What does ExclusiveArch and ExcludeArch do for sub-packages?

[FrostyX]

I recently worked on a feature for Copr where we wanted to skip builds on architectures based on ExclusiveArch and ExcludeArch.

The descriptions of those macros tags are quite clear.
https://rpm-software-management.github.io/rpm/manual/tags.html

Tag Name	Value	Type	Description
Excludearch	1059	string array	If present, limits the architectures on which the package is buildable by excluding those specified.
Exclusivearch	1061	string array	If present, limits the architectures on which the package is buildable exclusively to those specified.

However, I was surprised that those macros tags can be used not only for packages but also for sub-packages. For example procyon or binutils does this.

Can you please document that these macros tags (or possibly some other surprising ones) can be used for sub-packages as well and what does it mean when they are used for sub-packages?

[dmnks]

Actually, these two tags only pertain to the SRPM itself (thus being listed under the "Source packages" heading on that page.) In other words, to the SPEC parser, these two tags are not %package specific so wherever they're used, they will simply append the given value(s) to the respective top-level tag.

This can be seen e.g. with the binutils package:

$ fedpkg clone binutils
$ fedpkg srpm --define 'with_crossbuilds 1'
$ rpm -q --json /path/to/binutils-2.42.50-6.fc41.src.rpm | jq '.Excludearch'
[
  "aarch64-linux-gnu",
  "aarch64-redhat-linux",
  "ppc64le-linux-gnu",
  "ppc64le-redhat-linux",
  "s390x-linux-gnu",
  "s390x-redhat-linux",
  "x86_64-linux-gnu",
  "x86_64-redhat-linux",
  "i686-linux-gnu",
  "i686-redhat-linux"
]

I don't think the above is what was intended by the packagers, it's most likely just them having misunderstood the purpose of these tags. After all, one can't blame them - it's not entirely obvious from our docs, regardless of the heading. Some clarification is in order so I'll move this ticket into our TODO queue.

There's also the question of whether we shouldn't actually make this into a per-package tag. If we did, however, that would effectively mean package-level exclusion support, something touched upon in rpm-software-management/rpm#2795.

Thanks for the report!