> then autoconf could attempt to compile+run a program that splice(2)s from /dev/random to a known-working sink And then the next day you, or your user, update

> then autoconf could attempt to compile+run a program that splice(2)s from /dev/random to a known-working sink And then the next day you, or your user, update your kernel, the result is out of date and your program crashes. That's just not how autoconf (or cmake or meson for that matter) are used. > running autoconf checks inside a target-machine emulator Run tests are quite rare. Older autoconf used to use printf to detect the size or alignment of a type, but for 15-20 years it has instead been doing binary search (basically "guess the number") so that only compilation tests are needed instead. (I am a former autoconf developer and GCC build system maintainer).