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fix: void_function_in_ternary false positive inside if/switch expressions #6510

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fix: void_function_in_ternary false positive inside if/switch expressions #6510

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934285e
fix: void_function_in_ternary false positive in if/switch expressions…
Feb 24, 2026
b59c911
fix: correct ExpressionStmtSyntax parent traversal in isIfExprOrSwitc…
Feb 24, 2026
93d1c91
fix: avoid recursive isImplicitReturn call to prevent thread-safety i…
Mar 2, 2026
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fix: avoid recursive isImplicitReturn call to prevent thread-safety i… 
…ssues

Replace recursive call to isImplicitReturn inside isIfExprOrSwitchExprImplicitReturn
with a new non-recursive isImplicitReturnExcludingIfSwitchExpr property. This avoids
potential data races when multiple rules traverse the same syntax tree concurrently
during parallel rule execution in SwiftLint's linter.
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WZBbiao committed Mar 2, 2026
commit 93d1c918cf1a131111483bd40883331b3c233318
17 changes: 15 additions & 2 deletions Source/SwiftLintBuiltInRules/Rules/Idiomatic/VoidFunctionInTernaryConditionRule.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -204,6 +204,15 @@ private extension CodeBlockItemSyntax {
isAccessorImplicitReturn || isIfExprOrSwitchExprImplicitReturn
}

/// Like `isImplicitReturn` but without checking `isIfExprOrSwitchExprImplicitReturn`.
/// Used inside `isIfExprOrSwitchExprImplicitReturn` to avoid recursive calls that can
/// trigger thread-safety issues when multiple rules traverse the syntax tree concurrently.
var isImplicitReturnExcludingIfSwitchExpr: Bool {
isClosureImplicitReturn || isFunctionImplicitReturn ||
isVariableImplicitReturn || isSubscriptImplicitReturn ||
isAccessorImplicitReturn
}

var isClosureImplicitReturn: Bool {
guard let parent = parent?.as(CodeBlockItemListSyntax.self),
let grandparent = parent.parent else {
Expand Down Expand Up @@ -265,15 +274,19 @@ private extension CodeBlockItemSyntax {
// Note: IfExprSyntax used as a statement is wrapped in ExpressionStmtSyntax inside the CodeBlockItemSyntax.
if let ifExpr = parent.parent?.parent?.as(IfExprSyntax.self),
let ifCodeBlockItem = ifExpr.parent?.as(ExpressionStmtSyntax.self)?.parent?.as(CodeBlockItemSyntax.self) {
return ifCodeBlockItem.isImplicitReturn
// Use isImplicitReturnExcludingIfSwitchExpr instead of isImplicitReturn to avoid
// recursive calls that traverse shared syntax nodes concurrently during parallel rule execution.
return ifCodeBlockItem.isImplicitReturnExcludingIfSwitchExpr
}

// Check if inside a switch expression case body.
// Chain: CodeBlockItemListSyntax -> SwitchCaseSyntax -> SwitchCaseListSyntax -> SwitchExprSyntax
// Note: SwitchExprSyntax used as a statement is wrapped in ExpressionStmtSyntax inside the CodeBlockItemSyntax.
if let switchExpr = parent.parent?.parent?.parent?.as(SwitchExprSyntax.self),
let switchCodeBlockItem = switchExpr.parent?.as(ExpressionStmtSyntax.self)?.parent?.as(CodeBlockItemSyntax.self) {
return switchCodeBlockItem.isImplicitReturn
// Use isImplicitReturnExcludingIfSwitchExpr instead of isImplicitReturn to avoid
// recursive calls that traverse shared syntax nodes concurrently during parallel rule execution.
return switchCodeBlockItem.isImplicitReturnExcludingIfSwitchExpr
}

return false
Expand Down