Fix a NPE in the CastResolver from rewriting QualifiedName nodes to F…

…ieldAccess nodes.

	Change on 2015/06/19 by kstanger <kstanger@google.com>
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=96423936

translator/src/main/java/com/google/devtools/j2objc/ast/TreeUtil.java

@@ -335,6 +335,9 @@ public static void insertBefore(Statement node, Statement toInsert) {
    * Replaces (in place) a QualifiedName node with an equivalent FieldAccess
    * node. This is helpful when a mutation needs to replace the qualifier with
    * a node that has Expression type but not Name type.
+   * CAUTION: It is strongly recommended that this method be used within a
+   * "visit", and not a "endVisit" because it will rewrite all QualifiedNode
+   * ancestors.
    */
   public static FieldAccess convertToFieldAccess(QualifiedName node) {
     TreeNode parent = node.getParent();

translator/src/main/java/com/google/devtools/j2objc/translate/CastResolver.java

@@ -304,10 +304,15 @@ public void endVisit(MethodInvocation node) {
   }
 
   @Override
-  public void endVisit(QualifiedName node) {
+  public boolean visit(QualifiedName node) {
     if (needsCast(node.getQualifier(), true)) {
-      maybeAddCast(TreeUtil.convertToFieldAccess(node).getExpression(), true);
+      // The qualifier child has type Name and can't be replaced with a
+      // CastExpression, so we must convert to a FieldAccess.
+      FieldAccess newNode = TreeUtil.convertToFieldAccess(node);
+      newNode.accept(this);
+      return false;
     }
+    return true;
   }
 
   @Override

translator/src/test/java/com/google/devtools/j2objc/translate/CastResolverTest.java

@@ -122,4 +122,21 @@ public void testCapturedType() throws IOException {
     assertTranslation(translation,
         "[((id<Test_Bar>) nil_chk([((Test_Foo *) nil_chk(foo)) get])) bar];");
   }
+
+  public void testChainedFieldLookup() throws IOException {
+    String translation = translateSourceFile(
+        "class Test {"
+        + " static class Foo { Bar bar; }"
+        + " static class Bar { int baz; }"
+        + " static class GenericImpl<T> { T foo; }"
+        + " static class Impl extends GenericImpl<Foo> {"
+        + " int test() {"
+        // Need to call "foo.bar.baz" twice so that the second expression is
+        // free of nil_chk's.
+        + " int i = foo.bar.baz;"
+        + " return foo.bar.baz; } } }", "Test", "Test.m");
+    // This is actually a regression for a NPE in the translator, but we may as
+    // well check the output.
+    assertTranslation(translation, "return ((Test_Foo *) foo_)->bar_->baz_;");
+  }
 }