Add tests.

tests/ui/impl-trait/issue-108591.rs

@@ -0,0 +1,30 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+struct MyTy<'a>(Vec<u8>, &'a ());
+
+impl MyTy<'_> {
+    fn one(&mut self) -> &mut impl Sized {
+        &mut self.0
+    }
+    fn two(&mut self) -> &mut (impl Sized + 'static) {
+        self.one()
+    }
+}
+
+type Opaque<'a> = impl Sized;
+fn define<'a>() -> Opaque<'a> {}
+
+fn test<'a>() {
+    None::<&'static Opaque<'a>>;
+}
+
+fn one<'a, 'b: 'b>() -> &'a impl Sized {
+    &()
+}
+fn two<'a, 'b>() {
+    one::<'a, 'b>();
+}
+
+fn main() {}

tests/ui/impl-trait/issue-108592.rs

@@ -0,0 +1,21 @@
+// check-pass
+#![feature(type_alias_impl_trait)]
+
+fn opaque<'a: 'a>() -> impl Sized {}
+fn assert_static<T: 'static>(_: T) {}
+
+fn test_closure() {
+    let closure = |_| {
+        assert_static(opaque());
+    };
+    closure(&opaque());
+}
+
+type Opaque<'a> = impl Sized;
+fn define<'a>() -> Opaque<'a> {}
+
+fn test_tait(_: &Opaque<'_>) {
+    None::<&'static Opaque<'_>>;
+}
+
+fn main() {}

tests/ui/impl-trait/issue-108592.stderr

@@ -0,0 +1,21 @@
+error[E0428]: the name `test` is defined multiple times
+  --> $DIR/issue-108592.rs:17:1
+   |
+LL | fn test() {
+   | --------- previous definition of the value `test` here
+...
+LL | fn test(_: &Opaque<'_>) {
+   | ^^^^^^^^^^^^^^^^^^^^^^^ `test` redefined here
+   |
+   = note: `test` must be defined only once in the value namespace of this module
+
+error[E0601]: `main` function not found in crate `issue_108592`
+  --> $DIR/issue-108592.rs:20:2
+   |
+LL | }
+   |  ^ consider adding a `main` function to `$DIR/issue-108592.rs`
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0428, E0601.
+For more information about an error, try `rustc --explain E0428`.