Add regression test for #89436

Author: Manishearth

src/test/ui/higher-rank-trait-bounds/normalize-under-binder/issue-89436.rs

@@ -0,0 +1,44 @@
+// check-pass
+
+#![allow(unused)]
+
+trait MiniYokeable<'a> {
+    type Output;
+}
+
+struct MiniYoke<Y: for<'a> MiniYokeable<'a>> {
+    pub yokeable: Y,
+}
+
+fn map_project_broken<Y, P>(
+    source: MiniYoke<Y>,
+    f: impl for<'a> FnOnce(
+        <Y as MiniYokeable<'a>>::Output,
+        core::marker::PhantomData<&'a ()>,
+    ) -> <P as MiniYokeable<'a>>::Output,
+) -> MiniYoke<P>
+where
+    Y: for<'a> MiniYokeable<'a>,
+    P: for<'a> MiniYokeable<'a>
+{
+    unimplemented!()
+}
+
+struct Bar<'a> {
+    string_1: &'a str,
+    string_2: &'a str,
+}
+
+impl<'a> MiniYokeable<'a> for Bar<'static> {
+    type Output = Bar<'a>;
+}
+
+impl<'a> MiniYokeable<'a> for &'static str {
+    type Output = &'a str;
+}
+
+fn demo_broken(bar: MiniYoke<Bar<'static>>) -> MiniYoke<&'static str> {
+    map_project_broken(bar, |bar, _| bar.string_1)
+}
+
+fn main() {}