[Bug c++/51196] FAIL: g++.dg/cpp0x/Wzero-as-null-pointer-constant-1.C

["paolo.carlini at oracle dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51196

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|Greta.Yorsh at arm dot com  |

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-11-21 15:53:55 UTC ---
Unexpectedly ;) I'm making progress debugging this: what happens is that, for
arm, in cp_build_binary_op, case EQ_EXPR (this is for 'if (pmf == 0)') here:

      if (TARGET_PTRMEMFUNC_VBIT_LOCATION
          == ptrmemfunc_vbit_in_delta)
        {
          tree pfn0 = pfn_from_ptrmemfunc (op0);
          tree delta0 = delta_from_ptrmemfunc (op0);
          tree e1 = cp_build_binary_op (location,
                        EQ_EXPR,
                              pfn0,    
                              build_zero_cst (TREE_TYPE (pfn0)),
                        complain);
          tree e2 = cp_build_binary_op (location,
                        BIT_AND_EXPR, 
                        delta0,
                            integer_one_node,
                        complain);
          e2 = cp_build_binary_op (location,
                       EQ_EXPR, e2, integer_zero_node,
                       complain);
          op0 = cp_build_binary_op (location,
                    TRUTH_ANDIF_EXPR, e1, e2,
                    complain);
          op1 = cp_convert (TREE_TYPE (op0), integer_one_node); 
        }
           else 
        {
          op0 = build_ptrmemfunc_access_expr (op0, pfn_identifier);
          op1 = cp_convert (TREE_TYPE (op0), op1);
        }

the condition is true, thus we don't call cp_convert with op1, which is
integer_zero_node here, instead we pass integer_one_node to cp_convert and the
warning down in cp_convert_to_pointer cannot possibly trigger (actually, for
arm we don't even reach cp_convert_to_pointer)

Thus, an idea for fixing the problem would be just warn right here for arm and
similar targets, because here we know that op1 is indeed integer_zero_node (and
that TYPE_PTRMEMFUNC_P (type0) is true of course)

Jason, can you imagine something neater?