From 79c2687e973a280663ac5846448bb9422cd893b8 Mon Sep 17 00:00:00 2001
From: Jim Meyering <jim@meyering.net>
Date: Sat, 4 Jul 1998 16:45:18 +0000
Subject: [PATCH] Use syscmd, ifelse, and sysval.  Mainly as an exercise to
 prove that this macro can be used in packages without regex.c.

---
 m4/regex.m4 | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/m4/regex.m4 b/m4/regex.m4
index 001d203b82..073dac5b42 100644
--- a/m4/regex.m4
+++ b/m4/regex.m4
@@ -1,15 +1,23 @@
 #serial 1
 
-dnl From grep.
+dnl Derived from code in GNU grep.
 
 AC_DEFUN(jm_WITH_REGEX,
   [
-    AC_ARG_WITH(included-regex,
+    dnl Even packages that don't use regex.c can use this macro.
+    dnl Of course, for them it doesn't do anything.
+
+    syscmd([test -f lib/regex.c])
+    ifelse(sysval, 0,
+      [
+	AC_ARG_WITH(included-regex,
 	    [  --without-included-regex don't compile regex (use with caution)],
-		jm_with_regex=$withval,
-		jm_with_regex=yes)
-    if test "$jm_with_regex" = yes; then
-      LIBOBJS="$LIBOBJS regex.o"
-    fi
+		    jm_with_regex=$withval,
+		    jm_with_regex=yes)
+	if test "$jm_with_regex" = yes; then
+	  LIBOBJS="$LIBOBJS regex.o"
+	fi
+      ],
+    )
   ]
 )
-- 
2.30.2