Normalize when finding trait object candidates

1 files changed, 37 insertions, 0 deletions

diff --git a/src/test/ui/traits/normalize-super-trait.rs b/src/test/ui/traits/normalize-super-trait.rs
new file mode 100644
index 00000000000..021a93eacff
--- /dev/null
+++ b/src/test/ui/traits/normalize-super-trait.rs
@@ -0,0 +1,37 @@
+// Regression test for #77653
+// When monomorphizing `f` we need to prove `dyn Derived<()>: Base<()>`. This
+// requires us to normalize the `Base<<() as Proj>::S>` to `Base<()>` when
+// comparing the supertrait `Derived<()>` to the expected trait.
+
+// build-pass
+
+trait Proj {
+    type S;
+}
+
+impl Proj for () {
+    type S = ();
+}
+
+impl Proj for i32 {
+    type S = i32;
+}
+
+trait Base<T> {
+    fn is_base(&self);
+}
+
+trait Derived<B: Proj>: Base<B::S> + Base<()> {
+    fn is_derived(&self);
+}
+
+fn f<P: Proj>(obj: &dyn Derived<P>) {
+    obj.is_derived();
+    Base::<P::S>::is_base(obj);
+    Base::<()>::is_base(obj);
+}
+
+fn main() {
+    let x: fn(_) = f::<()>;
+    let x: fn(_) = f::<i32>;
+}