Does anyone have strong objections to this? It simplifies our codebase to get rid of the conditionals and extra code we carry for builds in the absence of zlib. The Windows build has treated it as required since forever. The zlib is always available on every supported platform otherwise given how fundamental it is.
FWICS Gentoo has always enabled zlib, so no opposition here. I can imagine quite a few things unexpectedly breaking should someone build Python without zlib.
It seems to mostly be a hold over from the post-autoconf 90s when building on unix systems without third party libraries available. I assume the only way it happens now is likely accidental: When someone trys to build python and hasn’t installed their distro’s -dev headers for the common libraries they already have installed. We don’t need to support that.
One thing to keep in mind here is that requiring zlib means we’re also requiring that zlib be buildable without Python. Considering how fundamental zlib is, and how simple its build is, this is probably fine… but it does make it potentially harder to bootstrap new systems, especially ones that rely on Python for its build system.