Add a regression test for issue-69323

src/test/ui/type-alias-impl-trait/issue-69323.full.stderr

@@ -0,0 +1,11 @@
+warning: the feature `type_alias_impl_trait` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/issue-69323.rs:5:27
+   |
+LL | #![cfg_attr(full, feature(type_alias_impl_trait))]
+   |                           ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+   = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
+
+warning: 1 warning emitted
+

src/test/ui/type-alias-impl-trait/issue-69323.rs

@@ -0,0 +1,19 @@
+// check-pass
+
+// revisions: min full
+#![feature(min_type_alias_impl_trait)]
+#![cfg_attr(full, feature(type_alias_impl_trait))]
+//[full]~^ WARN incomplete
+
+use std::iter::{once, Chain};
+
+fn test1<A: Iterator<Item = &'static str>>(x: A) -> Chain<A, impl Iterator<Item = &'static str>> {
+    x.chain(once(","))
+}
+
+type I<A> = Chain<A, impl Iterator<Item = &'static str>>;
+fn test2<A: Iterator<Item = &'static str>>(x: A) -> I<A> {
+    x.chain(once(","))
+}
+
+fn main() {}