source: trunk/diffutils/m4/regex.m4@ 2840

#serial 12

dnl Initially derived from code in GNU grep.
dnl Mostly written by Jim Meyering.

dnl Usage: jm_INCLUDED_REGEX([lib/regex.c])
dnl
AC_DEFUN([jm_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.

    # 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 first 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(
[#include <stdio.h>
#include <regex.h>
          int
          main ()
          {
            static struct re_pattern_buffer regex;
            const char *s;
            struct re_registers regs;
            re_set_syntax (RE_SYNTAX_POSIX_EGREP);
            [s = re_compile_pattern ("a[[:@:>@:]]b\n", 9, &regex);]
            /* This should fail with _Invalid character class name_ error.  */
            if (!s)
              exit (1);

            /* This should succeed, but doesn't for e.g. glibc-2.1.3.  */
            s = re_compile_pattern ("{1", 2, &regex);

            if (s)
              exit (1);

            /* The following example is derived from a problem report
               against gawk from Jorge Stolfi <stolfi@ic.unicamp.br>.  */
            s = re_compile_pattern ("[[anù]]*n", 7, &regex);
            if (s)
              exit (1);

            /* This should match, but doesn't for e.g. glibc-2.2.1.  */
            if (re_match (&regex, "an", 2, 0, &regs) != 2)
              exit (1);

            exit (0);
          }
        ],
               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])
    m4_syscmd([test -f $1])
    ifelse(m4_sysval, 0,
      [
        AC_ARG_WITH(included-regex,
        [  --without-included-regex don't compile regex; this is the default on
                          systems with version 2 of the GNU C library
                          (use with caution on other system)],
                    jm_with_regex=$withval,
                    jm_with_regex=$ac_use_included_regex)
        if test "$jm_with_regex" = yes; then
          AC_LIBOBJ(regex)
        fi
      ],
    )
  ]
)