Do we officially support NetBSD? Do you know how to find out if we do? You might think to look at
https://www.python.org/dev/peps/pep-0011/#supporting-platforms , but that just loosely defines the criteria and it still doesn't list the actual platforms we support. (BTW I don't know if we do officially support NetBSD, hence this email.)
I think we should clarify this sort of thing and be a bit more upfront with the level of support we expect/provide for a platform. As such, I want to restructure PEP 11 to list the platforms we support, not just list the platforms we stopped supporting. To do this I want define 3 different tiers that outline what our support requirements and promises are for platforms.
Tier 1 is the stuff we run CI against: latest Windows, latest macOS, Linux w/ the latest glibc (I don't know of a better way to define Linux support as I don't know if a per-distro list is the right abstraction). These are platforms we won't even let code be committed for if they would break; they block releases if they don't work. These platforms we all implicitly promise to support.
Tier 2 is the platforms we would revert a change within 24 hours if they broke: latest FeeBSD, older Windows, older macOS, Linux w/ older glibc.This is historically the "stable buildbot plus a core dev" group of platforms. The change I would like to see is two core devs (in case one is on vacation), and a policy as to how a platform ends up here (e.g. SC must okay it based on consensus of everyone). The stable buildbot would still be needed to know if a release is blocked as we would hold a release up if they were red. The platform and the core devs supporting these platforms would be listed in PEP 11.
Tier 3 are platforms we accept PRs for to keep working, but they won't block a release. At least one core dev must be listed to be in charge of PRs that affect the platform. A buildbot would be nice but not required. I'm thinking either historical platforms we support or something like Emscripten that's working towards being a tier 2 platform. I'm not sure if we want to have explicit approval to be in this tier beyond the outlined requirements, but obviously if a core dev isn't keeping up with PRs then the platform will be dropped.
All other platforms we do not directly support in the repository and it is up to the community to keep functioning. We can obviously keep accepting general patches to up compatibility, but platform-specific patches for anything outside of these tiers wouldn't. No issue if someone provides a buildbot for their own benefit, but these buildbots would never hold anything up.
When a Python version hits b1, then that platform is considered supported for that version as long as the requirements outlined above continue to be met. Once the Python version hits EOL then like anything, support ends no matter what. We could capture the supported platforms for a version in the release schedule PEP if people want.
I would expect appropriate labels being added to the builders listed at
https://buildbot.python.org/all/#/builders to signify which platforms we block releases for (e.g. `tier-1,`, `tier-2`, or `release-blocker` as a generic label).
I would expect PEP 11 to list the appropriate C symbol that's set for that platform, e.g. __linux__.
I don't know if we want to bother listing CPU architectures since we are a pure C project which makes CPU architecture less of a thing, but I'm personally open to the idea of CPU architectures being a part of the platform definition.
I don't think we should cover C compilers here as that's covered by PEP 7. Otherwise PEP 7 should only list C versions/features and PEP 11 lists compilers and their versions.