[nnbd_migration] Add an edge origin for return;

MichaelRFairhurst · commit-bot@chromium.org · commit 3ae91fc8c5ed · 2020-02-28T23:26:22.000Z
Change-Id: I94e56933c4fb8d8c8b80ca0c427fc34c56674d04 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/137841 Reviewed-by: Paul Berry <paulberry@google.com>
diff --git a/pkg/analysis_server/lib/src/edit/nnbd_migration/info_builder.dart b/pkg/analysis_server/lib/src/edit/nnbd_migration/info_builder.dart
@@ -192,6 +192,9 @@ class InfoBuilder {
 
     if (origin.kind == EdgeOriginKind.uninitializedRead) {
       return 'Used on line $lineNumber, when it is possibly uninitialized';
+    } else if (origin.kind == EdgeOriginKind.implicitNullReturn) {
+      return 'This function contains a return statement with no value on line '
+          '$lineNumber, which implicitly returns null.';
     }
 
     /// If the [node] is inside the return expression for a function body,
diff --git a/pkg/analysis_server/test/src/edit/nnbd_migration/info_builder_test.dart b/pkg/analysis_server/test/src/edit/nnbd_migration/info_builder_test.dart
@@ -1568,6 +1568,24 @@ String? g() {
     assertDetail(detail: regions[0].details[0], offset: 15, length: 6);
   }
 
+  Future<void> test_returnNoValue() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+int f() {
+  return;
+}
+''', migratedContent: '''
+int? f() {
+  return;
+}
+''');
+    List<RegionInfo> regions = unit.fixRegions;
+    expect(regions, hasLength(1));
+    assertRegion(region: regions[0], offset: 3, details: [
+      'This function contains a return statement with no value on line 2,'
+          ' which implicitly returns null.'
+    ]);
+  }
+
   Future<void> test_returnType_function_expression() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 int _f = null;
diff --git a/pkg/nnbd_migration/lib/instrumentation.dart b/pkg/nnbd_migration/lib/instrumentation.dart
@@ -137,6 +137,7 @@ enum EdgeOriginKind {
   ifNull,
   implicitMixinSuperCall,
   implicitNullInitializer,
+  implicitNullReturn,
   inferredTypeParameterInstantiation,
   initializerInference,
   instanceCreation,
diff --git a/pkg/nnbd_migration/lib/src/edge_builder.dart b/pkg/nnbd_migration/lib/src/edge_builder.dart
@@ -1234,7 +1234,7 @@ class EdgeBuilder extends GeneralizingAstVisitor<DecoratedType>
           offset: node.offset);
       _graph.makeNullable(
           implicitNullType.node, AlwaysNullableTypeOrigin(source, node));
-      _checkAssignment(null,
+      _checkAssignment(ImplicitNullReturnOrigin(source, node),
           source: isAsync
               ? _futureOf(implicitNullType, offset: node.offset)
               : implicitNullType,
diff --git a/pkg/nnbd_migration/lib/src/edge_origin.dart b/pkg/nnbd_migration/lib/src/edge_origin.dart
@@ -202,6 +202,29 @@ class ImplicitNullInitializerOrigin extends EdgeOrigin {
   EdgeOriginKind get kind => EdgeOriginKind.implicitNullInitializer;
 }
 
+/// Edge origin resulting from a `return;` statement which implicitly returns
+/// `null`.
+class ImplicitNullReturnOrigin extends EdgeOrigin {
+  ImplicitNullReturnOrigin(Source source, ReturnStatement node)
+      : super(source, node);
+
+  @override
+  EdgeOriginKind get kind => EdgeOriginKind.implicitNullReturn;
+
+  @override
+  ReturnStatement get node => super.node as ReturnStatement;
+}
+
+/// Edge origin resulting from the inference of a type parameter, which
+/// can affects the nullability of that type parameter's bound.
+class InferredTypeParameterInstantiationOrigin extends EdgeOrigin {
+  InferredTypeParameterInstantiationOrigin(Source source, AstNode node)
+      : super(source, node);
+
+  @override
+  EdgeOriginKind get kind => EdgeOriginKind.inferredTypeParameterInstantiation;
+}
+
 /// Edge origin resulting from a type that is inferred from its initializer.
 class InitializerInferenceOrigin extends EdgeOrigin {
   InitializerInferenceOrigin(Source source, VariableDeclaration node)
@@ -434,16 +457,6 @@ class TypeParameterInstantiationOrigin extends EdgeOrigin {
   TypeAnnotation get node => super.node as TypeAnnotation;
 }
 
-/// Edge origin resulting from the inference of a type parameter, which
-/// can affects the nullability of that type parameter's bound.
-class InferredTypeParameterInstantiationOrigin extends EdgeOrigin {
-  InferredTypeParameterInstantiationOrigin(Source source, AstNode node)
-      : super(source, node);
-
-  @override
-  EdgeOriginKind get kind => EdgeOriginKind.inferredTypeParameterInstantiation;
-}
-
 /// Edge origin resulting from the read of a variable that has not been
 /// definitely assigned a value.
 class UninitializedReadOrigin extends EdgeOrigin {

Original file line number	Diff line number	Diff line change
`@@ -192,6 +192,9 @@ class InfoBuilder {`
`192`	`192`
`193`	`193`	`if (origin.kind == EdgeOriginKind.uninitializedRead) {`
`194`	`194`	`return 'Used on line $lineNumber, when it is possibly uninitialized';`
	`195`	`+ } else if (origin.kind == EdgeOriginKind.implicitNullReturn) {`
	`196`	`+ return 'This function contains a return statement with no value on line '`
	`197`	`+ '$lineNumber, which implicitly returns null.';`
`195`	`198`	`}`
`196`	`199`
`197`	`200`	`/// If the [node] is inside the return expression for a function body,`