As part of the USE_CXX_FEATURES scheme (yay, and thanks nia@ for leading
it), we have a plan to require a limited set of compilers aligned with
NetBSD releases, e.g. to avoid building gcc 8, 9, and 10 on a system
with 7 in base, when just building 10 would be better.
This plan is mostly followed, but not quite. The following change would
follow it harder, and align charconv with filesystem and paralellism_ts.
My view is that there is no good reason it's set to 8 now, other than
the history of how we got here (using 8 dates from the grand rototill to
USE_CXX_FEATURES).
I believe that fixing this results in choosing 10 instead of 8 on NetBSD
9, and thus removing a reason why gcc8 is built, instead of just having
10. I've been carrying this as a local patch for a while with no ill
effects, and the comment asking for an explanation has been there since
June.
I'll commit this in a few days absent objections with rationale. If you
object, please provide rationale for one of: