Fixed compiler so that it passes Switch1NegativeTest.dart.

gen.dart

 // Copyright (c) 2011, 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.
 
 /**
  * Top level generator object for writing code and keeping track of
  * dependencies.
  *
  * Should have two compilation models, but only one implemented so far.
  *
@@ skipping 1322 matching lines @@
     var test = visitValue(node.test);
     writer.enterBlock('switch (${test.code}) {');
     for (var case_ in node.cases) {
       if (case_.label != null) {
         world.error('unimplemented: labeled case statement', case_.span);
       }
       _pushBlock();
       for (int i=0; i < case_.cases.length; i++) {
         var expr = case_.cases[i];
         if (expr == null) {
+          // Default can only be the last case.
+          if (i < case_.cases.length - 1) {
+            world.error('default clause must be the last case', case_.span);
+          }
           writer.writeln('default:');
         } else {
           var value = visitValue(expr);
           writer.writeln('case ${value.code}:');
         }
       }
       writer.enterBlock('');
       for (var stmt in case_.statements) {
         stmt.visit(this);

[jimhug, 2011/10/27 17:45:11]

This needs to do some sort of minimal checking for flow here.  In particular, we
shouldn't be adding the throw immediately after a break of a return.

[Emily Fortuna, 2011/10/27 17:59:04]

Done in the next CL.

       }
+      if (case_ != node.cases[node.cases.length - 1]) {
+        var span = case_.statements[case_.statements.length - 1].span;
+        //TODO(efortuna): This error message isn't 100% correct because 
+        // constructors are not being built correctly. Check back when I've
+        // fixed constructors. 
+        writer.writeln('\$throw(new FallThroughError("${span.file.filename}",' +
+            ' ${span.file.getLine(span.start)}))');
+      }
       writer.exitBlock('');
       _popBlock();
     }
     writer.exitBlock('}');
   }
 
   void visitBlockStatement(BlockStatement node) {
     _pushBlock();
     writer.enterBlock('{');
     for (var stmt in node.body) {
@@ skipping 772 matching lines @@
 
   static removeTrailingNulls(List<Value> argsCode) {
     // We simplify calls with null defaults by relying on JS and our
     // choice to make undefined === null for Dart generated code. This helps
     // and ensures correct defaults values for native calls.
     while (argsCode.length > 0 && argsCode.last() == 'null') {
       argsCode.removeLast();
     }
   }
 }