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Keep the buffer in the invalid UTF8 handling path of String(unsafeUninitializedCapacity:initializingWith:) alive while we're using it #39105

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Merged
merged 6 commits into from
Aug 31, 2021
Merged

Keep the buffer in the invalid UTF8 handling path of String(unsafeUninitializedCapacity:initializingWith:) alive while we're using it #39105

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4bdc8e3
Copy the code units into a temporary buffer in the invalid UTF8 handl…
Catfish-Man Aug 31, 2021
ce17877
Remove unnecessary _fixLifetime
Catfish-Man Aug 31, 2021
52f9c77
Revert "Remove unnecessary _fixLifetime"
Catfish-Man Aug 31, 2021
4209361
Revert "Copy the code units into a temporary buffer in the invalid UT…
Catfish-Man Aug 31, 2021
8914430
Keep the __StringStorage alive while we're using its buffer
Catfish-Man Aug 31, 2021
3f716e3
Tests for invalid UTF8 handling
Catfish-Man Aug 31, 2021
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1 change: 1 addition & 0 deletions stdlib/public/core/StringCreate.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -120,6 +120,7 @@ extension String {
)
return result.asString
case .error(let initialRange):
defer { _fixLifetime(result) }
//This could be optimized to use excess tail capacity
return repairUTF8(result.codeUnits, firstKnownBrokenRange: initialRange)
}
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37 changes: 24 additions & 13 deletions test/stdlib/StringCreate.swift
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Expand Up @@ -57,22 +57,33 @@ if #available(macOS 10.16, iOS 14.0, watchOS 7.0, tvOS 14.0, *) {
}
expectEqual(expected, actual)
}

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Nit: trailing whitespace.

let validUTF8: [UInt8] = [0x43, 0x61, 0x66, 0xC3, 0xA9]
let invalidUTF8: [UInt8] = [0x43, 0x61, 0x66, 0xC3]

let cafe1 = String(unsafeUninitializedCapacity: validUTF8.count) {
_ = $0.initialize(from: validUTF8)
return validUTF8.count
}
expectEqual("Café", cafe1)

let cafe2 = String(unsafeUninitializedCapacity: invalidUTF8.count) {
_ = $0.initialize(from: invalidUTF8)
return invalidUTF8.count
let longerValidUTF8: [UInt8] = [0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x21, 0x43, 0x61, 0x66, 0xC3, 0xA9]
let longerInvalidUTF8: [UInt8] = [0x21, 0x21, 0x43, 0x61, 0x66, 0xC3, 0x43, 0x61, 0x66, 0xC3, 0x43, 0x61, 0x66, 0xC3]

func test(bufferSize: Int, input: [UInt8], expected: String) {
let strs = (0..<100).map { _ in
String(unsafeUninitializedCapacity: bufferSize) { buffer in
_ = buffer.initialize(from: input)
return input.count
}
}
for str in strs {
expectEqual(expected, str)
}
}
expectEqual("Caf�", cafe2)


test(bufferSize: validUTF8.count, input: validUTF8, expected: "Café")
test(bufferSize: invalidUTF8.count, input: invalidUTF8, expected: "Caf�")
// Force non-smol strings by using a larger capacity
test(bufferSize: 16, input: validUTF8, expected: "Café")
test(bufferSize: 16, input: invalidUTF8, expected: "Caf�")
test(bufferSize: longerValidUTF8.count, input: longerValidUTF8, expected: "!!!!!!!!!!Café")
test(bufferSize: longerInvalidUTF8.count, input: longerInvalidUTF8, expected: "!!Caf�Caf�Caf�")
test(bufferSize: 16, input: longerValidUTF8, expected: "!!!!!!!!!!Café")
test(bufferSize: 16, input: longerInvalidUTF8, expected: "!!Caf�Caf�Caf�")
let empty = String(unsafeUninitializedCapacity: 16) { _ in
// Can't initialize the buffer (e.g. the capacity is too small).
return 0
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