[wildcards] local and parameter scopes

Update wildcard variable scopes.

See:  #55862 and #55680.

See discussion on related/ updated co19 test (`co19/LanguageFeatures/Wildcards/wildcards_do_not_shadow_A01_t04`) here: dart-lang/co19#2698.





Change-Id: I388895ef7bac69617700504a964ce9f3021b2d24
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/368526
Commit-Queue: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>

Author: pq

pkg/analyzer/lib/src/dart/element/scope.dart

@@ -93,7 +93,9 @@ class FormalParameterScope extends EnclosedScope {
     for (var parameter in elements) {
       if (parameter is! FieldFormalParameterElement &&
           parameter is! SuperFormalParameterElement) {
-        _addGetter(parameter);
+        if (!parameter.isWildcardVariable) {
+          _addGetter(parameter);
+        }
       }
     }
   }
@@ -174,7 +176,9 @@ class LocalScope extends EnclosedScope {
   LocalScope(super.parent);
 
   void add(Element element) {
-    _addGetter(element);
+    if (!element.isWildcardVariable) {
+      _addGetter(element);
+    }
   }
 }
 
@@ -436,3 +440,10 @@ class _LibraryOrAugmentationImportScope implements Scope {
     return _nullPrefixScope.lookup(id);
   }
 }
+
+extension on Element {
+  bool get isWildcardVariable =>
+      name == '_' &&
+      (this is LocalVariableElement || this is ParameterElement) &&
+      (library?.featureSet.isEnabled(Feature.wildcard_variables) ?? false);
+}

pkg/analyzer/test/src/dart/resolution/local_variable_test.dart

@@ -133,4 +133,43 @@ void f() {
     expect(x.isLate, isTrue);
     expect(x.isStatic, isFalse);
   }
+
+  test_localVariable_wildcardVariable_field() async {
+    await assertNoErrorsInCode('''
+class C {
+  var _ = 1;
+  void m() {
+    var _ = 0;
+    _;
+  }
+}
+''');
+
+    var node = findNode.simple('_;');
+    assertResolvedNodeText(node, r'''
+SimpleIdentifier
+  token: _
+  staticElement: self::@class::C::@getter::_
+  staticType: int
+''');
+  }
+
+  test_localVariable_wildcardVariable_topLevel() async {
+    await assertNoErrorsInCode('''
+var _ = 1;
+
+void f() {
+  var _ = 0;
+  _;
+}
+''');
+
+    var node = findNode.simple('_;');
+    assertResolvedNodeText(node, r'''
+SimpleIdentifier
+  token: _
+  staticElement: self::@getter::_
+  staticType: int
+''');
+  }
 }

pkg/analyzer/test/src/dart/resolution/method_declaration_test.dart

@@ -51,4 +51,23 @@ class B {
       findElement.parameter('a'),
     );
   }
+
+  test_formalParameterScope_wildcardVariable() async {
+    await assertNoErrorsInCode('''
+class A {
+  var _ = 1;
+  void m(int? _) {
+    _;
+  }
+}
+''');
+
+    var node = findNode.simple('_;');
+    assertResolvedNodeText(node, r'''
+SimpleIdentifier
+  token: _
+  staticElement: self::@class::A::@getter::_
+  staticType: int
+''');
+  }
 }

pkg/analyzer/test/src/diagnostics/unused_catch_clause_test.dart

@@ -2,36 +2,46 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:analyzer/dart/analysis/features.dart';
-import 'package:analyzer/src/error/codes.g.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import '../dart/resolution/context_collection_resolution.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(UnusedCatchClauseTest);
-    defineReflectiveTests(UnusedCatchClauseTestWildCardVariablesTest);
   });
 }
 
 @reflectiveTest
 class UnusedCatchClauseTest extends PubPackageResolutionTest {
   test_on_unusedException() async {
     await assertErrorsInCode(r'''
-main() {
+f() {
   try {
   } on String catch (exception) {
   }
 }
 ''', [
-      error(WarningCode.UNUSED_CATCH_CLAUSE, 38, 9),
+      error(WarningCode.UNUSED_CATCH_CLAUSE, 35, 9),
+    ]);
+  }
+
+  test_on_unusedStack_underscores() async {
+    await assertErrorsInCode(r'''
+f() {
+  try {
+  } on String catch (exception, __) {
+  }
+}
+''', [
+      error(WarningCode.UNUSED_CATCH_STACK, 46, 2),
     ]);
   }
 
   test_on_unusedStack_wildcard() async {
     await assertNoErrorsInCode(r'''
-main() {
+f() {
   try {
   } on String catch (exception, _) {
   }
@@ -41,7 +51,7 @@ main() {
 
   test_on_usedException() async {
     await assertNoErrorsInCode(r'''
-main() {
+f() {
   try {
   } on String catch (exception) {
     print(exception);
@@ -52,7 +62,7 @@ main() {
 
   test_unusedException() async {
     await assertNoErrorsInCode(r'''
-main() {
+f() {
   try {
   } catch (exception) {
   }
@@ -62,7 +72,7 @@ main() {
 
   test_unusedException_underscores() async {
     await assertNoErrorsInCode(r'''
-main() {
+f() {
   try {
   } catch (__) {
   }
@@ -72,7 +82,7 @@ main() {
 
   test_unusedException_wildcard() async {
     await assertNoErrorsInCode(r'''
-main() {
+f() {
   try {
   } catch (_) {
   }
@@ -82,7 +92,7 @@ main() {
 
   test_usedException() async {
     await assertNoErrorsInCode(r'''
-main() {
+f() {
   try {
   } catch (exception) {
     print(exception);
@@ -91,24 +101,3 @@ main() {
 ''');
   }
 }
-
-@reflectiveTest
-class UnusedCatchClauseTestWildCardVariablesTest extends UnusedCatchClauseTest {
-  @override
-  List<String> get experiments => [
-        ...super.experiments,
-        Feature.wildcard_variables.enableString,
-      ];
-
-  test_on_unusedStack_underscores() async {
-    await assertErrorsInCode(r'''
-main() {
-  try {
-  } on String catch (exception, __) {
-  }
-}
-''', [
-      error(WarningCode.UNUSED_CATCH_STACK, 49, 2),
-    ]);
-  }
-}

pkg/analyzer/test/src/diagnostics/unused_field_test.dart

@@ -186,6 +186,30 @@ print(x) {}
 ''');
   }
 
+  test_isUsed_underscoreField_shadowsLocal() async {
+    await assertNoErrorsInCode(r'''
+class A {
+  var _ = 1;
+  void m() {
+    var _ = 0;
+    print(_);
+  }
+}
+''');
+  }
+
+  // See: https://github.com/dart-lang/sdk/issues/55862
+  test_isUsed_underscoreField_shadowsParameter() async {
+    await assertNoErrorsInCode(r'''
+class A {
+  var _ = 1;
+  void m(int? _) {
+    print(_);
+  }
+}
+''');
+  }
+
   test_notUsed_compoundAssign() async {
     await assertErrorsInCode(r'''
 class A {