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Use box in shadow memory test for reliable object count #3380

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Use box in shadow memory test for reliable object count #3380

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10 changes: 5 additions & 5 deletions tests/expected/shadow/unsupported_num_objects/test.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,14 +15,14 @@ fn check_max_objects<const N: usize>() {
// - the NULL pointer whose object ID is 0, and
// - the object ID for `i`
while i < N {
let x = i;
assert_eq!(kani::mem::pointer_object(&x as *const usize), i + 2);
let x: Box<usize> = Box::new(i);
assert_eq!(kani::mem::pointer_object(&*x as *const usize), 2 * i + 2);
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@zhassan-aws zhassan-aws Jul 24, 2024

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What is the reason for the multiplication by 2? Is there an object for the box and another for the variable x? If so, would inlining the Box:new operation in the assert remove the doubling?

i += 1;
}

// create a new object whose ID is `N` + 2
let x = 42;
assert_eq!(kani::mem::pointer_object(&x as *const i32), N + 2);
assert_eq!(kani::mem::pointer_object(&x as *const i32), 2 * N + 2);
// the following call to `set` would fail if the object ID for `x` exceeds
// the maximum allowed by Kani's shadow memory model
unsafe {
Expand All @@ -32,10 +32,10 @@ fn check_max_objects<const N: usize>() {

#[kani::proof]
fn check_max_objects_pass() {
check_max_objects::<1021>();
check_max_objects::<510>();
}

#[kani::proof]
fn check_max_objects_fail() {
check_max_objects::<1022>();
check_max_objects::<511>();
}