Subject: Re: #39595: M-x compile still very line-length weak

From: Mattias Engdegård <[email-masked]>
Date: Fri, 14 Feb 2020 12:18:29 +0100

> aaa:; perl -we 'print " "  x 9999;' #finishes right away.
> bbb:; perl -we 'print "\n" x 9999;' #takes several seconds, even on the latest hardware. 

(The comments seem to have been swapped around, but we get the idea.)

This is not a rare edge case. Long lines are not uncommon in compilation output, and a sluggish M-x compile reflects badly on Emacs since it is a commonly used function.

The main culprit seems to be 'omake' -- try removing it from compilation-error-regexp-alist. There is still an annoying delay; further investigation is needed. (For instance, 'msft' occurs twice; this must be a mistake.)