Issue 26874. Don't report CAN_BE_NULL_AFTER_NULL_AWARE for members of the Null class.

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

 // Copyright (c) 2014, 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.
 
 library analyzer.src.generated.resolver;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 46 matching lines @@
    * is deprecated.
    */
   bool inDeprecatedMember;
 
   /**
    * The error reporter by which errors will be reported.
    */
   final ErrorReporter _errorReporter;
 
   /**
+   * The type [Null].
+   */
+  final InterfaceType _nullType;
+
+  /**
    * The type Future<Null>, which is needed for determining whether it is safe
    * to have a bare "return;" in an async method.
    */
   final InterfaceType _futureNullType;
 
   /**
    * The type system primitives
    */
   TypeSystem _typeSystem;
 
   /**
    * The current library
    */
   LibraryElement _currentLibrary;
 
   /**
    * Create a new instance of the [BestPracticesVerifier].
    *
    * @param errorReporter the error reporter
    */
   BestPracticesVerifier(
       this._errorReporter, TypeProvider typeProvider, this._currentLibrary,
       {TypeSystem typeSystem})
-      : _futureNullType = typeProvider.futureNullType,
+      : _nullType = typeProvider.nullType,
+        _futureNullType = typeProvider.futureNullType,
         _typeSystem = typeSystem ?? new TypeSystemImpl() {
     inDeprecatedMember = _currentLibrary.isDeprecated;
   }
 
   @override
   Object visitAnnotation(Annotation node) {
     if (node.elementAnnotation?.isFactory == true) {
       AstNode parent = node.parent;
       if (parent is MethodDeclaration) {
         _checkForInvalidFactory(parent);
@@ skipping 167 matching lines @@
       _checkForMissingReturn(node.returnType, node.body);
       _checkForUnnecessaryNoSuchMethod(node);
       return super.visitMethodDeclaration(node);
     } finally {
       inDeprecatedMember = wasInDeprecatedMember;
     }
   }
 
   @override
   Object visitMethodInvocation(MethodInvocation node) {
-    _checkForCanBeNullAfterNullAware(node.realTarget, node.operator);
+    _checkForCanBeNullAfterNullAware(
+        node.realTarget, node.operator, null, node.methodName);
     DartType staticInvokeType = node.staticInvokeType;
     if (staticInvokeType is InterfaceType) {
       MethodElement methodElement = staticInvokeType.lookUpMethod(
           FunctionElement.CALL_METHOD_NAME, _currentLibrary);
       _checkForDeprecatedMemberUse(methodElement, node);
     }
     return super.visitMethodInvocation(node);
   }
 
   @override
   Object visitPostfixExpression(PostfixExpression node) {
     _checkForDeprecatedMemberUse(node.bestElement, node);
     return super.visitPostfixExpression(node);
   }
 
   @override
   Object visitPrefixExpression(PrefixExpression node) {
     _checkForDeprecatedMemberUse(node.bestElement, node);
     return super.visitPrefixExpression(node);
   }
 
   @override
   Object visitPropertyAccess(PropertyAccess node) {
-    _checkForCanBeNullAfterNullAware(node.realTarget, node.operator);
+    _checkForCanBeNullAfterNullAware(
+        node.realTarget, node.operator, node.propertyName, null);
     return super.visitPropertyAccess(node);
   }
 
   @override
   Object visitRedirectingConstructorInvocation(
       RedirectingConstructorInvocation node) {
     _checkForDeprecatedMemberUse(node.staticElement, node);
     return super.visitRedirectingConstructorInvocation(node);
   }
 
@@ skipping 201 matching lines @@
     bool problemReported = false;
     for (Expression argument in argumentList.arguments) {
       if (_checkForArgumentTypeNotAssignableForArgument(argument)) {
         problemReported = true;
       }
     }
     return problemReported;
   }
 
   /**
-   * Produce a hint if the given [target] could have a value of `null`.
+   * Produce a hint if the given [target] could have a value of `null`, and
+   * [identifier] is not a name of a getter or a method that exists in the
+   * class [Null].
    */
-  void _checkForCanBeNullAfterNullAware(Expression target, Token operator) {
+  void _checkForCanBeNullAfterNullAware(
+      Expression target, Token operator, SimpleIdentifier propertyName, SimpleIdentifier methodName) {
     if (operator?.type == TokenType.QUESTION_PERIOD) {
       return;
     }
+    bool isNullTypeMember() {
+      if (propertyName != null) {
+        String name = propertyName.name;
+        return _nullType.lookUpGetter(name, _currentLibrary) != null;
+      }
+      if (methodName != null) {
+        String name = methodName.name;
+        return _nullType.lookUpMethod(name, _currentLibrary) != null;
+      }
+      return false;
+    }
+
     target = target?.unParenthesized;
     if (target is MethodInvocation) {
-      if (target.operator?.type == TokenType.QUESTION_PERIOD) {
+      if (target.operator?.type == TokenType.QUESTION_PERIOD &&
+          !isNullTypeMember()) {
         _errorReporter.reportErrorForNode(
             HintCode.CAN_BE_NULL_AFTER_NULL_AWARE, target);
       }
     } else if (target is PropertyAccess) {
-      if (target.operator.type == TokenType.QUESTION_PERIOD) {
+      if (target.operator.type == TokenType.QUESTION_PERIOD &&
+          !isNullTypeMember()) {
         _errorReporter.reportErrorForNode(
             HintCode.CAN_BE_NULL_AFTER_NULL_AWARE, target);
       }
     }
   }
 
   /**
    * Given some [Element], look at the associated metadata and report the use of the member if
    * it is declared as deprecated.
    *
@@ skipping 10588 matching lines @@
       return null;
     }
     if (identical(node.staticElement, variable)) {
       if (node.inSetterContext()) {
         result = true;
       }
     }
     return null;
   }
 }