(jm_FUNC_STRERROR_R): New file/macro.

[gnulib.git] / m4 / regex.m4

diff --git a/m4/regex.m4 b/m4/regex.m4
index 733ad3a..3047d4d 100644 (file)
--- a/m4/regex.m4
+++ b/m4/regex.m4
@@ -1,31 +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],
-               USE_REGEX=$withval,
-               USE_REGEX=yes)
+    dnl Even packages that don't use regex.c can use this macro.
+    dnl Of course, for them it doesn't do anything.
 
-    if test "$USE_REGEX" = yes; then
+    # Assume we'll default to using the included regex.c.
+    ac_use_included_regex=yes
 
-      LIBOBJS="$LIBOBJS regex.o"
+    # 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
 
-    else
-      if test x = y; then
-       # This code is deliberately never run via ./configure.
-       # FIXME: this is a hack to make autoheader put the corresponding
-       # HAVE_* undef for this symbol in config.h.in.  This saves me the
-       # trouble of having to maintain the #undef in acconfig.h manually.
-       AC_CHECK_FUNCS(LIBC_REGEX)
-      fi
-      # Defining it this way (rather than via AC_DEFINE) short-circuits the
-      # autoheader check -- autoheader doesn't know it's already been taken
-      # care of by the hack above.
-      ac_kludge=HAVE_LIBC_REGEX
-      AC_DEFINE_UNQUOTED($ac_kludge)
+              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
+      ],
+    )
   ]
 )