Re: Merging native-comp and pgtk

[Andy Moreton]

On Fri 12 Feb 2021, Eli Zaretskii wrote:

>> From: Stefan Monnier <monnier@iro.umontreal.ca>
>> Date: Fri, 12 Feb 2021 13:14:08 -0500
>> 
>> Where are we w.r.t merging those two branches into `master`?
>> 
>> IIUC the plan is to include those features as "experimental" in
>> Emacs-28.1, right?  If so, I think it's becoming urgent that we merge
>> them into `master`.
>
> I don't thin it's ready yet, see my other message.
>
> (And why is it urgent?  Emacs 27.2 is not out yet, and Emacs 28 is
> supposed to have native-comp included.  So we still have quite a long
> way to go.)

For me, the native-comp branch is not yet usable on mingw64 64bit:

 - The async background compile and intrusive warnings are intrusive and
   make emacs unresponsive to user input. The async background compile
   is difficult to control (other than disabling completely), or to see
   which files are still in the queue to be compiled.

 - The AOT build ignores prebuilt .eln files due to incorrect filename
   comparison (see bug #46256), and so does an async rebuild of all .eln
   files even if AOT prebuilt files already exist. This makes the
   effects of the first problem above more severe.

 - The dependencies for building .eln files do not work. If the .elc
   file for a .el file exists, the .eln will not be built (even if the
   .eln does not exist).

On mingw64 32bit configured with "--wide":

 - the build fails: bootstrap-emacs.exe crashes when compiling lisp).
   gdb does not produce anything informative in the backtrace.

 - the "--wide" configure flag affects ABI, so should be included in the
   native-comp ABI hash identifier in .eln filenames.

As a pre-existing problem (present in master), the .elc files are built
in the source tree, rather than the build tree. That prevents doing
out-of-tree builds for different platforms/ABIs from the same source
tree.

The native-comp branch looks promising, but still needs a little more
work to make it suitable for wider use. Whether that should be done on a
development branch or after merging into master is a separate issue.

    AndyM