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DougGregor/false_recursion.swift

Created February 24, 2017 05:44
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False recursion
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false_recursion.swift
protocol P {
associatedtype PType
}
public protocol Q {
associatedtype QType: R
}
public protocol R {
associatedtype RType
}
func f<T: P>(_: T) where T.PType.RType: Q, T.PType.RType.QType == T.PType {}
// We get this signature: <T where T : P, T.PType : R, T.PType == T.PType.RType.QType, T.PType.RType : Q>
// But we should get this signature: <T where T : P, T.PType == T.PType.RType.QType, T.PType.RType : Q>
// The “T.PType: R” requirement is redundant, but pops up when building the canonical generic environment due to the recursion-breaking code being wrong.
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