Rollup merge of #132459 - RalfJung:byte_sub_ptr, r=scottmcm · qinheping/verify-rust-std@ecd55b1 (original) (raw)
`@@ -582,7 +582,7 @@ impl<T: ?Sized> *const T {
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` intrinsics::ptr_mask(self.cast::<()>(), mask).with_metadata_of(self)
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`}
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/// Calculates the distance between two pointers. The returned value is in
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/// Calculates the distance between two pointers within the same allocation. The returned value is in
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`` /// units of T: the distance in bytes divided by mem::size_of::<T>().
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`///
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`` /// This is equivalent to (self as isize - origin as isize) / (mem::size_of::<T>() as isize),
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`@@ -677,7 +677,7 @@ impl<T: ?Sized> *const T {
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`unsafe { intrinsics::ptr_offset_from(self, origin) }
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`}
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``
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/// Calculates the distance between two pointers. The returned value is in
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/// Calculates the distance between two pointers within the same allocation. The returned value is in
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`/// units of bytes.
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`///
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`` /// This is purely a convenience for casting to a u8 pointer and
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`@@ -695,7 +695,7 @@ impl<T: ?Sized> *const T {
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`unsafe { self.cast::().offset_from(origin.cast::()) }
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`}
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``
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/// Calculates the distance between two pointers, *where it's known that
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/// Calculates the distance between two pointers within the same allocation, *where it's known that
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`` /// self is equal to or greater than origin*. The returned value is in
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`` /// units of T: the distance in bytes is divided by mem::size_of::<T>().
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`///
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`@@ -790,6 +790,25 @@ impl<T: ?Sized> *const T {
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`unsafe { intrinsics::ptr_offset_from_unsigned(self, origin) }
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`}
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``
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/// Calculates the distance between two pointers within the same allocation, *where it's known that
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/// self is equal to or greater than origin*. The returned value is in
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/// units of bytes.
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///
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/// This is purely a convenience for casting to a u8 pointer and
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/// using [sub_ptr][pointer::sub_ptr] on it. See that method for
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/// documentation and safety requirements.
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///
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/// For non-Sized pointees this operation considers only the data pointers,
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/// ignoring the metadata.
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#[unstable(feature = "ptr_sub_ptr", issue = "95892")]
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#[rustc_const_unstable(feature = "const_ptr_sub_ptr", issue = "95892")]
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#[inline]
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#[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
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pub const unsafe fn byte_sub_ptr<U: ?Sized>(self, origin: *const U) -> usize {
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// SAFETY: the caller must uphold the safety contract for sub_ptr.
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unsafe { self.cast::().sub_ptr(origin.cast::()) }
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}
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`/// Returns whether two pointers are guaranteed to be equal.
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`///
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`` /// At runtime this function behaves like Some(self == other).
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