Report PRIVATE_SETTER.

Change-Id: I823582328b4b9cc63ac734e9ea1c9354175a6e18
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153880
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

pkg/analyzer/lib/error/error.dart

@@ -288,6 +288,7 @@ const List<ErrorCode> errorCodeValues = [
   CompileTimeErrorCode.PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT,
   CompileTimeErrorCode.PRIVATE_COLLISION_IN_MIXIN_APPLICATION,
   CompileTimeErrorCode.PRIVATE_OPTIONAL_PARAMETER,
+  CompileTimeErrorCode.PRIVATE_SETTER,
   CompileTimeErrorCode.RECURSIVE_COMPILE_TIME_CONSTANT,
   CompileTimeErrorCode.RECURSIVE_CONSTRUCTOR_REDIRECT,
   CompileTimeErrorCode.RECURSIVE_FACTORY_REDIRECT,

pkg/analyzer/lib/src/error/codes.dart

@@ -5608,6 +5608,12 @@ class CompileTimeErrorCode extends AnalyzerErrorCode {
       CompileTimeErrorCode('PRIVATE_OPTIONAL_PARAMETER',
           "Named optional parameters can't start with an underscore.");
 
+  static const CompileTimeErrorCode PRIVATE_SETTER = CompileTimeErrorCode(
+      'PRIVATE_SETTER',
+      "The setter '{0}' is private and can't be accessed outside of the "
+          "library that declares it.",
+      correction: "Try making it public.");
+
   /**
    * 12.1 Constants: It is a compile-time error if the value of a compile-time
    * constant expression depends on itself.

pkg/analyzer/lib/src/generated/element_resolver.dart

@@ -1334,8 +1334,15 @@ class ElementResolver extends SimpleAstVisitor<void> {
         ExecutableElement element;
 
         var setter = typeReference.getSetter(propertyName.name);
-        if (setter != null && setter.isAccessibleIn(_definingLibrary)) {
+        if (setter != null) {
           element = setter;
+          if (!setter.isAccessibleIn(_definingLibrary)) {
+            _errorReporter.reportErrorForNode(
+              CompileTimeErrorCode.PRIVATE_SETTER,
+              propertyName,
+              [propertyName.name, typeReference.name],
+            );
+          }
         }
 
         if (element != null) {

pkg/analyzer/test/src/diagnostics/private_setter_test.dart

@@ -0,0 +1,113 @@
+// Copyright (c) 2020, 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.
+
+import 'package:analyzer/src/error/codes.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../dart/resolution/driver_resolution.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(PrivateSetterTest);
+  });
+}
+
+@reflectiveTest
+class PrivateSetterTest extends DriverResolutionTest {
+  test_typeLiteral_privateField_differentLibrary() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  static int _foo = 0;
+}
+''');
+    await assertErrorsInCode(r'''
+import 'a.dart';
+
+main() {
+  A._foo = 0;
+}
+''', [
+      error(CompileTimeErrorCode.PRIVATE_SETTER, 31, 4),
+    ]);
+
+    var aImport = findElement.importFind('package:test/a.dart');
+    assertElement(
+      findNode.simple('_foo = 0'),
+      aImport.setter('_foo'),
+    );
+  }
+
+  test_typeLiteral_privateField_sameLibrary() async {
+    await assertNoErrorsInCode(r'''
+class A {
+  // ignore:unused_field
+  static int _foo = 0;
+}
+
+main() {
+  A._foo = 0;
+}
+''');
+  }
+
+  test_typeLiteral_privateSetter__sameLibrary() async {
+    await assertNoErrorsInCode(r'''
+class A {
+  static set _foo(int _) {}
+}
+
+main() {
+  A._foo = 0;
+}
+''');
+  }
+
+  test_typeLiteral_privateSetter_differentLibrary_hasGetter() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  static set _foo(int _) {}
+  
+  static int get _foo => 0;
+}
+''');
+    await assertErrorsInCode(r'''
+import 'a.dart';
+
+main() {
+  A._foo = 0;
+}
+''', [
+      error(CompileTimeErrorCode.PRIVATE_SETTER, 31, 4),
+    ]);
+
+    var aImport = findElement.importFind('package:test/a.dart');
+    assertElement(
+      findNode.simple('_foo = 0'),
+      aImport.setter('_foo'),
+    );
+  }
+
+  test_typeLiteral_privateSetter_differentLibrary_noGetter() async {
+    newFile('/test/lib/a.dart', content: r'''
+class A {
+  static set _foo(int _) {}
+}
+''');
+    await assertErrorsInCode(r'''
+import 'a.dart';
+
+main() {
+  A._foo = 0;
+}
+''', [
+      error(CompileTimeErrorCode.PRIVATE_SETTER, 31, 4),
+    ]);
+
+    var aImport = findElement.importFind('package:test/a.dart');
+    assertElement(
+      findNode.simple('_foo = 0'),
+      aImport.setter('_foo'),
+    );
+  }
+}

pkg/analyzer/test/src/diagnostics/test_all.dart

@@ -397,6 +397,7 @@ import 'prefix_identifier_not_followed_by_dot_test.dart'
 import 'private_collision_in_mixin_application_test.dart'
     as private_collision_in_mixin_application;
 import 'private_optional_parameter_test.dart' as private_optional_parameter;
+import 'private_setter_test.dart' as private_setter;
 import 'receiver_of_type_never_test.dart' as receiver_of_type_never;
 import 'recursive_compile_time_constant_test.dart'
     as recursive_compile_time_constant;
@@ -805,6 +806,7 @@ main() {
     prefix_identifier_not_followed_by_dot.main();
     private_collision_in_mixin_application.main();
     private_optional_parameter.main();
+    private_setter.main();
     receiver_of_type_never.main();
     recursive_compile_time_constant.main();
     recursive_constructor_redirect.main();