Use messages for (some) public API errors

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 '../deprecated_problems.dart' show deprecated_printUnexpected;
 
+import '../fasta_codes.dart';
+
 import 'redirecting_factory_body.dart' show RedirectingFactoryBody;
 
-List<VerificationError> verifyProgram(Program program,
-    {bool isOutline: false}) {
+List<LocatedMessage> verifyProgram(Program program, {bool isOutline: false}) {
   FastaVerifyingVisitor verifier = new FastaVerifyingVisitor(isOutline);
   program.accept(verifier);
-  return verifier.errors;
+  return verifier.errors.map(convertError).toList();
 }
 
 class FastaVerifyingVisitor extends VerifyingVisitor
     implements TypeSchemaVisitor {
   final List<VerificationError> errors = <VerificationError>[];
 
   String fileUri;
 
   FastaVerifyingVisitor(bool isOutline) {
     this.isOutline = isOutline;
@@ skipping 55 matching lines @@
   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.");
   }
 }
+
+LocatedMessage convertError(VerificationError error) {

[ahe, 2017/07/12 13:14:43]

This is probably a better solution than what I have.

+  var node = error.node ?? error.context;
+  int offset = node?.fileOffset ?? -1;
+  var file = node?.location?.file;
+  Uri uri = file == null ? null : Uri.parse(file);
+  return templateVerificationError
+      .withArguments(error.details)
+      .withLocation(uri, offset);
+}