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[WIP][pointer] Support generic TransmuteFrom
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Makes progress on #1122

gherrit-pr-id: I7af68cdaa5ea47ab245a942d1cbd8bc5e6407223
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@joshlf
joshlf committed Oct 18, 2024
1 parent ac629d9 commit af10d3d
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Showing 7 changed files with 822 additions and 469 deletions.
78 changes: 39 additions & 39 deletions src/impls.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -443,13 +443,13 @@ mod atomics {
use super::*;

macro_rules! impl_traits_for_atomics {
($($atomics:ident),* $(,)?) => {
($($atomics:ident[$repr:ty]),* $(,)?) => {
$(
impl_known_layout!($atomics);
impl_for_transparent_wrapper!(=> TryFromBytes for $atomics);
impl_for_transparent_wrapper!(=> FromZeros for $atomics);
impl_for_transparent_wrapper!(=> FromBytes for $atomics);
impl_for_transparent_wrapper!(=> IntoBytes for $atomics);
impl_for_transmute_from!(=> TryFromBytes for $atomics[UnsafeCell<$repr>]);
impl_for_transmute_from!(=> FromZeros for $atomics[UnsafeCell<$repr>]);
impl_for_transmute_from!(=> FromBytes for $atomics[UnsafeCell<$repr>]);
impl_for_transmute_from!(=> IntoBytes for $atomics[UnsafeCell<$repr>]);
)*
};
}
Expand All @@ -461,13 +461,13 @@ mod atomics {

use super::*;

impl_traits_for_atomics!(AtomicU8, AtomicI8);
impl_traits_for_atomics!(AtomicU8[u8], AtomicI8[i8]);

impl_known_layout!(AtomicBool);

impl_for_transparent_wrapper!(=> TryFromBytes for AtomicBool);
impl_for_transparent_wrapper!(=> FromZeros for AtomicBool);
impl_for_transparent_wrapper!(=> IntoBytes for AtomicBool);
impl_for_transmute_from!(=> TryFromBytes for AtomicBool[UnsafeCell<bool>]);
impl_for_transmute_from!(=> FromZeros for AtomicBool[UnsafeCell<bool>]);
impl_for_transmute_from!(=> IntoBytes for AtomicBool[UnsafeCell<bool>]);

safety_comment! {
/// SAFETY:
Expand Down Expand Up @@ -497,7 +497,7 @@ mod atomics {
/// SAFETY:
/// All of these pass an atomic type and that type's native equivalent, as
/// required by the macro safety preconditions.
unsafe_impl_transparent_wrapper_for_atomic!(AtomicU8 [u8], AtomicI8 [i8], AtomicBool [bool]);
unsafe_impl_transmute_from_for_atomic!(AtomicU8 [u8], AtomicI8 [i8], AtomicBool [bool]);
}
}

Expand All @@ -508,13 +508,13 @@ mod atomics {

use super::*;

impl_traits_for_atomics!(AtomicU16, AtomicI16);
impl_traits_for_atomics!(AtomicU16[u16], AtomicI16[i16]);

safety_comment! {
/// SAFETY:
/// All of these pass an atomic type and that type's native equivalent, as
/// required by the macro safety preconditions.
unsafe_impl_transparent_wrapper_for_atomic!(AtomicU16 [u16], AtomicI16 [i16]);
unsafe_impl_transmute_from_for_atomic!(AtomicU16 [u16], AtomicI16 [i16]);
}
}

Expand All @@ -525,13 +525,13 @@ mod atomics {

use super::*;

impl_traits_for_atomics!(AtomicU32, AtomicI32);
impl_traits_for_atomics!(AtomicU32[u32], AtomicI32[i32]);

safety_comment! {
/// SAFETY:
/// All of these pass an atomic type and that type's native equivalent, as
/// required by the macro safety preconditions.
unsafe_impl_transparent_wrapper_for_atomic!(AtomicU32 [u32], AtomicI32 [i32]);
unsafe_impl_transmute_from_for_atomic!(AtomicU32 [u32], AtomicI32 [i32]);
}
}

