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addr_of on places derived from raw pointers should preserve permissions

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This commit is contained in:
Ralf Jung 2024-08-27 15:08:45 +02:00
parent 1ef4f5d924
commit b5bd0fe48a
1 changed files with 7 additions and 3 deletions
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10
library/core/src/ptr/mod.rs
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@ -2285,9 +2285,13 @@ impl<F: FnPtr> fmt::Debug for F {
/// `addr_of!(expr)` is equivalent to `&raw const expr`. The macro is *soft-deprecated*;
/// use `&raw const` instead.
///
/// It is still an open question whether writing through an `addr_of!`-created pointer is permitted
/// or not. Until that is decided, the same rules as for shared references apply: it is UB to write
/// through a pointer created with this operation, except for bytes located inside an `UnsafeCell`.
/// It is still an open question under which conditions writing through an `addr_of!`-created
/// pointer is permitted. If the place `expr` evaluates to is based on a raw pointer, then the
/// result of `addr_of!` inherits all permissions from that raw pointer. However, if the place is
/// based on a reference, local variable, or `static`, then until all details are decided, the same
/// rules as for shared references apply: it is UB to write through a pointer created with this
/// operation, except for bytes located inside an `UnsafeCell`. Use `&raw mut` (or [`addr_of_mut`])
/// to create a raw pointer that definitely permits mutation.
///
/// Creating a reference with `&`/`&mut` is only allowed if the pointer is properly aligned
/// and points to initialized data. For cases where those requirements do not hold,