Make it usable with 1.82.0+ #2
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The kernel version of pinned_init implemented InPlaceWrite on UniqueArc, not Arc. This ensures that InPlaceWrite is not writing to a shared Arc. Userspace does not have this facility and therefore cannot lift the kernel implementation of InPlaceWrite directly into Arc<>. One possibility would be to use Arc::get_mut(), though this would introduce a panic in the case where the Arc is shared. So just revert part of commit 6841b61 ("rust: init: add `write_[pin_]init` functions", 2024-11-22). Suggested-by: Benno Lossin <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
Instead of using an unstable feature use unreachable_unchecked() to enable optimization. Suggested-by: Benno Lossin <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
The only dependency of the InPlaceInit trait on the allocator API is the AllocError type. Replace it with Infallible instead, i.e. allow any error as long as it has an "impl From<Infallible> for MyError" - which can have a trivial implementation as seen in examples/rror.rs. While admittedly of limited usefulness due to orphan rules, this is a first step towards allowing usage of pinned_init entirely without the allocator API, and therefore on stable Rust. Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Memory allocation (i.e. the Box and Arc) can be present even without the allocator_api. Allow feature = "std" when the code is simply checking for the existence of Box and Arc, and the allocator API is not used. Signed-off-by: Paolo Bonzini <[email protected]>
When compiling without allocator_api, assume that allocations cannot fail. This way, nightly Rust features are not absolutely needed for pinned_init, and it can be used with stable Rust; right now the minimum supported Rust version is 1.82.0, where the new_uninit version was stabilized. Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
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