[analyzer] Propagate nullability in InterfaceType.allSupertypes

Fixes https://github.com/Dart-Code/Dart-Code/issues/4185.

Change-Id: Ic9fcd60ef3eae24e3921c25162ec405a56c62c53
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/261840
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>

pkg/analyzer/lib/src/dart/element/type.dart

@@ -492,7 +492,8 @@ class InterfaceTypeImpl extends TypeImpl implements InterfaceType {
   List<InterfaceType> get allSupertypes {
     var substitution = Substitution.fromInterfaceType(this);
     return element.allSupertypes
-        .map((t) => substitution.substituteType(t) as InterfaceType)
+        .map((t) => (substitution.substituteType(t) as InterfaceTypeImpl)
+            .withNullability(nullabilitySuffix))
         .toList();
   }
 

pkg/analyzer/test/src/dart/element/element_test.dart

@@ -734,6 +734,8 @@ class InterfaceTypeImplTest extends AbstractTypeSystemTest {
     check(objectNone, []);
     check(numNone, ['Comparable<num>', 'Object']);
     check(intNone, ['Comparable<num>', 'Object', 'num']);
+    check(intQuestion, ['Comparable<num>?', 'Object?', 'num?']);
+    check(intStar, ['Comparable<num>*', 'Object*', 'num*']);
     check(listNone(intQuestion), ['Iterable<int?>', 'Object']);
   }
 

pkg/analyzer_plugin/lib/src/utilities/change_builder/change_builder_dart.dart

@@ -44,10 +44,17 @@ class DartEditBuilderImpl extends EditBuilderImpl implements DartEditBuilder {
   /// If not `null`, [write] will copy everything into this buffer.
   StringBuffer? _carbonCopyBuffer;
 
+  /// Whether the target file is non-null by default.
+  ///
+  /// When `true`, question `?` suffixes will be included on nullable types.
+  final bool isNonNullableByDefault;
+
   /// Initialize a newly created builder to build a source edit.
   DartEditBuilderImpl(
       DartFileEditBuilderImpl sourceFileEditBuilder, int offset, int length)
-      : super(sourceFileEditBuilder, offset, length);
+      : isNonNullableByDefault = sourceFileEditBuilder
+            .resolvedUnit.libraryElement.isNonNullableByDefault,
+        super(sourceFileEditBuilder, offset, length);
 
   DartFileEditBuilderImpl get dartFileEditBuilder =>
       fileEditBuilder as DartFileEditBuilderImpl;
@@ -579,12 +586,11 @@ class DartEditBuilderImpl extends EditBuilderImpl implements DartEditBuilder {
       Expression argument, int index, Set<String> usedNames) {
     // append type name
     var type = argument.staticType;
-    var library = dartFileEditBuilder.resolvedUnit.libraryElement;
     if (type == null || type.isBottom || type.isDartCoreNull) {
       type = DynamicTypeImpl.instance;
     }
     if (argument is NamedExpression &&
-        library.isNonNullableByDefault &&
+        isNonNullableByDefault &&
         type.nullabilitySuffix == NullabilitySuffix.none) {
       write('required ');
     }
@@ -874,8 +880,7 @@ class DartEditBuilderImpl extends EditBuilderImpl implements DartEditBuilder {
       return false;
     }
     if (type.isBottom) {
-      var library = dartFileEditBuilder.resolvedUnit.libraryElement;
-      if (library.isNonNullableByDefault) {
+      if (isNonNullableByDefault) {
         return true;
       }
       return false;
@@ -1224,8 +1229,7 @@ class DartEditBuilderImpl extends EditBuilderImpl implements DartEditBuilder {
       return false;
     }
     if (type.isBottom) {
-      var library = dartFileEditBuilder.resolvedUnit.libraryElement;
-      if (library.isNonNullableByDefault) {
+      if (isNonNullableByDefault) {
         write('Never');
         return true;
       }
@@ -1929,26 +1933,34 @@ class DartFileEditBuilderImpl extends FileEditBuilderImpl
 class DartLinkedEditBuilderImpl extends LinkedEditBuilderImpl
     implements DartLinkedEditBuilder {
   /// Initialize a newly created linked edit builder.
-  DartLinkedEditBuilderImpl(EditBuilderImpl editBuilder) : super(editBuilder);
+  DartLinkedEditBuilderImpl(DartEditBuilderImpl editBuilder)
+      : super(editBuilder);
+
+  DartEditBuilderImpl get dartEditBuilder => editBuilder as DartEditBuilderImpl;
 
