bug#37527: [PATCH] Install C source code for for debugging help

[Eli Zaretskii <eliz@gnu.org>]

> Cc: stefan@marxist.se, michael.albinus@gmx.de, rgm@gnu.org,
>  37527@debbugs.gnu.org
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Thu, 23 Jan 2020 00:58:11 -0800
> 
> On 1/21/20 7:31 PM, Eli Zaretskii wrote:
> > Then I still think an additional variable might be a better solution,
> > because the original source tree might still exist, and so losing the
> > information about its location would be a disadvantage.
> 
> ? The code in question does not lose information about the location of the 
> original source tree. On the contrary, it supplies that information.

If the source tree still exists, the information is already available,
it is recorded at build time.

> If you're suggesting that every installed Emacs should contain a string pointing 
> to where it was built, I'm not sure that's a good idea. Generally speaking, 
> builds should be reproducible and build products should not contain unimportant 
> information about the build (such as timestamps and whatnot) as that makes it 
> harder to reproduce them later.

Reproducible builds is a separate issue; in a reproducible build no
directories should be recorded at build time.  Let's consider builds
that aren't meant to be reproducible.

Let me turn the table and ask: if Emacs was installed with the
sources, but the original source tree where it was built still exists,
where will source-directory point after your changes?  Will it point
to the installed sources or to the original source tree?