On 1/11/23 20:03, Carlo Arenas wrote:
> Your suggested code doesn't address
> that, it merely changes the error message with one that would be IMHO
> even less clear and worsens the problem.

In that case let's improve the error message wording; something like the 
attached patch, say.


> Using a non Unicode PCRE library is perfectly fine, and there is no
> "undefined behavior" risk, and indeed `grep -P` without the UTF flag
> is exactly what the alternate path uses and what is recommended for
> speed, so?

It's not a question of undefined behavior. It's a question of whether 
grep does what the user requested. Without the attached patch, in a 
UTF-8 locale "grep -P '[[:alpha:]]'" won't report matching alphabetic 
characters, if they're multibyte. Silent misbehavior is quite bad, and 
it's better for grep to issue a diagnostic and exit than to silently do 
the wrong thing.