MIR episode 5

Author: HKalbasi

Cargo.lock

@@ -165,7 +165,7 @@ impl Body {
         };
         let expander = Expander::new(db, file_id, module);
         let (mut body, source_map) =
-            Body::new(db, expander, params, body, module.krate, is_async_fn);
+            Body::new(db, def, expander, params, body, module.krate, is_async_fn);
         body.shrink_to_fit();
 
         (Arc::new(body), Arc::new(source_map))
@@ -189,13 +189,14 @@ impl Body {
 
     fn new(
         db: &dyn DefDatabase,
+        owner: DefWithBodyId,
         expander: Expander,
         params: Option<(ast::ParamList, impl Iterator<Item = bool>)>,
         body: Option<ast::Expr>,
         krate: CrateId,
         is_async_fn: bool,
     ) -> (Body, BodySourceMap) {
-        lower::lower(db, expander, params, body, krate, is_async_fn)
+        lower::lower(db, owner, expander, params, body, krate, is_async_fn)
     }
 
     fn shrink_to_fit(&mut self) {

crates/hir-def/src/body.rs

@@ -40,11 +40,12 @@ use crate::{
     nameres::{DefMap, MacroSubNs},
     path::{GenericArgs, Path},
     type_ref::{Mutability, Rawness, TypeRef},
-    AdtId, BlockId, BlockLoc, ModuleDefId, UnresolvedMacro,
+    AdtId, BlockId, BlockLoc, DefWithBodyId, ModuleDefId, UnresolvedMacro,
 };
 
 pub(super) fn lower(
     db: &dyn DefDatabase,
+    owner: DefWithBodyId,
     expander: Expander,
     params: Option<(ast::ParamList, impl Iterator<Item = bool>)>,
     body: Option<ast::Expr>,
@@ -53,6 +54,7 @@ pub(super) fn lower(
 ) -> (Body, BodySourceMap) {
     ExprCollector {
         db,
+        owner,
         krate,
         def_map: expander.module.def_map(db),
         source_map: BodySourceMap::default(),
@@ -80,6 +82,7 @@ pub(super) fn lower(
 struct ExprCollector<'a> {
     db: &'a dyn DefDatabase,
     expander: Expander,
+    owner: DefWithBodyId,
     def_map: Arc<DefMap>,
     ast_id_map: Arc<AstIdMap>,
     krate: CrateId,
@@ -269,16 +272,13 @@ impl ExprCollector<'_> {
                 }
                 Some(ast::BlockModifier::Const(_)) => {
                     self.with_label_rib(RibKind::Constant, |this| {
-                        this.collect_as_a_binding_owner_bad(
-                            |this| {
-                                this.collect_block_(e, |id, statements, tail| Expr::Const {
-                                    id,
-                                    statements,
-                                    tail,
-                                })
-                            },
-                            syntax_ptr,
-                        )
+                        let (result_expr_id, prev_binding_owner) =
+                            this.initialize_binding_owner(syntax_ptr);
+                        let inner_expr = this.collect_block(e);
+                        let x = this.db.intern_anonymous_const((this.owner, inner_expr));
+                        this.body.exprs[result_expr_id] = Expr::Const(x);
+                        this.current_binding_owner = prev_binding_owner;
+                        result_expr_id
                     })
                 }
                 None => self.collect_block(e),

crates/hir-def/src/body/lower.rs

@@ -436,8 +436,8 @@ impl<'a> Printer<'a> {
             Expr::Async { id: _, statements, tail } => {
                 self.print_block(Some("async "), statements, tail);
             }
-            Expr::Const { id: _, statements, tail } => {
-                self.print_block(Some("const "), statements, tail);
+            Expr::Const(id) => {
+                w!(self, "const {{ /* {id:?} */ }}");
             }
         }
     }

crates/hir-def/src/body/pretty.rs

@@ -218,9 +218,10 @@ fn compute_expr_scopes(expr: ExprId, body: &Body, scopes: &mut ExprScopes, scope
             scopes.set_scope(expr, scope);
             compute_block_scopes(statements, *tail, body, scopes, &mut scope);
         }
-        Expr::Unsafe { id, statements, tail }
-        | Expr::Async { id, statements, tail }
-        | Expr::Const { id, statements, tail } => {
+        Expr::Const(_) => {
+            // FIXME: This is broken.
+        }
+        Expr::Unsafe { id, statements, tail } | Expr::Async { id, statements, tail } => {
             let mut scope = scopes.new_block_scope(*scope, *id, None);
             // Overwrite the old scope for the block expr, so that every block scope can be found
             // via the block itself (important for blocks that only contain items, no expressions).

crates/hir-def/src/body/scope.rs

@@ -16,16 +16,17 @@ use crate::{
         TraitAliasData, TraitData, TypeAliasData,
     },
     generics::GenericParams,
+    hir::ExprId,
     import_map::ImportMap,
     item_tree::{AttrOwner, ItemTree},
     lang_item::{LangItem, LangItemTarget, LangItems},
     nameres::{diagnostics::DefDiagnostic, DefMap},
     visibility::{self, Visibility},
-    AttrDefId, BlockId, BlockLoc, ConstId, ConstLoc, DefWithBodyId, EnumId, EnumLoc, ExternBlockId,
-    ExternBlockLoc, FunctionId, FunctionLoc, GenericDefId, ImplId, ImplLoc, LocalEnumVariantId,
-    LocalFieldId, Macro2Id, Macro2Loc, MacroRulesId, MacroRulesLoc, ProcMacroId, ProcMacroLoc,
-    StaticId, StaticLoc, StructId, StructLoc, TraitAliasId, TraitAliasLoc, TraitId, TraitLoc,
-    TypeAliasId, TypeAliasLoc, UnionId, UnionLoc, VariantId,
+    AnonymousConstId, AttrDefId, BlockId, BlockLoc, ConstId, ConstLoc, DefWithBodyId, EnumId,
+    EnumLoc, ExternBlockId, ExternBlockLoc, FunctionId, FunctionLoc, GenericDefId, ImplId, ImplLoc,
+    LocalEnumVariantId, LocalFieldId, Macro2Id, Macro2Loc, MacroRulesId, MacroRulesLoc,
+    ProcMacroId, ProcMacroLoc, StaticId, StaticLoc, StructId, StructLoc, TraitAliasId,
+    TraitAliasLoc, TraitId, TraitLoc, TypeAliasId, TypeAliasLoc, UnionId, UnionLoc, VariantId,
 };
 