   @override
   void addSuperTypesAsSuggestions(DartType? type) {
-    _addSuperTypesAsSuggestions(type, <DartType>{});
+    if (type is InterfaceType) {
+      _addTypeAsSuggestions(type);
+      type.allSupertypes.forEach(_addTypeAsSuggestions);
+    }
   }
 
-  /// Safely implement [addSuperTypesAsSuggestions] by using the set of
-  /// [alreadyAdded] types to prevent infinite loops.
-  void _addSuperTypesAsSuggestions(DartType? type, Set<DartType> alreadyAdded) {
-    if (type is InterfaceType && alreadyAdded.add(type)) {
-      addSuggestion(
-        LinkedEditSuggestionKind.TYPE,
-        type.getDisplayString(withNullability: false),
-      );
-      _addSuperTypesAsSuggestions(type.superclass, alreadyAdded);
-      for (var interfaceType in type.interfaces) {
-        _addSuperTypesAsSuggestions(interfaceType, alreadyAdded);
-      }
-    }
+  void _addTypeAsSuggestions(InterfaceType type) {
+    addSuggestion(
+      LinkedEditSuggestionKind.TYPE,
+      _getTypeSuggestionText(type),
+    );
+  }
+
+  String _getTypeSuggestionText(InterfaceType type) {
+    // Add the suffix manually, because it should only be included for '?' and
+    // not '*'.
+    var typeDisplay = type.getDisplayString(withNullability: false);
+    return dartEditBuilder.isNonNullableByDefault &&
+            type.nullabilitySuffix == NullabilitySuffix.question
+        ? '$typeDisplay?'
+        : typeDisplay;
   }
 }
 

pkg/analyzer_plugin/test/src/utilities/change_builder/change_builder_dart_test.dart

