Fix dart-lang#2546. Add constant context tests

Language/Expressions/Constants/Constant_Contexts/constant_context_A01_t01.dart

@@ -0,0 +1,29 @@
+// 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 Let e be an expression; e occurs in a constant context iff one of
+/// the following applies:
+/// • e is an element of a list or set literal whose first token is const, or e
+///   is a key or a value of an entry of a map literal whose first token is
+///   const.
+///
+/// @description Checks that an expression `e` is a constant expression if `e`
+/// is an element of a list whose first token is `const`. In this case `const`
+/// modifier for `e` can be omitted
+/// @author [email protected]
+
+import '../../../../Utils/expect.dart';
+
+class C {
+  final val;
+  const C(this.val);
+}
+
+main() {
+  var c1 = const [C(1)];
+  var c2 = const {C(2)};
+
+  Expect.identical(const C(1), c1[0]);
+  Expect.identical(const C(2), c2.lookup(const C(2)));
+}

Language/Expressions/Constants/Constant_Contexts/constant_context_A01_t02.dart

@@ -0,0 +1,28 @@
+// 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 Let e be an expression; e occurs in a constant context iff one of
+/// the following applies:
+/// • e is an element of a list or set literal whose first token is const, or e
+///   is a key or a value of an entry of a map literal whose first token is
+///   const.
+///
+/// @description Checks that an expression `e` is a constant expression if `e`
+/// is an element of a map whose first token is `const`. In this case `const`
+/// modifier for `e` can be omitted
+/// @author [email protected]
+
+import '../../../../Utils/expect.dart';
+
+class C {
+  final val;
+  const C(this.val);
+}
+
+main() {
+  var c = const {C(1): C(2)};
+
+  Expect.identical(const C(2), c[const C(1)]);
+  Expect.identical(const C(1), c.keys.toList()[0]);
+}

Language/Expressions/Constants/Constant_Contexts/constant_context_A01_t03.dart

@@ -0,0 +1,42 @@
+// 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 Let e be an expression; e occurs in a constant context iff one of
+/// the following applies:
+/// • e is an element of a list or set literal whose first token is const, or e
+///   is a key or a value of an entry of a map literal whose first token is
+///   const.
+///
+/// @description Checks that it is a compile-time error if `e` is an element of
+/// a list or set literal whose first token is `const`, or `e` is a key or a
+/// value of an entry of a map literal whose first token is `const` but `e` is
+/// not a constant expression.
+/// @author [email protected]
+
+class C {
+  final val;
+  C(this.val);
+}
+
+main() {
+  const c1 = const [C(1)];
+//                  ^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  const c2 = const {C(2)};
+//                  ^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  const c3 = const {C(3): 0};
+//                  ^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  const c4 = const {0: C(4)};
+//                     ^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}

Language/Expressions/Constants/Constant_Contexts/constant_context_A02_t01.dart

@@ -0,0 +1,27 @@
+// 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 Let e be an expression; e occurs in a constant context iff one of
+/// the following applies:
+/// ...
+/// • e occurs as @e in a construct derived from ⟨metadata⟩.
+///
+/// @description Checks that an expression `e` is a constant expression if `e`
+/// occurs as `@e` in a construct derived from ⟨metadata⟩
+/// @author [email protected]
+
+import 'dart:mirrors';
+import '../../../../Utils/expect.dart';
+
+class C {
+  final val;
+  const C(this.val);
+}
+
+@C(1)
+class A {}
+
+main() {
+  Expect.identical(const C(1), reflectClass(A).metadata[0].reflectee);
+}

Language/Expressions/Constants/Constant_Contexts/constant_context_A03_t01.dart

@@ -0,0 +1,25 @@
+// 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 Let e be an expression; e occurs in a constant context iff one of
+/// the following applies:
+/// ...
+/// • e is an actual argument in an expression derived from
+///   ⟨constObjectExpression⟩.
+///
+/// @description Checks that an expression `e` is a constant expression if `e`
+/// is an actual argument in an expression derived from ⟨constObjectExpression⟩
+/// @author [email protected]
+
+import '../../../../Utils/expect.dart';
+
+class C {
+  final val;
+  const C(this.val);
+}
+
+main() {
+  const c = const C(1);
+  Expect.identical(c, const C(1));
+}

