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[Frama-c-discuss] New Version of "ACSL by Example" for Frama-C Fluorine

  • Subject: [Frama-c-discuss] New Version of "ACSL by Example" for Frama-C Fluorine
  • From: jens.gerlach at fokus.fraunhofer.de (Gerlach, Jens)
  • Date: Mon, 16 Dec 2013 11:01:03 +0000
  • In-reply-to: <mailman.39308.1387188705.1111.frama-c-discuss@lists.gforge.inria.fr>
  • References: <mailman.39308.1387188705.1111.frama-c-discuss@lists.gforge.inria.fr>
Hello Pascal and Lo?c,

thanks for discussing the additional ensures clauses of swap.
The main reason I added them is related to an incertitude I have about \valid and free.

Imagine I have a function foo with the following contract that is verified by WP.

/*@
    requires \valid(a);
    assigns \nothing;
    ensures \result == *a;
*/
int foo(int* a)
{
    return *a;
}

But what if someone provides the following implementation

int foo(int* a)
{
    int tmp = *a;
    free(a);
    return tmp;
}

Wouldn?t this implementation also satisfy the contract BUT invalidating the pointer a?
Adding the clause ?ensures \valid(a);? would in my opinion exclude the second implementation. 

Jens