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[Frama-c-discuss] Enforcing assigns contract with EVA/from plugin?

  • Subject: [Frama-c-discuss] Enforcing assigns contract with EVA/from plugin?
  • From: rod at (Roderick Chapman)
  • Date: Mon, 10 Jun 2019 14:47:04 +0100

Next question: is it possible to have the EVA/From plug-in report an 
error when a user-written "assigns" contract does not precisely match 
the computed dependency relation?

For example, in the code below, the "assigns" contract and the code do 
not match.

If I use -from-verify-assigns, then I get

[eva:alarm] try.c:5: Warning:
   function try: \from ... part in assign clause got status unknown 
(cannot validate direct and indirect dependencies).
[eva] done for function try
[from] entry point:
   \result FROM x; g


1. What does the first warning really mean? Why can't it validate the 

2. The reported computed dependency is correct and doesn't match the 
assigns contract. Can I get it to report an error in this case?



--- cut ---

static int g = 5;

/*@ requires x == 20;
     assigns \result \from x; // wrong - should be x, g;
int try (int x)
   int t = 0;
   int t2;
   if (x > 10)
     t = g + 1; // here is ref to g
   t2 = x - t;

   return t2;

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