#2485. Add constant evaluation tests for Set (#2509)

Add constant evaluation tests for `Set`

Language/Expressions/Constants/constant_set_t01.dart

@@ -0,0 +1,39 @@
+// 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 potentially constant expression is an expression that will
+/// generally yield a constant value when the values of certain parameters are
+/// given. The constant expressions is a subset of the potentially constant
+/// expressions that can be evaluated at compile time.
+/// ...
+/// The potentially constant expressions and constant expressions are the
+/// following:
+/// ...
+/// • A constant set literal, const <T>{e1, ..., en}, or <T>{e1, ..., en} that
+///   occurs in a constant context, is a potentially constant expression if T is
+///   a constant type expression, and e1, . . . , en are constant expressions.
+///   It is further a constant expression if the set literal evaluates to an
+///   object.
+///
+/// @description Checks that a constant set literal of the form
+/// `const <T>{e1, ..., en}`, or `<T>{e1, ..., en}` that occurs in a constant
+/// context are constants
+/// @author sgrekhov22@gmail.com
+
+import '../../../Utils/expect.dart';
+
+main() {
+  const c1 = <int>{1, 2};
+  var c2 = const {1, 2};
+
+  var c3 = const <num>{};
+  const Set<num> c4 = {};
+
+  const c5 = <Object>{[], {}, ()};
+  var c6 = const {[], {}, ()};
+
+  Expect.identical(c1, c2);
+  Expect.identical(c3, c4);
+  Expect.identical(c5, c6);
+}

Language/Expressions/Constants/constant_set_t02.dart

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+// 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 potentially constant expression is an expression that will
+/// generally yield a constant value when the values of certain parameters are
+/// given. The constant expressions is a subset of the potentially constant
+/// expressions that can be evaluated at compile time.
+/// ...
+/// The potentially constant expressions and constant expressions are the
+/// following:
+/// ...
+/// • A constant set literal, const <T>{e1, ..., en}, or <T>{e1, ..., en} that
+///   occurs in a constant context, is a potentially constant expression if T is
+///   a constant type expression, and e1, . . . , en are constant expressions.
+///   It is further a constant expression if the set literal evaluates to an
+///   object.
+///
+/// @description Checks that it is a compile-time error if in a constant set
+/// literal of the form const `<T>{e1, ..., en}`, or `<T>{e1, ..., en}`, `T` is
+/// not a constant type expression
+/// @author sgrekhov22@gmail.com
+
+test<T extends num>() {
+  const c1 = <T>{};
+//            ^
+// [analyzer] unspecified
+// [cfe] unspecified
+  print(const <T>{});
+//             ^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+main() {
+  print(test);
+}

Language/Expressions/Constants/constant_set_t03.dart

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+// 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 potentially constant expression is an expression that will
+/// generally yield a constant value when the values of certain parameters are
+/// given. The constant expressions is a subset of the potentially constant
+/// expressions that can be evaluated at compile time.
+/// ...
+/// The potentially constant expressions and constant expressions are the
+/// following:
+/// ...
+/// • A constant set literal, const <T>{e1, ..., en}, or <T>{e1, ..., en} that
+///   occurs in a constant context, is a potentially constant expression if T is
+///   a constant type expression, and e1, . . . , en are constant expressions.
+///   It is further a constant expression if the set literal evaluates to an
+///   object.
+///
+/// @description Checks that it is a compile-time error if in a constant set
+/// literal of the form const `<T>{e1, ..., en}`, or `<T>{e1, ..., en}`, any of
+/// `ei` is not a constant expression
+/// @author sgrekhov22@gmail.com
+
+final nonconstant1 = 1;
+
+const a = {nonconstant1};
+//         ^^^^^^^^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+Set<int> get test => const {1, nonconstant1};
+//                          ^^^^^^^^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+class C {
+  final int nonconstant2 = 1;
+
+  const C();
+
+  Set<int> get test1 => const {nonconstant2, 2};
+//                             ^^^^^^^^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  Set<int> test2() => const {0, nonconstant2, 2};
+//                              ^^^^^^^^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+main() {
+  print(a);
+  print(test);
+  print(C);
+}