Language/Expressions/Constants/Constant_Contexts/constant_context_A04_t01.dart

@@ -0,0 +1,24 @@
+// 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 Let e be an expression; e occurs in a constant context iff one of
+/// the following applies:
+/// ...
+/// • e is the initializing expression of a constant variable declaration
+///
+/// @description Checks that an expression `e` is a constant expression if `e`
+/// is the initializing expression of a constant variable declaration
+/// @author [email protected]
+
+import '../../../../Utils/expect.dart';
+
+class C {
+  final val;
+  const C(this.val);
+}
+
+main() {
+  const c = C(1);
+  Expect.identical(c, const C(1));
+}

Language/Expressions/Constants/Constant_Contexts/constant_context_A05_t01.dart

@@ -0,0 +1,35 @@
+// 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 Let e be an expression; e occurs in a constant context iff one of
+/// the following applies:
+/// ...
+/// • e is an immediate subexpression of an expression e0 which occurs in a
+///   constant context, where e0 is not a function literal
+///
+/// @description Checks that an expression `e` is a constant expression if `e`
+/// is an immediate subexpression of an expression `e0` which occurs in a
+/// constant context, where `e0` is not a function literal
+/// @author [email protected]
+
+import '../../../../Utils/expect.dart';
+
+class C {
+  final val;
+  const C(this.val);
+}
+
+Object foo(Object o) => o;
+
+main() {
+  var c1 = const C(C(1));
+  const c2 = 2 > 1 ? C(0) : C(1);
+  var c3 = identical(C(3), C(3));
+  const c4 = identical(C(3), C(3));
+
+  Expect.identical(const C(1), c1.val);
+  Expect.identical(const C(0), c2);
+  Expect.isFalse(c3);
+  Expect.isTrue(c4);
+}

Language/Expressions/Constants/Constant_Contexts/constant_context_A05_t02.dart

@@ -0,0 +1,36 @@
+// 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 Let e be an expression; e occurs in a constant context iff one of
+/// the following applies:
+/// ...
+/// • e is an immediate subexpression of an expression e0 which occurs in a
+///   constant context, where e0 is not a function literal
+///
+/// @description Checks that it is a compile-time error if `e` is an immediate
+/// subexpression of an expression `e0` which occurs in a constant context but
+/// `e0` is a function literal
+/// @author [email protected]
+
+class C {
+  final val;
+  const C(this.val);
+}
+
+main() {
+  const c1 = (){C(1);};
+//           ^^^^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  var c2 = const (){C(1);};
+//               ^^^^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  var c3 = const [(){C(1);}];
+//                ^^^^^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}

Language/Expressions/Constants/Constant_Contexts/constant_context_A06_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 A constant context is introduced in situations where an
+/// expression is required to be constant. This is used to allow the const
+/// modifier to be omitted in cases where it does not contribute any new
+/// information.
+///
+/// @description Checks that an initializers list is not a constant context
+/// @author [email protected]
+
+class A {
+  const A();
+}
+
+class C {
+  final val;
+  const C.c1() : this.val = [];
+//                          ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  const C.c2() : this.val = A();
+//                          ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+main() {
+  print(C);
+}

Language/Expressions/Constants/Constant_Contexts/constant_context_A06_t02.dart

@@ -0,0 +1,43 @@
+// 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 A constant context is introduced in situations where an
+/// expression is required to be constant. This is used to allow the const
+/// modifier to be omitted in cases where it does not contribute any new
+/// information.
+///
+/// @description Checks that `when` part of a guard pattern is not a constant
+/// context
+/// @author [email protected]
+
+import '../../../../Utils/expect.dart';
+
+class C {
+  final val;
+  const C(this.val);
+}
+
+const c1 = C(1);
+
+bool test(bool b) => switch(b) {
+  true when identical(c1, C(1)) => true,
+  _ => false
+};
+
+main() {
+  bool wasTrue = false;
+
+  if (2 > 1 case true when identical(c1, C(1))) {
+    wasTrue = true;
+  }
+  Expect.isFalse(wasTrue);
+
+  switch (true) {
+    case true when identical(c1, C(1)):
+      wasTrue = true;
+    default:
+  }
+  Expect.isFalse(wasTrue);
+  Expect.isFalse(test(true));
+}