bug#46859: 28.0.50; [PATCH]: Add option to truncate long lines in xref.el

[Dmitry Gutov]

On 03.03.2021 18:13, Theodor Thornhill via Bug reports for GNU Emacs, 
the Swiss army knife of text editors wrote:
> This long line has 25 matches, so yeah, that takes some time. With your
> hint here I tried another approach which yielded some nice results.

Thank you.

Could you also try this benchmark with an input string that has no more 
than, say, 3 matches in the big one-line file? Or maybe just 1.

I'd like to compare the relative performance in such scenario, too.

> However, only my patch actually renders the long file as a match in the
output buffer. All the others seem to drop it altogether. IMO that is
one point in favour of my approaches.

Indeed.

> In addition, we could add another
defcustom for the xref--collect-matches-1 function,

That can be done already by the user customizing 
xref-search-program-alist, I think.