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various updates based on review
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@RalfJung
RalfJung committed Sep 11, 2024
1 parent 5835079 commit 916eb13
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Showing 2 changed files with 38 additions and 24 deletions.
31 changes: 19 additions & 12 deletions library/core/src/ptr/const_ptr.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -355,8 +355,8 @@ impl<T: ?Sized> *const T {
///
/// If any of the following conditions are violated, the result is Undefined Behavior:
///
/// * The computed offset, `count * size_of::<T>()` bytes (using unbounded arithmetic),
/// must fit in an `isize`.
/// * The offset in bytes, `count * size_of::<T>()`, computed on mathematical integers (without
/// "wrapping around"), must fit in an `isize`.
///
/// * If the computed offset is non-zero, then `self` must be derived from a pointer to some
/// [allocated object], and the entire memory range between `self` and the result must be in
Expand Down Expand Up @@ -399,7 +399,7 @@ impl<T: ?Sized> *const T {
unsafe { intrinsics::offset(self, count) }
}

/// Calculates the offset from a pointer in bytes.
/// Adds a signed offset in bytes to a pointer.
///
/// `count` is in units of **bytes**.
///
Expand Down Expand Up @@ -808,7 +808,11 @@ impl<T: ?Sized> *const T {
}
}

/// Adds an offset to a pointer.
/// Adds an unsigned offset to a pointer.
///
/// This can only move the pointer forward (or not move it). If you need to move forward or
/// backward depending on the value, then you might want [`offset`](#method.offset) instead
/// which takes a signed offset.
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
Expand All @@ -817,8 +821,8 @@ impl<T: ?Sized> *const T {
///
/// If any of the following conditions are violated, the result is Undefined Behavior:
///
/// * The computed offset, `count * size_of::<T>()` bytes (using unbounded arithmetic),
/// must fit in an `isize`.
/// * The offset in bytes, `count * size_of::<T>()`, computed on mathematical integers (without
/// "wrapping around"), must fit in an `isize`.
///
/// * If the computed offset is non-zero, then `self` must be derived from a pointer to some
/// [allocated object], and the entire memory range between `self` and the result must be in
Expand Down Expand Up @@ -861,7 +865,7 @@ impl<T: ?Sized> *const T {
unsafe { intrinsics::offset(self, count) }
}

/// Calculates the offset from a pointer in bytes (convenience for `.byte_offset(count as isize)`).
/// Adds an unsigned offset in bytes to a pointer.
///
/// `count` is in units of bytes.
///
Expand All @@ -882,7 +886,11 @@ impl<T: ?Sized> *const T {
unsafe { self.cast::<u8>().add(count).with_metadata_of(self) }
}

/// Subtracts an offset from a pointer.
/// Subtracts an unsigned offset from a pointer.
///
/// This can only move the pointer backward (or not move it). If you need to move forward or
/// backward depending on the value, then you might want [`offset`](#method.offset) instead
/// which takes a signed offset.
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
Expand All @@ -891,8 +899,8 @@ impl<T: ?Sized> *const T {
///
/// If any of the following conditions are violated, the result is Undefined Behavior:
///
/// * The computed offset, `count * size_of::<T>()` bytes (using unbounded arithmetic),
/// must fit in an `isize`.
/// * The offset in bytes, `count * size_of::<T>()`, computed on mathematical integers (without
/// "wrapping around"), must fit in an `isize`.
///
/// * If the computed offset is non-zero, then `self` must be derived from a pointer to some
/// [allocated object], and the entire memory range between `self` and the result must be in
Expand Down Expand Up @@ -943,8 +951,7 @@ impl<T: ?Sized> *const T {
}
}

/// Calculates the offset from a pointer in bytes (convenience for
/// `.byte_offset((count as isize).wrapping_neg())`).
/// Subtracts an unsigned offset in bytes from a pointer.
///
/// `count` is in units of bytes.
///
Expand Down
31 changes: 19 additions & 12 deletions library/core/src/ptr/mut_ptr.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -353,8 +353,8 @@ impl<T: ?Sized> *mut T {
///
/// If any of the following conditions are violated, the result is Undefined Behavior:
///
/// * The computed offset, `count * size_of::<T>()` bytes (using unbounded arithmetic),
/// must fit in an `isize`.
/// * The offset in bytes, `count * size_of::<T>()`, computed on mathematical integers (without
/// "wrapping around"), must fit in an `isize`.
///
/// * If the computed offset is non-zero, then `self` must be derived from a pointer to some
/// [allocated object], and the entire memory range between `self` and the result must be in
Expand Down Expand Up @@ -399,7 +399,7 @@ impl<T: ?Sized> *mut T {
unsafe { intrinsics::offset(self, count) }
}

/// Calculates the offset from a pointer in bytes.
/// Adds a signed offset in bytes to a pointer.
///
/// `count` is in units of **bytes**.
///
Expand Down Expand Up @@ -889,7 +889,11 @@ impl<T: ?Sized> *mut T {
unsafe { (self as *const T).sub_ptr(origin) }
}

/// Adds an offset to a pointer.
/// Adds an unsigned offset to a pointer.
///
/// This can only move the pointer forward (or not move it). If you need to move forward or
/// backward depending on the value, then you might want [`offset`](#method.offset) instead
/// which takes a signed offset.
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
Expand All @@ -898,8 +902,8 @@ impl<T: ?Sized> *mut T {
///
/// If any of the following conditions are violated, the result is Undefined Behavior:
///
/// * The computed offset, `count * size_of::<T>()` bytes (using unbounded arithmetic),
/// must fit in an `isize`.
/// * The offset in bytes, `count * size_of::<T>()`, computed on mathematical integers (without
/// "wrapping around"), must fit in an `isize`.
///
/// * If the computed offset is non-zero, then `self` must be derived from a pointer to some
/// [allocated object], and the entire memory range between `self` and the result must be in
Expand Down Expand Up @@ -942,7 +946,7 @@ impl<T: ?Sized> *mut T {
unsafe { intrinsics::offset(self, count) }
}

/// Calculates the offset from a pointer in bytes (convenience for `.byte_offset(count as isize)`).
/// Adds an unsigned offset in bytes to a pointer.
///
/// `count` is in units of bytes.
///
Expand All @@ -963,7 +967,11 @@ impl<T: ?Sized> *mut T {
unsafe { self.cast::<u8>().add(count).with_metadata_of(self) }
}

/// Subtracts an offset from a pointer.
/// Subtracts an unsigned offset from a pointer.
///
/// This can only move the pointer backward (or not move it). If you need to move forward or
/// backward depending on the value, then you might want [`offset`](#method.offset) instead
/// which takes a signed offset.
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
Expand All @@ -972,8 +980,8 @@ impl<T: ?Sized> *mut T {
///
/// If any of the following conditions are violated, the result is Undefined Behavior:
///
/// * The computed offset, `count * size_of::<T>()` bytes (using unbounded arithmetic),
/// must fit in an `isize`.
/// * The offset in bytes, `count * size_of::<T>()`, computed on mathematical integers (without
/// "wrapping around"), must fit in an `isize`.
///
/// * If the computed offset is non-zero, then `self` must be derived from a pointer to some
/// [allocated object], and the entire memory range between `self` and the result must be in
Expand Down Expand Up @@ -1024,8 +1032,7 @@ impl<T: ?Sized> *mut T {
}
}

/// Calculates the offset from a pointer in bytes (convenience for
/// `.byte_offset((count as isize).wrapping_neg())`).
/// Subtracts an unsigned offset in bytes from a pointer.
///
/// `count` is in units of bytes.
///
Expand Down

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