I think it is fine if this is an open problem but I would like more graceful failure. Isn’t it possible to catch this behavior and turn it into a lisp-level error?

On 11 Mar 2020, at 16:17, Eli Zaretskii <eliz@gnu.org<mailto:eliz@gnu.org>> wrote:

From: Robert Pluim <rpluim@gmail.com<mailto:rpluim@gmail.com>>
Date: Wed, 11 Mar 2020 16:32:14 +0100
Cc: 40023@debbugs.gnu.org<mailto:40023@debbugs.gnu.org>

On Wed, 11 Mar 2020 13:50:22 +0000, Holger Pirk <holger@pirk.name<mailto:holger@pirk.name>> said:

   Holger> I have spent some time digging around the code and couldn't quite figure
   Holger> out the logic behind the `fd < FD_SETSIZE`-assert. I suspect the CCLS
   Holger> opens files without going through emacs' infrastructure which leads to
   Holger> high file descriptors which emacs cannot handle. I would say that CCLS
   Holger> is, in part, to blame but emacs shouldn't simply crash.

Emacs is limited by the limits of select, which supports a maximum of
FD_SETSIZE file descriptors, which on macOS is 1024

At least on macOS, itʼs possible to increase that value to eg 8192 by
setting FD_SETSIZE, which might alleviate this, but then you'd
probably run into the 'ulimit -n' maximum, so you'd have to remember
to increase that.

Wasn't this fixed lately by Yamamoto-san?