On Sat, Dec 23, 2017 at 3:44 AM, Rocky Bernstein <rocky@gnu.org> wrote:

>
> Path names give you good places to start looking for the file.
>
> And often they can quickly give information as to what's up, e.g. I am
> running  from the stable or development branch. Or running from an Ubuntu
> build or a source-code build.
>

​If you are actually running a branch of Emacs and using a .elc file
included therein, then ​your load-path should be configured to take you to
the proper associated source file with the find-library command, unless
filenames are duplicated within the lisp tree.  Only uses outside of that,
i.e. working on files outside of the branch you are running, would this be
an issue, I would think, or if there ever is a bundled format of .elc that
combines the byte-compiled output of multiple files.

If anything of this nature is ever done, it should be based on the source
file's default installed location relative to the Emacs root directory for
portability.  Any reasonable function/tool could then find the source file.

Bob