libc/regex: r302824 added invalid check breaking collating ranges

[Yuri Pankov]

On Tue, Jan 23, 2018 at 03:53:19AM +0300, Yuri Pankov wrote:
> (CCing Kyle as he's working on regex at the moment and not because he
> broke something)
> 
> Hi,
> 
> r302284 added an invalid check which breaks collating ranges:
> 
> -if (table->__collate_load_error) {
> -    (void)REQUIRE((uch)start <= (uch)finish, REG_ERANGE);
> +if (table->__collate_load_error || MB_CUR_MAX > 1) {
> +    (void)REQUIRE(start <= finish, REG_ERANGE);
> 
> The "MB_CUR_MAX > 1" is wrong, we should be doing proper comparison
> according to current locale's collation and not simply comparing the
> wchar_t values.

After re-reading the specification I now see that what looked like a bug 
is actually an implementation choice, though the one that needs to be 
documentated.  I'll update the man page if anyone is willing to review 
(and commit) the changes.