52 lines
1.5 KiB
Rust
52 lines
1.5 KiB
Rust
use std::mem::MaybeUninit;
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use std::ptr::NonNull;
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#[test]
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fn unitialized_zero_size_box() {
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assert_eq!(
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&*Box::<()>::new_uninit() as *const _,
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NonNull::<MaybeUninit<()>>::dangling().as_ptr(),
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);
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assert_eq!(
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Box::<[()]>::new_uninit_slice(4).as_ptr(),
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NonNull::<MaybeUninit<()>>::dangling().as_ptr(),
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);
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assert_eq!(
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Box::<[String]>::new_uninit_slice(0).as_ptr(),
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NonNull::<MaybeUninit<String>>::dangling().as_ptr(),
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);
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}
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#[derive(Clone, PartialEq, Eq, Debug)]
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struct Dummy {
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_data: u8,
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}
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#[test]
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fn box_clone_and_clone_from_equivalence() {
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for size in (0..8).map(|i| 2usize.pow(i)) {
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let control = vec![Dummy { _data: 42 }; size].into_boxed_slice();
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let clone = control.clone();
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let mut copy = vec![Dummy { _data: 84 }; size].into_boxed_slice();
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copy.clone_from(&control);
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assert_eq!(control, clone);
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assert_eq!(control, copy);
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}
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}
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/// This test might give a false positive in case the box realocates, but the alocator keeps the
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/// original pointer.
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///
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/// On the other hand it won't give a false negative, if it fails than the memory was definitly not
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/// reused
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#[test]
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fn box_clone_from_ptr_stability() {
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for size in (0..8).map(|i| 2usize.pow(i)) {
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let control = vec![Dummy { _data: 42 }; size].into_boxed_slice();
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let mut copy = vec![Dummy { _data: 84 }; size].into_boxed_slice();
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let copy_raw = copy.as_ptr() as usize;
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copy.clone_from(&control);
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assert_eq!(copy.as_ptr() as usize, copy_raw);
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}
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}
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