Add some tests

tests/ui/impl-trait/method-resolution.rs

@@ -0,0 +1,29 @@
+//! Check that we do not constrain hidden types during method resolution.
+//! Otherwise we'd pick up that calling `bar` can be satisfied iff `u32`
+//! is the hidden type of the RPIT.
+
+//@ revisions: current next
+//@[next] compile-flags: -Znext-solver
+//@[next] check-pass
+
+trait Trait {}
+
+impl Trait for u32 {}
+
+struct Bar<T>(T);
+
+impl Bar<u32> {
+    fn bar(self) {}
+}
+
+fn foo(x: bool) -> Bar<impl Sized> {
+    //[current]~^ ERROR: cycle detected
+    if x {
+        let x = foo(false);
+        x.bar();
+        //[current]~^ ERROR: no method named `bar` found
+    }
+    todo!()
+}
+
+fn main() {}