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Re: [PATCH] sys/types.h: Avoid bit-manipulation of signed values

From: Corinna Vinschen <vinschen at redhat dot com>
To: newlib at sourceware dot org
Date: Thu, 12 Nov 2015 13:57:02 +0100
Subject: Re: [PATCH] sys/types.h: Avoid bit-manipulation of signed values
Authentication-results: sourceware.org; auth=none
References: <1447301487 dot 1005 dot 12 dot camel at anu dot edu dot au> <1447301650 dot 1005 dot 14 dot camel at anu dot edu dot au>
Reply-to: newlib at sourceware dot org

On Nov 12 15:14, Nick Withers wrote:
> Sorry, let's try that again...
> 
> On Thu, 2015-11-12 at 15:11 +1100, Nick Withers wrote:
> > Hi all,
> > 
> > The patch below attempts to resolve potential undefined behaviour in
> > bit-manipulation in the FD_* macros, also clearing up the GCC warning
> > "conversion to 'unsigned int' from 'int' may change the sign of the
> > result" with -Wsign-conversion and an int FD parameter.

Sorry if I'm dense, but... all these macros (NBBY, FD_SETSIZE, howmany)
are defined using int values, not unsigned int values, in glibc and
everywhere else, e.g. X11/Xpoll.h, python2.7/pyport.h, etc.  I don't
think we should use different definitions which potentially collide.

Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
Red Hat

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Follow-Ups:
- Re: [PATCH] sys/types.h: Avoid bit-manipulation of signed values
  - From: Nick Withers

References:
- [PATCH] sys/types.h: Avoid bit-manipulation of signed values
  - From: Nick Withers
- Re: [PATCH] sys/types.h: Avoid bit-manipulation of signed values
  - From: Nick Withers

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