Grab-bag of bit-field fixes:

  - References to ObjC bit-field ivars are bit-field lvalues;
    fixes rdar://13794269, which got me started down this.
  - Introduce Expr::refersToBitField, switch a couple users to
    it where semantically important, and comment the difference
    between this and the existing API.
  - Discourage Expr::getBitField by making it a bit longer and
    less general-sounding.
  - Lock down on const_casts of bit-field gl-values until we
    hear back from the committee as to whether they're allowed.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@181252 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index c11a075..529ba12 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -1837,7 +1837,7 @@
   // conversion.
   using llvm::APSInt;
   if (From)
-    if (FieldDecl *MemberDecl = From->getBitField()) {
+    if (FieldDecl *MemberDecl = From->getSourceBitField()) {
       APSInt BitWidth;
       if (FromType->isIntegralType(Context) &&
           MemberDecl->getBitWidth()->isIntegerConstantExpr(BitWidth, Context)) {