Paul Eggert via tz <tz@iana.org> writes:
So I propose we add a Makefile or similar build-time option to let tzdb users have it either way. Set the flag one way, and it will be as if the recently-proposed changes did not occur. Set it the other way, and you'll get the changes.
Works for me, as long as it's possible to get the formerly-default zone data (that is, without the old backzone additions).
This will be similar to our vanguard/rearguard support, which helped address a similar disagreement back in 2018. We could even control things via the existing vanguard/rearguard build-time option; that might be simpler. If you have ideas about what the the option's specific effects should be, please let me know.
Please *do not* tie this to vanguard/rearguard. The fact that tzdb consumers might disagree with your revisions to the data classification doesn't mean that they want to get locked into obsolete file formats. regards, tom lane