_gmp_build_version

Return the version of libgmp this module is built on, as a v-string.

printf "built on libgmp %vd\n", Math::GMP::_gmp_build_version();   # 6.3.0

Upstream reports the GMP headers it was compiled against. libgmp is bound here when the module loads, not at compile time, so the library it is built on is the one loaded: this is _gmp_lib_version’s value.