Add test

src/test/ui/resolve/name-collision-in-trait-fn-sig.rs

@@ -0,0 +1,11 @@
+// check-pass
+// This is currently stable behavior, which was almost accidentally made an
+// error in #102161 since there is no test exercising it. I am not sure if
+// this _should_ be the desired behavior, but at least we should know if it
+// changes.
+
+fn main() {}
+
+trait Foo {
+    fn fn_with_type_named_same_as_local_in_param(b: i32, b: i32);
+}