[stdlib] tolerate empty source buffers in UMRBP.copyMemory
#41836
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- The previous implementation trapped when the source buffer was empty. That behaviour is both not documented and unnecessary. If the source buffer is empty, its length is necessarily shorter or equal than the length of the destination. - The updated version simply returns when the source buffer is empty.
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@swift-ci please test |
stephentyrone
approved these changes
Mar 16, 2022
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@swift-ci please smoke test macOS platform |
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The implementation previously trapped when the source buffer was empty and the source's
baseAddresswas nil. That behaviour is neither documented nor necessary. The real precondition is that the source buffer cannot be larger than the destination. When the source buffer is empty, that precondition is necessarily met.This updated version of
UnsafeMutableRawBufferPointer.copyMemorysimply returns when the source buffer is empty.Resolves SR-15994 (rdar://90350360).