Re: [PATCH] Fortran: fix passing of optional dummies to bind(c) procedures [PR113866]

[Harald Anlauf <anlauf@gmx.de>]

Hi Steve,

Am 13.02.24 um 18:21 schrieb Steve Kargl:
> On Mon, Feb 12, 2024 at 09:57:08PM +0100, Harald Anlauf wrote:
>> Dear all,
>>
>> the attached patch fixes a mis-handling of optional dummy arguments
>> passed to optional dummy arguments of procedures with the bind(c)
>> attribute.  When those procedures are expecting CFI descriptors,
>> there is no special treatment like a presence check necessary
>> that by default passes a NULL pointer as default.
>>
>> The testcase tries to exercise various combinations of passing
>> assumed-length character between bind(c) and non-bind(c), which
>> apparently was insufficiently covered in the testsuite.
>>
>> Regtested on x86_64-pc-linux-gnu.  OK for mainline?
>>
>
> Yes.  Thanks for filling out the more detailed testcase.

indeed the new testcase just regressed due to commit
r14-8947-g6caec7d9ec37e6 ... :-(

Reduced testcase which fails on trunk:

program p
   implicit none
   integer, parameter :: n = 100, l = 10
   character(l) :: a = 'a234567890', b(n) = 'bcdefghijk'
   character(:), allocatable :: d, e(:)
   allocate (d, source=a)
   allocate (e, source=b)
   print *, len (d), len (e), size (e)
   call not_bindc_optional_deferred (d, e)
   deallocate (d, e)
contains
   subroutine not_bindc_optional_deferred (c5, c6)
     character(:), allocatable, optional :: c5, c6(:)
     if (.not. present (c5) .or. .not. present (c6)) stop 6
     print *, len (c5), len (c6), size (c6)
     if (len (c5) /= l .or. len (c6) /= l) stop 84
   end
end

Expected:

           10          10         100
           10          10         100

After above commit:

           10          10         100
           10           0         100
STOP 84

Will have to wait until the cause is found and fixed...