checktools ()
{

	# Check that a clang build is not attempted.
	[ -z "${BUILDRUMP_HAVE_LLVM}" ] \
	    || die rumprun does not yet support clang ${CC:+(\$CC: $CC)}

	delay=5

	# check that gcc is modern enough
	vers=$(${CC:-cc} -E -dM - < /dev/null | LANG=C awk '
	    /__GNUC__/ {version += 100*$3}
	    /__GNUC_MINOR__/ {version += $3}
	    END { print version; if (version) exit 0; exit 1; }') \
		|| unable to probe cc version
	if [ ${vers} -lt 406 ]; then
		die gcc is too old, need 4.6 or later. ${CC:+(\$CC: $CC)}
	elif [ ${vers} -lt 408 ]; then
		echo '>>'
		echo ">> WARNING: gcc is old. ${CC:+(\$CC: $CC)}"
		echo '>> Version 4.8 or later is recommended.'