Damian, I submitted a patch a long time ago to make -fcoarray=single the default behavior. The patch made -fcoarray=none a NOP. With inclusion of a shmem implementation of the runtime parts, this might be the way to go. I'll leave that decision to Andre, Thomas, and Nicolas.
I believe that the gfortran contributors have not considered coarray as an optional add-on. The problem for gfortran is that it runs on dozens of CPUs and dozens upon dozens of operating systems. The few gfortran contributors simply cannot ensure that opencoarray+mpich or opencoarray+openmpi runs on all of the possible combinations of hardware and OS's. Andre has hinted that he expects some rough edges on non-linux system. I'll find out this weekend when I give his patch a spin on FreeBSD. Hopefully, a windows10/11 user can test the patch. -- steve On Tue, Jun 24, 2025 at 06:34:53AM -0700, Damian Rouson wrote: > If gfortran will have a shared-memory coarray implemented, it would be > great to also drop the requirement to pass -fcoarray. Other compilers > have trended in the direction of dropping the flag too, including Cray and > NAG. > > Even all these years after Fortran 2008 introduced multi-image execution, I > still here vendors talk about the multi-image features as if they are an > optional add-on rather than a large and significant feature set that was > fully integrated into the language 3 standards ago. Making the flag > optional would help to communicate that coarrays are a first-class feature > rather than an after-thought. Users who want to link in an external > library such as OpenCoarrays (or someday Caffeine?) can still use the flag > for that purpose. > > D > > On Tue, Jun 24, 2025 at 06:14 Andre Vehreschild <ve...@gmx.de> wrote: > > > Hi all, > > > > this is the last patch of the mini-series. It just updates the testcases > > common > > to coarrays in the gfortran testsuite. All tests in the > > gcc/testsuite/gfortran.dg/caf directory are now also run with caf_shmem. > > The > > test driver ensures, that no more than 8 images are used per testcase (if > > not > > specified differently by the tester, setting GFORTRAN_NUM_IMAGES > > beforehand). > > This is to prevent large machines testing on all hardware threads without > > any > > benefit. The minimum number of images required is 8 and therefore that > > number > > was chosen. > > > > Bootstrapped and regtests fine on x86_64-pc-linux-gnu / F41. Ok for > > mainline? > > > > Regards, > > Andre > > -- > > Andre Vehreschild * Email: vehre ad gmx dot de > > -- Steve
