As mentioned in another thread, POSIX requires the presence of a C compiler,

Though to be fair, POSIX is increasingly outdated.

	▲	pjmlp an hour ago \| parent [-]
		GNU/Linux isn't the only system out there, POSIX last update was in 2024 (when C requirement got upgraded to C17), and yes some parts of it are outdated in modern platforms, especially Apple, Google, Microsoft OSes and Cloud infrastructure. Still, who supports POSIX is expected to have a C compiler available if applying for the OpenGroup stamp.