libtextstyle: Make gl_INIT_PACKAGE work with Automake >= 1.16.4.

Reported and analyzed by Nicole Mazzuca <mazzucan@outlook.com> in
<https://lists.gnu.org/archive/html/bug-libunistring/2021-08/msg00002.html>.

* m4/init-package-version.m4 (gl_INIT_PACKAGE): Use a new macro gl_INIT_EMPTY.
(gl_INIT_DUMMY): Expand to empty in two steps, via a new macro gl_INIT_DUMMY2.

diff --git a/libtextstyle/m4/init-package-version.m4 b/libtextstyle/m4/init-package-version.m4
index f131a844f0568a12de827d53f44c2fabb4f5b97d..a26b1ab88158d149b5a0de2318f58b426d66e265 100644 (file)
--- a/libtextstyle/m4/init-package-version.m4
+++ b/libtextstyle/m4/init-package-version.m4
@@ -1,5 +1,5 @@
-# init-package-version.m4 serial 1 (gettext-0.18)
-dnl Copyright (C) 1992-2009 Free Software Foundation, Inc.
+# init-package-version.m4 serial 2
+dnl Copyright (C) 1992-2021 Free Software Foundation, Inc.
 dnl This file is free software, distributed under the terms of the GNU
 dnl General Public License.  As a special exception to the GNU General
 dnl Public License, this file may be distributed as part of a program
@@ -77,7 +77,7 @@ AC_DEFUN([gl_INIT_PACKAGE],
             m4_bpatsubst(m4_dquote(
                 m4_defn([AM_INIT_AUTOMAKE])),
               [AC_PACKAGE_NAME], [gl_INIT_DUMMY])),
-          [AC_PACKAGE_TARNAME], [gl_INIT_DUMMY])),
+          [AC_PACKAGE_TARNAME], [gl_INIT_EMPTY])),
       [AC_PACKAGE_VERSION], [gl_INIT_DUMMY])
     [AC_SUBST([PACKAGE], [$1])
      AC_SUBST([VERSION], [$2])
@@ -85,7 +85,11 @@ AC_DEFUN([gl_INIT_PACKAGE],
   m4_define([AM_INIT_AUTOMAKE],
     m4_defn([gl_RPL_INIT_AUTOMAKE]))
 ])
-m4_define([gl_INIT_DUMMY], [])
+m4_define([gl_INIT_EMPTY], [])
+dnl Automake 1.16.4 no longer accepts an empty value for gl_INIT_DUMMY.
+dnl But a macro that later expands to empty works.
+m4_define([gl_INIT_DUMMY], [gl_INIT_DUMMY2])
+m4_define([gl_INIT_DUMMY2], [])
 AC_DEFUN([gl_RPL_INIT_AUTOMAKE], [
   m4_ifval([$2],
     [m4_fatal([After gl_INIT_PACKAGE, the two-argument form of AM_INIT_AUTOMAKE cannot be used.])])