C++ PATCH for c++/71576 (bitfield and rvalue reference)

[Jason Merrill]

The code for recognizing problems with binding a glvalue to a
reference was using real_lvalue_p, which returns 0 for xvalues, so the
code that used that to handle bitfields wasn't handling a bitfield
member of an xvalue.  Fixed by using lvalue_kind instead.

Tested x86_64-pc-linux-gnu, applying to trunk.

commit be097879a53ff700b0b220671e52ab671ab4ddce
Author: Jason Merrill <ja...@redhat.com>
Date:   Fri Jul 22 13:51:50 2016 -0400

        PR c++/71576 - bitfield and rvalue reference
    
        * call.c (convert_like_real): Use is_bitfield_expr_with_lowered_type.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 061e708..835b02a 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -6771,7 +6771,7 @@ convert_like_real (conversion *convs, tree expr, tree fn, 
int argnum,
                          expr, ref_type);
                return error_mark_node;
              }
-           if (lvalue & clk_bitfield)
+           if (is_bitfield_expr_with_lowered_type (expr))
              {
                expr = convert_bitfield_to_declared_type (expr);
                expr = fold_convert (type, expr);
diff --git a/gcc/testsuite/g++.dg/cpp0x/rv-bitfield3.C 
b/gcc/testsuite/g++.dg/cpp0x/rv-bitfield3.C
new file mode 100644
index 0000000..9d2d872
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/rv-bitfield3.C
@@ -0,0 +1,14 @@
+// PR c++/71576
+// { dg-do compile { target c++11 } }
+
+template < typename T > T && foo ();
+
+struct A 
+{
+  int i:5;
+};
+
+void foo ()
+{
+  int &&j = foo < A > ().i;
+}