Auto merge of #125457 - fmease:gacs-diag-infer-plac-missing-ty, r=compiler-errors
Properly deal with missing/placeholder types inside GACs
Fixes #124833.
r? oli-obk (#123130)
diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
index b9a99fb..86fe275 100644
--- a/compiler/rustc_hir_typeck/src/lib.rs
+++ b/compiler/rustc_hir_typeck/src/lib.rs
@@ -235,11 +235,17 @@
if let Some(item) = tcx.opt_associated_item(def_id.into())
&& let ty::AssocKind::Const = item.kind
&& let ty::ImplContainer = item.container
- && let Some(trait_item) = item.trait_item_def_id
+ && let Some(trait_item_def_id) = item.trait_item_def_id
{
- let args =
- tcx.impl_trait_ref(item.container_id(tcx)).unwrap().instantiate_identity().args;
- Some(tcx.type_of(trait_item).instantiate(tcx, args))
+ let impl_def_id = item.container_id(tcx);
+ let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().instantiate_identity();
+ let args = ty::GenericArgs::identity_for_item(tcx, def_id).rebase_onto(
+ tcx,
+ impl_def_id,
+ impl_trait_ref.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
deleted file mode 100644
index f1c4847..0000000
--- a/tests/crashes/124833.rs
+++ /dev/null
@@ -1,10 +0,0 @@
-//@ known-bug: rust-lang/rust#124833
-#![feature(generic_const_items)]
-
-trait Trait {
- const C<'a>: &'a str;
-}
-
-impl Trait for () {
- const C<'a>: = "C";
-}
diff --git a/tests/ui/generic-const-items/assoc-const-missing-type.rs b/tests/ui/generic-const-items/assoc-const-missing-type.rs
new file mode 100644
index 0000000..93160f0
--- /dev/null
+++ b/tests/ui/generic-const-items/assoc-const-missing-type.rs
@@ -0,0 +1,21 @@
+// Ensure that we properly deal with missing/placeholder types inside GACs.
+// issue: rust-lang/rust#124833
+#![feature(generic_const_items)]
+#![allow(incomplete_features)]
+
+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
new file mode 100644
index 0000000..6f35c09
--- /dev/null
+++ b/tests/ui/generic-const-items/assoc-const-missing-type.stderr
@@ -0,0 +1,48 @@
+error[E0308]: mismatched types
+ --> $DIR/assoc-const-missing-type.rs:12:18
+ |
+LL | const K<T> = ();
+ | - ^^ expected type parameter `T`, found `()`
+ | |
+ | expected this type parameter
+ |
+ = note: expected type parameter `T`
+ found unit type `()`
+
+error: missing type for `const` item
+ --> $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:12:18
+ |
+LL | const K<T> = ();
+ | - ^^ expected type parameter `T`, found `()`
+ | |
+ | expected this type parameter
+ |
+ = note: expected type parameter `T`
+ found unit type `()`
+ = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0195, E0308.
+For more information about an error, try `rustc --explain E0195`.
