Hello
I build gcc version 12.0.0 20210603 (experimental) locally, then tried REL_13_STABLE with same CFLAGS as serinus
./configure --prefix=/home/melkij/tmp/pgdev/inst CFLAGS="-O3 -ggdb -g3 -Wall -Wextra -Wno-unused-parameter
-Wno-sign-compare-Wno-missing-field-initializers" --enable-tap-tests --enable-cassert --enable-debug
check-world passed.
regards, Sergei