[5.9] IRGen: Only use clang protocol emission on newer deployment targets #65555
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…gets We started using clang to emit the _OBJC_PROTOCOL_ definition. But we would use a different name for the proto_list definition than clang. "OBJC_LABEL_PROTOCOL$" (objc) |--> OBJC_PROTOCOL "\01l_OBJC_LABEL_PROTOCOL$_" (swift) |--> OBJC_PROTOCOL If an Objective C object also emitted the same protocol definition you could end up in a situation where both clang's and swift's proto_list definitions point to the same protocol definition. Older linkers don't like that. rdar://108505376
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@swift-ci test |
airspeedswift
approved these changes
May 1, 2023
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@aschwaighofer Hi Arnold! Sorry for bothering you. Could I ask what will happen if deployment target doesn't satisfied with getSwift58Availability()? Will it cause a runtime crash or..? |
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We started using clang to emit the OBJC_PROTOCOL definition.
But we would use a different name for the proto_list definition than clang.
"OBJC_LABEL_PROTOCOL$" (objc)
|--> OBJC_PROTOCOL
"\01l_OBJC_LABEL_PROTOCOL$_" (swift)
|--> OBJC_PROTOCOL
If an Objective C object also emitted the same protocol definition you could end up in a situation where both clang's and swift's proto_list definitions point to the same protocol definition.
Older linkers don't like that.
main PR: #65549
Risk: Should be quite low, were are restoring behavior that the compiler had pre 5.8 dependent on the deployment target
rdar://108505376