ObjectiveC driver change. re-apply patch reverted in
r194450 with a modified test. // rdar://15363492


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194489 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 03459f0..84f756f 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -3297,6 +3297,13 @@
     }
   }
 
+  // When ObjectiveC legacy runtime is in effect on MacOSX,
+  // turn on the option to do Array/Dictionary subscripting
+  // by default.
+  if (objcRuntime.getKind() == ObjCRuntime::FragileMacOSX &&
+      objcRuntime.isNeXTFamily())
+    CmdArgs.push_back("-fobjc-subscripting-legacy-runtime");
+  
   // -fencode-extended-block-signature=1 is default.
   if (getToolChain().IsEncodeExtendedBlockSignatureDefault()) {
     CmdArgs.push_back("-fencode-extended-block-signature");