#2976. Add non-ambiguity tests

LanguageFeatures/Static-access-shorthand/non_ambiguity_A01_t01.dart

@@ -0,0 +1,36 @@
+// Copyright (c) 2025, 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 postfix expression expression can follow a `?` in a conditional
+/// expression, as in `{e1 ? . id : e2}`. This is not ambiguous with `e1?.id`
+/// since we parse `?.` as a single token, and will keep doing so. It does mean
+/// that `{e1?.id:e2}` and `{e1? .id:e2}` will now both be valid and have
+/// different meanings, where the existing grammar didn’t allow the `?` token to
+/// be followed by `.` anywhere.
+///
+/// @description Checks that `{e1?.id:e2}` is parsed like a map literal.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands
+
+import '../../Utils/expect.dart';
+
+class C {
+  static C id = C();
+}
+
+extension on bool {
+  int get id => 42;
+}
+
+main() {
+  bool e1 = 2 > 1; // true
+  var e2 = "value";
+  Object o = C();
+  if (o is C) {
+    o = {e1?.id: e2}; // ignore: invalid_null_aware_operator
+    Expect.isTrue(o is Map);
+    Expect.mapEquals({42: "value"}, o);
+  }
+}

LanguageFeatures/Static-access-shorthand/non_ambiguity_A01_t02.dart

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+// Copyright (c) 2025, 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 postfix expression expression can follow a `?` in a conditional
+/// expression, as in `{e1 ? . id : e2}`. This is not ambiguous with `e1?.id`
+/// since we parse `?.` as a single token, and will keep doing so. It does mean
+/// that `{e1?.id:e2}` and `{e1? .id:e2}` will now both be valid and have
+/// different meanings, where the existing grammar didn’t allow the `?` token to
+/// be followed by `.` anywhere.
+///
+/// @description Checks that `{e1? .id:e2}` is parsed like a set literal.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands
+
+import '../../Utils/expect.dart';
+
+class C {
+  int value;
+  C(this.value);
+  static C id = C(0);
+}
+
+extension on bool {
+  int get id => 42;
+}
+
+main() {
+  bool e1 = 2 > 1; // true
+  var e2 = "value";
+  Object o = <C>{C(1)};
+  if (o is Set<C>) {
+    o = {e1? .id: e2};
+    Expect.isTrue(o is Set);    // ignore: unnecessary_type_check
+    Expect.setEquals({C.id}, o as Set);
+  }
+}

LanguageFeatures/Static-access-shorthand/non_ambiguity_A02_t01.dart

@@ -0,0 +1,101 @@
+// Copyright (c) 2025, 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 postfix expression expression can follow a `?` in a conditional
+/// expression, as in `{e1 ? . id : e2}`. This is not ambiguous with `e1?.id`
+/// since we parse `?.` as a single token, and will keep doing so. It does mean
+/// that `{e1?.id:e2}` and `{e1? .id:e2}` will now both be valid and have
+/// different meanings, where the existing grammar didn’t allow the `?` token to
+/// be followed by `.` anywhere.
+///
+/// @description Checks that for null-aware elements `? .id` is parsed as
+/// `? C.id`.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands,null-aware-elements
+
+import '../../Utils/expect.dart';
+
+class C {
+  int value;
+  C(this.value);
+  C.id(this.value);
+  static C? one = C(1);
+  static C? get two => C(2);
+  static C? three() => C(3);
+
+  @override
+  bool operator ==(Object other) {
+    if (other is C) {
+      return value == other.value;
+    }
+    return false;
+  }
+
+  @override
+  int get hashCode => value.hashCode;
+}
+
+mixin M on C {
+  static M? one = MC(1);
+  static M? get two => MC(2);
+  static M? three() => MC(3);
+}
+
+class MC = C with M;
+
+enum E {
+  e1, e2, e3;
+  static E? one = E.e1;
+  static E? get two => E.e2;
+  static E? three() => E.e3;
+}
+
+extension type ET(int value) {
+  ET.id(this.value);
+  static ET? one = ET(1);
+  static ET? get two => ET(2);
+  static ET? three() => ET(3);
+}
+
+main() {
+  var l1 = <C>[
+      ? .id(0),
+      ? .new(0),
+      ? .one,
+      ? .two,
+      ? .three()
+  ];
+  Expect.listEquals([C(0), C(0), C(1), C(2), C(3)], l1);
+
+  var s = <M>{
+      ? .one,
+      ? .two,
+      ? .three()
+  };
+  Expect.setEquals({MC(1), MC(2), MC(3)}, s);
+
+  var m1 = <String, E>{
+      "key0": ? .e1,
+      "key1": ? .one,
+      "key2": ? .two,
+      "key3": ? .three()
+  };
+  Expect.mapEquals({"key0": E.e1, "key1": E.e1, "key2": E.e2, "key3":E.e3}, m1);
+
+  var m2 = <ET, String> {
+      ? .id(-1): "value0",
+      ? .new(0): "value1",
+      ? .one: "value2",
+      ? .two: "value3",
+      ? .three(): "value4"
+  };
+  Expect.mapEquals({
+      ET(-1): "value0",
+      ET(0): "value1",
+      ET(1): "value2",
+      ET(2): "value3",
+      ET(3): "value4"
+  }, m2);
+}

