Make const_finder work with implemented and extended classes (#20614)

tools/const_finder/lib/const_finder.dart

@@ -13,11 +13,11 @@ class _ConstVisitor extends RecursiveVisitor<void> {
     this.classLibraryUri,
     this.className,
   )  : assert(kernelFilePath != null),
-        assert(classLibraryUri != null),
-        assert(className != null),
-        _visitedInstances = <String>{},
-        constantInstances = <Map<String, dynamic>>[],
-        nonConstantLocations = <Map<String, dynamic>>[];
+       assert(classLibraryUri != null),
+       assert(className != null),
+       _visitedInstances = <String>{},
+       constantInstances = <Map<String, dynamic>>[],
+       nonConstantLocations = <Map<String, dynamic>>[];
 
   /// The path to the file to open.
   final String kernelFilePath;
@@ -32,9 +32,19 @@ class _ConstVisitor extends RecursiveVisitor<void> {
   final List<Map<String, dynamic>> constantInstances;
   final List<Map<String, dynamic>> nonConstantLocations;
 
+  // A cache of previously evaluated classes.
+  static Map<Class, bool> _classHeirarchyCache = <Class, bool>{};
   bool _matches(Class node) {
-    return node.enclosingLibrary.importUri.toString() == classLibraryUri &&
-      node.name == className;
+    assert(node != null);
+    final bool result = _classHeirarchyCache[node];
+    if (result != null) {
+      return result;
+    }
+    final bool exactMatch = node.name == className
+        && node.enclosingLibrary.importUri.toString() == classLibraryUri;
+    _classHeirarchyCache[node] = exactMatch
+        || node.supers.any((Supertype supertype) => _matches(supertype.classNode));
+    return _classHeirarchyCache[node];
   }
 
   // Avoid visiting the same constant more than once.

tools/const_finder/test/const_finder_test.dart

@@ -71,11 +71,28 @@ void _checkConsts() {
         <String, dynamic>{'stringValue': '10', 'intValue': 10, 'targetValue': null},
         <String, dynamic>{'stringValue': '9', 'intValue': 9},
         <String, dynamic>{'stringValue': '7', 'intValue': 7, 'targetValue': null},
+        <String, dynamic>{'stringValue': '11', 'intValue': 11, 'targetValue': null},
+        <String, dynamic>{'stringValue': '12', 'intValue': 12, 'targetValue': null},
         <String, dynamic>{'stringValue': 'package', 'intValue':-1, 'targetValue': null},
       ],
       'nonConstantLocations': <dynamic>[],
     }),
   );
+
+  final ConstFinder finder2 = ConstFinder(
+    kernelFilePath: constsDill,
+    classLibraryUri: 'package:const_finder_fixtures/target.dart',
+    className: 'MixedInTarget',
+  );
+  expect<String>(
+    jsonEncode(finder2.findInstances()),
+    jsonEncode(<String, dynamic>{
+      'constantInstances': <Map<String, dynamic>>[
+        <String, dynamic>{'val': '13'},
+      ],
+      'nonConstantLocations': <dynamic>[],
+    }),
+  );
 }
 
 void _checkNonConsts() {

tools/const_finder/test/fixtures/lib/consts.dart

@@ -31,6 +31,14 @@ void main() {
 
   final StaticConstInitializer staticConstMap = StaticConstInitializer();
   staticConstMap.useOne(1);
+
+  const ExtendsTarget extendsTarget = ExtendsTarget('11', 11, null);
+  extendsTarget.hit();
+  const ImplementsTarget implementsTarget = ImplementsTarget('12', 12, null);
+  implementsTarget.hit();
+
+  const MixedInTarget mixedInTraget = MixedInTarget('13');
+  mixedInTraget.hit();
 }
 
 class IgnoreMe {

tools/const_finder/test/fixtures/lib/target.dart

@@ -13,3 +13,39 @@ class Target {
     print('$stringValue $intValue');
   }
 }
+
+class ExtendsTarget extends Target {
+  const ExtendsTarget(String stringValue, int intValue, Target targetValue)
+      : super(stringValue, intValue, targetValue);
+}
+
+class ImplementsTarget implements Target {
+  const ImplementsTarget(this.stringValue, this.intValue, this.targetValue);
+
+  @override
+  final String stringValue;
+  @override
+  final int intValue;
+  @override
+  final Target targetValue;
+
+  @override
+  void hit() {
+    print('ImplementsTarget - $stringValue $intValue');
+  }
+}
+
+mixin MixableTarget {
+  String get val;
+
+  void hit() {
+    print(val);
+  }
+}
+
+class MixedInTarget with MixableTarget {
+  const MixedInTarget(this.val);
+
+  @override
+  final String val;
+}
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