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Update type-layout.md

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Joshua Liebow-Feeser 2023-08-28 15:48:44 -07:00 committed by GitHub
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@ -56,17 +56,6 @@ Most primitives are generally aligned to their size, although this is
platform-specific behavior. In particular, on x86 u64 and f64 are only
aligned to 32 bits.
For every primitive numeric type (`u8`, `i8`, `u16`, `i16`, `u32`, `i32`, `u64`,
`i64`, `u128`, `i128`, `usize`, `isize`, `f32`, and `f64`), `T`, the bit validity
of `T` is equivalent to the bit validity of `[u8; size_of::<T>()]`. An
uninitialized byte is not a valid `u8`. A byte at any offset in a reference or
pointer type may not be a valid `u8` (the semantics of transmuting a reference or
pointer to a non-pointer type is currently undecided).
For `bool` and `char`, every byte is
guaranteed to be initialized (in other words, for every such type, `T`,
`transmute::<T, [u8; size_of::<T>()]>(...)` is always sound -- but the inverse is not).
## Pointers and References Layout
Pointers and references have the same layout. Mutability of the pointer or