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31f7dfe475
* [stdlib] Backward compatibility fix for a flatMap on [String]
Since String started to conform to Collection, the flatMap with a
sequence returning closure is now a better match that the one that
relies on the optional promotion in this code:
[""].flatMap { $0 }
which results in the default type of this expression changing from
[String] to [Character].
Restoring the old behavior in Swift 3 mode by adding a very explicit
overload.
Fixes: <rdar://problem/32024978>
* [stdlib] Fixing another compatibility issue with [String].flatMap
43 lines
965 B
Swift
43 lines
965 B
Swift
// RUN: rm -rf %t ; mkdir -p %t
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// RUN: %target-build-swift %s -o %t/a.out3 -swift-version 3 && %target-run %t/a.out3
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// RUN: %target-build-swift %s -o %t/a.out4 -swift-version 4 && %target-run %t/a.out4
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import StdlibUnittest
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#if swift(>=4)
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public typealias ExpectedResultType = [Character]
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#else
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public typealias ExpectedResultType = [String]
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#endif
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var Tests = TestSuite("StringFlatMap")
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Tests.test("DefaultReturnType") {
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var result = ["hello", "world"].flatMap { $0 }
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expectType(ExpectedResultType.self, &result)
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}
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Tests.test("ExplicitTypeContext") {
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expectEqualSequence(["hello", "world"],
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["hello", "world"].flatMap { $0 } as [String])
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expectEqualSequence("helloworld".characters,
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["hello", "world"].flatMap { $0 } as [Character])
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}
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Tests.test("inference") {
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let result = [1, 2].flatMap { x in
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if String(x) == "foo" {
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return "bar"
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} else {
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return nil
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}
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}
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expectEqualSequence([], result)
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}
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runAllTests()
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