Check associated opaque types in check_opaque_types

src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.rs

@@ -0,0 +1,18 @@
+// Ensure that we don't ICE if associated type impl trait is used in an impl
+// with an unconstrained type parameter.
+
+#![feature(type_alias_impl_trait)]
+
+trait X {
+    type I;
+    fn f() -> Self::I;
+}
+
+impl<T> X for () {
+    type I = impl Sized;
+    //~^ ERROR could not find defining uses
+    fn f() -> Self::I {}
+    //~^ ERROR type annotations needed
+}
+
+fn main() {}

src/test/ui/type-alias-impl-trait/impl-with-unconstrained-param.stderr

@@ -0,0 +1,15 @@
+error[E0282]: type annotations needed
+  --> $DIR/impl-with-unconstrained-param.rs:14:23
+   |
+LL |     fn f() -> Self::I {}
+   |                       ^^ cannot infer type for type parameter `T`
+
+error: could not find defining uses
+  --> $DIR/impl-with-unconstrained-param.rs:12:14
+   |
+LL |     type I = impl Sized;
+   |              ^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0282`.

src/test/ui/type-alias-impl-trait/issue-60564.rs

@@ -17,11 +17,8 @@ where
 {
     type BitsIter = IterBitsIter<T, E, u8>;
     fn iter_bits(self, n: u8) -> Self::BitsIter {
-    //~^ ERROR non-defining opaque type use in defining scope
-    //~| ERROR non-defining opaque type use in defining scope
-        (0u8..n)
-            .rev()
-            .map(move |shift| ((self >> T::from(shift)) & T::from(1)).try_into().unwrap())
+        //~^ ERROR non-defining opaque type use in defining scope
+        (0u8..n).rev().map(move |shift| ((self >> T::from(shift)) & T::from(1)).try_into().unwrap())
     }
 }
 

src/test/ui/type-alias-impl-trait/issue-60564.stderr

@@ -1,15 +1,3 @@
-error: non-defining opaque type use in defining scope
-  --> $DIR/issue-60564.rs:19:34
-   |
-LL |     fn iter_bits(self, n: u8) -> Self::BitsIter {
-   |                                  ^^^^^^^^^^^^^^
-   |
-note: used non-generic type `_` for generic parameter
-  --> $DIR/issue-60564.rs:8:22
-   |
-LL | type IterBitsIter<T, E, I> = impl std::iter::Iterator<Item = I>;
-   |                      ^
-
 error: non-defining opaque type use in defining scope
   --> $DIR/issue-60564.rs:19:34
    |
@@ -22,5 +10,5 @@ note: used non-generic type `u8` for generic parameter
 LL | type IterBitsIter<T, E, I> = impl std::iter::Iterator<Item = I>;
    |                         ^
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error