bug#48079: Temporary files while building after native-comp merge

[Andrea Corallo via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Andrea Corallo <akrl@sdf.org>
>> Cc: Stefan Kangas <stefan@marxist.se>, 48079@debbugs.gnu.org
>> Date: Thu, 29 Apr 2021 08:19:31 +0000
>> 
>> > Do you have some kind of auto-revert feature turned on?  If not, how
>> > come magit-status even knows these files are created?
>> 
>> I believe he's referring to a new invocation of `magit-status' while
>> compilation is happening.
>
> Btw, what is the reason that these temporary *.elc files live longer
> with the native compilation?

Yes, essentially just the fact that compilation takes longer.

When we compile Emacs the makefile uses
`batch-byte-native-compile-for-bootstrap' to produce both the .elc and
the .eln.  As the eln is produced as side product of the .elc to have
the makefile dependecy model work we can't rename the .elc before the
.eln is also finished even if we could, otherwise in case of
interruption we may have the .elc produced but not the .eln.

  Andrea

> Does the native compilation need the
> *.elc file for its processing?  If not, perhaps we could rename or
> delete them earlier?
>