Hey there,
I filed this bug. Sorry that I mentioned it was to do with the TODO - I tried
to trace it back myself, found that the substitution map was giving a null for
the same-type requirement (and that “getDependentTypes()” explicitly skips
them), and assumed that was the reason. Try as I might, I couldn’t figure out
how to resolve it so I assumed I was lacking requisite knowledge of
substitution maps to fix it (which turns out to be correct - thanks for the
great explanation, Slava!)
> On 31 Dec 2016, at 01:09, Slava Pestov via swift-dev <swift-dev@swift.org>
> wrote:
>
> extension Array where Element == S, Element : P {
> func doSomething() {}
> }
>
> The ‘Element : P’ requirement is redundant and is dropped from the signature,
> and ‘doSomething’ has the same exact type as if we had written:
>
> extension Array where Element == S {
> func doSomething() {}
> }
What if the S: P conformance is conditional or introduced by another module?
The presence same-type constraint isn’t enough to say that S will _never_
conform to P (if it doesn’t already conform).
extension S: P where S.SomeType == Int, S.AnotherType: Collection,
S.AnotherType.Index == SomeType {
// conform to P
}
extension Array where Element == S, S.SomeType == Int, S.AnotherType:
Collection, // …etc
vs
extension Array where Element == S, S: P
- Karl_______________________________________________
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