[nnbd_migration] Add an edge origin for inferred parameter substitution

MichaelRFairhurst · commit-bot@chromium.org · commit e9df1ee07ad1 · 2020-02-28T23:26:22.000Z
Change-Id: I37ce933e05a6b7ad7b8fdcc26f44968ae92516be Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/137658 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
@@ -182,6 +182,10 @@ class InfoBuilder {
     if (origin.kind == EdgeOriginKind.typeParameterInstantiation) {
       return 'This type parameter is instantiated with a nullable type';
     }
+    if (origin.kind == EdgeOriginKind.inferredTypeParameterInstantiation) {
+      return 'This type parameter is instantiated with an inferred nullable '
+          'type';
+    }
 
     CompilationUnit unit = node.thisOrAncestorOfType<CompilationUnit>();
     int lineNumber = unit.lineInfo.getLocation(node.offset).lineNumber;
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
@@ -342,6 +342,27 @@ void main() {
         details: ['This type parameter is instantiated with a nullable type']);
   }
 
+  Future<void> test_bound_method_implicit() async {
+    UnitInfo unit = await buildInfoForSingleTestFile('''
+f<T extends Object>(T/*!*/ t) {}
+
+void main() {
+  f(null);
+}
+''', migratedContent: '''
+f<T extends Object?>(T/*!*/ t) {}
+
+void main() {
+  f(null);
+}
+''');
+    List<RegionInfo> regions = unit.regions;
+    expect(regions, hasLength(2));
+    assertRegion(region: regions[0], offset: 18, details: [
+      'This type parameter is instantiated with an inferred nullable type'
+    ]);
+  }
+
   Future<void> test_discardCondition() async {
     UnitInfo unit = await buildInfoForSingleTestFile('''
 void g(int i) {
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,
+  inferredTypeParameterInstantiation,
   initializerInference,
   instanceCreation,
   instantiateToBounds,
diff --git a/pkg/nnbd_migration/lib/src/edge_builder.dart b/pkg/nnbd_migration/lib/src/edge_builder.dart
@@ -2304,7 +2304,11 @@ class EdgeBuilder extends GeneralizingAstVisitor<DecoratedType>
                   offset: node.offset))
               .toList();
           instrumentation?.implicitTypeArguments(source, node, argumentTypes);
-          calleeType = _handleInstantiation(calleeType, argumentTypes, null);
+          calleeType = _handleInstantiation(
+              calleeType,
+              argumentTypes,
+              List.filled(argumentTypes.length,
+                  InferredTypeParameterInstantiationOrigin(source, node)));
         } else if (constructorTypeParameters != null) {
           // No need to instantiate; caller has already substituted in the
           // correct type arguments.
diff --git a/pkg/nnbd_migration/lib/src/edge_origin.dart b/pkg/nnbd_migration/lib/src/edge_origin.dart
@@ -434,6 +434,16 @@ 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 {
