how to make gcc warn about arithmetic signed overflow

Andrew Haley aph@redhat.com
Thu Sep 26 18:19:00 GMT 2013


On 09/26/2013 06:02 PM, Vincent Lefevre wrote:
> On 2013-09-26 15:49:05 +0100, Andrew Haley wrote:
>> On 09/26/2013 09:29 AM, Vincent Lefevre wrote:
>>> On 2013-09-25 22:29:58 -0400, James K. Lowden wrote:
>>>> You mean that a naïve rendering of the source code implies an overflow
>>>> where none might exist in the actual emitted object code.  And,
>>>> presumably, the converse: that even if the source is written such that
>>>> there logically can't be an overflow, the compiler might render object
>>>> code that does.
>>>
>>> The converse is forbidden.
>>
>> You'll find it hard to justify that by any language in the standard.
> 
> What do you mean?

There is no reason why a compiler should not generate an overflow
where none is written in the program, as long as it doesn't generate
a different result.

Andrew.



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