Add test for getter/setter conflicts with extension members.

Change-Id: I9332e29d021d126d6678f6866d484185e2f1da73
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/115211
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Leaf Petersen <leafp@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>

tests/language_2/extension_methods/static_extension_getter_setter_conflicts_test.dart

@@ -0,0 +1,162 @@
+// Copyright (c) 2019, 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.
+
+// SharedOptions=--enable-experiment=extension-methods
+
+// Tests interactions between getters and setters where there is a conflict.
+
+// Conflicting class declarations.
+
+class C0 {
+  int get m1 => 0;
+  void set m2(int x) {}
+}
+
+extension E0 on C0 {
+  void set m1(int x) {}
+  int get m2 => 0;
+}
+
+void test0() {
+  C0 c0 = C0();
+  c0.m1;
+  c0.m1 = 0;
+  // ^^^^^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+  E0(c0).m1 = 0;
+  E0(c0).m1;
+  //     ^^
+  // [analyzer] COMPILE_TIME_ERROR.UNDEFINED_EXTENSION_GETTER
+  // [cfe] unspecified
+
+  c0.m1 += 0;
+  // ^^^^^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+
+  c0.m2 = 0;
+  c0.m2;
+  // ^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+  c0.m2 += 0;
+  // ^^^^^^^
+  // [analyzer] unspecified
+  // [cfe] unspecified
+  E0(c0).m2;
+}
+
+// Conflicting extensions.
+
+class C1<T> {
+}
+
+extension E1A<T> on C1<T> {
+  int get m1 => 0;
+  void set m2(int x) {}
+}
+
+extension E1B on C1<Object> {
+  void set m1(int x) {}
+  int get m2 => 0;
+}
+
+void test1() {
+  C1<int> c1a = C1<Null>; // E1A is more specific.
+  c1a.m1;
+
+  c1a.m1 = 0;
+  //  ^^^^^^
+  // [analyzer] COMPILE_TIME_ERROR.UNDEFINED_EXTENSION_SETTER
+  // [cfe] unspecified
+
+  c1a.m2;
+  //  ^^
+  // [analyzer] COMPILE_TIME_ERROR.UNDEFINED_EXTENSION_GETTER
+  // [cfe] unspecified
+
+  c1a.m2 = 0;
+
+  C1<Object> c1b = C1<Null>;  // Neither extension is more specific.
+
+  c1b.m1;
+  //  ^^
+  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
+  // [cfe] unspecified
+
+  c1b.m1 = 0;
+  //  ^^^^^^
+  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
+  // [cfe] unspecified
+
+  c1b.m2;
+  //  ^^
+  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
+  // [cfe] unspecified
+
+  c1b.m2 = 0;
+  //  ^^^^^^
+  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
+  // [cfe] unspecified
+}
+
+// Getter on the extension itself.
+class C2 {
+  int get m1 => 0;
+  void set m2(int x) {}
+  int get mc => 0;
+}
+
+extension E2 on C2 {
+  void set m1(int x) {}
+  int get m2 => 0;
+  String get me => "";
+
+  void test2() {
+    // Using `this.member` means using the `on` type.
+
+    this.m1;
+    this.m1 = 0;
+    //   ^^^^^^
+    // [analyzer] COMPILE_TIME_ERROR.UNDEFINED_EXTENSION_SETTER
+    // [cfe] unspecified
+
+    this.m2 = 0;
+    this.m2;
+    //   ^^
+    // [analyzer] COMPILE_TIME_ERROR.UNDEFINED_EXTENSION_GETTER
+    // [cfe] unspecified
+
+    // Check that `this.mc` refers to `C2.mc`.
+    this.mc.toRadixString(16);
+    // Check that `this.me` refers to `E2.me`.
+    this.me.substring(0);
+
+    // An unqualified identifier is matched against the extension (by basename).
+
+    m1 = 0;
+    1 + m1;
+    //  ^^
+    // [analyzer] COMPILE_TIME_ERROR.UNDEFINED_EXTENSION_GETTER
+    // [cfe] unspecified
+
+    1 + m2;
+    if (true) m2 = 0; // for the indent!
+    //        ^^^^^^
+    // [analyzer] COMPILE_TIME_ERROR.UNDEFINED_EXTENSION_SETTER
+    // [cfe] unspecified
+
+    // Check that `mc` refers to `C2.me`.
+    mc.toRadixString(16);
+    // Check that `me` refers to `E2.me`.
+    me.substring(0);
+  }
+}
+
+main() {
+  test0();
+  test1();
+  C2().test2();
+}