Fix a failing test

The reason this test passed previously is not because it was working as intended, but because prior to the previous commit we did not resolve the `use` at all!

Now, `use self as _` is invalid code anyway (it prints E0429), and because we fallback to the value namespace if we can't resolve in the type namespace (which is a reasonable behavior), this test now actually fails.

I don't think we want to change the fallback, so I removed `use self as _` and instead added a new test, where the value can be resolved in the type namespace.

src/tools/rust-analyzer/crates/ide/src/rename.rs

@@ -2001,19 +2001,37 @@ impl Foo {
             "foo",
             r#"
 fn f($0self) -> i32 {
-    use self as _;
     self.i
 }
 "#,
             r#"
 fn f(foo: _) -> i32 {
-    use self as _;
     foo.i
 }
 "#,
         );
     }
 
+    #[test]
+    fn no_type_value_ns_confuse() {
+        // Test that we don't rename items from different namespaces.
+        check(
+            "bar",
+            r#"
+struct foo {}
+fn f(foo$0: i32) -> i32 {
+    use foo as _;
+}
+"#,
+            r#"
+struct foo {}
+fn f(bar: i32) -> i32 {
+    use foo as _;
+}
+"#,
+        );
+    }
+
     #[test]
     fn test_self_in_path_to_parameter() {
         check(