Merge pull request rust-lang#21074 from Aditya-PS-05/fix/param-macro-names-21070

fix: show no error when parameters match macro names

Author: ChayimFriedman2

src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_missing_impl_members.rs

@@ -2470,4 +2470,37 @@ impl b::Checker for MyChecker {
 }"#,
         );
     }
+
+    #[test]
+    fn test_parameter_names_matching_macros_not_qualified() {
+        // Parameter names that match macro names should not be qualified
+        check_assist(
+            add_missing_impl_members,
+            r#"
+//- /lib.rs crate:dep
+#[macro_export]
+macro_rules! my_macro {
+    () => {}
+}
+
+pub trait Foo {
+    fn foo(&self, my_macro: usize);
+}
+
+//- /main.rs crate:main deps:dep
+struct Bar;
+
+impl dep::Foo for Bar {$0}
+"#,
+            r#"
+struct Bar;
+
+impl dep::Foo for Bar {
+    fn foo(&self, my_macro: usize) {
+        ${0:todo!()}
+    }
+}
+"#,
+        );
+    }
 }

src/tools/rust-analyzer/crates/ide-db/src/path_transform.rs

@@ -546,6 +546,13 @@ impl Ctx<'_> {
 
         match resolution {
             hir::PathResolution::Def(def) if def.as_assoc_item(self.source_scope.db).is_none() => {
+                // Macros cannot be used in pattern position, and identifiers that happen
+                // to have the same name as macros (like parameter names `vec`, `format`, etc.)
+                // are bindings, not references. Don't qualify them.
+                if matches!(def, hir::ModuleDef::Macro(_)) {
+                    return None;
+                }
+
                 let cfg = FindPathConfig {
                     prefer_no_std: false,
                     prefer_prelude: true,