[Bug fortran/55978] [4.8 Regression] class_optional_2.f90 -Os fails

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55978

--- Comment #7 from Tobias Burnus <burnus at gcc dot gnu.org> 2013-01-15 14:47:31 UTC ---
(In reply to comment #6)
> Looks as if code of the form:
>   if (y.data)
>     D.1914 = _gfortran_internal_pack (&y);
>   else
>     D.1914 = NULL;
> 
> is missing

The bug is in trans-array.c's gfc_conv_array_parameter, which currently has:

  7156        ptr = build_call_expr_loc (input_location,
  7157                               gfor_fndecl_in_pack, 1, desc);
  7158  
  7159        if (fsym && fsym->attr.optional && sym && sym->attr.optional)
  7160          {
  7161            tmp = gfc_conv_expr_present (sym);


If the actual argument has sym->attr.optional, the code should work. Looking at
line 39 of class_optional_2.f90, there seems to be something not working, which
might be a bug in gfc_conv_expr_present.


If sym->attr.optional is not present, it is currently not handled by
gfc_conv_expr_present (assert).

Similarly, if the actual argument is an expression like "var%comp" - here, the
".data == NULL" check has to be done for "comp" and not for "var" alias "sym".
Similarly for expressions instead of variables. (There are presumably more
issues.)