bandb: Don't attempt to write to a NULL helper.

[solanum.git] / aclocal.m4

diff --git a/aclocal.m4 b/aclocal.m4
index b2aec7a9b2ef28f4b3f315d832685a9c527cc5fe..dadc38d90f305b2e6e9c0a811982c207be29b86c 100644 (file)
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -4,9 +4,14 @@ AC_DEFUN([AC_DEFINE_DIR], [
   test "x$exec_prefix" = xNONE && exec_prefix='${prefix}'
   last_ac_define_dir=`eval echo [$]$2`
   ac_define_dir=`eval echo [$]last_ac_define_dir`
+  ac_define_dir_counter=0
   while test "x[$]last_ac_define_dir" != "x[$]ac_define_dir"; do
     last_ac_define_dir="[$]ac_define_dir"
     ac_define_dir=`eval echo [$]last_ac_define_dir`
+    AS_VAR_ARITH([ac_define_dir_counter], [$ac_define_dir_counter + 1])
+    AS_VAR_IF([ac_define_dir_counter], [128],
+       [AC_MSG_ERROR([detected recusive directory expansion when expanding $1=[$]$2: [$]ac_define_dir])
+       break])
   done
   $1="$ac_define_dir"
   AC_SUBST($1)