Add a regression test for #109054

tests/ui/type-alias-impl-trait/issue-109054.rs

@@ -0,0 +1,22 @@
+// edition:2021
+
+#![feature(type_alias_impl_trait)]
+
+struct CallMe;
+
+type ReturnType<'a> = impl std::future::Future<Output = u32> + 'a;
+type FnType = impl Fn(&u32) -> ReturnType;
+
+impl std::ops::Deref for CallMe {
+    type Target = FnType;
+
+    fn deref(&self) -> &Self::Target {
+        fn inner(val: &u32) -> ReturnType {
+            async move { *val * 2 }
+        }
+
+        &inner //~ ERROR: expected generic lifetime parameter, found `'_`
+    }
+}
+
+fn main() {}

tests/ui/type-alias-impl-trait/issue-109054.stderr

@@ -0,0 +1,12 @@
+error[E0792]: expected generic lifetime parameter, found `'_`
+  --> $DIR/issue-109054.rs:18:9
+   |
+LL | type ReturnType<'a> = impl std::future::Future<Output = u32> + 'a;
+   |                 -- this generic parameter must be used with a generic lifetime parameter
+...
+LL |         &inner
+   |         ^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0792`.