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cdb38c1e97
Use the same infrastructure we have for same-type-to-concrete constraints to check superclass constraints. Specifically, * Track all superclass constraints; never "update" a requirement source * Remove self-derived superclass constraints * Pick the best superclass constraint within each connected component of an equivalence class and use that for requirement generation. * Diagnose conflicting superclass requirements during finalization * Diagnose redundant superclass requirements (during finalization)
20 lines
704 B
Swift
20 lines
704 B
Swift
// RUN: %target-swift-frontend %s -typecheck -verify
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class Base<T> { }
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class Derived: Base<Int> { }
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func foo<T>(_ x: T) -> Derived where T: Base<Int>, T: Derived {
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// expected-warning@-1{{redundant superclass constraint 'T' : 'Base<Int>'}}
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// expected-note@-2{{superclass constraint 'T' : 'Derived' written here}}
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return x
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}
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// FIXME: Should not be an error
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// expected-error@+2{{generic parameter 'U' cannot be a subclass of both 'Derived' and 'Base<T>'}}
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// expected-note@+1{{superclass constraint 'U' : 'Base<T>' written here}}
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func bar<T, U>(_ x: U, y: T) -> (Derived, Int) where U: Base<T>, U: Derived {
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// FIXME
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// expected-error@+1{{cannot convert return expression}}
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return (x, y)
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}
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