Rollup merge of #68438 - Aaron1011:fix/tait-non-defining, r=estebank

Account for non-types in substs for opaque type error messages

Fixes #68368

Previously, I assumed that the substs contained only types, which caused
the computed index number to be wrong.

2 files changed, 27 insertions, 0 deletions

diff --git a/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.rs b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.rs
new file mode 100644
index 00000000000..d00f8d7a901
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.rs
@@ -0,0 +1,13 @@
+// Regression test for issue #68368
+// Ensures that we don't ICE when emitting an error
+// for a non-defining use when lifetimes are involved
+
+#![feature(type_alias_impl_trait)]
+trait Trait<T> {}
+type Alias<'a, U> = impl Trait<U>; //~ ERROR could not find defining uses
+fn f<'a>() -> Alias<'a, ()> {}
+//~^ ERROR defining opaque type use does not fully define opaque type: generic parameter `U`
+
+fn main() {}
+
+impl Trait<()> for () {}
diff --git a/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.stderr b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.stderr
new file mode 100644
index 00000000000..b585942406f
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/issue-68368-non-defining-use.stderr
@@ -0,0 +1,14 @@
+error: defining opaque type use does not fully define opaque type: generic parameter `U` is specified as concrete type `()`
+  --> $DIR/issue-68368-non-defining-use.rs:8:1
+   |
+LL | fn f<'a>() -> Alias<'a, ()> {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: could not find defining uses
+  --> $DIR/issue-68368-non-defining-use.rs:7:1
+   |
+LL | type Alias<'a, U> = impl Trait<U>;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+