netcdf @4.1.1 +openmpi Adding Fortran+MPI support

[jcharris@…]

Presently parallel I/O is not possible from Fortran with NetCDF files using the existing MacPorts packages. Attached is a patch that would add Fortran support to the +openmpi variant.

Since openmpi depends on gcc44, Fortran is already installed if someone installs 'netcdf +openmpi', so there is no apparent reason to leave out this functionality. In order to combine it with HDF5 to allow parallel I/O with the Fortran API, see an additionally suggested patch: #22480.

(In addition, adding parallel-netcdf support in the future would be useful.)

[jcharris@…]

Suggested patch allowing openmpi variant to work with Fortran.

[tenomoto (Takeshi Enomoto)]

You could probably specify both +openmpi and one of +gcc43 +gcc44 +gcc45 to enable openmpi and fortran support.

[jcharris@…]

I can confirm that this works. However, I would still request that Fortran support be enabled when +openmpi is used. (I have not checked, but I imagine it'd be the same for mpich2).

For example, one does not have to specify +enable-fortran when gcc4* is installed, and since openmpi depends on gcc44 (or a different version), and is not just a variant, it makes sense to not require someone to have a special variant just for netcdf. (Especially since adding the +gcc44 variant, like you suggest, would only be for the purpose of removing the --disable-fortran flag, not for enabling a specific compiler.)

[tenomoto (Takeshi Enomoto)]

Fortran support is deliberately separated (in netcdf and other ports if possible). It takes a long time to compile a compiler suite gcc4* every time it updates. Some people do not require a fortran binding. I need fortran but I prefer g95 and I do not like to have gcc4* at all. Some people even do not want compiler support at all and netcdf is installed automatically. Most of the software that requires netcdf and fortran, gcc44 variant is a default and they have fortran support. It is not possible to satisfy everyone. I would like to ask you to use +gcc44 +openmpi.

[jcharris@…]

Perhaps I was not clear -- I am not suggesting forcing any Fortran compiler to be added to any variant. Rather, as far as I can tell, no variants of openmpi exist (as that Portfile is written currently) where Fortran would not be installed, so the only "extra" would be the Fortran bindings for a very useful package. If someone is using +openmpi, they already have some version of Fortran installed!

If you seriously oppose removing the --disable-f77 and --disable-f90 flags from the +openmpi variant, could at least a comment be added to this effect in the Portfile? It took several hours of searching to figure out a potential solution, and I am sure the next person that comes along would appreciate having that time saved. A more consistent objection along your reasoning would be to have an +enable-fortran variant, and to keep Fortran disabled for the +gcc4* variants, which would also make it clear for newcomers to MacPorts how to proceed.

[tenomoto (Takeshi Enomoto)]

I understand you felt you wasted long hours. Me too, I spend many hours maintaining a number of ports and supporting many users. All gcc4* and g95 have comments that they enable fortran support. If a newcomer does not know much about variants we are here to answer questions.