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bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9
From: |
Po Lu |
Subject: |
bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9 |
Date: |
Thu, 18 May 2023 21:21:51 +0800 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
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.
>> Btw, couldn't the macro be defined to something along the lines of this
>> when the compiler only supports C99?
>>
>> #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.
- bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9, Spencer Baugh, 2023/05/17
- bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9, Eli Zaretskii, 2023/05/17
- bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9, Paul Eggert, 2023/05/17
- bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9, Paul Eggert, 2023/05/18
- bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9, Po Lu, 2023/05/18
- bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9, Paul Eggert, 2023/05/18
- bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9, Po Lu, 2023/05/18
bug#63556: 29.0.90; Use of _Generic breaks Emacs build on GCC <4.9, Paul Eggert, 2023/05/18