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Implement Strict on pointers to unsized types. #15

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Implement Strict on pointers to unsized types. #15

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96ef55b
Implement Strict on pointers to unsized types.
remexre Oct 7, 2023
7a2dc5d
Remove Sized bounds on methods that can be implemented without it sta…
remexre Oct 7, 2023
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46 changes: 15 additions & 31 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -502,7 +502,7 @@ mod private {
}

pub trait Strict: private::Sealed {
type Pointee;
type Pointee: ?Sized;
/// Gets the "address" portion of the pointer.
///
/// This is similar to `self as usize`, which semantically discards *provenance* and
Expand All @@ -527,9 +527,7 @@ pub trait Strict: private::Sealed {
/// might change in the future (including possibly weakening this so it becomes wholly
/// equivalent to `self as usize`). See the [module documentation][crate] for details.
#[must_use]
fn addr(self) -> usize
where
Self::Pointee: Sized;
fn addr(self) -> usize;

/// Gets the "address" portion of the pointer, and 'exposes' the "provenance" part for future
/// use in [`from_exposed_addr`][].
Expand All @@ -556,9 +554,7 @@ pub trait Strict: private::Sealed {
///
/// [`from_exposed_addr`]: crate::from_exposed_addr
#[must_use]
fn expose_addr(self) -> usize
where
Self::Pointee: Sized;
fn expose_addr(self) -> usize;

/// Creates a new pointer with the given address.
///
Expand Down Expand Up @@ -591,32 +587,26 @@ pub trait Strict: private::Sealed {
Self::Pointee: Sized;
}

impl<T> private::Sealed for *mut T {}
impl<T> private::Sealed for *const T {}
impl<T: ?Sized> private::Sealed for *mut T {}
impl<T: ?Sized> private::Sealed for *const T {}

impl<T> Strict for *mut T {
impl<T: ?Sized> Strict for *mut T {
type Pointee = T;

#[must_use]
#[inline]
fn addr(self) -> usize
where
T: Sized,
{
fn addr(self) -> usize {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
// SAFETY: Pointer-to-integer transmutes are valid (if you are okay with losing the
// provenance).
unsafe { core::mem::transmute(self) }
unsafe { core::mem::transmute(self.cast::<()>()) }
}

#[must_use]
#[inline]
fn expose_addr(self) -> usize
where
T: Sized,
{
fn expose_addr(self) -> usize {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
self as usize
self.cast::<()>() as usize
}

#[must_use]
Expand Down Expand Up @@ -650,29 +640,23 @@ impl<T> Strict for *mut T {
}
}

impl<T> Strict for *const T {
impl<T: ?Sized> Strict for *const T {
type Pointee = T;

#[must_use]
#[inline]
fn addr(self) -> usize
where
T: Sized,
{
fn addr(self) -> usize {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
// SAFETY: Pointer-to-integer transmutes are valid (if you are okay with losing the
// provenance).
unsafe { core::mem::transmute(self) }
unsafe { core::mem::transmute(self.cast::<()>()) }
}

#[must_use]
#[inline]
fn expose_addr(self) -> usize
where
T: Sized,
{
fn expose_addr(self) -> usize {
// FIXME(strict_provenance_magic): I am magic and should be a compiler intrinsic.
self as usize
self.cast::<()>() as usize
}

#[must_use]
Expand Down