Recover from read errors.

dart/pkg/compiler/lib/src/apiimpl.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.
 
 library leg_apiimpl;
 
 import 'dart:async';
 
 import '../compiler.dart' as api;
 import 'dart2jslib.dart' as leg;
@@ skipping 190 matching lines @@
       if (node == null) node = leg.NO_LOCATION_SPANNABLE;
       internalError(node,
           'Relative uri $readableUri provided to readScript(Uri).');
     }
 
     // We need to store the current element since we are reporting read errors
     // asynchronously and therefore need to restore the current element for
     // [node] to be valid.
     elements.Element element = currentElement;
     void reportReadError(exception) {
-      withCurrentElement(element, () {
-        reportError(node,
-                    leg.MessageKind.READ_SCRIPT_ERROR,
-                    {'uri': readableUri, 'exception': exception});
-      });
+      if (element == null || node == null) {
+        reportError(
+            new leg.SourceSpan(readableUri, 0, 0),
+            leg.MessageKind.READ_SELF_ERROR,
+            {'uri': readableUri, 'exception': exception});
+      } else {
+        withCurrentElement(element, () {
+          reportError(
+              node,
+              leg.MessageKind.READ_SCRIPT_ERROR,
+              {'uri': readableUri, 'exception': exception});
+        });
+      }
     }
 
     Uri resourceUri = translateUri(node, readableUri);
-    String resourceUriString = resourceUri.toString();
+    String resourceUriString = '$resourceUri';
     if (resourceUri.scheme == 'dart-ext') {
       if (!allowNativeExtensions) {
         withCurrentElement(element, () {
           reportError(node, leg.MessageKind.DART_EXT_NOT_SUPPORTED);
         });
       }
-      return new Future.value(new leg.Script(readableUri, resourceUri,
-          new StringSourceFile(resourceUriString,
-              "// Synthetic source file generated for '$readableUri'.")));
+      return synthesizeScript(node, readableUri);
     }
 
     // TODO(johnniwinther): Wrap the result from [provider] in a specialized
     // [Future] to ensure that we never execute an asynchronous action without
     // setting up the current element of the compiler.
     return new Future.sync(() => callUserProvider(resourceUri)).then((data) {
       SourceFile sourceFile;
       if (data is List<int>) {
         sourceFile = new Utf8BytesSourceFile(resourceUriString, data);
       } else if (data is String) {
         sourceFile = new StringSourceFile(resourceUriString, data);
       } else {
         String message = "Expected a 'String' or a 'List<int>' from the input "
                          "provider, but got: ${Error.safeToString(data)}.";
         reportReadError(message);
       }
       // We use [readableUri] as the URI for the script since need to preserve
       // the scheme in the script because [Script.uri] is used for resolving
       // relative URIs mentioned in the script. See the comment on
       // [LibraryLoader] for more details.
       return new leg.Script(readableUri, resourceUri, sourceFile);
     }).catchError((error) {
       reportReadError(error);
-      return null;
+      return synthesizeScript(node, readableUri);
     });
   }
 
+  Future<leg.Script> synthesizeScript(leg.Spannable node, Uri readableUri) {
+    Uri resourceUri = translateUri(node, readableUri);
+    return new Future.value(
+        new leg.Script(
+            readableUri, resourceUri,
+            new StringSourceFile(
+                '$resourceUri',
+                "// Synthetic source file generated for '$readableUri'."),
+            isSynthesized: true));
+  }
+
   /**
    * Translates a readable URI into a resource URI.
    *
    * See [LibraryLoader] for terminology on URIs.
    */
   Uri translateUri(leg.Spannable node, Uri readableUri) {
     switch (readableUri.scheme) {
       case 'package': return translatePackageUri(node, readableUri);
       default: return readableUri;
     }
@@ skipping 121 matching lines @@
     print('$message: ${tryToString(exception)}');
     print(tryToString(stackTrace));
   }
 
   fromEnvironment(String name) => environment[name];
 
   LibraryInfo lookupLibraryInfo(String libraryName) {
     return library_info.LIBRARIES[libraryName];
   }
 }