#!/bin/sh
set -eu

echo > config.mk

compiles ()
{
	stage="$(mktemp -d)"
	echo "$2" > "$stage/test.c"
	(cc -Werror "$1" -o "$stage/test" "$stage/test.c" >/dev/null 2>&1)
	cc_success=$?
	rm -rf "$stage"
	return $cc_success
}

if compiles "-D_POSIX_C_SOURCE=200112L" "
	#include <sys/types.h>
	int main(void)
	{
		return (ssize_t)0;
	}"
then
	echo "CFLAGS += -DHAVE_SSIZE_T" >> config.mk
fi