While Autoconf was relatively dormant in the late 1990s, Automake
provided Autoconf-like macros for a while. Starting with Autoconf 2.50
in 2001, Autoconf provided
versions of these macros, integrated in the
AM_. But in order to ease the upgrading via
autoupdate, bindings to such
AM_ macros are provided.
Unfortunately older versions of Automake (e.g., Automake 1.4)
did not quote the names of these macros.
Therefore, when m4 finds something like
‘AC_DEFUN(AM_TYPE_PTRDIFF_T, ...)’ in aclocal.m4,
expanded, replaced with its Autoconf definition.
Fortunately Autoconf catches pre-
AC_INIT expansions, and
complains, in its own words:
$ cat configure.ac AC_INIT([Example], [1.0], [email@example.com]) AM_TYPE_PTRDIFF_T $ aclocal-1.4 $ autoconf aclocal.m4:17: error: m4_defn: undefined macro: _m4_divert_diversion aclocal.m4:17: the top level autom4te: m4 failed with exit status: 1 $
Modern versions of Automake no longer define most of these macros, and properly quote the names of the remaining macros. If you must use an old Automake, do not depend upon macros from Automake as it is simply not its job to provide macros (but the one it requires itself):
$ cat configure.ac AC_INIT([Example], [1.0], [firstname.lastname@example.org]) AM_TYPE_PTRDIFF_T $ rm aclocal.m4 $ autoupdate autoupdate: `configure.ac' is updated $ cat configure.ac AC_INIT([Example], [1.0], [email@example.com]) AC_CHECK_TYPES([ptrdiff_t]) $ aclocal-1.4 $ autoconf $