bug#39121: 27.0.60; occur: Add bindings for next-error-no-select

["Mattias Engdegård" <mattiase@acm.org>]

23 juli 2021 kl. 16.05 skrev Lars Ingebrigtsen <larsi@gnus.org>:

> (defvar occur-highlight-regexp t
>  "Regexp matching part of visited source lines to highlight temporarily.
> Highlight entire line if t; don't highlight source lines if nil.")
> 
> So I think your patch looks correct.

Well yes, but that variable itself isn't really useful -- it is really just something transplanted from compilation-mode in order to achieve the same highlighting effect in Occur, but Occur shouldn't need it at all. So my patch is a bit rubbish; we could do better.

Currently, Occur buffers use `occur-target` properties to direct each line to the start of the first match on that line. We could use the property to indicating the exact extents (intervals) of matches, instead. For example, a buffer containing

 VENI VIDI VICI

with the Occur search regexp "VI.I", currently results in a line in *Occur* having the property `occur-target` with a marker to the start of 'VIDI' as value. Instead, we could make the value be ((m1 . m2) (m3 . m4)) where m1..m4 mark the beginning and end of 'VIDI' and 'VICI' respectively. Then occur-highlight-regexp could be done away entirely.