http://benji3up2kxewkqfcq7buxk2xd6zwy3zggnurkrm3l4cvwy2iipvyyad.onion/mirrors/gmpdoc/Autoconf.html
For example mpz_mul_si was added in
GMP 3.1, AC_CHECK_LIB(gmp, __gmpz_mul_si, ,
[AC_MSG_ERROR(
[GNU MP not found, or not 3.1 or up, see https://gmplib.org/])]) An alternative would be to test the version number in gmp.h using say AC_EGREP_CPP . That would make it possible to test the exact version,
if some particular sub-minor release is known to be necessary.