@@ -1990,7 +1990,8 @@ void functionAfter() {
 
 @reflectiveTest
 class DartLinkedEditBuilderImplTest extends AbstractContextTest {
-  Future<void> test_addSuperTypesAsSuggestions() async {
+  Future<void>
+      test_addSuperTypesAsSuggestions_legacyTargetFile_noneSuffix() async {
     var path = convertPath('/home/test/lib/test.dart');
     addSource(path, '''
 class A {}
@@ -1999,7 +2000,122 @@ class C extends B {}
 ''');
     var unit = (await resolveFile(path)).unit;
     var classC = unit.declarations[2] as ClassDeclaration;
-    var builder = DartLinkedEditBuilderImpl(MockEditBuilderImpl());
+    var builder = DartLinkedEditBuilderImpl(
+        MockDartEditBuilderImpl(isNonNullableByDefault: false));
+    builder.addSuperTypesAsSuggestions(
+      classC.declaredElement?.instantiate(
+        typeArguments: [],
+        nullabilitySuffix: NullabilitySuffix.none,
+      ),
+    );
+    var suggestions = builder.suggestions;
+    expect(suggestions, hasLength(4));
+    expect(suggestions.map((s) => s.value),
+        unorderedEquals(['Object', 'A', 'B', 'C']));
+  }
+
+  Future<void>
+      test_addSuperTypesAsSuggestions_legacyTargetFile_questionSuffix() async {
+    var path = convertPath('/home/test/lib/test.dart');
+    addSource(path, '''
+class A {}
+class B extends A {}
+class C extends B {}
+''');
+    var unit = (await resolveFile(path)).unit;
+    var classC = unit.declarations[2] as ClassDeclaration;
+    var builder = DartLinkedEditBuilderImpl(
+        MockDartEditBuilderImpl(isNonNullableByDefault: false));
+    builder.addSuperTypesAsSuggestions(
+      classC.declaredElement?.instantiate(
+        typeArguments: [],
+        nullabilitySuffix: NullabilitySuffix.question,
+      ),
+    );
+    var suggestions = builder.suggestions;
+    expect(suggestions, hasLength(4));
+    expect(suggestions.map((s) => s.value),
+        unorderedEquals(['Object', 'A', 'B', 'C']));
+  }
+
+  Future<void>
+      test_addSuperTypesAsSuggestions_legacyTargetFile_starSuffix() async {
+    var path = convertPath('/home/test/lib/test.dart');
+    addSource(path, '''
+class A {}
+class B extends A {}
+class C extends B {}
+''');
+    var unit = (await resolveFile(path)).unit;
+    var classC = unit.declarations[2] as ClassDeclaration;
+    var builder = DartLinkedEditBuilderImpl(
+        MockDartEditBuilderImpl(isNonNullableByDefault: false));
+    builder.addSuperTypesAsSuggestions(
+      classC.declaredElement?.instantiate(
+        typeArguments: [],
+        nullabilitySuffix: NullabilitySuffix.star,
+      ),
+    );
+    var suggestions = builder.suggestions;
+    expect(suggestions, hasLength(4));
+    expect(suggestions.map((s) => s.value),
+        unorderedEquals(['Object', 'A', 'B', 'C']));
+  }
+
+  Future<void> test_addSuperTypesAsSuggestions_noneSuffix() async {
+    var path = convertPath('/home/test/lib/test.dart');
+    addSource(path, '''
+class A {}
+class B extends A {}
+class C extends B {}
+''');
+    var unit = (await resolveFile(path)).unit;
+    var classC = unit.declarations[2] as ClassDeclaration;
+    var builder = DartLinkedEditBuilderImpl(MockDartEditBuilderImpl());
+    builder.addSuperTypesAsSuggestions(
+      classC.declaredElement?.instantiate(
+        typeArguments: [],
+        nullabilitySuffix: NullabilitySuffix.none,
+      ),
+    );
+    var suggestions = builder.suggestions;
+    expect(suggestions, hasLength(4));
+    expect(suggestions.map((s) => s.value),
+        unorderedEquals(['Object', 'A', 'B', 'C']));
+  }
+
+  Future<void> test_addSuperTypesAsSuggestions_questionSuffix() async {
+    var path = convertPath('/home/test/lib/test.dart');
+    addSource(path, '''
+class A {}
+class B extends A {}
+class C extends B {}
+''');
+    var unit = (await resolveFile(path)).unit;
+    var classC = unit.declarations[2] as ClassDeclaration;
+    var builder = DartLinkedEditBuilderImpl(MockDartEditBuilderImpl());
+    builder.addSuperTypesAsSuggestions(
+      classC.declaredElement?.instantiate(
+        typeArguments: [],
+        nullabilitySuffix: NullabilitySuffix.question,
+      ),
+    );
+    var suggestions = builder.suggestions;
+    expect(suggestions, hasLength(4));
+    expect(suggestions.map((s) => s.value),
+        unorderedEquals(['Object?', 'A?', 'B?', 'C?']));
+  }
+
+  Future<void> test_addSuperTypesAsSuggestions_starSuffix() async {
+    var path = convertPath('/home/test/lib/test.dart');
+    addSource(path, '''
+class A {}
+class B extends A {}
+class C extends B {}
+''');
+    var unit = (await resolveFile(path)).unit;
+    var classC = unit.declarations[2] as ClassDeclaration;
+    var builder = DartLinkedEditBuilderImpl(MockDartEditBuilderImpl());
     builder.addSuperTypesAsSuggestions(
       classC.declaredElement?.instantiate(
         typeArguments: [],

pkg/analyzer_plugin/test/src/utilities/change_builder/mocks.dart

@@ -7,6 +7,7 @@ import 'package:analyzer/dart/analysis/context_root.dart';
 import 'package:analyzer/dart/analysis/session.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer_plugin/src/utilities/change_builder/change_builder_core.dart';
+import 'package:analyzer_plugin/src/utilities/change_builder/change_builder_dart.dart';
 
 class MockAnalysisContext implements AnalysisContext {
   @override
@@ -48,6 +49,18 @@ class MockContextRoot implements ContextRoot {
   dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
 
+class MockDartEditBuilderImpl implements DartEditBuilderImpl {
+  @override
+  final bool isNonNullableByDefault;
+
+  MockDartEditBuilderImpl({this.isNonNullableByDefault = true});
+
+  @override
+  dynamic noSuchMethod(Invocation invocation) {
+    return super.noSuchMethod(invocation);
+  }
+}
+
 class MockEditBuilderImpl implements EditBuilderImpl {
   @override
   dynamic noSuchMethod(Invocation invocation) {