Initial patch to support definitions of id and Class from headers in Objective-C code.

This currently breaks test/SemaObjC/id-isa-ref.m and issues some spurious warnings when you attempt to assign a struct objc_class* value to a Class variable.  The test case probably should fail as it's written, because without the definition of Class the compiler should not assume struct objc_class* is a valid receiver type, but it's left broken because it would be nice if we could get that passing too for the special case of isa.

Approved by snaroff.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@79248 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index dad09ba..f0ab845 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -43,6 +43,8 @@
   LoadedExternalComments(false), FreeMemory(FreeMem), Target(t), 
   Idents(idents), Selectors(sels),
   BuiltinInfo(builtins), ExternalSource(0), PrintingPolicy(LOpts) {  
+  ObjCIdRedefinitionType = QualType();
+  ObjCClassRedefinitionType = QualType();
   if (size_reserve > 0) Types.reserve(size_reserve);    
   TUDecl = TranslationUnitDecl::Create(*this);
   InitBuiltinTypes();