extra_lifetime_params_map can only ever contain LifetimeRes::Fresh, so just encode the fields we need

Author: oli-obk

compiler/rustc_ast_lowering/src/item.rs

@@ -1928,11 +1928,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
         // Introduce extra lifetimes if late resolution tells us to.
         let extra_lifetimes = self.resolver.extra_lifetime_params(parent_node_id);
-        params.extend(extra_lifetimes.into_iter().map(|&(ident, node_id, res)| {
+        params.extend(extra_lifetimes.into_iter().map(|&(ident, node_id, kind)| {
             self.lifetime_res_to_generic_param(
                 ident,
                 node_id,
-                res,
+                kind,
                 hir::GenericParamSource::Generics,
             )
         }));

compiler/rustc_ast_lowering/src/lib.rs

@@ -55,7 +55,7 @@ use rustc_hir::definitions::PerParentDisambiguatorState;
 use rustc_hir::lints::DelayedLint;
 use rustc_hir::{
     self as hir, AngleBrackets, ConstArg, GenericArg, HirId, ItemLocalMap, LifetimeSource,
-    LifetimeSyntax, ParamName, Target, TraitCandidate, find_attr,
+    LifetimeSyntax, MissingLifetimeKind, ParamName, Target, TraitCandidate, find_attr,
 };
 use rustc_index::{Idx, IndexSlice, IndexVec};
 use rustc_macros::extension;
@@ -310,7 +310,7 @@ impl<'tcx> ResolverAstLowering<'tcx> {
     ///
     /// The extra lifetimes that appear from the parenthesized `Fn`-trait desugaring
     /// should appear at the enclosing `PolyTraitRef`.
-    fn extra_lifetime_params(&self, id: NodeId) -> &[(Ident, NodeId, LifetimeRes)] {
+    fn extra_lifetime_params(&self, id: NodeId) -> &[(Ident, NodeId, MissingLifetimeKind)] {
         self.extra_lifetime_params_map.get(&id).map_or(&[], |v| &v[..])
     }
 
@@ -948,36 +948,27 @@ impl<'hir> LoweringContext<'_, 'hir> {
         &mut self,
         ident: Ident,
         node_id: NodeId,
-        res: LifetimeRes,
+        kind: MissingLifetimeKind,
         source: hir::GenericParamSource,
     ) -> hir::GenericParam<'hir> {
-        let (name, kind) = match res {
-            LifetimeRes::Fresh { param, kind, .. } => {
-                // Late resolution delegates to us the creation of the `LocalDefId`.
-                let _def_id = self.create_def(
-                    param,
-                    Some(kw::UnderscoreLifetime),
-                    DefKind::LifetimeParam,
-                    ident.span,
-                );
-                debug!(?_def_id);
+        // Late resolution delegates to us the creation of the `LocalDefId`.
+        let _def_id = self.create_def(
+            node_id,
+            Some(kw::UnderscoreLifetime),
+            DefKind::LifetimeParam,
+            ident.span,
+        );
+        debug!(?_def_id);
 
-                (hir::ParamName::Fresh, hir::LifetimeParamKind::Elided(kind))
-            }
-            res => panic!(
-                "Unexpected lifetime resolution {:?} for {:?} at {:?}",
-                res, ident, ident.span
-            ),
-        };
         let hir_id = self.lower_node_id(node_id);
         let def_id = self.local_def_id(node_id);
         hir::GenericParam {
             hir_id,
             def_id,
-            name,
+            name: hir::ParamName::Fresh,
             span: self.lower_span(ident.span),
             pure_wrt_drop: false,
-            kind: hir::GenericParamKind::Lifetime { kind },
+            kind: hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Elided(kind) },
             colon_span: None,
             source,
         }

compiler/rustc_middle/src/ty/mod.rs

@@ -37,7 +37,7 @@ use rustc_data_structures::stable_hash::{StableHash, StableHashCtxt, StableHashe
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::unord::{UnordMap, UnordSet};
 use rustc_errors::{Diag, ErrorGuaranteed, LintBuffer};
-use rustc_hir as hir;
+use rustc_hir::{self as hir, MissingLifetimeKind};
 use rustc_hir::attrs::StrippedCfgItem;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, DocLinkResMap, LifetimeRes, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LocalDefIdMap};
@@ -232,7 +232,7 @@ pub struct ResolverAstLowering<'tcx> {
     /// Resolutions for lifetimes.
     pub lifetimes_res_map: NodeMap<LifetimeRes>,
     /// Lifetime parameters that lowering will have to introduce.
-    pub extra_lifetime_params_map: NodeMap<Vec<(Ident, ast::NodeId, LifetimeRes)>>,
+    pub extra_lifetime_params_map: NodeMap<Vec<(Ident, ast::NodeId, MissingLifetimeKind)>>,
 
     pub next_node_id: ast::NodeId,
 

compiler/rustc_resolve/src/late.rs

@@ -2151,7 +2151,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             .extra_lifetime_params_map
             .entry(binder)
             .or_insert_with(Vec::new)
-            .push((ident, param, res));
+            .push((ident, param, kind));
         res
     }
 

compiler/rustc_resolve/src/lib.rs

@@ -58,7 +58,7 @@ use rustc_hir::def::{
 };
 use rustc_hir::def_id::{CRATE_DEF_ID, CrateNum, DefId, LOCAL_CRATE, LocalDefId, LocalDefIdMap};
 use rustc_hir::definitions::{PerParentDisambiguatorState, PerParentDisambiguatorsMap};
-use rustc_hir::{PrimTy, TraitCandidate, find_attr};
+use rustc_hir::{MissingLifetimeKind, PrimTy, TraitCandidate, find_attr};
 use rustc_index::bit_set::DenseBitSet;
 use rustc_metadata::creader::CStore;
 use rustc_middle::metadata::{AmbigModChild, ModChild, Reexport};
@@ -1385,7 +1385,7 @@ pub struct Resolver<'ra, 'tcx> {
     /// Resolutions for lifetimes.
     lifetimes_res_map: NodeMap<LifetimeRes> = Default::default(),
     /// Lifetime parameters that lowering will have to introduce.
-    extra_lifetime_params_map: NodeMap<Vec<(Ident, NodeId, LifetimeRes)>> = Default::default(),
+    extra_lifetime_params_map: NodeMap<Vec<(Ident, NodeId, MissingLifetimeKind)>> = Default::default(),
 
     /// `CrateNum` resolutions of `extern crate` items.
     extern_crate_map: UnordMap<LocalDefId, CrateNum> = Default::default(),