If a C23 compiler is detected, try asking for C17.
Branches before 16 can't be compiled with a C23 compiler (see
deprecation warnings silenced by commit f9a56e72, and non-back-patchable
changes made in 16 by commit 1c27d16e). Test __STDC_VERSION__, and if
it's above C17 then try appending -std=gnu17. The test is done with the
user's CFLAGS, so an acceptable language version can also be configured
manually that way.
This is done in branches 15 and older, back to 9.2, per policy of
keeping them buildable with modern tools.
Discussion: https://postgr.es/m/87o72eo9iu.fsf%40gentoo.org
Branch
------
REL_12_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/3f302f0ed06f69c5ebd33d4df95895323a3cbef6
Modified Files
--------------
configure | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
configure.in | 20 ++++++++++++++++
2 files changed, 97 insertions(+)
