Closed
Description
The transcript below demonstrates the runtime error message that the OpenCoarrays function libcaf_mpi::caf_get_by_ref() produces in a simple scenario wherein a derived-type coarray has an allocatable, derived-type array component. A cumbersome workaround is to flatten such coarray data structures so that the components of derived type coarrays are intrinsic types. Even with this workaround, a source allocation will fail. A workaround for the lack of source allocation is to use mold allocation followed by element-by-element copying of the component array.
The following are the results of compiling the code below with the gfortran versions cited in bold:
- 8.3.0: the final allocation generates the runtime error message below.
- 9.2.0: the allocation completes without error but the subsequent component access generates a
segmentation fault - invalid memory reference. - 10.0.0: same as 8.3.0.
$ cat opencoarrays-missing-feature.f90 implicit none
type package
integer, allocatable :: surface_fluxes(:)
end type
type outbox
type(package), allocatable :: block_surfaces(:)
end type
type(outbox), save :: halo[*]
integer, parameter :: source_image = 1
integer, parameter :: message(1)=[99]
if (this_image() == source_image) then
allocate(halo%block_surfaces(1))
allocate(halo%block_surfaces(1)%surface_fluxes, source = message)
end if
sync all
if (this_image() /= source_image) then
allocate(halo%block_surfaces(1))
allocate(halo%block_surfaces(1)%surface_fluxes, mold = halo[source_image]%block_surfaces(1)%surface_fluxes)
halo%block_surfaces(1)%surface_fluxes(1) = halo[source_image]%block_surfaces(1)%surface_fluxes(1)
end if
end$ caf opencoarrays-missing-feature.f90
$ cafrun -n 2 ./a.out
Fortran runtime error on image 2: libcaf_mpi::caf_get_by_ref(): two or more array part references are not supported.
Error: Command:
`/usr/local/Cellar/mpich-3.2-gnu-8.3.0/bin/mpiexec -n 2 ./a.out`
failed to run.