[SR-12736] cannot add constraint 'Self.Model.Float32Components == Self.Model.Float32Components.Model.Float32Components' on 'Self' #55182
Labels
bug
A deviation from expected or documented behavior. Also: expected but undesirable behavior.
compiler
The Swift compiler in itself
type checker
Area → compiler: Semantic analysis
Comments
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@swift-ci create |
|
Seems like a declaration type-checking bug. If I minimize the example: protocol P1 {
associatedtype AT1: P2 where AT1.AT2 == Self
}
protocol P2 {
associatedtype AT2: P1
}
protocol P3 {
associatedtype AT3: P1
init<T: P3>(_ t: T) where T.AT3 == AT3 // error: initializer requirement 'init(_:)' cannot add constraint 'Self.AT3.AT1 == Self.AT3.AT1.AT2.AT1' on 'Self'
}On the other hand, if you add the initializer to an extension with a default implementation, that's fine. protocol P1 {
associatedtype AT1: P2 where AT1.AT2 == Self
}
protocol P2 {
associatedtype AT2: P1
}
protocol P3 {
associatedtype AT3: P1
}
extension P3 {
init<T: P3>(_ t: T) where T.AT3 == AT3 {
fatalError("AAAAA")
}
} |
|
I think this bug maybe related to SR-10532 |
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The order of constraints matters, though why I'm not quite sure as yet. This compiles: public protocol ColorModel {
associatedtype Float32Components: ColorComponents where Float32Components.Model == Self, Float32Components.Scalar == Float
init<T: ColorComponents>(_ components: T) where T.Model == Self
var float32Components: Float32Components { get set }
}
public protocol ColorComponents {
associatedtype Model: ColorModel
associatedtype Scalar
}
public protocol ColorPixel {
associatedtype Model: ColorModel
init(color: Model, opacity: Double)
init<C: ColorPixel>(_ color: C) where Self.Model == C.Model
} |
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Environment
swift 5.1
swift 5.2.3
Xcode 11.4.1
Additional Detail from JIRA
md5: 81036c9f59b1c54443089757184cc9ce
Issue Description:
The following code will produce a compilation error, but it should not happen.
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