-m4_version_prereq([2.64],[AC_DEFUN_ONCE],[AC_DEFUN])([gl_LIBUNISTRING],
+dnl This is tricky because of the way 'aclocal' is implemented:
+dnl - It requires defining an auxiliary macro whose name ends in AC_DEFUN.
+dnl Otherwise aclocal's initial scan pass would miss the macro definition.
+dnl - It requires a line break inside the AC_DEFUN_ONCE and AC_DEFUN expansions.
+dnl Otherwise aclocal would emit many "Use of uninitialized value $1"
+dnl warnings.
+m4_define([gl_libunistring_AC_DEFUN],
+ m4_version_prereq([2.64],
+ [[AC_DEFUN_ONCE(
+ [$1], [$2])]],
+ [m4_ifdef([gl_00GNULIB],
+ [[AC_DEFUN_ONCE(
+ [$1], [$2])]],
+ [[AC_DEFUN(
+ [$1], [$2])]])]))
+gl_libunistring_AC_DEFUN([gl_LIBUNISTRING],