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Add support for borrow and mutate accessors #3150

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Merged
merged 1 commit into from
Sep 26, 2025
Merged

Add support for borrow and mutate accessors #3150

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2 changes: 2 additions & 0 deletions CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift
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Expand Up @@ -120,6 +120,8 @@ public let DECL_NODES: [Node] = [
.keyword(._modify),
.keyword(.modify),
.keyword(.`init`),
.keyword(.borrow),
.keyword(.mutate),
])
),
Child(
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5 changes: 5 additions & 0 deletions CodeGeneration/Sources/SyntaxSupport/ExperimentalFeatures.swift
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Expand Up @@ -23,6 +23,7 @@ public enum ExperimentalFeature: String, CaseIterable {
case oldOwnershipOperatorSpellings
case defaultIsolationPerFile
case moduleSelector
case borrowAndMutateAccessors

/// The name of the feature as it is written in the compiler's `Features.def` file.
public var featureName: String {
Expand All @@ -47,6 +48,8 @@ public enum ExperimentalFeature: String, CaseIterable {
return "DefaultIsolationPerFile"
case .moduleSelector:
return "ModuleSelector"
case .borrowAndMutateAccessors:
return "BorrowAndMutateAccessors"
}
}

Expand All @@ -73,6 +76,8 @@ public enum ExperimentalFeature: String, CaseIterable {
return "set default actor isolation for a file"
case .moduleSelector:
return "Module selector syntax (`ModName::identifier`)"
case .borrowAndMutateAccessors:
return "borrow and mutate accessors"
}
}

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3 changes: 3 additions & 0 deletions CodeGeneration/Sources/SyntaxSupport/KeywordSpec.swift
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Expand Up @@ -201,6 +201,7 @@ public enum Keyword: CaseIterable {
case metadata
case modify
case module
case mutate
case mutableAddressWithNativeOwner
case mutableAddressWithOwner
case mutating
Expand Down Expand Up @@ -535,6 +536,8 @@ public enum Keyword: CaseIterable {
return KeywordSpec("modify", experimentalFeature: .coroutineAccessors)
case .module:
return KeywordSpec("module")
case .mutate:
return KeywordSpec("mutate", experimentalFeature: .borrowAndMutateAccessors)
case .mutableAddressWithNativeOwner:
return KeywordSpec("mutableAddressWithNativeOwner")
case .mutableAddressWithOwner:
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2 changes: 1 addition & 1 deletion Sources/SwiftParser/TokenPrecedence.swift
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Expand Up @@ -239,7 +239,7 @@ enum TokenPrecedence: Comparable {
.dependsOn, .scoped, .sending,
// Accessors
.get, .set, .didSet, .willSet, .unsafeAddress, .addressWithOwner, .addressWithNativeOwner, .unsafeMutableAddress,
.mutableAddressWithOwner, .mutableAddressWithNativeOwner, ._read, .read, ._modify, .modify,
.mutableAddressWithOwner, .mutableAddressWithNativeOwner, ._read, .read, ._modify, .modify, .mutate,
// Misc
.import, .using:
self = .declKeyword
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5 changes: 5 additions & 0 deletions Sources/SwiftParser/generated/ExperimentalFeatures.swift
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19 changes: 19 additions & 0 deletions Sources/SwiftParser/generated/Parser+TokenSpecSet.swift
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5 changes: 5 additions & 0 deletions Sources/SwiftSyntax/generated/Keyword.swift
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4 changes: 3 additions & 1 deletion Sources/SwiftSyntax/generated/raw/RawSyntaxValidation.swift
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4 changes: 3 additions & 1 deletion Sources/SwiftSyntax/generated/syntaxNodes/SyntaxNodesAB.swift
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22 changes: 22 additions & 0 deletions Tests/SwiftParserTest/DeclarationTests.swift
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Expand Up @@ -3473,6 +3473,28 @@ final class DeclarationTests: ParserTestCase {
)
}

func testBorrowAndMutateAccessors() {
assertParse(
"""
public class Klass {}

public struct Wrapper {
var _otherK: Klass

var k1: Klass {
borrow {
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I just want to mention that this will be source breaking for the following code, which is currently valid. I’ll leave it up to you to decide whether that source breakage is acceptable.

func borrow<T>(_ x: () -> T) -> T {
    return x()
}

var x: Int {
    borrow {
        1
    }
}

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Thanks for pointing that out. This is currently experimental and is not an immediate problem. We may gate the feature on language version in the future if source breakage becomes a concern.

return _otherK
}
mutate {
return &_otherK
}
}
}
""",
experimentalFeatures: .borrowAndMutateAccessors
)
}

func testMissingCommaInParameters() {
assertParse(
"func a(foo: Bar1️⃣ foo2: Bar2) {}",
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