[Bug c++/50025] [DR 1288] C++0x initialization syntax doesn't work for class members of reference type

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50025

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #12 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-01-19 20:42:14 UTC ---
Jason, I'd like to try and fix this, but need some clues.

A minimal example that fails to compile is:

  struct S { } s;
  S& r{s};

I find that in call.c:reference_binding we get compatible_p = false, which
seems to be wrong. Even if compatible_p is true we don't take the branch that
looks like it should be used:

  /* Directly bind reference when target expression's type is compatible with
     the reference and expression is an lvalue. In DR391, the wording in
     [8.5.3/5 dcl.init.ref] is changed to also require direct bindings for
     const and rvalue references to rvalues of compatible class type.
     We should also do direct bindings for non-class xvalues.  */
  if (compatible_p
      && (is_lvalue
      || (((CP_TYPE_CONST_NON_VOLATILE_P (to)
        && !(flags & LOOKUP_NO_RVAL_BIND))
           || TYPE_REF_IS_RVALUE (rto))
          && (gl_kind
          || (!(flags & LOOKUP_NO_TEMP_BIND)
              && (CLASS_TYPE_P (from)
              || TREE_CODE (from) == ARRAY_TYPE))))))

Naively I would expect compatible_p and is_lvalue to be true for the case
above. Does the code earlier in the function need to be adjusted for the case
where a braced-init-list has a single element of reference-compatible lvalue
type?