Re: source-directory, installed Emacs, and C source

[sbaugh]

Manuel Giraud via "Emacs development discussions." <emacs-devel@gnu.org>
writes:
> Eli Zaretskii <eliz@gnu.org> writes:
>
>>> From: Manuel Giraud <manuel@ledu-giraud.fr>
>>> Cc: sbaugh@catern.com,  emacs-devel@gnu.org
>>> Date: Wed, 25 Oct 2023 10:41:33 +0200
>>> 
>>> Eli Zaretskii <eliz@gnu.org> writes:
>>> 
>>> [...]
>>> 
>>> > AFAIR, Emacs looks for Lisp files by scanning load-path.  So if you
>>> > customize load-path to include the directories in the source tree, you
>>> > should be able to tell Emacs to look for the Lisp files in another
>>> > directory.  I think that's what we do when Emacs is run uninstalled,
>>> > and that's why it finds the Lisp files in the source tree.
>>> 
>>> This works… but not always.  Here is a test I've just done:
>>> 
>>>      - emacs -Q
>>>      - then load the following:
>>> --8<---------------cut here---------------start------------->8---
>>> (add-to-list 'load-path "~/emacs-repo/lisp/")
>>> (dolist (dir '("vc" "use-package" "url" "textmodes" "progmodes"
>>>            "play" "org" "nxml" "net" "mh-e" "mail" "leim"
>>>            "language" "international" "image" "gnus" "eshell"
>>>            "erc" "emulation" "emacs-lisp" "cedet" "calendar"
>>>            "calc" "obsolete"))
>>>   (add-to-list 'load-path (format "~/emacs-repo/lisp/%s/" dir)))
>>> --8<---------------cut here---------------end--------------->8---
>>
>> I never said you should just prepend the source tree to the previous
>> value, did I?
>
> No you did not say that.  But then what recipe with 'load-path' did you
> have in mind to always look into the source tree?
>
>> And anyway, are you sure you emulated Spencer's use case closely
>> enough?  He never described in detail which files are where, but AFAIU
>> at the very least you should have removed the *.el and *.el.gz files
>> from the installation directory, since that is what he does (again,
>> AFAIU).
>
> Maybe this is what he does.  But then it is not what I imagined:
> personally, I don't want to remove files from the installation
> directory.

That is not what I do.  As I said, what I'm looking for is:

> My suggestion, then, is that we should allow customizing Emacs to
> prefer jumping to source-directory over jumping to the installed
> copies of the Lisp files.

e.g. the installed copies of the Lisp files still exist, they just
aren't opened when jumping to the definitions.