+if test "$enable_pch" != no; then
+ dnl md5sum, sha224sum, sha256sum, sha384sum, sha512sum and b2sum are
+ dnl frequently available on Linux. md5 is available on macOS and OpenBSD.
+ dnl sha1, sha256, and sha512 are available on OpenBSD.
+ AC_PATH_PROGS(PCH_CHECKSUMMER, [md5sum md5 sha1sum sha1 sha224sum sha256sum sha256 sha384sum sha512sum sha512 b2sum], [none])
+ AC_ARG_VAR([PCH_CHECKSUMMER], [full path to a utility to compute the checksum for the precompiled header; checksum is for ccache's pch_external_checksum])
+fi
+