Elements. Break cycles in InterfaceElementImpl.

Change-Id: Iaea43db437064f21dee54b4c89938830caf60f39
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/445805
Reviewed-by: Johnni Winther <[email protected]>
Reviewed-by: Samuel Rawlins <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analysis_server/test/search/type_hierarchy_test.dart

@@ -64,7 +64,18 @@ class B extends A {
         'superclass': 1,
         'interfaces': [],
         'mixins': [],
-        'subclasses': [1],
+        'subclasses': [2],
+      },
+      {
+        'classElement': {
+          'kind': 'CLASS',
+          'name': 'Object',
+          'location': anything,
+          'flags': 0,
+        },
+        'interfaces': [],
+        'mixins': [],
+        'subclasses': [],
       },
       {
         'classElement': {
@@ -76,7 +87,7 @@ class B extends A {
         'superclass': 0,
         'interfaces': [],
         'mixins': [],
-        'subclasses': [],
+        'subclasses': [0],
       },
     ]);
   }

pkg/analyzer/lib/src/dart/analysis/driver.dart

@@ -109,7 +109,7 @@ testFineAfterLibraryAnalyzerHook;
 // TODO(scheglov): Clean up the list of implicitly analyzed files.
 class AnalysisDriver {
   /// The version of data format, should be incremented on every format change.
-  static const int DATA_VERSION = 522;
+  static const int DATA_VERSION = 523;
 
   /// The number of exception contexts allowed to write. Once this field is
   /// zero, we stop writing any new exception contexts in this process.

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

@@ -4600,6 +4600,10 @@ abstract class InterfaceElementImpl extends InstanceElementImpl
 
   InterfaceTypeImpl? _thisType;
 
+  /// If not `null`, this element was part of a supertypes cycle. The cycle
+  /// is broken by clearing supertypes for all cycle elements.
+  List<InterfaceElementImpl>? interfaceCycle;
+
   /// The cached result of [allSupertypes].
   List<InterfaceTypeImpl>? _allSupertypes;
 

pkg/analyzer/lib/src/error/inheritance_override.dart

@@ -560,82 +560,71 @@ class _ClassVerifier {
   /// [CompileTimeErrorCode.recursiveInterfaceInheritanceImplements],
   /// [CompileTimeErrorCode.recursiveInterfaceInheritanceOn],
   /// [CompileTimeErrorCode.recursiveInterfaceInheritanceWith].
-  bool _checkForRecursiveInterfaceInheritance(
-    InterfaceElementImpl element, [
-    List<InterfaceElement>? path,
-  ]) {
-    path ??= <InterfaceElement>[];
-
-    // Detect error condition.
-    int size = path.length;
-    // If this is not the base case (size > 0), and the enclosing class is the
-    // given class element then report an error.
-    if (size > 0 && classElement == element) {
-      String className = classElement.displayName;
-      if (size > 1) {
-        // Construct a string showing the cyclic implements path:
-        // "A, B, C, D, A"
-        String separator = ", ";
-        StringBuffer buffer = StringBuffer();
-        for (int i = 0; i < size; i++) {
-          buffer.write(path[i].displayName);
-          buffer.write(separator);
-        }
-        buffer.write(element.displayName);
-        reporter.atElement2(
-          classElement,
-          CompileTimeErrorCode.recursiveInterfaceInheritance,
-          arguments: [className, buffer.toString()],
-        );
-        return true;
-      } else {
-        // RECURSIVE_INTERFACE_INHERITANCE_BASE_CASE_EXTENDS or
-        // RECURSIVE_INTERFACE_INHERITANCE_BASE_CASE_IMPLEMENTS or
-        // RECURSIVE_INTERFACE_INHERITANCE_ON or
-        // RECURSIVE_INTERFACE_INHERITANCE_BASE_CASE_WITH
+  bool _checkForRecursiveInterfaceInheritance(InterfaceElementImpl element) {
+    var cycle = element.interfaceCycle;
+    if (cycle == null) {
+      return false;
+    }
+
+    if (superclass case var superclass?) {
+      if (superclass.element == element) {
         reporter.atElement2(
-          classElement,
-          _getRecursiveErrorCode(element),
-          arguments: [className],
+          element,
+          CompileTimeErrorCode.recursiveInterfaceInheritanceExtends,
+          arguments: [element.displayName],
         );
         return true;
       }
     }
 
-    if (path.indexOf(element) > 0) {
-      return false;
-    }
-    path.add(element);
-
-    // n-case
-    var supertype = element.supertype;
-    if (supertype != null &&
-        _checkForRecursiveInterfaceInheritance(supertype.element, path)) {
-      return true;
-    }
-
-    for (var type in element.mixins) {
-      if (_checkForRecursiveInterfaceInheritance(type.element, path)) {
-        return true;
+    if (onClause case var onClause?) {
+      for (var typeAnnotation in onClause.superclassConstraints) {
+        if (typeAnnotation.element == element) {
+          reporter.atElement2(
+            element,
+            CompileTimeErrorCode.recursiveInterfaceInheritanceOn,
+            arguments: [element.displayName],
+          );
+          return true;
+        }
       }
     }
 
-    if (element is MixinElementImpl) {
-      for (var type in element.superclassConstraints) {
-        if (_checkForRecursiveInterfaceInheritance(type.element, path)) {
+    if (withClause case var withClause?) {
+      for (var typeAnnotation in withClause.mixinTypes) {
+        if (typeAnnotation.element == element) {
+          reporter.atElement2(
+            element,
+            CompileTimeErrorCode.recursiveInterfaceInheritanceWith,
+            arguments: [element.displayName],
+          );
           return true;
         }
       }
     }
 
