Issue 3968. Support for redirecting factory constructors

compiler/java/com/google/dart/compiler/resolver/Resolver.java

Index: compiler/java/com/google/dart/compiler/resolver/Resolver.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/Resolver.java b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
index 767202d929d236d3b2b85d7d60a8c037d2f3f9bf..e6c915476996f56a99363f333358667af25dfc85 100644
--- a/compiler/java/com/google/dart/compiler/resolver/Resolver.java
+++ b/compiler/java/com/google/dart/compiler/resolver/Resolver.java
@@ -654,6 +654,7 @@ public class Resolver {
           && !Elements.isNonFactoryConstructor(member)
           && !member.getModifiers().isAbstract()
           && !member.getModifiers().isExternal()
+          && node.getRedirectedTypeName() == null
           && !isInterface) {
         onError(functionNode, ResolverErrorCode.METHOD_MUST_HAVE_BODY);
       }
@@ -664,6 +665,33 @@ public class Resolver {
         resolveInitializers(node, initializedFields);
       }
 
+      // resolve redirecting factory constructor
+      {
+        DartTypeNode rcTypeName = node.getRedirectedTypeName();
+        if (rcTypeName != null) {
+          InterfaceType rcType = (InterfaceType) resolveType(rcTypeName, true, true,
+              TypeErrorCode.NO_SUCH_TYPE, ResolverErrorCode.WRONG_NUMBER_OF_TYPE_ARGUMENTS);
+          switch (TypeKind.of(rcType)) {
+            case INTERFACE:
+              Element element = recordType(rcTypeName, rcType);
+              DartIdentifier rcName = node.getRedirectedConstructorName();
+              if (rcName != null) {
+                element = ((ClassElement) element).lookupConstructor(rcName.getName());
+                switch (ElementKind.of(element)) {
+                  case CONSTRUCTOR:
+                    recordElement(rcName, element);
+                    if (member.getModifiers().isConstant() && !element.getModifiers().isConstant()) {
+                      onError(rcName,
+                          ResolverErrorCode.REDIRECTION_CONSTRUCTOR_TARGET_MUST_BE_CONST);
+                    }
+                    break;
+                }
+              }
+              break;
+          }
+        }
+      }
+
       context = previousContext;
       innermostFunction = currentMethod = null;
       enclosingElement = previousEnclosingElement;