Handle multiple trait-def projection candidates

src/test/ui/associated-types/associated-types-projection-bound-ambiguity.rs

@@ -0,0 +1,16 @@
+// Check that if we have multiple applicable projection bounds we pick one (for
+// backwards compatibility reasons).
+
+// check-pass
+use std::ops::Mul;
+
+trait A {
+    type V;
+    type U: Mul<Self::V, Output = ()> + Mul<(), Output = ()>;
+}
+
+fn g<T: A<V = ()>>() {
+    let y: <T::U as Mul<()>>::Output = ();
+}
+
+fn main() {}