swift

74f18ef1 - [4.1] IRGen: Fix witness-table accessors for conditional conformances

[4.1] IRGen: Fix witness-table accessors for conditional conformances Explanation: After adding conditional conformances witness table accessors are no longer readnone because the witnesses are passed as an in memory argument. In optimized mode LLVM will optimize away the store of the witnesses because it believes the accessor function is readnone leading to crashes Scope: Introduced with conditional conformances, potentially affects any project that emit witness-table accessors on based types with conditional conformances Risk: Very low since the fix is to not emit LLVM's readnone attribute (which should do no harm) Testing: The project on which this was reported was tested and a CI test added SR-7228 rdar://38624842