Add safety preconditions to alloc/src/boxed/thin.rs #119
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Note that I've added `#[requires]` attributes to represent the safety conditions as code contracts. These are based on the "SAFETY:" comments in the original code. The conditions are: 1. For `with_header`, we require that the pointer is aligned. 2. For `drop`, we require that the value pointer is either null or aligned. 3. For `header`, we require that the pointer is aligned. These contracts ensure that the safety conditions mentioned in the comments are checked at compile-time or runtime, depending on the contract system used.
tautschnig
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Just as previously done for core: this will enable future use of
`safety::{ensures,requires}` in those crates.
These have SAFETY comments explaining why their `unsafe` sections are indeed safe, but the overall function should be safe for all inputs.
celinval
reviewed
Oct 17, 2024
| @@ -363,6 +369,8 @@ impl<H> WithHeader<H> { | |||
| // Safety: | |||
| // - Assumes that either `value` can be dereferenced, or is the | |||
| // `NonNull::dangling()` we use when both `T` and `H` are ZSTs. | |||
| #[requires((mem::size_of_val_raw(value) == 0 && size_of::<H>() == 0) || | |||
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We're still missing the safety of self for type T.
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Note that I've added
#[requires]attributes to represent the safety conditions as code contracts. These are based on the "SAFETY:" comments in the original code. The conditions are:with_header, we require that the pointer is aligned.drop, we require that the value pointer is either null or aligned.header, we require that the pointer is aligned.These contracts ensure that the safety conditions mentioned in the comments are checked at compile-time or runtime, depending on the contract system used.