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be915b9c04
This change enables inheritance constraints such as "T : NSObject", which specifies that the type parameter T must inherit (directly or indirectly) from NSObject. One can then implicit convert from T to NSObject and perform (checked) downcasts from an NSObject to a T. With this, we can type- IR generation still needs to be updated to handle these implicit conversions and downcasts. New AST nodes may follow. Swift SVN r3459
44 lines
849 B
Swift
44 lines
849 B
Swift
// RUN: %swift %s -verify
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class A {
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func foo() { }
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}
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class B : A {
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func bar() { }
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}
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class Other { }
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func acceptA(a : A) { }
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func f0<T : A>(obj : T, a : A, b : B) { // expected-note{{found this candidate}}
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// Method access
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obj.foo()
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obj.bar() // expected-error{{}}
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// Calls
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acceptA(obj)
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// Derived-to-base conversion for assignment
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a = obj
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// Invalid assignments
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obj = a // expected-error{{}}
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obj = b // expected-error{{}}
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// Downcasts
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a = A(obj)
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b = B(obj)
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}
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func call_f0(a : A, b : B, other : Other) {
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f0(a, a, b)
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f0(b, a, b)
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f0(other, a, b) // expected-error{{}}
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}
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// Declaration errors
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func f1<T : A requires T : Other>() { } // expected-error{{generic parameter 'T' cannot be a subclass of both 'A' and 'Other'}}
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func f2<T : A requires T : B>() { } // FIXME: expected-error{{cannot be a subclass}}
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