Fix for NPE when the assigned expression is synthetic at the end of the unit.

[email protected]

Change-Id: I6c221481fa0b8338847f6fb0d605c45c17a55fe3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150841
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analysis_server/lib/src/services/correction/dart/change_type_annotation.dart

@@ -23,7 +23,7 @@ class ChangeTypeAnnotation extends CorrectionProducer {
 
   @override
   Future<void> compute(DartChangeBuilder builder) async {
-    var declaration = coveredNode.parent;
+    var declaration = coveredNode?.parent;
     if (declaration is VariableDeclaration &&
         declaration.initializer == coveredNode) {
       var variableList = declaration.parent;

pkg/analysis_server/test/abstract_context.dart

@@ -132,18 +132,29 @@ class AbstractContextTest with ResourceProviderMixin {
   }
 
   /// Create an analysis options file based on the given arguments.
-  void createAnalysisOptionsFile(
-      {List<String> experiments, List<String> lints}) {
+  void createAnalysisOptionsFile({
+    List<String> experiments,
+    bool implicitCasts,
+    List<String> lints,
+  }) {
     var buffer = StringBuffer();
 
-    if (experiments != null) {
+    if (experiments != null || implicitCasts != null) {
       buffer.writeln('analyzer:');
+    }
+
+    if (experiments != null) {
       buffer.writeln('  enable-experiment:');
       for (var experiment in experiments) {
         buffer.writeln('    - $experiment');
       }
     }
 
+    if (implicitCasts != null) {
+      buffer.writeln('  strong-mode:');
+      buffer.writeln('    implicit-casts: $implicitCasts');
+    }
+
     if (lints != null) {
       buffer.writeln('linter:');
       buffer.writeln('  rules:');

pkg/analysis_server/test/src/services/correction/fix/change_type_annotation_test.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analysis_server/src/services/correction/fix.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ -69,4 +70,16 @@ main() {
 }
 ''');
   }
+
+  Future<void> test_synthetic_implicitCast() async {
+    createAnalysisOptionsFile(implicitCasts: false);
+    await resolveTestUnit('''
+int foo =
+''');
+    await assertNoFix(
+      errorFilter: (e) {
+        return e.errorCode == StaticTypeWarningCode.INVALID_ASSIGNMENT;
+      },
+    );
+  }
 }