Change the driver's logic about Objective-C runtimes:  abstract out a
structure to hold inferred information, then propagate each invididual
bit down to -cc1.  Separate the bits of "supports weak" and "has a native
ARC runtime";  make the latter a CodeGenOption.

The tool chain is still driving this decision, because it's the place that
has the required deployment target information on Darwin, but at least it's
better-factored now.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134453 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/PPMacroExpansion.cpp b/lib/Lex/PPMacroExpansion.cpp
index d7c4def..f1d0371 100644
--- a/lib/Lex/PPMacroExpansion.cpp
+++ b/lib/Lex/PPMacroExpansion.cpp
@@ -596,7 +596,7 @@
            .Case("objc_arr", LangOpts.ObjCAutoRefCount) // FIXME: REMOVE?
            .Case("objc_arc", LangOpts.ObjCAutoRefCount)
            .Case("objc_arc_weak", LangOpts.ObjCAutoRefCount && 
-                 !LangOpts.ObjCNoAutoRefCountRuntime)
+                 LangOpts.ObjCRuntimeHasWeak)
            .Case("objc_nonfragile_abi", LangOpts.ObjCNonFragileABI)
            .Case("objc_weak_class", LangOpts.ObjCNonFragileABI)
            .Case("ownership_holds", true)