--- layout: fc_discuss_archives title: Message 6 from Frama-C-discuss on November 2009 ---
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[Frama-c-discuss] Feature or bug?



Jens Gerlach a ?crit :

> However, all provers "proof" that for the second case the precondition 
> is fulfilled (see below).
> Is this behaviour of Jessie intended?

Yes. If you check which property is being sent to the provers on the 
right panel of Jessie/Why, you will notice that 0 <= -1 is part of the 
hypotheses. So it is fortunate that all the provers are able to prove 0 
<= -1, given this hypothesis.

Now, why is this false hypothesis part of the context? Because all 
previous preconditions and postconditions are assumed to be true when 
proving subsequent properties. In other words, it behaves as if you had 
written:

void bar()
{
     //@ assert 0 <= -1;
     foo(-2);
}

Regards,

Guillaume