Extend pkg/front_end/lib/src/fasta/kernel/verifier.dart to check for UnknownType.

pkg/front_end/lib/src/fasta/kernel/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 fasta.verifier;
 
+import 'package:front_end/src/fasta/type_inference/type_schema.dart'
+    show TypeSchemaVisitor, UnknownType;
+
 import 'package:kernel/ast.dart'
     show
         InvalidExpression,
         InvalidStatement,
         InvalidInitializer,
         Class,
         ExpressionStatement,
         Field,
         Library,
         Procedure,
         Program,
         TreeNode;
 
 import 'package:kernel/verifier.dart' show VerificationError, VerifyingVisitor;
 
 import '../errors.dart' show printUnexpected;
 
 import 'redirecting_factory_body.dart' show RedirectingFactoryBody;
 
 List<VerificationError> verifyProgram(Program program,
     {bool isOutline: false}) {
   FastaVerifyingVisitor verifier = new FastaVerifyingVisitor(isOutline);
   program.accept(verifier);
   return verifier.errors;
 }
 
-class FastaVerifyingVisitor extends VerifyingVisitor {
+class FastaVerifyingVisitor extends VerifyingVisitor
+    implements TypeSchemaVisitor {
   final List<VerificationError> errors = <VerificationError>[];
 
   String fileUri;
 
   FastaVerifyingVisitor(bool isOutline) {
     this.isOutline = isOutline;
   }
 
   @override
   problem(TreeNode node, String details) {
     VerificationError error = new VerificationError(context, node, details);
-    printUnexpected(Uri.parse(fileUri), node.fileOffset, "$error");
+    printUnexpected(Uri.parse(fileUri), node?.fileOffset ?? 0, "$error");

[ahe, 2017/04/27 16:38:20]

-1.

[Paul Berry, 2017/04/27 16:43:51]

Done.

     errors.add(error);
   }
 
   @override
   visitExpressionStatement(ExpressionStatement node) {
     // Bypass verification of the [StaticGet] in [RedirectingFactoryBody] as
     // this is a static get without a getter.
     if (node is! RedirectingFactoryBody) {
       super.visitExpressionStatement(node);
     }
@@ skipping 30 matching lines @@
 
   @override
   visitInvalidStatement(InvalidStatement node) {
     problem(node, "Invalid statement.");
   }
 
   @override
   visitInvalidInitializer(InvalidInitializer node) {
     problem(node, "Invalid initializer.");
   }
+
+  @override
+  visitUnknownType(UnknownType node) {
+    // Note: we can't pass [node] to [problem] because it's not a [TreeNode].
+    problem(null, "Unexpected appearance of the unknown type.");
+  }
 }