Better runtime type checks.

frog/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 89 matching lines @@
     for (var type in _orderValues(lib.types)) {
       if (type.isUsed && type.isClass) {
         writeType(type);
 
         if (type.isGeneric) {
           for (var ct in _orderValues(type._concreteTypes)) {
             writeType(ct);
           }
         }
       }
+      // Type check functions for builtin JS types
+      if (type.typeCheckCode != null) {
+        writer.writeln(type.typeCheckCode);
+      }
     }
   }
 
   genMethod(Member meth, [MethodGenerator enclosingMethod=null]) {
     if (!meth.isGenerated && meth.declaringType.isClass
         && meth.definition != null && !meth.isAbstract) {
       new MethodGenerator(meth, enclosingMethod).run();
     }
   }
 
@@ skipping 58 matching lines @@
       if (type is ConcreteType) {
         writer.writeln(
             '\$inherits(${type.jsname}, ${type.genericType.jsname});');
       } else if (!type.isNativeType) {
         if (type.parent != null && !type.parent.isObject) {
           writer.writeln('\$inherits(${type.jsname}, ${type.parent.jsname});');
         }
       }
     }
 
-    // Concrete types (like List<String>) will this already defined on their
-    // prototype from the generic type (like List)
+    // Concrete types (like List<String>) will have this already defined on
+    // their prototype from the generic type (like List)
     if (type is! ConcreteType) {
       _maybeIsTest(type, type);
     }
     if (type.genericType._concreteTypes != null) {
       for (var ct in _orderValues(type.genericType._concreteTypes)) {
         _maybeIsTest(type, ct);
       }
     }
 
     if (type.interfaces != null) {
@@ skipping 741 matching lines @@
 
   MethodMember _makeLambdaMethod(String name, FunctionDefinition func) {
     var meth = new MethodMember(name, method.declaringType, func);
     meth.isLambda = true;
     meth.resolve(method.declaringType);
     world.gen.genMethod(meth, this);
     return meth;
   }
 
   visitBool(Expression node) {
-    return visitTypedValue(node, world.boolType);
+    // Boolean conversions in if/while/do/for/conditions require non-null bool.
+
+    // TODO(jmesserly): why do we have this rule? It seems inconsistent with
+    // the rest of the type system, and just causes bogus asserts unless all
+    // bools are initialized to false.
+    return visitValue(node).convertToNonNullBool(this, node);
   }
 
   visitValue(Expression node) {
     if (node == null) return null;
 
     var value = node.visit(this);
     value.checkFirstClass(node.span);
     return value;
   }
 
@@ skipping 1198 matching lines @@
       result.add(new Value(world.varType, '\$$i', false, /*needsTemp:*/false));
     }
     for (int i = bareCount; i < length; i++) {
       var name = getName(i);
       if (name == null) name = '\$$i';
       result.add(new Value(world.varType, name, false, /*needsTemp:*/false));
     }
     return new Arguments(nodes, result);
   }
 }