CLHEP modulemap for CXXMODULES IB

[oshadura]

cc: @davidlange6 @vgvassilev

[cmsbuild]

A new Pull Request was created by @oshadura (Oksana Shadura) for branch cms/v2.4.1.3.

@cmsbuild, @smuzaffar, @mrodozov, @tulamor can you please review it and eventually sign? Thanks.
cms-bot commands are listed here

[smuzaffar]

@oshadura , instead of adding it here which will endup in all our IBs, I would suggest to add it in to cms-sw/cmsdist rootmodule branch by creating a new spec e.g. cxxmodulemaps.spec . In future we can also add modulemaps for other external tools (e.g. boost etc.)

[smuzaffar]

If no objections then I can create the cxxmodulemaps.spec

[vgvassilev]

One of the advantages when having the module.modulemap as part of the package is that it will speed up builds with clang -fmodules. Most of the apple sdk comes with these modulemap plus a handful of other unix libraries. I do not have a strong opinion but I can see these commits upstreamed in clhep mainline.

[vgvassilev]

Before taking any action, I proposed @oshadura to replace the current modulemap with

module clhep {
  export *
  requires cplusplus
  umbrella "CLHEP"
  module * { export *}
}

which is more maintainable and should have the same effect.

[smuzaffar]

I would still suggest to add this in cmsdist (rootmodule branch) and update clhep.spec to deploy deploy it. e.g something like this in clhep.spec would work

1. add a new file in cmsdist modulemaps/clhep.modulemap.file
2. Add the extra source

Source1: modulemaps/clhep.modulemap

3. deply the file in clhep include at rhe end of %install section

cp %{_sourcedir}/clhep.modulemap %(i}/include/

this way overhead to manage this file for every clhep update will be less.

[smuzaffar]

One of the advantages when having the module.modulemap as part of the package is that it will speed up builds with clang -fmodules. Most of the apple sdk comes with these modulemap plus a handful of other unix libraries. I do not have a strong opinion but I can see these commits upstreamed in clhep mainline.

all this is still in development, so I do not want to rebuild clhep for our production archs every other day because we want to update the modulemap. Once we have a working modoule map then I would suggest that we request to include it in upstream clhep repository instead of we patch it for every other version.

[smuzaffar]

cms-sw/cmsdist#5795 shall deploy clhep.modulemap in clhep/include directory now.

[oshadura]

@smuzaffar thank you so much! your and @vgvassilev solution is much more elegant 👍

[oshadura]

I will close this PR in favor of your PR?