LanguageFeatures/Static-access-shorthand/non_ambiguity_A02_t02.dart

@@ -0,0 +1,220 @@
+// Copyright (c) 2025, 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 postfix expression expression can follow a `?` in a conditional
+/// expression, as in `{e1 ? . id : e2}`. This is not ambiguous with `e1?.id`
+/// since we parse `?.` as a single token, and will keep doing so. It does mean
+/// that `{e1?.id:e2}` and `{e1? .id:e2}` will now both be valid and have
+/// different meanings, where the existing grammar didn’t allow the `?` token to
+/// be followed by `.` anywhere.
+///
+/// @description Checks that `?.id` is parsed as `?. id` which is a compile-time
+/// error.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands,null-aware-elements
+
+class C {
+  int value;
+  C(this.value);
+  C.id(this.value);
+  static C? one = C(1);
+  static C? get two => C(2);
+  static C? three() => C(3);
+
+  @override
+  bool operator ==(Object other) {
+    if (other is C) {
+      return value == other.value;
+    }
+    return false;
+  }
+
+  @override
+  int get hashCode => value.hashCode;
+}
+
+mixin M on C {
+  static M? one = MC(1);
+  static M? get two => MC(2);
+  static M? three() => MC(3);
+}
+
+class MC = C with M;
+
+enum E {
+  e1, e2, e3;
+  static E? one = E.e1;
+  static E? get two => E.e2;
+  static E? three() => E.e3;
+}
+
+extension type ET(int value) {
+  ET.id(this.value);
+  static ET? one = ET(1);
+  static ET? get two => ET(2);
+  static ET? three() => ET(3);
+}
+
+void testConstructors() {
+  var l = <C>[
+      ?.id(0)
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  ];
+
+  var s = <C>{
+      ?.new(0),
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m1 = <String, ET> {
+      "key": ?.id(0)
+//           ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+      ?.new(0): "value1",
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m2 = <ET, String> {
+      ?.new(0): "value"
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+}
+
+void testVariables() {
+  var l = <C>[
+      ?.one
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  ];
+
+  var s = <M>{
+      ?.one
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m1 = <String, E>{
+      "key": ?.one,
+//           ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m2 = <ET, String> {
+      ?.one: "value"
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+}
+
+void testGetters() {
+  var l = <C>[
+      ?.two
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  ];
+
+  var s = <M>{
+      ?.two
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m1 = <String, E>{
+      "key": ?.two,
+//           ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m2 = <ET, String> {
+      ?.two: "value"
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+}
+
+void testMethods() {
+  var l = <C>[
+      ?.three()
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  ];
+
+  var s = <M>{
+      ?.three()
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m1 = <String, E>{
+      "key": ?.three(),
+//           ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m2 = <ET, String> {
+      ?.three(): "value"
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+}
+
+void testEnumValues() {
+  var l = <E>[
+      ?.e0
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  ];
+
+  var s = <E>{
+      ?.e0
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m1 = <String, E>{
+      "key": ?.e0,
+//           ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+
+  var m2 = <E, String> {
+      ?.e0: "value"
+//    ^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  };
+}
+
+main() {
+  testConstructors();
+  testVariables();
+  testGetters();
+  testMetods();
+  testEnumValues();
+}