Expand All @@ -542,13 +542,13 @@ mod atomics {

use super::*;

impl_traits_for_atomics!(AtomicU64, AtomicI64);
impl_traits_for_atomics!(AtomicU64[u64], AtomicI64[i64]);

safety_comment! {
/// SAFETY:
/// All of these pass an atomic type and that type's native equivalent, as
/// required by the macro safety preconditions.
unsafe_impl_transparent_wrapper_for_atomic!(AtomicU64 [u64], AtomicI64 [i64]);
unsafe_impl_transmute_from_for_atomic!(AtomicU64 [u64], AtomicI64 [i64]);
}
}

Expand All @@ -559,21 +559,21 @@ mod atomics {

use super::*;

impl_traits_for_atomics!(AtomicUsize, AtomicIsize);
impl_traits_for_atomics!(AtomicUsize[usize], AtomicIsize[isize]);

impl_known_layout!(T => AtomicPtr<T>);

// TODO(#170): Implement `FromBytes` and `IntoBytes` once we implement
// those traits for `*mut T`.
impl_for_transparent_wrapper!(T => TryFromBytes for AtomicPtr<T>);
impl_for_transparent_wrapper!(T => FromZeros for AtomicPtr<T>);
impl_for_transmute_from!(T => TryFromBytes for AtomicPtr<T>[UnsafeCell<*mut T>]);
impl_for_transmute_from!(T => FromZeros for AtomicPtr<T>[UnsafeCell<*mut T>]);

safety_comment! {
/// SAFETY:
/// This passes an atomic type and that type's native equivalent, as
/// required by the macro safety preconditions.
unsafe_impl_transparent_wrapper_for_atomic!(AtomicUsize [usize], AtomicIsize [isize]);
unsafe_impl_transparent_wrapper_for_atomic!(T => AtomicPtr<T> [*mut T]);
unsafe_impl_transmute_from_for_atomic!(AtomicUsize [usize], AtomicIsize [isize]);
unsafe_impl_transmute_from_for_atomic!(T => AtomicPtr<T> [*mut T]);
}
}
}
Expand Down Expand Up @@ -603,12 +603,12 @@ safety_comment! {
assert_unaligned!(PhantomData<()>, PhantomData<u8>, PhantomData<u64>);
}

impl_for_transparent_wrapper!(T: Immutable => Immutable for Wrapping<T>);
impl_for_transparent_wrapper!(T: TryFromBytes => TryFromBytes for Wrapping<T>);
impl_for_transparent_wrapper!(T: FromZeros => FromZeros for Wrapping<T>);
impl_for_transparent_wrapper!(T: FromBytes => FromBytes for Wrapping<T>);
impl_for_transparent_wrapper!(T: IntoBytes => IntoBytes for Wrapping<T>);
impl_for_transparent_wrapper!(T: Unaligned => Unaligned for Wrapping<T>);
impl_for_transmute_from!(T: Immutable => Immutable for Wrapping<T>[T]);
impl_for_transmute_from!(T: TryFromBytes => TryFromBytes for Wrapping<T>[T]);
impl_for_transmute_from!(T: FromZeros => FromZeros for Wrapping<T>[T]);
impl_for_transmute_from!(T: FromBytes => FromBytes for Wrapping<T>[T]);
impl_for_transmute_from!(T: IntoBytes => IntoBytes for Wrapping<T>[T]);
impl_for_transmute_from!(T: Unaligned => Unaligned for Wrapping<T>[T]);
assert_unaligned!(Wrapping<()>, Wrapping<u8>);

safety_comment! {
Expand All @@ -620,22 +620,22 @@ safety_comment! {
unsafe_impl!(T => FromBytes for MaybeUninit<T>);
}

