9.2.4 Changed Directory Variables

In Autoconf 2.60, the set of directory variables has changed, and the defaults of some variables have been adjusted (see Installation Directory Variables) to changes in the GNU Coding Standards. Notably, datadir, infodir, and mandir are now expressed in terms of datarootdir. If you are upgrading from an earlier Autoconf version, you may need to adjust your files to ensure that the directory variables are substituted correctly (see Defining Directories), and that a definition of datarootdir is in place. For example, in a Makefile.in, adding

datarootdir = @datarootdir@

is usually sufficient. If you use Automake to create Makefile.in, it will add this for you.

To help with the transition, Autoconf warns about files that seem to use datarootdir without defining it. In some cases, it then expands the value of $datarootdir in substitutions of the directory variables. The following example shows such a warning:

$ cat configure.ac
AC_INIT
AC_CONFIG_FILES([Makefile])
AC_OUTPUT
$ cat Makefile.in
prefix = @prefix@
datadir = @datadir@
$ autoconf
$ configure
configure: creating ./config.status
config.status: creating Makefile
config.status: WARNING:
               Makefile.in seems to ignore the --datarootdir setting
$ cat Makefile
prefix = /usr/local
datadir = ${prefix}/share

Usually one can easily change the file to accommodate both older and newer Autoconf releases:

$ cat Makefile.in
prefix = @prefix@
datarootdir = @datarootdir@
datadir = @datadir@
$ configure
configure: creating ./config.status
config.status: creating Makefile
$ cat Makefile
prefix = /usr/local
datarootdir = ${prefix}/share
datadir = ${datarootdir}

In some cases, however, the checks may not be able to detect that a suitable initialization of datarootdir is in place, or they may fail to detect that such an initialization is necessary in the output file. If, after auditing your package, there are still spurious configure warnings about datarootdir, you may add the line

AC_DEFUN([AC_DATAROOTDIR_CHECKED])

to your configure.ac to disable the warnings. This is an exception to the usual rule that you should not define a macro whose name begins with AC_ (see Macro Names).