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

[Andrea Corallo]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Lars Ingebrigtsen <larsi@gnus.org>
>> Cc: stefan@marxist.se,  akrl@sdf.org,  48079@debbugs.gnu.org
>> Date: Wed, 05 May 2021 14:47:43 +0200
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> >> I guess we can't set up a signal trap to delete the temp file if we're
>> >> being interrupted?
>> >
>> > You mean, in the Makefile?  That won't handle the cases where the
>> > compilation is manually invoked (e.g., from a running Emacs).
>> 
>> I'm not actually sure -- I don't know what the possibilities at our
>> disposal are here, really.  If we can catch this in Emacs, that'd be
>> nicer...  but can we?
>
> With complicated enough code, sure, we could.
>
>> Another thing I'm wondering about is why we write the subr.elc0EdJIV
>> file at all, and then apparently don't rename it to .elc immediately?
>> It seems to linger on in that name for a very long time?  But I haven't
>> actually looked at the code here.
>
> AFAIR, we rename it atomically when we are done with it.  I guess with
> native-compilation it takes longer to "be done with it".

Exactly, we can't rename before the native compilation is done as native
compilation is a side product of byte compilation and the build system
knows only the latter.

>> So is it writing the subr.elc0EdJIV file, then doing the .eln
>> compilation, and then moving subr.elc0EdJIV to subr.elc?
>
> Yes, I think so.

Confirm.

  Andrea