bug#23179: 25.0.92; Restore `M-,' to continue etags search

[Dmitry Gutov]

On 04/03/2016 06:32 PM, Eli Zaretskii wrote:

> Etags isn't special, I just remembered that you said at some point you
> couldn't see how other back-ends will be able to implement a similar
> functionality.  But if I misremembered, or if you now see a way to do
> this with other back-ends, by all means let's do that.

Not sure what I said previously, but first and foremost, we don't have a 
backend-agnostic spec for that similar functionality.

When we have it, I'm sure other backends can implement regexp-search to 
the best of their ability.