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Update comment on pointer-to-usize transmute

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Co-authored-by: Ralf Jung <post@ralfj.de>
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Lukas 2022-11-16 15:08:35 +01:00 committed by Lukas Markeffsky
parent 3d7e9c4b7f
commit e90d15b247
1 changed files with 4 additions and 3 deletions
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7
library/core/src/ptr/mod.rs
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@ -1652,9 +1652,10 @@ pub unsafe fn write_volatile<T>(dst: *mut T, src: T) {
let stride = mem::size_of::<T>(); let stride = mem::size_of::<T>();
// SAFETY: At runtime, transmuting a pointer to `usize` is always safe, because they have the // SAFETY: This is just an inlined `p.addr()` (which is not
// same layout. During const eval, we hook this function to ensure that the pointer always has // a `const fn` so we cannot call it).
// an address (only the standard library can do this). // During const eval, we hook this function to ensure that the pointer never
// has provenance, making this sound.
let addr: usize = unsafe { mem::transmute(p) }; let addr: usize = unsafe { mem::transmute(p) };
// SAFETY: `a` is a power-of-two, therefore non-zero. // SAFETY: `a` is a power-of-two, therefore non-zero.