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/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index e14635e..a0998a4 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -4311,7 +4311,7 @@
     IntRange::forValueOfType(C, E->getType());
   }
 
-  if (FieldDecl *BitField = E->getBitField())
+  if (FieldDecl *BitField = E->getSourceBitField())
     return IntRange(BitField->getBitWidthValue(C),
                     BitField->getType()->isUnsignedIntegerOrEnumerationType());
 
@@ -4688,7 +4688,7 @@
 
   // We want to recurse on the RHS as normal unless we're assigning to
   // a bitfield.
-  if (FieldDecl *Bitfield = E->getLHS()->getBitField()) {
+  if (FieldDecl *Bitfield = E->getLHS()->getSourceBitField()) {
     if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
                                   E->getOperatorLoc())) {
       // Recurse, ignoring any implicit conversions on the RHS.