* vm.rs - calling Ctx data_finalizer upon destruction
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Hywan
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YaronWittenstein
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Jul 15, 2019
…struction"](wasmerio/wasmer#561) * updating crates
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Ummm... tests are broken on windows, so we have to take a deeper look. |
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(still investigating) |
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Hey @YaronWittenstein I found the issue on our side! We are breaking the contract on The reason is that we do something like let ctx = Box::new(std::mem::uninit());
something_else.val = Box::into_raw(ctx);
something_else.val = real_ctx; // this is invalid because it causes the uninit Ctx to DropAnd the solution is to change the last line to let mut real_ctx = real_ctx;
std::mem::swap(&mut real_ctx, &mut something_else.val);
std::mem::forget(real_ctx); // tell Rust to not Drop our garbage CtxI have a fix locally that I need to clean up -- and actually I need to port it to the new MaybeUninit style for Rust 1.38 -- but your PR was passing all the tests I tried on my computer last night. Thanks! I'll ping you again when its merged into master |
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576: fix Drop of uninit Ctx; use MaybeUninit r=MarkMcCaskey a=MarkMcCaskey I'm somewhat concerned that we need to call `intrinsics::panic_if_uninhabited::<T>();` or something to tell the compiler that we know it's safe. We just reinterpret the pointer later as initialized which is safe in theory due to `repr(transparent)` this should unblock #561 Co-authored-by: Mark McCaskey <[email protected]>
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576: fix Drop of uninit Ctx; use MaybeUninit r=MarkMcCaskey a=MarkMcCaskey I'm somewhat concerned that we need to call `intrinsics::panic_if_uninhabited::<T>();` or something to tell the compiler that we know it's safe. We just reinterpret the pointer later as initialized which is safe in theory due to `repr(transparent)` this should unblock #561 Co-authored-by: Mark McCaskey <[email protected]>
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576: fix Drop of uninit Ctx; use MaybeUninit r=MarkMcCaskey a=MarkMcCaskey I'm somewhat concerned that we need to call `intrinsics::panic_if_uninhabited::<T>();` or something to tell the compiler that we know it's safe. We just reinterpret the pointer later as initialized which is safe in theory due to `repr(transparent)` this should unblock #561 Co-authored-by: Mark McCaskey <[email protected]>
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576: fix Drop of uninit Ctx; use MaybeUninit r=MarkMcCaskey a=MarkMcCaskey I'm somewhat concerned that we need to call `intrinsics::panic_if_uninhabited::<T>();` or something to tell the compiler that we know it's safe. We just reinterpret the pointer later as initialized which is safe in theory due to `repr(transparent)` this should unblock #561 Co-authored-by: Mark McCaskey <[email protected]> Co-authored-by: Mark McCaskey <[email protected]>
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Jul 24, 2019
576: fix Drop of uninit Ctx; use MaybeUninit r=MarkMcCaskey a=MarkMcCaskey I'm somewhat concerned that we need to call `intrinsics::panic_if_uninhabited::<T>();` or something to tell the compiler that we know it's safe. We just reinterpret the pointer later as initialized which is safe in theory due to `repr(transparent)` this should unblock #561 Co-authored-by: Mark McCaskey <[email protected]> Co-authored-by: Mark McCaskey <[email protected]>
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syrusakbary
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Jul 24, 2019
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It seems that the
data_finalizerfield of theCtxis never being called upon instance destruction.It seems a bit tricky to assert that in though
@syrusakbary @Hywan