Preserve availability on ObjC subscript getters and setters #17105
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This resolves SR-7398.
jrose-apple
approved these changes
Jun 11, 2018
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It's a little unfortunate that the error message will always call out the getter or setter even if it's the whole subscript that's supposed to logically be deprecated/unavailable, but I guess that's just an artifact of Objective-C. (Maybe we can enhance this in the future if they have the same availability and message or something.) Looks good to me; thanks for taking this, Christopher!
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@swift-ci Please test |
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@swift-ci Please test source compatibility |
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@swift-ci Please test |
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Whoops, sorry for dropping this! Thanks, Anna. |
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Objective-C subscript accessors' attributes were being imported through the alternative declaration (
getAlternateDecls(decl)) of one of the accessors (usually the getter), and this alternative declaration was the entire subscript declaration, not the getter or setter. Since there is no 1:1 equivalent between Objective-C and Swift of a subscript declaration like there is a property declaration, I opted to not import any attributes to the Swift subscript declaration we generate. The accessor attributes are imported 1:1 to their respective Swift thunks.I noticed that, for "unavailable" subscripts, diagnostics outputs a "note" to point out where the subscript was marked unavailable but it doesn't output where. I would expect it to be able to point out the line in the Objective-C header, but it tries to point out the thunk, which is generated and thus nothing gets output. It seems there are similar problems with normal properties, except that it shows the hidden __ObjC module's generated Swift interface. Therefore I assumed that my fix didn't break those diagnostics.
I changed one
dyn_casttocastbecause I didn't think there would be a case where it would fail, and a couple of lines down there was a dereference anyways.Resolves SR-7398.