Sigh, autoconf has AC_CHECK_FUNC and AC_CHECK_FUNCS and both check whether some function exists or not. However in addition to the obvious difference that the later is able to check multiple functions it also defines HAVE_FUNCTION_NAME for each function. Commit 680d2f49da moved the code to separate file, but also blindly changed the macro to AC_CHECK_FUNC without confronting the documentation. Reported-by: John Ferlan <jferlan(a)redhat.com&gt; <https://www.redhat.com/archives/libvir-list/2016-December/msg01086.html> Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com&gt; --- m4/virt-gnutls.m4 | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/m4/virt-gnutls.m4 b/m4/virt-gnutls.m4 index bd861eec5f..77122c1202 100644 --- a/m4/virt-gnutls.m4 +++ b/m4/virt-gnutls.m4 @@ -60,8 +60,8 @@ AC_DEFUN([LIBVIRT_CHECK_GNUTLS],[ OLD_LIBS="$LIBS" LIBS="$LIBS $GNUTLS_LIBS" - AC_CHECK_FUNC([gnutls_rnd]) - AC_CHECK_FUNC([gnutls_cipher_encrypt]) + AC_CHECK_FUNCS([gnutls_rnd]) + AC_CHECK_FUNCS([gnutls_cipher_encrypt]) LIBS=$OLD_LIBS fi ])