id: hir::HirId,
-    span: Span,
     infcx: &InferCtxt<'_, 'tcx>,
     adt_ty: Ty<'tcx>,
+    cause: ObligationCause<'tcx>,
 ) -> bool {
     let mut fulfillment_cx = traits::FulfillmentContext::new();
-    let cause = ObligationCause::new(span, id, ConstPatternStructural);
     // require `#[derive(PartialEq)]`
-    let structural_peq_def_id = infcx.tcx.require_lang_item(StructuralPeqTraitLangItem, Some(span));
+    let structural_peq_def_id =
+        infcx.tcx.require_lang_item(StructuralPeqTraitLangItem, Some(cause.span));
     fulfillment_cx.register_bound(
         infcx,
         ty::ParamEnv::empty(),
         adt_ty,
         structural_peq_def_id,
-        cause,
+        cause.clone(),
     );
     // for now, require `#[derive(Eq)]`. (Doing so is a hack to work around
     // the type `for<'a> fn(&'a ())` failing to implement `Eq` itself.)
-    let cause = ObligationCause::new(span, id, ConstPatternStructural);
-    let structural_teq_def_id = infcx.tcx.require_lang_item(StructuralTeqTraitLangItem, Some(span));
+    let structural_teq_def_id =
+        infcx.tcx.require_lang_item(StructuralTeqTraitLangItem, Some(cause.span));
     fulfillment_cx.register_bound(
         infcx,
         ty::ParamEnv::empty(),
@@ -110,7 +110,6 @@ pub fn type_marked_structural(
 /// find instances of ADTs (specifically structs or enums) that do not implement
 /// the structural-match traits (`StructuralPartialEq` and `StructuralEq`).
 struct Search<'a, 'tcx> {
-    id: hir::HirId,
     span: Span,
 
     infcx: InferCtxt<'a, 'tcx>,
@@ -129,7 +128,7 @@ impl Search<'a, 'tcx> {
     }
 
     fn type_marked_structural(&self, adt_ty: Ty<'tcx>) -> bool {
-        type_marked_structural(self.id, self.span, &self.infcx, adt_ty)
+        adt_ty.is_structural_eq_shallow(self.tcx())
     }
 }
 
@@ -266,3 +265,12 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {
         false
     }
 }
+
+pub fn provide(providers: &mut Providers<'_>) {
+    providers.has_structural_eq_impls = |tcx, ty| {
+        tcx.infer_ctxt().enter(|infcx| {
+            let cause = ObligationCause::dummy();
+            type_marked_structural(&infcx, ty, cause)
+        })
+    };
+}

From 1dd45612f80e2b15d0346d4bdf8838572eeee3bf Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Fri, 12 Jun 2020 08:47:13 -0700
Subject: [PATCH 24/25] Use "reflexive equality" in docs

---
 src/librustc_middle/ty/util.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/librustc_middle/ty/util.rs b/src/librustc_middle/ty/util.rs
index 252a11129beda..c61e27528cef1 100644
--- a/src/librustc_middle/ty/util.rs
+++ b/src/librustc_middle/ty/util.rs
@@ -778,9 +778,9 @@ impl<'tcx> ty::TyS<'tcx> {
         }
     }
 
-    /// Returns `true` if equality for this type is both total and structural.
+    /// Returns `true` if equality for this type is both reflexive and structural.
     ///
-    /// Total equality for a type is indicated by an `Eq` impl for that type.
+    /// Reflexive equality for a type is indicated by an `Eq` impl for that type.
     ///
     /// Primitive types (`u32`, `str`) have structural equality by definition. For composite data
     /// types, equality for the type as a whole is structural when it is the same as equality

From 280176178b1449ce9ba3bc1d2b7ebf3f1d0abb6a Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Fri, 12 Jun 2020 08:47:26 -0700
Subject: [PATCH 25/25] Make `type_marked_structural` private

---
 src/librustc_trait_selection/traits/mod.rs              | 1 -
 src/librustc_trait_selection/traits/structural_match.rs | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/librustc_trait_selection/traits/mod.rs b/src/librustc_trait_selection/traits/mod.rs
index 225bbfeb262fd..9ab87e6b6ca01 100644
--- a/src/librustc_trait_selection/traits/mod.rs
+++ b/src/librustc_trait_selection/traits/mod.rs
@@ -60,7 +60,6 @@ pub use self::specialize::specialization_graph::FutureCompatOverlapError;
 pub use self::specialize::specialization_graph::FutureCompatOverlapErrorKind;
 pub use self::specialize::{specialization_graph, translate_substs, OverlapError};
 pub use self::structural_match::search_for_structural_match_violation;
-pub use self::structural_match::type_marked_structural;
 pub use self::structural_match::NonStructuralMatchTy;
 pub use self::util::{elaborate_predicates, elaborate_trait_ref, elaborate_trait_refs};
 pub use self::util::{expand_trait_aliases, TraitAliasExpander};
diff --git a/src/librustc_trait_selection/traits/structural_match.rs b/src/librustc_trait_selection/traits/structural_match.rs
index d01163a29d5ba..e59fbd313c8bc 100644
--- a/src/librustc_trait_selection/traits/structural_match.rs
+++ b/src/librustc_trait_selection/traits/structural_match.rs
@@ -66,7 +66,7 @@ pub fn search_for_structural_match_violation<'tcx>(
 ///
 /// Note that this does *not* recursively check if the substructure of `adt_ty`
 /// implements the traits.
-pub fn type_marked_structural(
+fn type_marked_structural(
     infcx: &InferCtxt<'_, 'tcx>,
     adt_ty: Ty<'tcx>,
     cause: ObligationCause<'tcx>,