Restore verifier flags after failed verification.

pkg/kernel/lib/verifier.dart

 // Copyright (c) 2016, 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.
 library kernel.checks;
 
 import 'ast.dart';
 import 'transformations/flags.dart';
 
 void verifyProgram(Program program) {
   VerifyingVisitor.check(program);
 }
 
 /// Checks that a kernel program is well-formed.
 ///
 /// This does not include any kind of type checking.
 class VerifyingVisitor extends RecursiveVisitor {
   final Set<Class> classes = new Set<Class>();
   final Set<TypeParameter> typeParameters = new Set<TypeParameter>();
   final List<VariableDeclaration> variableStack = <VariableDeclaration>[];
   bool classTypeParametersAreInScope = false;
 
+  /// If true, relax certain checks for *outline* mode. For example, don't
+  /// attempt to validate constructor initializers.
+  bool isOutline = false;
+
   Member currentMember;
   Class currentClass;
   TreeNode currentParent;
 
   TreeNode get context => currentMember ?? currentClass;
 
   static void check(Program program) {
     program.accept(new VerifyingVisitor());
   }
 
@@ skipping 74 matching lines @@
   }
 
   void checkVariableInScope(VariableDeclaration variable, TreeNode where) {
     if (variable.flags & VariableDeclaration.FlagInScope == 0) {
       throw 'Variable $variable used out of scope in $context '
           '(${where.location})';
     }
   }
 
   visitProgram(Program program) {
-    for (var library in program.libraries) {
-      for (var class_ in library.classes) {
-        if (!classes.add(class_)) {
-          throw 'Class $class_ declared more than once';
+    try {
+      for (var library in program.libraries) {
+        for (var class_ in library.classes) {
+          if (!classes.add(class_)) {
+            throw 'Class $class_ declared more than once.';
+          }
+        }
+        library.members.forEach(declareMember);
+        for (var class_ in library.classes) {
+          class_.members.forEach(declareMember);
         }
       }
-      library.members.forEach(declareMember);
-      for (var class_ in library.classes) {
-        class_.members.forEach(declareMember);
+      visitChildren(program);
+    } finally {
+      for (var library in program.libraries) {
+        library.members.forEach(undeclareMember);
+        for (var class_ in library.classes) {
+          class_.members.forEach(undeclareMember);
+        }
       }
-    }
-    visitChildren(program);
-    for (var library in program.libraries) {
-      library.members.forEach(undeclareMember);
-      for (var class_ in library.classes) {
-        class_.members.forEach(undeclareMember);
-      }
+      variableStack.forEach(undeclareVariable);
     }
   }
 
   visitField(Field node) {
     currentMember = node;
     var oldParent = enterParent(node);
     classTypeParametersAreInScope = !node.isStatic;
     node.initializer?.accept(this);
     classTypeParametersAreInScope = false;
     visitList(node.annotations, this);
@@ skipping 14 matching lines @@
 
   visitConstructor(Constructor node) {
     currentMember = node;
     classTypeParametersAreInScope = true;
     // The constructor member needs special treatment due to parameters being
     // in scope in the initializer list.
     var oldParent = enterParent(node);
     int stackHeight = enterLocalScope();
     visitChildren(node.function);
     visitList(node.initializers, this);
+    if (!isOutline) {
+      checkInitializers(node);
+    }
     exitLocalScope(stackHeight);
     classTypeParametersAreInScope = false;
     visitList(node.annotations, this);
     exitParent(oldParent);
     classTypeParametersAreInScope = false;
     currentMember = null;
   }
 
   visitClass(Class node) {
     currentClass = node;
@@ skipping 264 matching lines @@
       throw 'Parent pointer on ${node.runtimeType} '
           'is ${node.parent.runtimeType} '
           'but should be ${parent.runtimeType}';
     }
     var oldParent = parent;
     parent = node;
     node.visitChildren(this);
     parent = oldParent;
   }
 }
+
+void checkInitializers(Constructor constructor) {
+  // TODO(ahe): I'll add more here in other CLs.
+}