Eli Zaretskii <eliz@gnu.org> writes:

From: Elijah Gabe Pérez <eg642616@gmail.com>
Date: Mon, 17 Mar 2025 14:37:04 -0600

When Emacs was compiled with compress-install, using submit-emacs-patch gives an error because it
search for maintainer address in file.el instead file.el.gz.

Thanks, but this lacks details, IMO. AFAIU, submit-emacs-patch gleans
source file names from the patch file you are about to submit, and it
expands each file name in the patch against source-directory, before
looking them up for their maintainers. In the source tree (if you
still have it around) the files are not compressed. OTOH, if your
patch names files by their absolute file name (in which case
source-directory is not used), and the files are compressed in the
installation tree, then how did you produce the patch from compressed
files in the first place in a way that names the files without the .gz
extensions?

My emacs-git directory (where i use to contribute) doesn't have the lisp
files compressed, it seems that submit-emacs-patch search in
source-directory (which i have it pointing to usr/share/emacs/31.0.50)
for lisp.el, however my installed emacs was built with compress-install
which i have lisp.el.gz instead.

IOW, please show an example of a patch that could be used to reproduce
this issue and the recipe to reproduce,

Sure, here is:

Steps to reproduce:

1. emacs -Q
   
2. eval: (setq source-directory "usr/share/emacs/31.0.50")
   
3. M-x submit-emacs-patch RET /path/to/test.patch RET RET
   

and should display mail/message buffer with this

To: bug-gnu-emacs@gnu.org
Subject: 
From:
X-Debbugs-Cc: --text follows this line--

and give an error:

Opening input file: The file or directory does not exist, /usr/share/emacs/31.0.50/lisp/simple.el

and please tell whether you do or don't have the Emacs source tree
pointed to by source-directory.

I have source-directory pointing to usr/share/emacs/31.0.50, changing
it to my emacs-git directory path fix this.

However I haven't found any documentation about this variable and
changing its value, so I see it very dangerous do it.

Or maybe I'm missing something obvious, in which case please point out
what I missed.

You didn't miss anything, I think I've explained enough.