Report hint when target of an invocation uses '?.', so can be null.

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 engine.resolver;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/scanner.dart';
 
@@ skipping 200 matching lines @@
 
   @override
   Object visitMethodDeclaration(MethodDeclaration node) {
     // This was determined to not be a good hint, see: dartbug.com/16029
     //checkForOverridingPrivateMember(node);
     _checkForMissingReturn(node.returnType, node.body);
     return super.visitMethodDeclaration(node);
   }
 
   @override
+  Object visitMethodInvocation(MethodInvocation node) {
+    _checkForCanBeNullAfterNullAware(node.realTarget);
+    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);
+    return super.visitPropertyAccess(node);
+  }
+
+  @override
   Object visitRedirectingConstructorInvocation(
       RedirectingConstructorInvocation node) {
     _checkForDeprecatedMemberUse(node.staticElement, node);
     return super.visitRedirectingConstructorInvocation(node);
   }
 
   @override
   Object visitSimpleIdentifier(SimpleIdentifier node) {
     _checkForDeprecatedMemberUseAtIdentifier(node);
     return super.visitSimpleIdentifier(node);
@@ skipping 203 matching lines @@
     bool problemReported = false;
     for (Expression argument in argumentList.arguments) {
       if (_checkForArgumentTypeNotAssignableForArgument(argument)) {
         problemReported = true;
       }
     }
     return problemReported;
   }
 
   /**
+   * Produce a hint if the given [expression] could have a value of `null`.
+   */
+  void _checkForCanBeNullAfterNullAware(Expression expression) {
+    if (expression is ParenthesizedExpression) {
+      _checkForCanBeNullAfterNullAware(expression.expression);
+    } else if (expression is MethodInvocation) {
+      if (expression.operator?.type == TokenType.QUESTION_PERIOD) {
+        _errorReporter.reportErrorForNode(
+            HintCode.CAN_BE_NULL_AFTER_NULL_AWARE, expression);
+      }
+    } else if (expression is PropertyAccess) {
+      if (expression.operator?.type == TokenType.QUESTION_PERIOD) {

[Brian Wilkerson, 2015/10/28 22:09:11]

I don't think the operator for a property access can be null.

[scheglov, 2015/10/28 23:45:09]

Acknowledged.

+        _errorReporter.reportErrorForNode(
+            HintCode.CAN_BE_NULL_AFTER_NULL_AWARE, expression);
+      }
+    }
+  }
+
+  /**
    * Given some [Element], look at the associated metadata and report the use of the member if
    * it is declared as deprecated.
    *
    * @param element some element to check for deprecated use of
    * @param node the node use for the location of the error
    * @return `true` if and only if a hint code is generated on the passed node
    * See [HintCode.DEPRECATED_MEMBER_USE].
    */
   bool _checkForDeprecatedMemberUse(Element element, AstNode node) {
     if (element != null && element.isDeprecated) {
@@ skipping 15598 matching lines @@
     nonFields.add(node);
     return null;
   }
 
   @override
   Object visitNode(AstNode node) => node.accept(TypeResolverVisitor_this);
 
   @override
   Object visitWithClause(WithClause node) => null;
 }