GNU bug report logs - #39412
[PATCH 0/2] gnu: emacs-telega: Build with emacs-wide-int on 32-bit systems.

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From: Diego Nicola Barbato <dnbarbato <at> posteo.de>
To: 39412 <at> debbugs.gnu.org
Cc: Diego Nicola Barbato <dnbarbato <at> posteo.de>
Subject: [bug#39412] [PATCH 0/2] gnu: emacs-telega: Build with emacs-wide-int on 32-bit systems.
Date: Tue,  4 Feb 2020 10:43:51 +0100

Hi Guix,

Telega requires wide Emacs integers (62-bit), so it checks whether
`most-positive-fixnum' is equal to 2305843009213693951.  Due to a
performance penalty [0] wide Emacs integers have to be explicitly
enabled on 32-bit architectures.  Because of this `emacs-telega'
currently fails to build on armhf-linux and i686-linux.

The following two patches fix this by first adding a variant of
`emacs' with wide ints enabled and then using this `emacs-wide-int'
instead of `emacs' to build `emacs-telega' on 32-bit systems.

I am not completely happy with this solution, because wide ints are
not required to build Telega but to run it: A user installing
`emacs-telega' alongside "vanilla" `emacs' on a 32-bit machine will be
greeted with cryptic parse errors when trying to run Telega.  Would it
be enough to mention that `emacs-telega' has to be installed alongside
`emacs-wide-int' on 32-bit systems in the description?

I have chosen this approach over building the regular Emacs package
with the "--with-wide-ints" flag because I do not think the
performance penalty is justified.  What do others think?

In the long run it should be possible to drop this workaround once
Emacs 27, which introduces bignums, is released.  With those Telega
should work on 32-bit Emacs without wide ints.

Regards,

Diego

[0]: Emacs' configure.ac file talks about a 10% to 30% slowdown of the
Lisp interpreter and a larger memory footprint.

Diego Nicola Barbato (2):
  gnu: Add emacs-wide-int.
  gnu: emacs-telega: Build with emacs-wide-int on 32-bit systems.

 gnu/packages/emacs-xyz.scm |  7 ++++++-
 gnu/packages/emacs.scm     | 11 +++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

-- 
2.25.0

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