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f44064cbbc
Introduce callables: values of types that declare `func callAsFunction`
methods can be called like functions. The call syntax is shorthand for
applying `func callAsFunction` methods.
```swift
struct Adder {
var base: Int
func callAsFunction(_ x: Int) -> Int {
return x + base
}
}
var adder = Adder(base: 3)
adder(10) // desugars to `adder.callAsFunction(10)`
```
`func callAsFunction` argument labels are required at call sites.
Multiple `func callAsFunction` methods on a single type are supported.
`mutating func callAsFunction` is supported.
SR-11378 tracks improving `callAsFunction` diagnostics.
20 lines
472 B
Swift
20 lines
472 B
Swift
// RUN: %target-typecheck-verify-swift
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// Test extending `Optional` with `func callAsFunction`.
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// `Optional` is an edge case since constraint simplification has special
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// `Optional` stripping logic.
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extension Optional {
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func callAsFunction() -> Optional {
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return self
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}
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func callAsFunction(_ fn: (Int) -> Void) -> Optional {
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return self
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}
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}
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func testOptional<T>(_ x: T?) {
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_ = x()()()
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// Test trailing closure syntax.
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_ = x { _ in } ({ _ in })
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}
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