bug#32676: Feature request

[Eli Zaretskii]

> From: Ernesto Alfonso <erjoalgo@gmail.com>
> Date: Thu, 13 Sep 2018 08:02:48 -0700
> Cc: Eli Zaretskii <eliz@gnu.org>, 32676@debbugs.gnu.org
> 
> The problem is that there are two independent* markers, point, and a marker 
> at the beginning of the current
> error line in the next error buffer, for example compilation-current-error, 
> where the fringe arrow is displayed.
> 
> In the same way that the user can move around the point in the next-error 
> buffer between calls to
> {next,previous}-error without affecting the location of the fringe arrow, the 
> user should also be able to move
> point around without affecting highlighting of the current error message (for 
> example, to kill part of an error
> message in the compilation buffer), since this is really a visual enhancement 
> to the fringe arrow.  

You should be able to fix this problem by setting
hl-line-range-function to a suitable function (which should be quite
simple, AFAIU).

> Another problem with hl-line is what the original poster pointed out in the 
> screenshot below: hl-line only
> highlights on the current buffer's window, so if the user were to switch to 
> the source code buffer (or if he
> wasn't there in the first place, e.g. by having invokied next-error form the 
> source code buffer via a key
> binding) then highlighting of error messages is either lost or never happens.

This is only true for the global-hl-line-mode; the local mode's
highlight is "sticky" by default, and shows even in non-selected
windows.

Moreover, you can customize the global mode so that its highlight is
sticky as well (not that I see why would you want to in this case).

> Basically, the difference is that hl-line uses post-command-hooks to track 
> the current line and put an overlay
> on it, whereas in this case highlighting only changes whenever 
> next-error-hook is invoked.

Is this really important?  Those are just implementation details, no?