Normalize projections in evaluated const display and layout calculation

rust-lang · Feb 26, 2025 · 0c26312 · 0c26312
1 parent 8925544
commit 0c26312
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Showing 3 changed files with 66 additions and 5 deletions.
diff --git a/crates/hir-ty/src/display.rs b/crates/hir-ty/src/display.rs
@@ -890,12 +890,32 @@ fn render_const_scalar(
         TyKind::Closure(_, _) => f.write_str("<closure>"),
         TyKind::Coroutine(_, _) => f.write_str("<coroutine>"),
         TyKind::CoroutineWitness(_, _) => f.write_str("<coroutine-witness>"),
+        TyKind::AssociatedType(id, subst) => render_const_scalar(
+            f,
+            b,
+            memory_map,
+            &TyKind::Alias(AliasTy::Projection(ProjectionTy {
+                associated_ty_id: *id,
+                substitution: subst.clone(),
+            }))
+            .intern(Interner),
+        ),
+        TyKind::Alias(AliasTy::Projection(projection)) => {
+            let normalized = f.db.normalize_projection(projection.clone(), trait_env);
+            if !matches!(
+                normalized.kind(Interner),
+                TyKind::Alias(AliasTy::Projection(_)) | TyKind::AssociatedType(..)
+            ) {
+                render_const_scalar(f, b, memory_map, &normalized)
+            } else {
+                f.write_str("<placeholder-or-unknown-type>")
+            }
+        }
         // The below arms are unreachable, since const eval will bail out before here.
         TyKind::Foreign(_) => f.write_str("<extern-type>"),
         TyKind::Error
         | TyKind::Placeholder(_)
-        | TyKind::Alias(_)
-        | TyKind::AssociatedType(_, _)
+        | TyKind::Alias(AliasTy::Opaque(_))
         | TyKind::OpaqueType(_, _)
         | TyKind::BoundVar(_)
         | TyKind::InferenceVar(_, _) => f.write_str("<placeholder-or-unknown-type>"),

diff --git a/crates/hir-ty/src/layout.rs b/crates/hir-ty/src/layout.rs
@@ -25,7 +25,7 @@ use crate::{
     infer::normalize,
     layout::adt::struct_variant_idx,
     utils::ClosureSubst,
-    Interner, ProjectionTy, Substitution, TraitEnvironment, Ty,
+    AliasTy, Interner, ProjectionTy, Substitution, TraitEnvironment, Ty,
 };
 
 pub use self::{
@@ -435,14 +435,21 @@ pub fn layout_of_ty_query(
         TyKind::Error => return Err(LayoutError::HasErrorType),
         TyKind::AssociatedType(id, subst) => {
             // Try again with `TyKind::Alias` to normalize the associated type.
-            let ty = TyKind::Alias(chalk_ir::AliasTy::Projection(ProjectionTy {
+            let ty = TyKind::Alias(AliasTy::Projection(ProjectionTy {
                 associated_ty_id: *id,
                 substitution: subst.clone(),
             }))
             .intern(Interner);
             return db.layout_of_ty(ty, trait_env);
         }
-        TyKind::Alias(_)
+        TyKind::Alias(AliasTy::Projection(projection)) => {
+            let normalized = db.normalize_projection(projection.clone(), trait_env.clone());
+            return match normalized.kind(Interner) {
+                TyKind::Alias(_) | TyKind::AssociatedType(..) => Err(LayoutError::HasPlaceholder),
+                _ => db.layout_of_ty(normalized, trait_env),
+            };
+        }
+        TyKind::Alias(AliasTy::Opaque(_))
         | TyKind::Placeholder(_)
         | TyKind::BoundVar(_)
         | TyKind::InferenceVar(_, _) => return Err(LayoutError::HasPlaceholder),

diff --git a/crates/ide/src/hover/tests.rs b/crates/ide/src/hover/tests.rs
@@ -10947,3 +10947,37 @@ pub struct ManuallyDrop$0<T: ?Sized> {
         "#]],
     );
 }
+
+#[test]
+fn projection_const() {
+    check(
+        r#"
+pub trait PublicFlags {
+    type Internal;
+}
+
+pub struct NoteDialects(<NoteDialects as PublicFlags>::Internal);
+
+impl NoteDialects {
+    pub const CLAP$0: Self = Self(InternalBitFlags);
+}
+
+pub struct InternalBitFlags;
+
+impl PublicFlags for NoteDialects {
+    type Internal = InternalBitFlags;
+}
+    "#,
+        expect![[r#"
+            *CLAP*
+
+            ```rust
+            ra_test_fixture::NoteDialects
+            ```
+
+            ```rust
+            pub const CLAP: Self = NoteDialects(InternalBitFlags)
+            ```
+        "#]],
+    );
+}