Avoid invalidating @_objcImplementation #76270
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beccadax
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Revised the implementation—the original one would sometimes cause two diagnostics to be emitted on the same declaration. This wouldn't block a build that wasn't already being blocked, but it would make the developer experience worse. |
In swiftlang#69257, we modified `ObjCReason` to carry a pointer to the @implementation attribute for the `MemberOfObjCImplementationExtension` kind. This made it mark the @implementation attribute as invalid, suppressing diagnostics from the ObjCImplementationChecker. However, invalidating the attribute *also* causes it to be skipped by serialization. That isn’t a problem if the diagnostics are errors, since we’ll never emit the serialized module, but swiftlang#74135 softened these diagnostics to warnings for early adopters. The upshot was that if Swift emitted one of these warnings when it compiled a library, clients of that library would see the objcImpl extension as a normal extension instead. This would cause various kinds of mischief: ambiguous name lookups because implementations weren’t being excluded, overrides failing because an implementation was `public` instead of `open`, asserts and crashes in SILGen and IRGen because stored properties were found in seemingly normal extensions, etc. Fix this by setting a separate bit on ObjCImplementationAttr, rather than the invalid bit, and modifying the implementation checker to manually suppress many diagnostics when that bit is set. Fixes rdar://134730183.
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@swift-ci please test |
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| // expected-warning@-1 {{method cannot be in an @objc @implementation extension of a class (without final or @nonobjc) because the type of the parameter cannot be represented in Objective-C}} | ||
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| // CHECK-DAG: @objc func goodMethod() | ||
| @objc public func goodMethod() {} |
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Not a blocker, but it would be nice if this test also demonstrated end-to-end that a client can also deserialize and use the emitted module here, since that's where the failure manifested IIUC.
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In #69257, we modified
ObjCReasonto carry a pointer to the @implementation attribute for theMemberOfObjCImplementationExtensionkind. This made it mark the @implementation attribute as invalid, suppressing diagnostics from the ObjCImplementationChecker.However, invalidating the attribute also causes it to be skipped by serialization. That isn’t a problem if the diagnostics are errors, since we’ll never emit the serialized module, but #74135 softened these diagnostics to warnings for early adopters.
The upshot was that if Swift emitted one of these warnings when it compiled a library, clients of that library would see the objcImpl extension as a normal extension instead. This would cause various kinds of mischief: ambiguous name lookups because implementations weren’t being excluded, overrides failing because an implementation was
publicinstead ofopen, asserts and crashes in SILGen and IRGen because stored properties were found in seemingly normal extensions, etc.Fix this by setting a separate bit on ObjCImplementationAttr, rather than the invalid bit, and modifying the implementation checker to manually suppress many diagnostics when that bit is set.
Fixes rdar://134730183.