impl_for_transparent_wrapper!(T: Immutable => Immutable for MaybeUninit<T>);
impl_for_transparent_wrapper!(T: Unaligned => Unaligned for MaybeUninit<T>);
impl_for_transmute_from!(T: Immutable => Immutable for MaybeUninit<T>[T]);
impl_for_transmute_from!(T: Unaligned => Unaligned for MaybeUninit<T>[T]);
assert_unaligned!(MaybeUninit<()>, MaybeUninit<u8>);

impl_for_transparent_wrapper!(T: ?Sized + Immutable => Immutable for ManuallyDrop<T>);
impl_for_transparent_wrapper!(T: ?Sized + TryFromBytes => TryFromBytes for ManuallyDrop<T>);
impl_for_transparent_wrapper!(T: ?Sized + FromZeros => FromZeros for ManuallyDrop<T>);
impl_for_transparent_wrapper!(T: ?Sized + FromBytes => FromBytes for ManuallyDrop<T>);
impl_for_transparent_wrapper!(T: ?Sized + IntoBytes => IntoBytes for ManuallyDrop<T>);
impl_for_transparent_wrapper!(T: ?Sized + Unaligned => Unaligned for ManuallyDrop<T>);
impl_for_transmute_from!(T: ?Sized + Immutable => Immutable for ManuallyDrop<T>[T]);
impl_for_transmute_from!(T: ?Sized + TryFromBytes => TryFromBytes for ManuallyDrop<T>[T]);
impl_for_transmute_from!(T: ?Sized + FromZeros => FromZeros for ManuallyDrop<T>[T]);
impl_for_transmute_from!(T: ?Sized + FromBytes => FromBytes for ManuallyDrop<T>[T]);
impl_for_transmute_from!(T: ?Sized + IntoBytes => IntoBytes for ManuallyDrop<T>[T]);
impl_for_transmute_from!(T: ?Sized + Unaligned => Unaligned for ManuallyDrop<T>[T]);
assert_unaligned!(ManuallyDrop<()>, ManuallyDrop<u8>);

impl_for_transparent_wrapper!(T: ?Sized + FromZeros => FromZeros for UnsafeCell<T>);
impl_for_transparent_wrapper!(T: ?Sized + FromBytes => FromBytes for UnsafeCell<T>);
impl_for_transparent_wrapper!(T: ?Sized + IntoBytes => IntoBytes for UnsafeCell<T>);
impl_for_transparent_wrapper!(T: ?Sized + Unaligned => Unaligned for UnsafeCell<T>);
impl_for_transmute_from!(T: ?Sized + FromZeros => FromZeros for UnsafeCell<T>[T]);
impl_for_transmute_from!(T: ?Sized + FromBytes => FromBytes for UnsafeCell<T>[T]);
impl_for_transmute_from!(T: ?Sized + IntoBytes => IntoBytes for UnsafeCell<T>[T]);
impl_for_transmute_from!(T: ?Sized + Unaligned => Unaligned for UnsafeCell<T>[T]);
assert_unaligned!(UnsafeCell<()>, UnsafeCell<u8>);

// SAFETY: See safety comment in `is_bit_valid` impl.
Expand Down
2 changes: 1 addition & 1 deletion src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2720,7 +2720,7 @@ unsafe fn try_read_from<S, T: TryFromBytes>(
// We use `from_mut` despite not mutating via `c_ptr` so that we don't need
// to add a `T: Immutable` bound.
let c_ptr = Ptr::from_mut(&mut candidate);
let c_ptr = c_ptr.transparent_wrapper_into_inner();
let c_ptr = c_ptr.transmute::<_, pointer::transmute::BecauseBidirectional>();
// SAFETY: `c_ptr` has no uninitialized sub-ranges because it derived from
// `candidate`, which the caller promises is entirely initialized.
let c_ptr = unsafe { c_ptr.assume_validity::<invariant::Initialized>() };
Expand Down
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