Function gmp_mpfr_sys::gmp::__gmp_set_memory_functions

pub unsafe extern fn __gmp_set_memory_functions(arg1: Option<extern fn(_: size_t) -> *mut c_void>,
                                                arg2: Option<unsafe extern fn(_: *mut c_void, _: size_t, _: size_t) -> *mut c_void>,
                                                arg3: Option<unsafe extern fn(_: *mut c_void, _: size_t)>)