Recover from fatal parser errors.

dart/pkg/compiler/lib/src/patch_parser.dart

 // Copyright (c) 2012, 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.
 
 /**
  * This library contains the infrastructure to parse and integrate patch files.
  *
  * Three types of elements can be patched: [LibraryElement], [ClassElement],
  * [FunctionElement]. Patches are introduced in patch libraries which are loaded
  * together with the corresponding origin library. Which libraries that are
@@ skipping 152 matching lines @@
 
   void scanLibraryElements(CompilationUnitElement compilationUnit) {
     measure(() {
       // TODO(johnniwinther): Test that parts and exports are handled correctly.
       Script script = compilationUnit.script;
       Token tokens = new Scanner(script.file).tokenize();
       Function idGenerator = compiler.getNextFreeClassId;
       Listener patchListener = new PatchElementListener(compiler,
                                                         compilationUnit,
                                                         idGenerator);
-      new PartialParser(patchListener).parseUnit(tokens);
+      try {
+        new PartialParser(patchListener).parseUnit(tokens);
+      } on ParserError catch (e) {
+        // No need to recover from a parser error in platform libraries, user
+        // will never see this if the libraries are tested correctly.
+        compiler.internalError(
+            compilationUnit, "Parser error in patch file: $e");
+      }
     });
   }
 
   void parsePatchClassNode(PartialClassElement element) {
     // Parse [PartialClassElement] using a "patch"-aware parser instead
     // of calling its [parseNode] method.
     if (element.cachedNode != null) return;
 
     measure(() => compiler.withCurrentElement(element, () {
       MemberListener listener = new MemberListener(compiler, element);
       Parser parser = new PatchClassElementParser(listener);
-      Token token = parser.parseTopLevelDeclaration(element.beginToken);
-      assert(identical(token, element.endToken.next));
+      try {
+        Token token = parser.parseTopLevelDeclaration(element.beginToken);
+        assert(identical(token, element.endToken.next));
+      } on ParserError catch (e) {
+        // No need to recover from a parser error in platform libraries, user
+        // will never see this if the libraries are tested correctly.
+        compiler.internalError(
+            element, "Parser error in patch file: $e");
+      }
       element.cachedNode = listener.popNode();
       assert(listener.nodes.isEmpty);
 
       Link<Element> patches = element.localMembers;
       applyContainerPatch(element.origin, patches);
     }));
   }
 
   void applyContainerPatch(ClassElement originClass,
                            Link<Element> patches) {
@@ skipping 307 matching lines @@
         "Trying to patch a function more than once.");
   }
   origin.applyPatch(patch);
 }
 
 // TODO(johnniwinther): Add unittest when patch is (real) metadata.
 bool isPatchElement(Compiler compiler, Element element) {
   return EagerAnnotationHandler.checkAnnotation(compiler, element,
       const PatchAnnotationHandler());
 }