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.

llvm-svn: 181252

1 files changed, 16 insertions, 1 deletions

diff --git a/clang/test/CXX/expr/expr.post/expr.const.cast/p1-0x.cpp b/clang/test/CXX/expr/expr.post/expr.const.cast/p1-0x.cpp
index be898761faf..76ea96fe14a 100644
--- a/clang/test/CXX/expr/expr.post/expr.const.cast/p1-0x.cpp
+++ b/clang/test/CXX/expr/expr.post/expr.const.cast/p1-0x.cpp
@@ -1,5 +1,4 @@
 // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
-// expected-no-diagnostics
 
 // The result of the expression const_cast<T>(v) is of type T. If T is
 // an lvalue reference to object type, the result is an lvalue; if T
@@ -16,3 +15,19 @@ void test_classification(const int *ptr) {
   int *ptr1 = const_cast<int *&&>(xvalue<const int*>());
   int *ptr2 = const_cast<int *&&>(prvalue<const int*>());
 }
+
+struct A {
+  volatile unsigned ubf : 4;
+  volatile unsigned uv;
+  volatile int sv;
+  void foo();
+  bool pred();
+};
+
+void test(A &a) {
+  unsigned &t0 = const_cast<unsigned&>(a.ubf); // expected-error {{const_cast from bit-field lvalue to reference type}}
+  unsigned &t1 = const_cast<unsigned&>(a.foo(), a.ubf); // expected-error {{const_cast from bit-field lvalue to reference type}}
+  unsigned &t2 = const_cast<unsigned&>(a.pred() ? a.ubf : a.ubf); // expected-error {{const_cast from bit-field lvalue to reference type}}
+  unsigned &t3 = const_cast<unsigned&>(a.pred() ? a.ubf : a.uv); // expected-error {{const_cast from bit-field lvalue to reference type}}
+  unsigned &t4 = const_cast<unsigned&>(a.pred() ? a.ubf : a.sv); // expected-error {{const_cast from rvalue to reference type}}
+}