"Implement" #resource tag and various restrictions on library definitions.

dart/frog/leg/compiler.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.
 
 class WorkItem {
   final Element element;
   TreeElements resolutionTree;
   Function run;
   Map<int, BailoutInfo> bailouts = null;
   bool allowSpeculativeOptimization = true;
@@ skipping 252 matching lines @@
         const SourceString('JS_HAS_EQUALS'), library), this);
     library.define(new ForeignElement(
         const SourceString('JS_CURRENT_ISOLATE'), library), this);
     library.define(new ForeignElement(
         const SourceString('JS_CALL_IN_ISOLATE'), library), this);
   }
 
   void runCompiler(Uri uri) {
     scanBuiltinLibraries();
     mainApp = scanner.loadLibrary(uri, null);
-    Element element;
-    withCurrentElement(mainApp, () {
-      element = mainApp.find(MAIN);
-      if (element === null) cancel('Could not find $MAIN');
-    });
+    final Element mainMethod = mainApp.find(MAIN);
+    if (mainMethod === null) {
+      withCurrentElement(mainApp, () => cancel('Could not find $MAIN'));
+    } else {
+      withCurrentElement(mainMethod, () {
+        if (!mainMethod.isFunction()) {
+          cancel('main is not a function', element: mainMethod);
+        }
+        FunctionParameters parameters = mainMethod.computeParameters(this);
+        if (parameters.parameterCount > 0) {
+          cancel('main cannot have parameters', element: mainMethod);
+        }
+      });
+    }
     native.processNativeClasses(this, universe.libraries.getValues());
-    enqueue(new WorkItem.toCompile(element));
+    enqueue(new WorkItem.toCompile(mainMethod));
     codegenProgress.reset();
     while (!worklist.isEmpty()) {
       WorkItem work = worklist.removeLast();
       withCurrentElement(work.element, () => (work.run)(this));
     }
     workListIsClosed = true;
     assert(enqueuer.checkNoEnqueuedInvokedInstanceMethods());
     enqueuer.registerFieldClosureInvocations();
     emitter.assembleProgram();
     if (!worklist.isEmpty()) {
@@ skipping 237 matching lines @@
   }
 }
 
 class SourceSpan {
   final Uri uri;
   final int begin;
   final int end;
 
   const SourceSpan(this.uri, this.begin, this.end);
 }