[Foundation] Address exclusivity violation in Data #15823
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@swift-ci Please test |
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Can you leave behind a comment about this? Normally the only reason to make properties in a struct use |
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Also, probably needs some sort of in text reference to the bug to undo this. |
phausler
approved these changes
Apr 9, 2018
Address an exclusivity violation in Data's Iterator.next() by changing two private 'let' stored properties to be 'var'. Making the properties 'var' changes code generation of next() so that the stored properties are read independently of the other contents of the struct. This prevents an exclusivity violation when reading '_endIdx' and '_data' while simultaneously mutating '_buffer' with the call to withUnsafeMutablePointer(). The 'let' pattern is an idiom we would eventually like to support (see SR-7396), but for now we need to remove the exclusivity violation.
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I've added a comment to the code and included a reference to https://bugs.swift.org/browse/SR-7396 in the commit message. |
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@swift-ci please smoke test and merge |
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@swift-ci please smoke test and merge |
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Address an exclusivity violation in Data's Iterator.next() by changing two private
'let' stored properties to be 'var'.
Making the properties 'var' changes code generation of next() so that the stored
properties are read independently of the other contents of the struct. This prevents
an exclusivity violation when reading '_endIndex' and '_data' while simultaneously
mutating '_buffer' with the call to withUnsafeMutablePointer().
The 'let' pattern is an idiom we would eventually like to support, but for now we
need to remove the exclusivity violation.