+ 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 <string.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);
+ memset (®ex, 0, sizeof (regex));
+ [s = re_compile_pattern ("a[[:@:>@:]]b\n", 9, ®ex);]
+ /* 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. */
+ memset (®ex, 0, sizeof (regex));
+ s = re_compile_pattern ("{1", 2, ®ex);
+
+ if (s)
+ exit (1);
+
+ /* The following example is derived from a problem report
+ against gawk from Jorge Stolfi <stolfi@ic.unicamp.br>. */
+ memset (®ex, 0, sizeof (regex));
+ s = re_compile_pattern ("[[an\371]]*n", 7, ®ex);
+ if (s)
+ exit (1);
+
+ /* This should match, but doesn't for e.g. glibc-2.2.1. */
+ if (re_match (®ex, "an", 2, 0, ®s) != 2)
+ exit (1);