bug#43725: 28.0.50; Include feature/native-comp into master

[Andrea Corallo]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Andrea Corallo <akrl@sdf.org>
>> Cc: larsi@gnus.org, monnier@iro.umontreal.ca, 43725@debbugs.gnu.org
>> Date: Wed, 10 Mar 2021 15:45:49 +0000
>> 
>> this is not expected and I cannot reproduce it here.
>
> OK, so just to be sure we are taking about the same scenario:
>
>   . I touch comp.el while a comp-NNNNN.eln already exists in
>     ~/.emacs.d/eln-cache.
>   . I then start "emacs -Q" and invoke "C-h f" for some function whose
>     .el file doesn't yet have a .eln file.  For example,
>
>         C-h f ruler-mode RET
>
>   . What I see next is that Emacs starts compiling in the background,
>     and I later find that both ruler-mode.el and comp.el have been
>     natively-compiled.
>
> Hmmm... now I see that it doesn't happen every time.  So I guess some
> additional factor is at work here, indeed.
>
>> The file is hashed using the content + its filename so access and
>> modification times should not come into play.  Are we sure the file
>> content wasn't modified?
>
> The file wasn't modified, that's for sure.
>
>> Or we might be possibly looking at different issue here.
>
> Probably.  I'll try to step through the code, but could you give me
> some pointers: where do we decide whether to native-compile a file
> that we load?

The triggering point we are interested in here should be
'maybe_defer_native_compilation' (called by 'Fdefalias').

Thanks

  Andrea