Handle trait/impl GAC mismatches when inferring missing/placeholder t…

…ypes
abao168899 · May 23, 2024 · 39d9b84 · 39d9b84
1 parent 24afa42
commit 39d9b84
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Showing 4 changed files with 27 additions and 16 deletions.
diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
@@ -244,7 +244,8 @@ fn infer_type_if_missing<'tcx>(fcx: &FnCtxt<'_, 'tcx>, node: Node<'tcx>) -> Opti
  impl_def_id,
  impl_trait_ref.args,
  );
- Some(tcx.type_of(trait_item_def_id).instantiate(tcx, args))
+ tcx.check_args_compatible(trait_item_def_id, args)
+ .then(|| tcx.type_of(trait_item_def_id).instantiate(tcx, args))
  } else {
  Some(fcx.next_ty_var(span))
  }

diff --git a/tests/crashes/124833.rs b/tests/crashes/124833.rs
diff --git a/tests/ui/generic-const-items/assoc-const-missing-type.rs b/tests/ui/generic-const-items/assoc-const-missing-type.rs
@@ -5,13 +5,17 @@
 
 trait Trait {
  const K<T>: T;
+ const Q<'a>: &'a str;
 }
 
 impl Trait for () {
  const K<T> = ();
  //~^ ERROR missing type for `const` item
  //~| ERROR mismatched types
  //~| ERROR mismatched types
+ const Q = "";
+ //~^ ERROR missing type for `const` item
+ //~| ERROR lifetime parameters or bounds on const `Q` do not match the trait declaration
 }
 
 fn main() {}
diff --git a/tests/ui/generic-const-items/assoc-const-missing-type.stderr b/tests/ui/generic-const-items/assoc-const-missing-type.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
- --> $DIR/assoc-const-missing-type.rs:11:18
+ --> $DIR/assoc-const-missing-type.rs:12:18
  |
 LL | const K<T> = ();
  | - ^^ expected type parameter `T`, found `()`
@@ -10,13 +10,28 @@ LL | const K<T> = ();
  found unit type `()`
 
 error: missing type for `const` item
- --> $DIR/assoc-const-missing-type.rs:11:15
+ --> $DIR/assoc-const-missing-type.rs:12:15
  |
 LL | const K<T> = ();
  | ^ help: provide a type for the associated constant: `()`
 
+error[E0195]: lifetime parameters or bounds on const `Q` do not match the trait declaration
+ --> $DIR/assoc-const-missing-type.rs:16:12
+ |
+LL | const Q<'a>: &'a str;
+ | ---- lifetimes in impl do not match this const in trait
+...
+LL | const Q = "";
+ | ^ lifetimes do not match const in trait
+
+error: missing type for `const` item
+ --> $DIR/assoc-const-missing-type.rs:16:12
+ |
+LL | const Q = "";
+ | ^ help: provide a type for the associated constant: `: &str`
+
 error[E0308]: mismatched types
- --> $DIR/assoc-const-missing-type.rs:11:18
+ --> $DIR/assoc-const-missing-type.rs:12:18
  |
 LL | const K<T> = ();
  | - ^^ expected type parameter `T`, found `()`
@@ -27,6 +42,7 @@ LL | const K<T> = ();
  found unit type `()`
  = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
-error: aborting due to 3 previous errors
+error: aborting due to 5 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0195, E0308.
+For more information about an error, try `rustc --explain E0195`.