From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: wempwer@gmail.com
Cc: gcc-help <gcc-help@gcc.gnu.org>
Subject: Re: how to make gcc warn about arithmetic signed overflow
Date: Sat, 21 Sep 2013 18:30:00 -0000 [thread overview]
Message-ID: <CAH6eHdQzJNQY4Meysi259RheSaGscKUF28OW43OvOD1rf6FkxQ@mail.gmail.com> (raw)
In-Reply-To: <20130921174229.GD3086@a.lan>
On 21 September 2013 18:42, <wempwer@gmail.com> wrote:
>
> Hmm, I don't know too much about C++ but why would a C++ compiler
> produce a warning only if two operands were const? I learned that in C
> `const' modifier only means that I promise to the compiler that this
> variable will be read-only,
So the compiler knows that the values of ab and bc, because they must
always have the values they were initialized with.
If the compiler was smarter it would be able to also warn for
non-const values if it can prove that nothing has modified the
variables since they were initialized.
> its value can be changed using pointers
No, that's not true. You can't change the value of a const object in a
valid program.
> but the result is undefined and that const != constant expression.
In C++ a const of integral type is a constant expression.
next prev parent reply other threads:[~2013-09-21 18:30 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-21 16:45 wempwer
2013-09-21 17:24 ` Jonathan Wakely
2013-09-21 17:41 ` wempwer
2013-09-21 18:30 ` Jonathan Wakely [this message]
2013-09-21 18:50 ` wempwer
2013-09-21 19:55 ` Jędrzej Dudkiewicz
2013-09-21 20:16 ` wempwer
2013-09-21 20:52 ` Jędrzej Dudkiewicz
2013-09-21 21:07 ` wempwer
2013-09-23 4:04 ` James K. Lowden
2013-09-23 7:55 ` Jonathan Wakely
2013-09-23 15:47 ` James K. Lowden
2013-09-23 21:50 ` Jonathan Wakely
2013-09-23 22:44 ` James K. Lowden
2013-09-23 23:20 ` Jonathan Wakely
2013-09-23 19:38 ` Dave Allured - NOAA Affiliate
2013-09-23 19:43 ` Oleg Endo
2013-09-23 20:37 ` Dave Allured - NOAA Affiliate
2013-09-23 19:48 ` Andrew Haley
2013-09-23 22:00 ` James K. Lowden
2013-09-24 17:48 ` Andrew Haley
2013-09-26 2:30 ` James K. Lowden
2013-09-26 8:29 ` Vincent Lefevre
2013-09-26 14:49 ` Andrew Haley
2013-09-26 17:03 ` Vincent Lefevre
2013-09-26 18:19 ` Andrew Haley
2013-09-27 7:58 ` Vincent Lefevre
2013-09-27 8:23 ` Andrew Haley
2013-09-27 9:28 ` Vincent Lefevre
2013-09-27 9:43 ` Andrew Haley
2013-09-26 17:41 ` Andrew Haley
2013-09-24 7:42 ` Brian Drummond
2013-09-21 17:53 ` Marc Glisse
2013-09-21 18:09 ` wempwer
2013-09-21 18:27 ` Jonathan Wakely
2013-09-21 19:32 ` wempwer
2013-09-22 15:52 ` Jonathan Wakely
2013-09-23 13:04 ` David Brown
2013-09-21 17:36 ` Brian Drummond
2013-09-21 17:45 ` wempwer
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