ConcurrentReadableArray: Use std::uninitialized_copy_n() instead of std::copy() to avoid calling destructors on uninitialized memory
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grynspan
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Build failure appears unrelated to my changes, caused by swiftlang/swift-package-manager#3929. @tomerd |
mikeash
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Dec 11, 2021
…td::copy() to avoid calling destructors on uninitialized memory
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al45tair
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ConcurrentReadableArray: Usestd::uninitialized_copy_n()instead ofstd::copy()to avoid calling destructors on uninitialized memory.This change fixes a (currently benign) misuse of
std::copy()inConcurrentReadableArraywhen it is resized.std::copy()will call destructors on the destination buffer before copying in new values. Because the memory being copied into is uninitialized, this is undefined behavior. There shouldn't be any impact in the real world though because the only users ofConcurrentReadableArrayare POD types so there's nothing to destruct.I also took the opportunity to switch from
memcpy()tostd::uninitialized_copy_n()forConcurrentReadableHashMapwhich allows us to remove thestd::is_trivially_copyableconstraint onElemTy. For POD types, the resulting generated code should be identical.