Re: :alnum: broken?

[Eli Zaretskii]

> Cc: address@hidden, address@hidden
> From: Paul Eggert <address@hidden>
> Date: Fri, 28 Feb 2020 00:48:32 -0800
> 
> On 2/28/20 12:09 AM, Eli Zaretskii wrote:
> > I don't believe it is right for us to reject questionable but
> > valid code.
> 
> That begs the question. The code is valid only if we continue to insist that 
> it 
> be valid, despite the clear drawbacks of doing so.

I think it's valid due to regexp specification.

> Instead, we can easily change the definition of Emacs regular
> expressions so that the code is invalid. Since such code is
> invariably a mistake, it's a win to make such a change. That's what
> GNU grep has done for many years, and it works.

So what is your question?

> > I can even agree to reject this at
> > run time under a non-default value of some special variable
> 
> That would be better than nothing, but it's not very good since most people 
> won't know about the variable and thus will continue to suffer from these 
> errors. Better would be to make the default reject these buggy regexps, which 
> is 
> what GNU grep does (it accepts the buggy regexps only if POSIXLY_CORRECT is 
> set).

We disagree (as has been established already).