Re: How does Emacs load a non-existent .el file?

[Eli Zaretskii <eliz@gnu.org>]

> From: Konstantin Kharlamov <Hi-Angel@yandex.ru>
> Date: Fri, 01 Mar 2024 13:52:30 +0300
> 
> I was just looking whether it's too hard to add an option for reading
> from stdin (a very requested feature¹). Long story short, I presume
> command line parsing happens in `lisp/startup.el`, function `(command-
> line-1)`. That's where the weirdness starts. Since it is an ELisp file,
> I figured to avoid recompiling I can move its `.elc` file out of the
> way and just do edits to `startup.el` directly. Turned out though, not
> only Emacs does not notice these edits, it somehow manages to load the
> file when it does not exist!
> 
> So e.g. I did a `sudo rm /usr/share/emacs/30.0.50/lisp/startup*`, so no
> .el or elc files. But starting up `emacs -Q` and asking it `C-h f
> command-line-1` still results in Emacs answering that such function
> exists, except the help buffer doesn't have a link to it.
> 
> I am thoroughly confused. Any idea what's going on here?

Yes: startup.el is preloaded, see lisp/loadup.el.  So if you change
it, you need to rebuild Emacs to let the changes have their effect at
startup.  You can also load startup.el manually into a running
session, and then invoke functions you've changed, but that will only
be useful if what you are changing is not some special behavior that
happens only at startup.

> https://superuser.com/questions/31404/how-to-make-emacs-read-buffer-from-stdin-on-start

There are a few answers there that solve the problem, so I'm not sure
what else are you trying to do, and why.