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

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

Index: pkg/analyzer/lib/src/generated/resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/resolver.dart b/pkg/analyzer/lib/src/generated/resolver.dart
index 2d5fac3269d04c5bcd01af8a8d70c3c9d7b6a13e..f1a4d5b3ce4de559b263349af1fc9d8a97baccb1 100644
--- a/pkg/analyzer/lib/src/generated/resolver.dart
+++ b/pkg/analyzer/lib/src/generated/resolver.dart
@@ -218,6 +218,12 @@ class BestPracticesVerifier extends RecursiveAstVisitor<Object> {
   }
 
   @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);
@@ -230,6 +236,12 @@ class BestPracticesVerifier extends RecursiveAstVisitor<Object> {
   }
 
   @override
+  Object visitPropertyAccess(PropertyAccess node) {
+    _checkForCanBeNullAfterNullAware(node.realTarget);
+    return super.visitPropertyAccess(node);
+  }
+
+  @override
   Object visitRedirectingConstructorInvocation(
       RedirectingConstructorInvocation node) {
     _checkForDeprecatedMemberUse(node.staticElement, node);
@@ -453,6 +465,25 @@ class BestPracticesVerifier extends RecursiveAstVisitor<Object> {
   }
 
   /**
+   * 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.
    *