Regression test for RPIT inheriting lifetime

tests/ui/impl-trait/rpit/inherits-lifetime.rs

@@ -0,0 +1,24 @@
+//! Check that lifetimes are inherited in RPIT.
+//! Previously, the hidden lifetime of T::Bar would be overlooked
+//! and would instead end up as <T as Foo<'static>>::Bar.
+//!
+//! Regression test for <https://github.com/rust-lang/rust/issues/51525>.
+
+//@ check-pass
+
+trait Foo<'a> {
+    type Bar;
+}
+
+impl<'a> Foo<'a> for u32 {
+    type Bar = &'a ();
+}
+
+fn baz<'a, T>() -> impl IntoIterator<Item = T::Bar>
+where
+    T: Foo<'a>,
+{
+    None
+}
+
+fn main() {}