Swift generic strange behaviour

Asked Feb 03 '17 at 09:35

Active Feb 03 '17 at 12:58

Viewed 110 times

I've found a strange swift generic behaviour:

protocol Textable {}

class Test { 
    init<T: NSObject>(values: [T]) where T: Textable {}
}

func test<T: NSObject>(value: T) where T: Textable {
    let values = [value]
    Test(values: [value]) // Cannot convert value of type '[T]' to expected argument type '[_]'
}

This code with error:

Cannot convert value of type '[T]' to expected argument type '[_]'.

But if I change Test(values: [value]) to Test(values: values), it works fine. Maybe am I doing something wrong? Or it's just a swift's bug...

Created issue at Swift JIRA.

edited Feb 03 '17 at 12:58

asked Feb 03 '17 at 09:35

Nikita Ermolenko

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why do you want to set Test(values: [value]) to nothing? – Bertrand Bloc'h Feb 03 '17 at 09:39
It strangely works with: `let values = [value]; Test(values: values) ` – Mr. Xcoder Feb 03 '17 at 10:27
2

It looks like it's something about having `T` constrained to both inherit from a class and conform to a protocol that the compiler doesn't like – in any case, you should definitely [file a bug report](https://bugs.swift.org). – Hamish Feb 03 '17 at 12:04
1

@Hamish I've created the issue. Check the updated post. – Nikita Ermolenko Feb 03 '17 at 12:59

Swift generic strange behaviour

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