[Exclusivity] Disable dynamic enforcement in noescape closures. #9479
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I'll revise this PR with comment typo fixes once this is merged on master: |
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@devincoughlin Would you review for CCC for inclusion into swift-4.0-branch? |
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This looks good to me! |
devincoughlin
approved these changes
May 11, 2017
(cherry picked from commit c76269c)
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@swift-ci test and merge. |
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CCC
Explanation: Fully checking the exclusivity model requires enabling dynamic checks. We can't allow false positives, especially in a common case like mutation with a noescape closure. Instead we claim that these checks are currently incomplete for accesses within noescape closure. In the near future, once the lagnuage proposal is fully accepted, we will implement static checking of noescape closures. Static checking these cases is far superior for many reasons in addition to avoiding false positives.
Scope: Only affects -enforce-exclusivity=checked, which is purely opt-in.
Radar: rdar://problem/32119357 [Exclusivity] Disable dynamic enforcement in noescape closures.
Risk: Some code that violates the exclusivity model will pass without failure until static enforcement is enabled. This engenders a false sense of security.
Testing: All applications that have already been tested with enforcement need to be retested.