OpenMPI header 'mpi.h' not detected if in /usr/include

[Salamandar]

On archlinux, the OpenMPI header is /usr/include/mpi.h.

pkg-config filters -I/usr/include from cflags (because it's a standard include path), so the cflags detected from ompi-cxx do NOT contain this token…

The problem is that the header detection code in CMake is :

find_file(MpidotH mpi.h PATHS ${OPENMPI_INCLUDE_DIRS} NO_DEFAULT_PATH)

The NO_DEFAULT_PATH prevents CMake from searching in /usr/include. The header is thus not found.
You just have to remove NO_DEFAULT_PATH and everything works as intended.

[ceremcem]

Wouldn't it be a nice PR?

[Salamandar]

You are everywhere. :p
Yeah, will do.

[ceremcem]

I ammmmmmmmmm watchinggggggggg :P

[Salamandar]

Haha :p
PR waiting !

[realthunder]

I think this is better handled upstream. That mpi.h is introduced in b765193. Maybe you can directly ask the author @ysangkok as to why NO_DEFAULT_PATH is necessary.

[ysangkok]

I don't think it's really necessary to have nodefaultpath. I probably put it there cause I didn't think it should search paths where it won't find it anyway. I only tested on Ubuntu. Its probably harmless to expand the search path. The line is there to prevent a incomprehensible linker error, since the compiler won't complain if it can't find the header AFAIK.

[Salamandar]

The line is there to prevent a incomprehensible linker error, since the compiler won't complain if it can't find the header AFAIK.

It's the compiler who will complain, not the linker ;) The linker does not have any knowledge of what a header is.

[maidenone]

Was this upstreamed? Close or merge?

[realthunder]

@Salamandar Have you submitted a PR to upstream for this? I'll merge your patch here.

[luzpaz]

@Salamandar ping

[Salamandar]

Hi, sorry for the disappearing. It looks like this issue is not anymore : searching for OpenMPI is done by pkg_search_module. Closing.

[luzpaz]

@Salamandar ticket is still open

[Salamandar]

Not anymore :)