#2548. Add variance modifier declaration tests (#2554)

Add variance modifier declaration tests

TypeSystem/type-variance/declaration_A01_t01.dart

@@ -0,0 +1,32 @@
+// 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 It is a compile-time error if a variance modifier is specified
+/// for a type parameter declared by a static extension, a generic function
+/// type, a generic function or method, or a type alias.
+///
+/// @description Check that it is a compile-time error if a variance modifier is
+/// specified for a type parameter declared by a static extension
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=variance
+
+extension ExtList1<in T> on List<T> {}
+//                 ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+extension ExtList2<out T> on List<T> {}
+//                 ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+extension ExtList3<inout T> on List<T> {}
+//                 ^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+void main() {
+  print(List);
+}

TypeSystem/type-variance/declaration_A01_t02.dart

@@ -0,0 +1,52 @@
+// 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 It is a compile-time error if a variance modifier is specified
+/// for a type parameter declared by a static extension, a generic function
+/// type, a generic function or method, or a type alias.
+///
+/// @description Check that it is a compile-time error if a variance modifier is
+/// specified for a type parameter declared by a generic function type
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=variance
+
+typedef F1<in T>();
+//         ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef F2<out T>();
+//         ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef F3<inout T>();
+//         ^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef F4<in T> = void Function(T);
+//         ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef F5<out T> = void Function(T);
+//         ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef F6<inout T> = void Function(T);
+//         ^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+main() {
+  print(F1);
+  print(F2);
+  print(F3);
+  print(F4);
+  print(F5);
+  print(F6);
+}

TypeSystem/type-variance/declaration_A01_t03.dart

@@ -0,0 +1,34 @@
+// 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 It is a compile-time error if a variance modifier is specified
+/// for a type parameter declared by a static extension, a generic function
+/// type, a generic function or method, or a type alias.
+///
+/// @description Check that it is a compile-time error if a variance modifier is
+/// specified for a type parameter declared by a generic function
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=variance
+
+void f1<in T>(T t) {}
+//      ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+void f2<out T>(T t) {}
+//      ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+void f3<inout T>(T t) {}
+//      ^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+main() {
+  print(f1);
+  print(f2);
+  print(f3);
+}

TypeSystem/type-variance/declaration_A01_t04.dart

@@ -0,0 +1,48 @@
+// 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 It is a compile-time error if a variance modifier is specified
+/// for a type parameter declared by a static extension, a generic function
+/// type, a generic function or method, or a type alias.
+///
+/// @description Check that it is a compile-time error if a variance modifier is
+/// specified for a type parameter declared by a generic method
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=variance
+
+class C {
+  static void s1<in T>(T t) {}
+//               ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  static void s2<out T>(T t) {}
+//               ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  static void s3<inout T>(T t) {}
+//               ^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  void f1<in T>(T t) {}
+//        ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  void f2<out T>(T t) {}
+//        ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  void f3<inout T>(T t) {}
+//        ^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+main() {
+  print(C);
+}

TypeSystem/type-variance/declaration_A01_t05.dart

@@ -0,0 +1,34 @@
+// 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 It is a compile-time error if a variance modifier is specified
+/// for a type parameter declared by a static extension, a generic function
+/// type, a generic function or method, or a type alias.
+///
+/// @description Check that it is a compile-time error if a variance modifier is
+/// specified for a type parameter declared by a type alias
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=variance
+
+typedef AList1<in T> = List<T>;
+//             ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef AList2<out T> = List<T>;
+//             ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+typedef AList3<inout T> = List<T>;
+//             ^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+main() {
+  print(AList1);
+  print(AList2);
+  print(AList3);
+}