-    for (var type in element.interfaces) {
-      if (_checkForRecursiveInterfaceInheritance(type.element, path)) {
-        return true;
+    if (implementsClause case var implementsClause?) {
+      for (var typeAnnotation in implementsClause.interfaces) {
+        if (typeAnnotation.element == element) {
+          reporter.atElement2(
+            element,
+            CompileTimeErrorCode.recursiveInterfaceInheritanceImplements,
+            arguments: [element.displayName],
+          );
+          return true;
+        }
       }
     }
 
-    path.removeAt(path.length - 1);
-    return false;
+    reporter.atElement2(
+      classElement,
+      CompileTimeErrorCode.recursiveInterfaceInheritance,
+      arguments: [
+        element.displayName,
+        cycle.map((e) => e.displayName).join(', '),
+      ],
+    );
+    return true;
   }
 
   void _checkIllegalConcreteEnumMemberDeclaration(Token name) {
@@ -742,30 +731,6 @@ class _ClassVerifier {
     return true;
   }
 
-  /// Return the error code that should be used when the given class [element]
-  /// references itself directly.
-  DiagnosticCode _getRecursiveErrorCode(InterfaceElement element) {
-    if (element.supertype?.element == classElement) {
-      return CompileTimeErrorCode.recursiveInterfaceInheritanceExtends;
-    }
-
-    if (element is MixinElement) {
-      for (var type in element.superclassConstraints) {
-        if (type.element == classElement) {
-          return CompileTimeErrorCode.recursiveInterfaceInheritanceOn;
-        }
-      }
-    }
-
-    for (var type in element.mixins) {
-      if (type.element == classElement) {
-        return CompileTimeErrorCode.recursiveInterfaceInheritanceWith;
-      }
-    }
-
-    return CompileTimeErrorCode.recursiveInterfaceInheritanceImplements;
-  }
-
   /// If [name] is not implemented in the extended concrete class, the
   /// issue should be fixed there, and then [classElement] will not have it too.
   bool _isNotImplementedInConcreteSuperClass(Name name) {

pkg/analyzer/lib/src/summary2/bundle_reader.dart

@@ -293,6 +293,7 @@ class LibraryReader {
           element.supertype = reader._readOptionalInterfaceType();
           element.mixins = reader._readInterfaceTypeList();
           element.interfaces = reader._readInterfaceTypeList();
+          element.interfaceCycle = reader.readOptionalElementList();
         }),
       );
 
@@ -493,6 +494,7 @@ class LibraryReader {
           element.supertype = reader._readOptionalInterfaceType();
           element.mixins = reader._readInterfaceTypeList();
           element.interfaces = reader._readInterfaceTypeList();
+          element.interfaceCycle = reader.readOptionalElementList();
         }),
       );
 
@@ -632,6 +634,7 @@ class LibraryReader {
           reader._addTypeParameters2(element.typeParameters);
           element.typeErasure = reader.readRequiredType();
           element.interfaces = reader._readInterfaceTypeList();
+          element.interfaceCycle = reader.readOptionalElementList();
         }),
       );
 
@@ -967,6 +970,7 @@ class LibraryReader {
           reader._addTypeParameters2(element.typeParameters);
           element.superclassConstraints = reader._readInterfaceTypeList();
           element.interfaces = reader._readInterfaceTypeList();
+          element.interfaceCycle = reader.readOptionalElementList();
         }),
       );
 
@@ -1537,6 +1541,10 @@ class ResolutionReader {
     return _readNodeList();
   }
 
+  List<T>? readOptionalElementList<T extends Element>() {
+    return _reader.readOptionalObject(readElementList);
+  }
+
   ExpressionImpl? readOptionalExpression() {
     if (_reader.readBool()) {
       return _readRequiredNode() as ExpressionImpl;

pkg/analyzer/lib/src/summary2/bundle_writer.dart

@@ -160,6 +160,7 @@ class BundleWriter {
           _resolutionSink.writeType(element.supertype);
           _resolutionSink._writeTypeList(element.mixins);
           _resolutionSink._writeTypeList(element.interfaces);
+          _resolutionSink.writeOptionalElementList(element.interfaceCycle);
         });
       });
     });
@@ -275,6 +276,7 @@ class BundleWriter {
           _resolutionSink.writeType(element.supertype);
           _resolutionSink._writeTypeList(element.mixins);
           _resolutionSink._writeTypeList(element.interfaces);
+          _resolutionSink.writeOptionalElementList(element.interfaceCycle);
         });
       });
     });
@@ -369,6 +371,7 @@ class BundleWriter {
         _resolutionSink.withTypeParameters(element.typeParameters, () {
           _resolutionSink.writeType(element.typeErasure);
           _resolutionSink._writeTypeList(element.interfaces);
+          _resolutionSink.writeOptionalElementList(element.interfaceCycle);
         });
       });
     });
@@ -572,6 +575,7 @@ class BundleWriter {
         _resolutionSink.withTypeParameters(element.typeParameters, () {
           _resolutionSink._writeTypeList(element.superclassConstraints);
           _resolutionSink._writeTypeList(element.interfaces);
+          _resolutionSink.writeOptionalElementList(element.interfaceCycle);
         });
       });
     });
@@ -913,6 +917,10 @@ class ResolutionSink extends _SummaryDataWriter {
     }
   }
 
+  void writeOptionalElementList(List<Element>? elements) {
+    writeOptionalObject(elements, (it) => _writeElementList(it));
+  }
+
   void writeOptionalTypeList(List<DartType>? types) {
     if (types != null) {
       writeBool(true);