Re: Finalizing 'inhibit-automatic-native-compilation'

[Eli Zaretskii]

> From: Stephen Leake <stephen_leake@stephe-leake.org>
> Cc: emacs-devel@gnu.org,  Andrea Corallo <akrl@sdf.org>,  Lars Ingebrigtsen
>  <larsi@gnus.org>,  Stefan Monnier <monnier@iro.umontreal.ca>,  Rob
>  Browning <rlb@defaultvalue.org>
> Date: Fri, 27 Jan 2023 15:11:18 -0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Here are the questions I think we want to be answered to finalize the
> > implementation and effects of 'inhibit-automatic-native-compilation':
> >
> >   . Do people actually use 'inhibit-automatic-native-compilation' or
> >     the corresponding environment variable?  If so, for what reasons,
> >     and why tweaking 'native-comp-eln-load-path' to direct the *.eln
> >     files to some other place, including the temporary-file directory,
> >     was not enough?
> 
> I do.
> 
> When running Emacs ada-mode tests, I spawn lots of Emacsen. If each one
> tries to native compile stuff, it just slows down the tests.
> 
> I could try to ensure the stuff is native compiled first, but that's a
> maintenance burden.

Disabling async native-compilation was supported before we introduced
this variable (via native-comp-deferred-compilation) and will continue
being supported, for several valid reasons.  Removing that capability
is not on the table.

I understand that if inhibiting native-compilation would still produce
trampolines in the rare cases where they are needed, it will not do
any significant harm to your use case, is that right?

> >   . What do we want to do about compiling trampolines when
> >     native-compilation is disabled?
> 
> What is the name of the "temporary directory" that is not deleted on
> Windows? I can check it see if is created when I run my tests.

It's the system temporary directory, the one that's the value of
temporary-file-directory.  And it isn't the directory that is not
deleted, it's the comp-lambda-*.eln files (and maybe also *.eln files
under different names, like *--trampoline-*.eln) in that directory.

> >   . Do we want to keep the EMACS_INHIBIT_AUTOMATIC_NATIVE_COMPILATION
> >     environment variable?
> 
> I don't need this for my use case.

Thanks for the feedback.