Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date: Thu, 15 Mar 2018 18:38:01 -0400
From: Rich Felker <>
Subject: Re: Re: #define __MUSL__ in features.h

On Thu, Mar 15, 2018 at 10:46:56PM +0100, Szabolcs Nagy wrote:
> * Rich Felker <> [2018-03-15 15:32:44 -0400]:
> > Perhaps this should be documented more explicitly, but there is no
> > guarantee that building with -Werror[=anything except warnings which
> > are constraint violations in C] will succeed, especially when GCC is
> > not honoring its usual promise not to produce warnings for code
> > expanded from macros from -isystem paths. I did just test and indeed
> > the warning is produced with gcc 6.3.0.
> > 
> how did you reproduce it? -Wsign-conversion (or -Wconversion)
> is not even enabled by

Manually using -Wsign-conversion with the attached program.

> what would be acceptable is some form of assertion that the
> fd must be positive, however it seems nobody cares about this
> warning so neither gcc nor clang tries to use available range
> information to see if conversion can ever change the result:
>   if (d > 0) FD_SET(d,s);
> still warns.

This basically settles it that it's a buggy warning option.

> if users care about this warning they should first make
> sure the compilers dont emit false positives for such
> trivial cases.



View attachment "signed-conversion.c" of type "text/plain" (112 bytes)

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.