X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fregex.m4;h=3047d4d4970aad1bbfb49f8d875a4ba821800b78;hb=1e42e55b8d4e17667c2dc04b1c77fb5ec84ebfb9;hp=a9c238356722338c8e5a5aea6213b9fbbc11b552;hpb=1552be320dc029cfecda95ec298ee7f2913e5a7e;p=gnulib.git

diff --git a/m4/regex.m4 b/m4/regex.m4
index a9c238356..3047d4d49 100644
--- a/m4/regex.m4
+++ b/m4/regex.m4
@@ -1,15 +1,69 @@
-#serial 1
+#serial 5
 
-dnl From grep.
+dnl Initially derived from code in GNU grep.
+dnl Mostly written by Jim Meyering.
 
-AC_DEFUN(jm_WITH_REGEX,
+dnl Usage: jm_INCLUDED_REGEX([lib/regex.c])
+dnl
+AC_DEFUN(jm_INCLUDED_REGEX,
   [
-    AC_ARG_WITH(included-regex,
-		[  --without-included-regex don't compile regex],
-		jm_with_regex=$withval,
-		jm_with_regex=yes)
-    if test "$jm_with_regex" = yes; then
-      LIBOBJS="$LIBOBJS regex.o"
+    dnl Even packages that don't use regex.c can use this macro.
+    dnl Of course, for them it doesn't do anything.
+
+    # Assume we'll default to using the included regex.c.
+    ac_use_included_regex=yes
+
+    # However, if the system regex support is good enough that it passes the
+    # the following run test, then default to *not* using the included regex.c.
+    # If cross compiling, assume the test would fail and use the included
+    # regex.c.  The failing regular expression is from `Spencer ere test #75'
+    # in grep-2.3.
+    AC_CACHE_CHECK([for working re_compile_pattern],
+		   jm_cv_func_working_re_compile_pattern,
+      AC_TRY_RUN(
+	changequote(<<, >>)dnl
+	<<
+#include <stdio.h>
+#include <regex.h>
+	  int
+	  main ()
+	  {
+	    static struct re_pattern_buffer regex;
+	    const char *s;
+	    re_set_syntax (RE_SYNTAX_POSIX_EGREP);
+	    /* Add this third left square bracket, [, to balance the
+	       three right ones below.  Otherwise autoconf-2.14 chokes.  */
+	    s = re_compile_pattern ("a[[:]:]]b\n", 9, &regex);
+	    /* This should fail with _Invalid character class name_ error.  */
+	    exit (s ? 0 : 1);
+	  }
+	>>,
+	changequote([, ])dnl
+
+	       jm_cv_func_working_re_compile_pattern=yes,
+	       jm_cv_func_working_re_compile_pattern=no,
+	       dnl When crosscompiling, assume it's broken.
+	       jm_cv_func_working_re_compile_pattern=no))
+    if test $jm_cv_func_working_re_compile_pattern = yes; then
+      ac_use_included_regex=no
     fi
+
+    test -n "$1" || AC_MSG_ERROR([missing argument])
+    syscmd([test -f $1])
+    ifelse(sysval, 0,
+      [
+
+	AC_ARG_WITH(included-regex,
+	[  --without-included-regex don't compile regex; this is the default on
+                          systems with version 2 of the GNU C library
+                          (use with caution on other system)],
+		    jm_with_regex=$withval,
+		    jm_with_regex=$ac_use_included_regex)
+	if test "$jm_with_regex" = yes; then
+	  AC_SUBST(LIBOBJS)
+	  LIBOBJS="$LIBOBJS regex.$ac_objext"
+	fi
+      ],
+    )
   ]
 )