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!
