From: Alexander Monakov <amonakov@ispras.ru>
To: musl@lists.openwall.com
Subject: Re: [musl] Musl's FD_{SET,ISSET,CLR} macros from sys/select.h trigger gcc's -Wsign-conversion warnings
Date: Sun, 2 Aug 2020 21:53:19 +0300 (MSK) [thread overview]
Message-ID: <alpine.LNX.2.20.13.2008022148160.2454@monopod.intra.ispras.ru> (raw)
In-Reply-To: <959b7861-f028-02cc-5226-d7116aab8e2b@gmail.com>
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On Sun, 2 Aug 2020, Petr Skocik wrote:
> #define FD_SET(d, s) ((s)->fds_bits[(d)/(8*(int)sizeof(long))] |=
> (1UL<<((d)%(8*(int)sizeof(long)))))
> #define FD_CLR(d, s) ((s)->fds_bits[(d)/(8*(int)sizeof(long))] &=
> ~(1UL<<((d)%(8*(int)sizeof(long)))))
> #define FD_ISSET(d, s) !!((s)->fds_bits[(d)/(8*(int)sizeof(long))] &
> (1UL<<((d)%(8*(int)sizeof(long)))))
>
> You might want to add them.
(casting 'd' to size_t would have been more appropriate, as there's no need
to perform signed division and modulus here)
This is one of the cases where the warning should have been suppressed by
GCC unless -Wsystem-headers is also given: the problem appears when expanding
a macro defined in a system header, so the user can't cleanly avoid it.
Would you care to open an issue in the GCC Bugzilla about it?
Alexander
next prev parent reply other threads:[~2020-08-02 18:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-02 18:24 Petr Skocik
2020-08-02 18:53 ` Alexander Monakov [this message]
2020-08-02 18:56 ` Alexander Monakov
2020-08-02 19:43 ` Petr Skocik
2020-08-03 5:43 ` Markus Wichmann
2020-08-03 17:47 ` Rich Felker
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