[ddc] Fixing switch label finder.

Our previous visitor was manually implemented. Extending the recursive visitor instead helps us be more robust to future CFE updates.

Fixes #51802

Change-Id: I9efebdf28fdf9146c2d1f948e01363a77807aa16
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/290280
Reviewed-by: Nicholas Shahan <nshahan@google.com>
Commit-Queue: Mark Zhou <markzipan@google.com>

pkg/dev_compiler/lib/src/kernel/kernel_helpers.dart

@@ -277,54 +277,16 @@ bool hasLabeledContinue(SwitchStatement node) {
   return visitor.found;
 }
 
-class LabelContinueFinder extends StatementVisitor<void> {
+class LabelContinueFinder extends RecursiveVisitor<void> {
   var found = false;
 
   void visit(Statement? s) {
     if (!found && s != null) s.accept(this);
   }
 
-  @override
-  void visitBlock(Block node) => node.statements.forEach(visit);
-  @override
-  void visitAssertBlock(AssertBlock node) => node.statements.forEach(visit);
-  @override
-  void visitWhileStatement(WhileStatement node) => visit(node.body);
-  @override
-  void visitDoStatement(DoStatement node) => visit(node.body);
-  @override
-  void visitForStatement(ForStatement node) => visit(node.body);
-  @override
-  void visitForInStatement(ForInStatement node) => visit(node.body);
   @override
   void visitContinueSwitchStatement(ContinueSwitchStatement node) =>
       found = true;
-
-  @override
-  void visitSwitchStatement(SwitchStatement node) {
-    node.cases.forEach((c) => visit(c.body));
-  }
-
-  @override
-  void visitIfStatement(IfStatement node) {
-    visit(node.then);
-    visit(node.otherwise);
-  }
-
-  @override
-  void visitTryCatch(TryCatch node) {
-    visit(node.body);
-    node.catches.forEach((c) => visit(c.body));
-  }
-
-  @override
-  void visitTryFinally(TryFinally node) {
-    visit(node.body);
-    visit(node.finalizer);
-  }
-
-  @override
-  void defaultStatement(Statement node) {}
 }
 
 /// Ensures that all of the known DartType implementors are handled.

tests/language/switch/label3_test.dart

@@ -0,0 +1,40 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:expect/expect.dart';
+
+enum Color { red, green, blue }
+
+enum Taste { sweet, sour, salty, bitter, umami }
+
+void main() {
+  Expect.equals(getValue(Taste.sweet, Color.blue), 1);
+  Expect.equals(getValue(Taste.bitter, Color.blue), 1);
+  Expect.equals(getValue(Taste.salty, Color.red), 2);
+  Expect.equals(getValue(Taste.salty, Color.blue), 4);
+  Expect.equals(getValue(Taste.salty, Color.green), 3);
+  Expect.equals(getValue(Taste.umami, Color.red), 4);
+}
+
+int getValue(Taste taste, Color color) {
+  switch (taste) {
+    case Taste.sweet:
+    case Taste.sour:
+    case Taste.bitter:
+      return 1;
+    case Taste.salty:
+      switch (color) {
+        case Color.red:
+          return 2;
+        case Color.blue:
+          continue LABEL;
+        case Color.green:
+          return 3;
+      }
+      throw Exception('Invalid state.');
+    LABEL:
+    case Taste.umami:
+      return 4;
+  }
+}

tests/language_2/switch/label3_test.dart

@@ -0,0 +1,42 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// @dart = 2.9
+
+import 'package:expect/expect.dart';
+
+enum Color { red, green, blue }
+
+enum Taste { sweet, sour, salty, bitter, umami }
+
+void main() {
+  Expect.equals(getValue(Taste.sweet, Color.blue), 1);
+  Expect.equals(getValue(Taste.bitter, Color.blue), 1);
+  Expect.equals(getValue(Taste.salty, Color.red), 2);
+  Expect.equals(getValue(Taste.salty, Color.blue), 4);
+  Expect.equals(getValue(Taste.salty, Color.green), 3);
+  Expect.equals(getValue(Taste.umami, Color.red), 4);
+}
+
+int getValue(Taste taste, Color color) {
+  switch (taste) {
+    case Taste.sweet:
+    case Taste.sour:
+    case Taste.bitter:
+      return 1;
+    case Taste.salty:
+      switch (color) {
+        case Color.red:
+          return 2;
+        case Color.blue:
+          continue LABEL;
+        case Color.green:
+          return 3;
+      }
+      throw Exception('Invalid state.');
+    LABEL:
+    case Taste.umami:
+      return 4;
+  }
+}