SILGen: Delay function conversions to types with opened archetype arguments. #18085
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…uments.
This comes up when invoking protocol methods on an existential that have covariant arguments of function type with Self arguments, e.g.:
```swift
protocol P {
mutating func foo(_: (Self) -> Void)
}
func bar(x: inout P) {
x.foo { y in return }
}
```
Although the type-erased method is presented as formally taking an argument of the existential type P, it still has a conversion thunk to perform type erasure on the argument coming from the underlying implementation. Since the `self` argument is inout, it isn't formally opened until late when formal accesses begin, so this closure conversion must also be deferred until after that occurs.
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@swift-ci Please test |
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@swift-ci Please test source compatibility |
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Wow, that’s simpler than I expected! Nice job. |
slavapestov
approved these changes
Jul 19, 2018
|
@jckarter Thanks! |
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This comes up when invoking protocol methods on an existential that have covariant arguments of function type with Self arguments, e.g.:
Although the type-erased method is presented as formally taking an argument of the existential type P, it still has a conversion thunk to perform type erasure on the argument coming from the underlying implementation. Since the
selfargument is inout, it isn't formally opened until late when formal accesses begin, so this closure conversion must also be deferred until after that occurs.rdar://problem/42215661