bug#27681: grep: Combining Mark-Nonspacing are classified as [:punct:]

[Paul Eggert]

Surely this is a glibc bug, not a grep bug. Grep is just following the 
character classification of glibc. I can reproduce the problem by 
compiling and running the attached program, which uses only glibc (not 
grep). This program exits with status 1, whereas you want it to exit 
with status 0. So I suggest filing a glibc bug report.
#include <locale.h>
#include <regex.h>

static char const combining_acute_accent[] = "\xcc\x81";
int
main (void)
{
  regex_t re;
  if (! setlocale (LC_ALL, "en_US.UTF-8"))
    return 3;
  if (regcomp (&re, "[[:alpha:]]", 0) != 0)
    return 2;
  if (regexec (&re, combining_acute_accent, 0, 0, 0) != 0)
    return 1;
  return 0;
}