[SR-2817] selector mismatch with obj-c delegates + extensions #45421
Comments
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@DougGregor, you changed this, right? |
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Comment by Cezary Wojcik (JIRA) Some context here: since this used to work in Swift 2.3, in the migration from 2.3 to 3.0, there are now a LOT of hard-to-find silent bugs that have been introduced as a result of the migration. It's pretty scary. |
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Comment by Jacek (JIRA) +1 this is very unpleasant |
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Comment by Alex Matjuk (JIRA) • 2nd case is not a bug because method is optional. |
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Comment by Alex Matjuk (JIRA) Actually bugs are:
class Test: UIViewController, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 150.0, height: 150.0)
}
}2) no warning to add renaming @objc attribute when method is implemented inside class extension which adds protocol conformance: extension Test: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 150.0, height: 150.0)
}
}3) no warning to add renaming @objc attribute in subclass both inside class itself class Test: UIViewController, UICollectionViewDelegateFlowLayout {}
class TestSubclass: Test {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 150.0, height: 150.0)
}
}or its extension class Test: UIViewController, UICollectionViewDelegateFlowLayout {}
class TestSubclass: Test {}
extension TestSubclass {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 150.0, height: 150.0)
}
} |
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Comment by Alex Matjuk (JIRA) Is reproducible with any protocol which uses NS_SWIFT_NAME. E.g. @protocol TestProtocol <NSObject>
- (void) objc_protocolMethod NS_SWIFT_NAME(swift_protocolMethod()) ;
@end |
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Comment by Daniel Resnick (JIRA) This appears to be fixed in Swift 3.0.1 for normal subclasses, but is not fixed for generic subclasses: class A: NSObject, UITableViewDelegate {}
class B: A {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {}
}
class C<T>: A {
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {}
}
print(#selector(B.tableView(_:didSelectRowAt:))) // tableView:didSelectRowAtIndexPath:
print(#selector(C<Int>.tableView(_:didSelectRowAt:))) // tableView:didSelectRowAt: |
Additional Detail from JIRA
md5: 9c5b0f645140d6f33adb8b7c263e85dd
is duplicated by:
Issue Description:
Summary:
When protocol conformance functions are added within an extension that doesn't explicitly declare itself to conform to this protocol, you get an error that says that the obj-c selectors don't match. This is weird, but at least we get an error. Even worse is that if this happens in a subclass, it fails silently, which can cause hard-to-find errors.
Steps to Reproduce:
Case 1: There is an error:
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