[Bug c++/12963] Wrong and misleading warning encourages writing non-portable code

["jsm at polyomino dot org dot uk" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From jsm at polyomino dot org dot uk  2004-09-20 23:08 -------
Subject: Re:  Wrong and misleading warning encourages writing
 non-portable code

On Mon, 20 Sep 2004, giovannibajo at libero dot it wrote:

> Besides the consistency issue, which is a bug and should be reported elsewhere, 
> I do not understand how this encourage writing non-portable code. On the 
> contrary, it does *help* it.

A program has some data in a type such as char or uid_t which needs to be 
stored in an externally defined structure, or transmitted by an externally 
defined protocol.  This external definition imposes a limit of (say 255) 
on the value held in (say) unsigned char.  A portable program checks that 
the data is within the defined range before storing or transmitting it.  
Some checks are redundant on a particular system, so receive these 
warnings; if the warnings are to be silenced, that means removing checks 
that are not dead code on other systems.  I have encountered such problems 
(warnings that cannot effectively be silenced) in real code, both with 
system typedefs such as uid_t and user typedefs that may be configured to 
be a type such as unsigned char or a wider type.  My comment #8 still 
applies: this does not even belong in -Wall.



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12963