Change the return type of SharedMemory::data
#5240
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This commit is an attempt at improving the safety of using the return value of the `SharedMemory::data` method. Previously this returned `*mut [u8]` which, while correct, is unwieldy and unsafe to work with. The new return value of `&[UnsafeCell<u8>]` has a few advantages: * The lifetime of the returned data is now connected to the `SharedMemory` itself, removing the possibility for a class of errors of accidentally using the prior `*mut [u8]` beyond its original lifetime. * It's not possibly to safely access `.len()` as opposed to requiring an `unsafe` dereference before. * The data internally within the slice is now what retains the `unsafe` bits, namely indicating that accessing any memory inside of the contents returned is `unsafe` but addressing it is safe. I was inspired by the `wiggle`-based discussion on bytecodealliance#5229 and felt it appropriate to apply a similar change here.
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This commit is an attempt at improving the safety of using the return value of the
SharedMemory::datamethod. Previously this returned*mut [u8]which, while correct, is unwieldy and unsafe to work with. The new return value of&[UnsafeCell<u8>]has a few advantages:The lifetime of the returned data is now connected to the
SharedMemoryitself, removing the possibility for a class of errors of accidentally using the prior*mut [u8]beyond its original lifetime.It's now possibly to safely access
.len()as opposed to requiring anunsafedereference before.The data internally within the slice is now what retains the
unsafebits, namely indicating that accessing any memory inside of the contents returned isunsafebut addressing it is safe.I was inspired by the
wiggle-based discussion on #5229 and felt it appropriate to apply a similar change here.