#2641. Check that it is still an error to declare more than one class member named _ (#2669)

Check that it is still an error to declare more than one class member named `_`

Author: sgrekhov

LanguageFeatures/Wildcards/unchanged_A05_t02.dart

@@ -0,0 +1,63 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// 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.
+
+/// @assertion Other declarations: top-level variables, top-level function
+/// names, type names, member names, etc. are unchanged. They can be named `_`
+/// as they are today.
+///
+/// @description Checks that a member named `_` is still accessible and its
+/// value can be used. Test mixin members
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=wildcard-variables
+
+import '../../Utils/expect.dart';
+
+mixin M1 {
+  static int _ = 1;
+}
+
+mixin M2 {
+  static int _() => 2;
+}
+
+mixin M3 {
+  static int get _ => 3;
+}
+
+mixin M4 {
+  static void set _(int v) {}
+}
+
+mixin M5 {
+  int _ = 5;
+}
+
+mixin M6 {
+  int _() => 6;
+}
+
+mixin M7 {
+  int get _ => 7;
+}
+
+mixin M8 {
+  void set _(int v) {}
+}
+
+class MA5 = Object with M5;
+class MA6 = Object with M6;
+class MA7 = Object with M7;
+class MA8 = Object with M8;
+
+main() {
+  Expect.equals(1, M1._);
+  Expect.equals(2, M2._());
+  Expect.equals(3, M3._);
+  M4._ = 42;
+  Expect.equals(5, MA5()._);
+  Expect.equals(6, MA6()._());
+  Expect.equals(7, MA7()._);
+  MA8()._ = 42;
+}

LanguageFeatures/Wildcards/unchanged_A05_t03.dart

@@ -0,0 +1,66 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// 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.
+
+/// @assertion Other declarations: top-level variables, top-level function
+/// names, type names, member names, etc. are unchanged. They can be named `_`
+/// as they are today.
+///
+/// @description Checks that a member named `_` is still accessible and its
+/// value can be used. Test enum members
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=wildcard-variables
+
+import '../../Utils/expect.dart';
+
+enum E1 {
+  e1;
+  static int _ = 1;
+}
+
+enum E2 {
+  e1;
+  static int _() => 2;
+}
+
+enum E3 {
+  e1;
+  static int get _ => 3;
+}
+
+enum E4 {
+  e1;
+  static void set _(int v) {}
+}
+
+enum E5 {
+  e1;
+  final int _ = 5;
+}
+
+enum E6 {
+  e1;
+  int _() => 6;
+}
+
+enum E7 {
+  e1;
+  int get _ => 7;
+}
+
+enum E8 {
+  e1;
+  void set _(int v) {}
+}
+
+main() {
+  Expect.equals(1, E1._);
+  Expect.equals(2, E2._());
+  Expect.equals(3, E3._);
+  E4._ = 42;
+  Expect.equals(5, E5.e1._);
+  Expect.equals(6, E6.e1._());
+  Expect.equals(7, E7.e1._);
+  E8.e1._ = 42;
+}

LanguageFeatures/Wildcards/unchanged_A05_t04.dart

@@ -0,0 +1,53 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// 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.
+
+/// @assertion Other declarations: top-level variables, top-level function
+/// names, type names, member names, etc. are unchanged. They can be named `_`
+/// as they are today.
+///
+/// @description Checks that a member named `_` is still accessible and its
+/// value can be used. Test extension type members
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=wildcard-variables
+
+import '../../Utils/expect.dart';
+
+extension type ET1(int id) {
+  static int _ = 1;
+}
+
+extension type ET2(int id) {
+  static int _() => 2;
+}
+
+extension type ET3(int id) {
+  static int get _ => 3;
+}
+
+extension type ET4(int id) {
+  static void set _(int v) {}
+}
+
+extension type ET5(int id) {
+  int _() => 5;
+}
+
+extension type ET6(int id) {
+  int get _ => 6;
+}
+
+extension type ET7(int id) {
+  void set _(int v) {}
+}
+
+main() {
+  Expect.equals(1, ET1._);
+  Expect.equals(2, ET2._());
+  Expect.equals(3, ET3._);
+  ET4._ = 42;
+  Expect.equals(5, ET5(1)._());
+  Expect.equals(6, ET6(1)._);
+  ET7(1)._ = 42;
+}

LanguageFeatures/Wildcards/unchanged_A05_t05.dart

@@ -0,0 +1,60 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// 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.
+
+/// @assertion Other declarations: top-level variables, top-level function
+/// names, type names, member names, etc. are unchanged. They can be named `_`
+/// as they are today.
+///
+/// @description Checks that a member named `_` is still accessible and its
+/// value can be used. Test extension members
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=wildcard-variables
+
+import '../../Utils/expect.dart';
+
+class A1 {}
+extension Ext1 on A1 {
+  static int _ = 1;
+}
+
+class A2 {}
+extension Ext2 on A2 {
+  static int _() => 2;
+}
+
+class A3 {}
+extension Ext3 on A3 {
+  static int get _ => 3;
+}
+
+class A4 {}
+extension Ext4 on A4 {
+  static void set _(int v) {}
+}
+
+class A5 {}
+extension Ext5 on A5 {
+  int _() => 5;
+}
+
+class A6 {}
+extension Ext6 on A6 {
+  int get _ => 6;
+}
+
+class A7 {}
+extension Ext7 on A7 {
+  void set _(int v) {}
+}
+
+main() {
+  Expect.equals(1, Ext1._);
+  Expect.equals(2, Ext2._());
+  Expect.equals(3, Ext3._);
+  Ext4._ = 42;
+  Expect.equals(5, A5()._());
+  Expect.equals(6, A6()._);
+  A7()._ = 42;
+}