Subject: Re: bug#63272: 29.0.90; xref fails on long lines

From: Gregory Heytings <[email-masked]>
Date: Thu, 04 May 2023 15:58:02 +0000

>
> 1. Create a file with a long line, e.g. type
>
> a C-u 500000 b c
>
> Save the file and commit to git.
>
> (long-line-optimizations-p returns t)
>
> 2. Try to search a regexp that matches the whole long line, e.g.
>
>   C-x p g a.*c RET
>
> Debugger entered--Lisp error: (error "Stack overflow in regexp matcher")
>

That seems to be a problem with/limitation of the regexp engine that is 
not immediately related to (displaying) long lines.  After (setq 
long-line-threshold nil) you will get the same error.