[Merged by Bors] - Improve safety for BlobVec::replace_unchecked
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JoJoJet
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JoJoJet
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Jan 13, 2023
crates/bevy_utils/src/lib.rs
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| /// A type which calls a function when dropped. | ||
| /// This can be used to ensure that cleanup code is run even in case of a panic. | ||
| pub struct OnDrop<F: FnOnce()> { | ||
| callback: ManuallyDrop<F>, | ||
| } |
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The previous (private) version of this type used F: FnMut(), which made working with owned values complicated. Since we need unsafe code in order to make this work using FnOnce(), I figured it's worth going the extra mile and making this public.
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Very clever: I like this. It would be nice to see a small doc test here.
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Jan 13, 2023
| let old_len = self.len; | ||
| let ptr = self.get_unchecked_mut(index).promote().as_ptr(); | ||
| self.len = 0; |
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Thinking on this a bit more. This doesn't need to be done unless the drop value is Some.
Perhaps we should just branch on - drop and simplify the non-drop path.
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I was doubtful at first but this suggestion turned out very nicely.
james7132
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Jan 14, 2023
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| /// A type which calls a function when dropped. | ||
| /// This can be used to ensure that cleanup code is run even in case of a panic. | ||
| pub struct OnDrop<F: FnOnce()> { |
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Btw, bevy_tasks also has a CallOnDrop impl which could replaced with this. Not sure if it's worth taking on bevy_utils as a dependency.
BoxyUwU
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Jan 15, 2023
Co-authored-by: Boxy <supbscripter@gmail.com> Co-authored-by: James Liu <contact@jamessliu.com>
alice-i-cecile
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Jan 15, 2023
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Jan 16, 2023
# Objective - The function `BlobVec::replace_unchecked` has informal use of safety comments. - This function does strange things with `OwningPtr` in order to get around the borrow checker. ## Solution - Put safety comments in front of each unsafe operation. Describe the specific invariants of each operation and how they apply here. - Added a guard type `OnDrop`, which is used to simplify ownership transfer in case of a panic. --- ## Changelog + Added the guard type `bevy_utils::OnDrop`. + Added conversions from `Ptr`, `PtrMut`, and `OwningPtr` to `NonNull<u8>`.
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BlobVec::replace_uncheckedBlobVec::replace_unchecked
alradish
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Jan 22, 2023
# Objective - The function `BlobVec::replace_unchecked` has informal use of safety comments. - This function does strange things with `OwningPtr` in order to get around the borrow checker. ## Solution - Put safety comments in front of each unsafe operation. Describe the specific invariants of each operation and how they apply here. - Added a guard type `OnDrop`, which is used to simplify ownership transfer in case of a panic. --- ## Changelog + Added the guard type `bevy_utils::OnDrop`. + Added conversions from `Ptr`, `PtrMut`, and `OwningPtr` to `NonNull<u8>`.
ItsDoot
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Feb 1, 2023
# Objective - The function `BlobVec::replace_unchecked` has informal use of safety comments. - This function does strange things with `OwningPtr` in order to get around the borrow checker. ## Solution - Put safety comments in front of each unsafe operation. Describe the specific invariants of each operation and how they apply here. - Added a guard type `OnDrop`, which is used to simplify ownership transfer in case of a panic. --- ## Changelog + Added the guard type `bevy_utils::OnDrop`. + Added conversions from `Ptr`, `PtrMut`, and `OwningPtr` to `NonNull<u8>`.
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Objective
BlobVec::replace_uncheckedhas informal use of safety comments.OwningPtrin order to get around the borrow checker.Solution
OnDrop, which is used to simplify ownership transfer in case of a panic.Changelog
bevy_utils::OnDrop.Ptr,PtrMut, andOwningPtrtoNonNull<u8>.