Fix TAIT & ATPIT feature gating in the presence of anon consts

1 files changed, 25 insertions, 0 deletions

diff --git a/tests/ui/impl-trait/inside-item-nested-in-anon-const.rs b/tests/ui/impl-trait/inside-item-nested-in-anon-const.rs
new file mode 100644
index 00000000000..ab54d5f87ba
--- /dev/null
+++ b/tests/ui/impl-trait/inside-item-nested-in-anon-const.rs
@@ -0,0 +1,25 @@
+// Ensure we don't misclassify `impl Trait` as TAIT/ATPIT if located inside an anon const in a
+// type alias/assoc type.
+// issue: <https://github.com/rust-lang/rust/issues/139055>
+//@ check-pass
+#![forbid(unstable_features)]
+
+struct Girder<const N: usize>;
+
+type Alias = Girder<{
+    fn pass(input: impl Sized) -> impl Sized { input }
+    0
+}>;
+
+trait Trait {
+    type Assoc;
+}
+
+impl Trait for () {
+    type Assoc = [(); {
+        fn pass(input: impl Sized) -> impl Sized { input }
+        0
+    }];
+}
+
+fn main() {}