Rollup merge of #117371 - compiler-errors:unique-params, r=oli-obk

Ignore RPIT duplicated lifetimes in `opaque_types_defined_by`

An RPIT's or TAIT's own generics are kinda useless -- so just ignore them. For TAITs, they will always be empty, and for RPITs, they're always duplicated lifetimes.

Fixes #115013.

2 files changed, 28 insertions, 0 deletions

diff --git a/tests/ui/type-alias-impl-trait/duplicate-lifetimes-from-rpit-containing-tait.rs b/tests/ui/type-alias-impl-trait/duplicate-lifetimes-from-rpit-containing-tait.rs
new file mode 100644
index 00000000000..4c56fe2d1dc
--- /dev/null
+++ b/tests/ui/type-alias-impl-trait/duplicate-lifetimes-from-rpit-containing-tait.rs
@@ -0,0 +1,13 @@
+// check-pass
+
+#![feature(type_alias_impl_trait)]
+
+type Opaque<'lt> = impl Sized + 'lt;
+
+fn test<'a>(
+    arg: impl Iterator<Item = &'a u8>,
+) -> impl Iterator<Item = Opaque<'a>> {
+    arg
+}
+
+fn main() {}
diff --git a/tests/ui/type-alias-impl-trait/duplicate-lifetimes-from-rpit-containing-tait2.rs b/tests/ui/type-alias-impl-trait/duplicate-lifetimes-from-rpit-containing-tait2.rs
new file mode 100644
index 00000000000..97f8c799fc5
--- /dev/null
+++ b/tests/ui/type-alias-impl-trait/duplicate-lifetimes-from-rpit-containing-tait2.rs
@@ -0,0 +1,15 @@
+// check-pass
+// edition: 2021
+
+#![feature(type_alias_impl_trait)]
+
+struct Foo<'a>(&'a ());
+
+impl<'a> Foo<'a> {
+    async fn new() -> () {
+        type T = impl Sized;
+        let _: T = ();
+    }
+}
+
+fn main() {}