[Bug fortran/47023] C_Sizeof: Rejects valid code

["burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47023

Tobias Burnus <burnus at gcc dot gnu.org> changed:

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

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2010-12-22 10:28:28 UTC ---
The reason for rejecting it is:

  if (verify_c_interop (&arg->ts) != SUCCESS)
    {
      gfc_error ("'%s' argument of '%s' intrinsic at %L must be be an "
                 "interoperable data entity",

If one looks at decl.c, one see that the check makes only sense for BT_DERIVED
- but not for intrinsic variables. In decl.c one afterwards prints only an
error for BT_DERIVED - otherwise only a warning is printed (which does not make
sense here). And there is additionally a check for string-length == 1.

 * * *

In decl.c, I think one should additionally check for BT_CLASS and reject the
following program (currently there is just a "may not be C interoperable"
warning as it is not BT_DERIVED).

module m
  use iso_c_binding
  type t
    integer(c_int) :: i
  end type t
contains
  subroutine test(a) bind(c)
    class(t) :: a
  end subroutine
end