From: Eli Zaretskii <eliz@gnu.org>
To: Po Lu <luangruo@yahoo.com>
Cc: sbaugh@janestreet.com, eggert@cs.ucla.edu, 63556@debbugs.gnu.org
Subject: bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9
Date: Thu, 18 May 2023 17:12:27 +0300 [thread overview]
Message-ID: <83r0rdvid0.fsf@gnu.org> (raw)
In-Reply-To: <87r0rd4vww.fsf@yahoo.com> (message from Po Lu on Thu, 18 May 2023 21:21:51 +0800)
> From: Po Lu <luangruo@yahoo.com>
> Cc: eggert@cs.ucla.edu, sbaugh@janestreet.com, 63556@debbugs.gnu.org
> Date: Thu, 18 May 2023 21:21:51 +0800
>
> Eli Zaretskii <eliz@gnu.org> writes:
>
> > Depends on how complex is that, and what problem does it solve.
>
> The problem of using `long long' on systems with less than 64
> significant bits in their words. I don't think that's a particularly
> good idea -- once such uses pile up, Emacs will gradually become slower
> and slower on such systems.
What does this have to do with _Generic?
> >> #define foo(expression) \
> >> (sizeof (expression) == sizeof (signed char) \
> >> ? code_for_signed_char \
> >> : (sizeof (expression) == sizeof (short int) \
> >> ? code_for_short_int \
> >> : (sizeof (expression) == sizeof (int) \
> >> ? code_for_int \
> >> ... and so on
> >
> > AFAIR, sizeof is a compile-time expression, the preprocessor cannot
> > evaluate it.
>
> It doesn't have to be evaluated by the preprocessor (and nor is
> _Generic.) It just needs to expand to an expression that does the right
> thing.
And what is "the right thing" in this case?
I guess I don't understand what this has to do with _Generic.
next prev parent reply other threads:[~2023-05-18 14:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-17 17:38 bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9 Spencer Baugh
2023-05-17 17:45 ` Eli Zaretskii
2023-05-17 17:57 ` Paul Eggert
2023-05-18 11:11 ` Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-05-18 11:42 ` Eli Zaretskii
2023-05-18 13:21 ` Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-05-18 14:12 ` Eli Zaretskii [this message]
2023-05-18 14:40 ` Paul Eggert
2023-05-19 0:46 ` Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-05-19 3:05 ` Paul Eggert
2023-05-19 3:18 ` Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-05-18 20:32 ` Paul Eggert
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