feature request: allow "available: word-size != 32"

[hannesm]

Some opam packages are only compiling on 64 bit systems (due to using large literals in OCaml code, ...). At the moment, it is cumbersome to figure out what to state in an opam file to define "this does not work on 32 bit systems", since arch != "x86_32" & arch != "arm32" may be sufficient today, but tomorrow when risc-v (or ppc32) is getting traction, it is no longer sufficient.

In OCaml, Sys.word_size is very useful and available. It would be nice to have this functionality in opam as well -- it should be easy to implement, and straightforward to expose it in the opam file. This would be a welcome change in the soon future (maybe even in 2.1?).

Thanks for reading.

[kit-ty-kate]

I like this feature request very much, it would help opam-repository tremendously. opam 2.1 is expected to have its rc1 released very very soon so if it is accepted it would most likely be in opam 2.2.

[avsm]

This is a good one to put on the opam 2.2+ wishlist (definitely not opam 2.1, which is on the verge of release).

[AltGr]

Note: implementing an additional variable word-size for this would be straight-forward. A little more work, of course, to think about backwards compatibility and maybe lint arch != "x86_32" & arch != "arm32" to advise a replacement.

[hannesm]

Maybe related is "big-endian" / "little-endian", so an opam package can specify which platforms it expects to work on with future compatibility (obviously, some packages would still need to {allow,deny} specific architectures).