[Bug fortran/100337] New: Should be able to pass non-present optional arguments to CO_BROADCAST

[Bug fortran/100337] New: Should be able to pass non-present optional arguments to CO_BROADCAST

[everythingfunctional at protonmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100337

            Bug ID: 100337
           Summary: Should be able to pass non-present optional arguments
                    to CO_BROADCAST
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: everythingfunctional at protonmail dot com
  Target Milestone: ---

Attempting to write a CO_BROADCAST wrapper for a derived type, I found that
passing optional arguments to CO_BROADCAST caused a segfault if the arguments
were not present. This should be allowed. See the following minimal example

module iso_varying_string
    implicit none

    type :: varying_string
        character(len=1), allocatable :: characters(:)
    contains
        procedure :: co_broadcast => co_broadcast_varying_string
    end type
contains
    subroutine co_broadcast_varying_string(a, source_image, stat, errmsg)
        class(varying_string), intent(inout) :: a
        integer, intent(in) :: source_image
        integer, intent(out), optional :: stat
        character(len=*), intent(inout), optional :: errmsg

        integer :: string_length

        if (this_image() == source_image) string_length = size(a%characters)

        call co_broadcast(string_length, source_image, stat, errmsg)

        if (present(stat)) then
            if (stat /= 0) return
        end if

        if (this_image() /= source_image) then
            allocate(a%characters(string_length))
        end if

        call co_broadcast(a%characters, source_image, stat, errmsg)
    end subroutine
end module

program main
    use iso_varying_string, only: varying_string

    implicit none

    character(len=*), parameter :: MESSAGE = "Hello, World!"
    integer :: i
    type(varying_string) :: the_string

    if (this_image() == 1) the_string%characters = [(MESSAGE(i:i), i = 1,
len(MESSAGE))]
    call the_string%co_broadcast(1)
    print *, the_string%characters
end program

Compiling and executing with gfortran produces the following:

$ gfortran -fcoarray=single -g example.f90
$ ./a.out                                 

Program received signal SIGSEGV: Segmentation fault - invalid memory reference.

Backtrace for this error:
#0  0x7fed85487d01 in ???
#1  0x7fed85486ed5 in ???
#2  0x7fed852be94f in ???
#3  0x55cd33d21683 in __iso_varying_string_MOD_co_broadcast_varying_string
        at /home/brad/tmp/co_broadcast_optional/example.f90:20
#4  0x55cd33d21872 in MAIN__
        at /home/brad/tmp/co_broadcast_optional/example.f90:43
#5  0x55cd33d21915 in main
        at /home/brad/tmp/co_broadcast_optional/example.f90:35
zsh: segmentation fault (core dumped)  ./a.out

Note that using opencoarrays this program works, as follows:

$ caf example.f90                         
$ cafrun -n 2 ./a.out                     
 Hello, World!
 Hello, World!

[Bug fortran/100337] Should be able to pass non-present optional arguments to CO_BROADCAST

[vehre at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100337

Andre Vehreschild <vehre at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |vehre at gcc dot gnu.org
                 CC|                            |vehre at gcc dot gnu.org
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-05-21
             Status|UNCONFIRMED                 |ASSIGNED

[Bug fortran/100337] Should be able to pass non-present optional arguments to CO_BROADCAST

[vehre at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100337

--- Comment #1 from Andre Vehreschild <vehre at gcc dot gnu.org> ---
Created attachment 50853
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50853&action=edit
Check for unset before assigning to stat.

[Bug fortran/100337] Should be able to pass non-present optional arguments to CO_BROADCAST

[vehre at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100337

Andre Vehreschild <vehre at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |WAITING

--- Comment #2 from Andre Vehreschild <vehre at gcc dot gnu.org> ---
Waiting for review

[Bug fortran/100337] Should be able to pass non-present optional arguments to CO_BROADCAST

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100337

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Andre Vehreschild <vehre@gcc.gnu.org>:

https://gcc.gnu.org/g:da13e4ebebb07a47d5fb50eab8893f8fe38683df

commit r12-1741-gda13e4ebebb07a47d5fb50eab8893f8fe38683df
Author: Andre Vehreschild <vehre@gcc.gnu.org>
Date:   Wed Jun 23 10:09:29 2021 +0200

    fortran: Fix deref of optional in gen. code. [PR100337]

    gcc/fortran/ChangeLog:

            PR fortran/100337
            * trans-intrinsic.c (conv_co_collective): Check stat for null ptr
            before dereferrencing.

    gcc/testsuite/ChangeLog:

            PR fortran/100337
            * gfortran.dg/coarray_collectives_17.f90: New test.

[Bug fortran/100337] Should be able to pass non-present optional arguments to CO_BROADCAST

[vehre at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100337

--- Comment #4 from Andre Vehreschild <vehre at gcc dot gnu.org> ---
Waiting two weeks before backporting to gcc-11.

[Bug fortran/100337] Should be able to pass non-present optional arguments to CO_BROADCAST

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100337

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Andre Vehreschild
<vehre@gcc.gnu.org>:

https://gcc.gnu.org/g:ae57aae60d1be821feccb3160f8fdd5987ecba79

commit r11-9568-gae57aae60d1be821feccb3160f8fdd5987ecba79
Author: Andre Vehreschild <vehre@gcc.gnu.org>
Date:   Mon Feb 14 16:47:16 2022 +0100

    fortran: Fix deref of optional in gen. code. [PR100337, backport]

    gcc/fortran/ChangeLog:

            PR fortran/100337
            Backport from master.
            * trans-intrinsic.c (conv_co_collective): Check stat for null ptr
            before dereferrencing.

    gcc/testsuite/ChangeLog:

            PR fortran/100337
            * gfortran.dg/coarray_collectives_17.f90: New test.

[Bug fortran/100337] Should be able to pass non-present optional arguments to CO_BROADCAST

[vehre at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100337

Andre Vehreschild <vehre at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|---                         |FIXED

--- Comment #6 from Andre Vehreschild <vehre at gcc dot gnu.org> ---
Backported to gcc-11. Closing as fixed now.