 #[salsa::query_group(InternDatabaseStorage)]
@@ -220,6 +221,9 @@ pub trait DefDatabase: InternDatabase + ExpandDatabase + Upcast<dyn ExpandDataba
     fn recursion_limit(&self, crate_id: CrateId) -> u32;
 
     fn crate_supports_no_std(&self, crate_id: CrateId) -> bool;
+
+    #[salsa::interned]
+    fn intern_anonymous_const(&self, id: (DefWithBodyId, ExprId)) -> AnonymousConstId;
 }
 
 fn crate_def_map_wait(db: &dyn DefDatabase, krate: CrateId) -> Arc<DefMap> {

crates/hir-def/src/db.rs

@@ -26,7 +26,7 @@ use crate::{
     builtin_type::{BuiltinFloat, BuiltinInt, BuiltinUint},
     path::{GenericArgs, Path},
     type_ref::{Mutability, Rawness, TypeRef},
-    BlockId,
+    AnonymousConstId, BlockId,
 };
 
 pub use syntax::ast::{ArithOp, BinaryOp, CmpOp, LogicOp, Ordering, RangeOp, UnaryOp};
@@ -169,11 +169,7 @@ pub enum Expr {
         statements: Box<[Statement]>,
         tail: Option<ExprId>,
     },
-    Const {
-        id: Option<BlockId>,
-        statements: Box<[Statement]>,
-        tail: Option<ExprId>,
-    },
+    Const(AnonymousConstId),
     Unsafe {
         id: Option<BlockId>,
         statements: Box<[Statement]>,
@@ -355,10 +351,10 @@ impl Expr {
             Expr::Let { expr, .. } => {
                 f(*expr);
             }
+            Expr::Const(_) => (),
             Expr::Block { statements, tail, .. }
             | Expr::Unsafe { statements, tail, .. }
-            | Expr::Async { statements, tail, .. }
-            | Expr::Const { statements, tail, .. } => {
+            | Expr::Async { statements, tail, .. } => {
                 for stmt in statements.iter() {
                     match stmt {
                         Statement::Let { initializer, else_branch, .. } => {

crates/hir-def/src/hir.rs

@@ -48,6 +48,7 @@ pub mod visibility;
 pub mod find_path;
 pub mod import_map;
 
+use db::DefDatabase;
 pub use rustc_abi as layout;
 use triomphe::Arc;
 
@@ -59,7 +60,11 @@ mod pretty;
 
 use std::hash::{Hash, Hasher};
 
-use base_db::{impl_intern_key, salsa, CrateId, ProcMacroKind};
+use base_db::{
+    impl_intern_key,
+    salsa::{self, InternId},
+    CrateId, ProcMacroKind,
+};
 use hir_expand::{
     ast_id_map::FileAstId,
     attrs::{Attr, AttrId, AttrInput},
@@ -472,6 +477,46 @@ impl_from!(
     for ModuleDefId
 );
 
+// FIXME: make this a DefWithBodyId
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
+pub struct AnonymousConstId(InternId);
+impl_intern_key!(AnonymousConstId);
+
+/// A constant, which might appears as a const item, an annonymous const block in expressions
+/// or patterns, or as a constant in types with const generics.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum GeneralConstId {
+    ConstId(ConstId),
+    AnonymousConstId(AnonymousConstId),
+}
+
+impl_from!(ConstId, AnonymousConstId for GeneralConstId);
+
+impl GeneralConstId {
+    pub fn generic_def(self, db: &dyn DefDatabase) -> Option<GenericDefId> {
+        match self {
+            GeneralConstId::ConstId(x) => Some(x.into()),
+            GeneralConstId::AnonymousConstId(x) => {
+                let (parent, _) = db.lookup_intern_anonymous_const(x);
+                parent.as_generic_def_id()
+            }
+        }
+    }
+
+    pub fn name(self, db: &dyn DefDatabase) -> String {
+        match self {
+            GeneralConstId::ConstId(const_id) => db
+                .const_data(const_id)
+                .name
+                .as_ref()
+                .and_then(|x| x.as_str())
+                .unwrap_or("_")
+                .to_owned(),
+            GeneralConstId::AnonymousConstId(id) => format!("{{anonymous const {id:?}}}"),
+        }
+    }
+}
+
 /// The defs which have a body.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum DefWithBodyId {

crates/hir-def/src/lib.rs

@@ -12,6 +12,9 @@ use crate::{
 };
 
 pub(crate) fn print_path(path: &Path, buf: &mut dyn Write) -> fmt::Result {
+    if let Path::LangItem(x) = path {
+        return write!(buf, "$lang_item::{x:?}");
+    }
     match path.type_anchor() {
         Some(anchor) => {
             write!(buf, "<")?;

crates/hir-def/src/pretty.rs

@@ -376,6 +376,7 @@ pub mod known {
         deref,
         div_assign,
         div,
+        drop,
         fn_mut,
         fn_once,
         future_trait,