Ensure that associated `async fn`s have unique fresh param names

1 files changed, 23 insertions, 0 deletions

diff --git a/src/test/ui/async-await/async-assoc-fn-anon-lifetimes.rs b/src/test/ui/async-await/async-assoc-fn-anon-lifetimes.rs
new file mode 100644
index 00000000000..8e08b82b9d3
--- /dev/null
+++ b/src/test/ui/async-await/async-assoc-fn-anon-lifetimes.rs
@@ -0,0 +1,23 @@
+// check-pass
+// Check that the anonymous lifetimes used here aren't considered to shadow one
+// another. Note that `async fn` is different to `fn` here because the lifetimes
+// are numbered by HIR lowering, rather than lifetime resolution.
+
+// edition:2018
+
+struct A<'a, 'b>(&'a &'b i32);
+struct B<'a>(&'a i32);
+
+impl A<'_, '_> {
+    async fn assoc(x: &u32, y: B<'_>) {
+        async fn nested(x: &u32, y: A<'_, '_>) {}
+    }
+
+    async fn assoc2(x: &u32, y: A<'_, '_>) {
+        impl A<'_, '_> {
+            async fn nested_assoc(x: &u32, y: B<'_>) {}
+        }
+    }
+}
+
+fn main() {}