Nice messages on uncaught exceptions.

dart/sdk/lib/_internal/compiler/implementation/ssa/builder.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.
 
 part of ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 3061 matching lines @@
             'Isolate library and compiler mismatch', node: node);
       }
       HStatic target = new HStatic(element);
       add(target);
       List<HInstruction> inputs = <HInstruction>[target];
       addGenericSendArgumentsToList(link, inputs);
       push(new HInvokeStatic(inputs));
     }
   }
 
-  void handleForeignDartClosureToJs(Send node) {
+  FunctionSignature handleForeignRawFunctionRef(Send node, String name) {

[ahe, 2013/01/15 10:34:30]

Found a type error during testing.

     if (node.arguments.isEmpty || !node.arguments.tail.isEmpty) {
-      compiler.cancel('Exactly one argument required',
+      compiler.cancel('$name requires exactly one argument',
                       node: node.argumentsNode);
     }
     Node closure = node.arguments.head;
     Element element = elements[closure];
     if (!Elements.isStaticOrTopLevelFunction(element)) {
       compiler.cancel(
-          'JS_TO_CLOSURE requires a static or top-level method',
+          '$name requires a static or top-level method',
           node: closure);
     }
     FunctionElement function = element;
     // TODO(johnniwinther): Try to eliminate the need to distinguish declaration
     // and implementation signatures. Currently it is need because the
     // signatures have different elements for parameters.
     FunctionElement implementation = function.implementation;
     FunctionSignature params = implementation.computeSignature(compiler);
     if (params.optionalParameterCount != 0) {
       compiler.cancel(
-          'JS_TO_CLOSURE does not handle closure with optional parameters',
+          '$name does not handle closure with optional parameters',
           node: closure);
     }
     visit(closure);
+    return params;
+  }
+
+  void handleForeignDartClosureToJs(Send node, String name) {
+    FunctionSignature params = handleForeignRawFunctionRef(node, name);
     List<HInstruction> inputs = <HInstruction>[pop()];
     String invocationName = backend.namer.closureInvocationName(
         new Selector.callClosure(params.requiredParameterCount));
     push(new HForeign(new DartString.literal('#.$invocationName'),
                       const LiteralDartString('var'),
                       inputs));
   }
 
   void handleForeignSetCurrentIsolate(Send node) {
     if (node.arguments.isEmpty || !node.arguments.tail.isEmpty) {
@@ skipping 25 matching lines @@
       handleForeignJs(node);
     } else if (name == const SourceString('UNINTERCEPTED')) {
       handleForeignUnintercepted(node);
     } else if (name == const SourceString('JS_HAS_EQUALS')) {
       handleForeignJsHasEquals(node);
     } else if (name == const SourceString('JS_CURRENT_ISOLATE')) {
       handleForeignJsCurrentIsolate(node);
     } else if (name == const SourceString('JS_CALL_IN_ISOLATE')) {
       handleForeignJsCallInIsolate(node);
     } else if (name == const SourceString('DART_CLOSURE_TO_JS')) {
-      handleForeignDartClosureToJs(node);
+      handleForeignDartClosureToJs(node, 'DART_CLOSURE_TO_JS');
+    } else if (name == const SourceString('RAW_DART_FUNCTION_REF')) {
+      handleForeignRawFunctionRef(node, 'RAW_DART_FUNCTION_REF');
     } else if (name == const SourceString('JS_SET_CURRENT_ISOLATE')) {
       handleForeignSetCurrentIsolate(node);
     } else if (name == const SourceString('JS_CREATE_ISOLATE')) {
       handleForeignCreateIsolate(node);
     } else {
       throw "Unknown foreign: ${selector}";
     }
   }
 
   generateSuperNoSuchMethodSend(Send node) {
@@ skipping 1939 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }