13.4.5 configure.ac at top level

configure.ac or configure.in - this is the source from which autoconf generates the configure script.

1. Declare the package and version.

   This is done by a set of lines like these:

   PACKAGE=gettext
   VERSION=0.19.7
   AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE")
   AC_DEFINE_UNQUOTED(VERSION, "$VERSION")
   AC_SUBST(PACKAGE)
   AC_SUBST(VERSION)
   

   or, if you are using GNU automake, by a line like this:

   AM_INIT_AUTOMAKE(gettext, 0.19.7)
   

   Of course, you replace ‘gettext’ with the name of your package, and ‘0.19.7’ by its version numbers, exactly as they should appear in the packaged tar file name of your distribution (gettext-0.19.7.tar.gz, here).

2. Check for internationalization support.

   Here is the main m4 macro for triggering internationalization support. Just add this line to configure.ac:

   AM_GNU_GETTEXT
   

   This call is purposely simple, even if it generates a lot of configure time checking and actions.

   If you have suppressed the intl/ subdirectory by calling gettextize without ‘--intl’ option, this call should read

   AM_GNU_GETTEXT([external])
   

3. Have output files created.

   The AC_OUTPUT directive, at the end of your configure.ac file, needs to be modified in two ways:

   AC_OUTPUT([existing configuration files intl/Makefile po/Makefile.in],
   [existing additional actions])
   

   The modification to the first argument to AC_OUTPUT asks for substitution in the intl/ and po/ directories. Note the ‘.in’ suffix used for po/ only. This is because the distributed file is really po/Makefile.in.in.

   If you have suppressed the intl/ subdirectory by calling gettextize without ‘--intl’ option, then you don’t need to add intl/Makefile to the AC_OUTPUT line.

If, after doing the recommended modifications, a command like ‘aclocal -I m4’ or ‘autoconf’ or ‘autoreconf’ fails with a trace similar to this:

configure.ac:44: warning: AC_COMPILE_IFELSE was called before AC_GNU_SOURCE
../../lib/autoconf/specific.m4:335: AC_GNU_SOURCE is expanded from...
m4/lock.m4:224: gl_LOCK is expanded from...
m4/gettext.m4:571: gt_INTL_SUBDIR_CORE is expanded from...
m4/gettext.m4:472: AM_INTL_SUBDIR is expanded from...
m4/gettext.m4:347: AM_GNU_GETTEXT is expanded from...
configure.ac:44: the top level
configure.ac:44: warning: AC_RUN_IFELSE was called before AC_GNU_SOURCE

you need to add an explicit invocation of ‘AC_GNU_SOURCE’ in the configure.ac file - after ‘AC_PROG_CC’ but before ‘AM_GNU_GETTEXT’, most likely very close to the ‘AC_PROG_CC’ invocation. This is necessary because of ordering restrictions imposed by GNU autoconf.