Find diagnostic locations for use in new compiler API.

dart/frog/leg/resolver.dart

Index: dart/frog/leg/resolver.dart
diff --git a/dart/frog/leg/resolver.dart b/dart/frog/leg/resolver.dart
index db1a755a6da2ba991350c1ddcbccdb723e8d0f04..ca3edcd9c99772c1a531b2471ff795e6ef83785d 100644
--- a/dart/frog/leg/resolver.dart
+++ b/dart/frog/leg/resolver.dart
@@ -70,13 +70,9 @@ class ResolverTask extends CompilerTask {
                                     [noConstructor(Element)]) {
     final SourceString constructorName = getConstructorName(send);
     final SourceString className = classElement.name;
-    FunctionElement result = classElement.lookupConstructor(className,
-                                                            constructorName,
-                                                            noConstructor);
-    if (result === null && send.arguments.isEmpty()) {
-      result = classElement.getSynthesizedConstructor();
-    }
-    return result;
+    return classElement.lookupConstructor(className,
+                                          constructorName,
+                                          noConstructor);
   }
 
   FunctionElement resolveConstructorRedirection(FunctionElement constructor) {
@@ -182,13 +178,6 @@ class ResolverTask extends CompilerTask {
               defaultClass.name.slowToString()));
       constructor.defaultImplementation = defaultClass.lookupConstructor(name);
 
-      if (constructor.defaultImplementation === null
-          && name == defaultClass.name
-          && constructor.computeParameters(compiler).parameterCount === 0) {
-        constructor.defaultImplementation =
-            defaultClass.getSynthesizedConstructor();
-      }
-
       if (constructor.defaultImplementation === null) {
         // We failed find a constrcutor named either
         // "MyInterface.name" or "MyClass.name".
@@ -1201,6 +1190,23 @@ class ClassResolverVisitor extends CommonResolverVisitor<Type> {
          link = link.tail) {
       element.interfaces = element.interfaces.prepend(visit(link.head));
     }
+
+    if (element.constructors.length == 0) {
+      // Add a synthetic nullary constructor if there are no other
+      // constructors.
+      SynthesizedConstructorElement constructor =
+        new SynthesizedConstructorElement(element);
+      element.constructors[element.name] = constructor;
+      Type returnType = compiler.types.voidType;
+      constructor.type = new FunctionType(returnType, const EmptyLink<Type>(),
+                                          constructor);
+      constructor.cachedNode =
+        new FunctionExpression(new Identifier(element.position()),
+                               new NodeList.empty(),
+                               new Block(new NodeList.empty()),
+                               null, null, null, null);
+    }
+
     return element.computeType(compiler);
   }
 
@@ -1444,12 +1450,7 @@ class ConstructorResolver extends CommonResolverVisitor<Element> {
       if (cls.isInterface() && (cls.defaultClass === null)) {
         error(selector, MessageKind.CANNOT_INSTANTIATE_INTERFACE, [cls.name]);
       }
-      FunctionElement constructor = cls.lookupConstructor(cls.name);
-      if (constructor === null && node.send.argumentsNode.isEmpty()) {
-        e = cls.getSynthesizedConstructor();
-      } else {
-        e = constructor;
-      }
+      e = cls.lookupConstructor(cls.name);
     }
     return e;
   }