Re: Enabling native compilation by default when libgccjit is present

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: Michael Heerdegen <michael_heerdegen@web.de>,  Eli Zaretskii
>  <eliz@gnu.org>,  emacs-devel@gnu.org
> Date: Wed, 08 Dec 2021 08:52:01 -0500
> 
> > But how are those warnings different from what the user will get if he
> > runs `package-install' on a package that causes warnings from the
> > byte-compiler?
> 
> - By default, package-install compiles all the new files, one after the
>   other, in the current Emacs session.  So it tends to emit fewer
>   warnings than the native compilation (which compiles each file in
>   a fresh new process) because many more packages have already been
>   loaded.  This same difference can cause the native-compiled files to
>   be miscompiled (because of a lack of `require`s) while the .elc files
>   generated during `package-install` work properly.
> 
> - Native compilation of a package kicks in when a package that has been
>   byte-compiled gets loaded in an Emacs session.
>   So the warnings emitted by native-compilation are always *in addition*
>   to the warnings that were emitted during `package-install`.
> 
> - `.eln` files are specific to a particular Emacs executable, so all the
>   `.elc` files you use will be *re*compiled to `.eln` every time you
>   start using a new Emacs executable.  For "normal" users this means
>   every time they upgrade to a new release.  For people who track
>   `master` it can mean "every other day".

There's no argument that there are more warnings with
native-compilation.  The argument is whether these warnings should
surprise people as something that "never happens otherwise".