Fix crash when disable command is preceded by unicode character

CHANGELOG.md

@@ -19,6 +19,10 @@
 * Fix issue referencing the Tests package from another Bazel workspace.  
   [jszumski](https://github.com/jszumski)
 
+* Fix crash when a disable command is preceded by a unicode character.  
+  [SimplyDanny](https://github.com/SimplyDanny)
+  [#5945](https://github.com/realm/SwiftLint/issues/5945)
+
 * Allow severity of `duplicate_imports` rule to be configurable.  
   [SimplyDanny](https://github.com/SimplyDanny)
   [#5978](https://github.com/realm/SwiftLint/issues/5978)

Source/SwiftLintBuiltInRules/Rules/Lint/BlanketDisableCommandRule.swift

@@ -38,6 +38,7 @@ struct BlanketDisableCommandRule: Rule, SourceKitFreeRule {
             Example("""
             // swiftlint:enable ↓unused_import
             """),
+            Example("// swiftlint:disable all"),
         ].skipWrappingInCommentTests().skipDisableCommandTests()
      )
 
@@ -189,7 +190,7 @@ struct BlanketDisableCommandRule: Rule, SourceKitFreeRule {
 
 private extension Command {
     func location(of ruleIdentifier: String, in file: SwiftLintFile) -> Location {
-        var location = character
+        var location = range?.upperBound
         if line > 0, line <= file.lines.count {
             let line = file.lines[line - 1].content
             if let ruleIdentifierIndex = line.range(of: ruleIdentifier)?.lowerBound {

Source/SwiftLintBuiltInRules/Rules/Lint/InvalidSwiftLintCommandRule.swift

@@ -1,3 +1,5 @@
+import Foundation
+
 struct InvalidSwiftLintCommandRule: Rule, SourceKitFreeRule {
     var configuration = SeverityConfiguration<Self>(.warning)
 
@@ -13,6 +15,8 @@ struct InvalidSwiftLintCommandRule: Rule, SourceKitFreeRule {
             Example("// swiftlint:disable:previous unused_import"),
             Example("// swiftlint:disable:this unused_import"),
             Example("//swiftlint:disable:this unused_import"),
+            Example("_ = \"🤵🏼‍♀️\" // swiftlint:disable:this unused_import", excludeFromDocumentation: true),
+            Example("_ = \"🤵🏼‍♀️ 🤵🏼‍♀️\" // swiftlint:disable:this unused_import", excludeFromDocumentation: true),
         ],
         triggeringExamples: [
             Example("// ↓swiftlint:"),
@@ -30,6 +34,7 @@ struct InvalidSwiftLintCommandRule: Rule, SourceKitFreeRule {
             Example("// ↓swiftlint:enable: "),
             Example("// ↓swiftlint:disable: unused_import"),
             Example("// s↓swiftlint:disable unused_import"),
+            Example("// 🤵🏼‍♀️swiftlint:disable unused_import", excludeFromDocumentation: true),
         ].skipWrappingInCommentTests()
     )
 
@@ -39,16 +44,13 @@ struct InvalidSwiftLintCommandRule: Rule, SourceKitFreeRule {
 
     private func badPrefixViolations(in file: SwiftLintFile) -> [StyleViolation] {
         (file.commands + file.invalidCommands).compactMap { command in
-            if let precedingCharacter = command.precedingCharacter(in: file)?.trimmingCharacters(in: .whitespaces) {
-                if !precedingCharacter.isEmpty, precedingCharacter != "/" {
-                    return styleViolation(
-                        for: command,
-                        in: file,
-                        reason: "swiftlint command should be preceded by whitespace or a comment character"
-                    )
-                }
-            }
-            return nil
+            command.isPrecededByInvalidCharacter(in: file)
+                ? styleViolation(
+                    for: command,
+                    in: file,
+                    reason: "swiftlint command should be preceded by whitespace or a comment character"
+                )
+                : nil
         }
     }
 
@@ -59,34 +61,26 @@ struct InvalidSwiftLintCommandRule: Rule, SourceKitFreeRule {
     }
 
     private func styleViolation(for command: Command, in file: SwiftLintFile, reason: String) -> StyleViolation {
-        let character = command.startingCharacterPosition(in: file)
-        return StyleViolation(
+        StyleViolation(
             ruleDescription: Self.description,
             severity: configuration.severity,
-            location: Location(file: file.path, line: command.line, character: character),
+            location: Location(file: file.path, line: command.line, character: command.range?.lowerBound),
             reason: reason
         )
     }
 }
 
 private extension Command {
-    func startingCharacterPosition(in file: SwiftLintFile) -> Int? {
-        var position = character
-        if line > 0, line <= file.lines.count {
-            let line = file.lines[line - 1].content
-            if let commandIndex = line.range(of: "swiftlint:")?.lowerBound {
-                position = line.distance(from: line.startIndex, to: commandIndex) + 1
-            }
+    func isPrecededByInvalidCharacter(in file: SwiftLintFile) -> Bool {
+        guard line > 0, let character = range?.lowerBound, character > 1, line <= file.lines.count else {
+            return false
         }
-        return position
-    }
-
-    func precedingCharacter(in file: SwiftLintFile) -> String? {
-        if let startingCharacterPosition = startingCharacterPosition(in: file), startingCharacterPosition > 2 {
-            let line = file.lines[line - 1].content
-            return line.substring(from: startingCharacterPosition - 2, length: 1)
+        let line = file.lines[line - 1].content
+        guard line.count > character,
+              let char = line[line.index(line.startIndex, offsetBy: character - 2)].unicodeScalars.first else {
+            return false
         }
-        return nil
+        return !CharacterSet.whitespaces.union(CharacterSet(charactersIn: "/")).contains(char)
     }
 
     func invalidReason() -> String? {

Source/SwiftLintCore/Extensions/String+SwiftLint.swift

@@ -128,4 +128,17 @@ public extension String {
     func linesPrefixed(with prefix: Self) -> Self {
         split(separator: "\n").joined(separator: "\n\(prefix)")
     }
+
+    func characterPosition(of utf8Offset: Int) -> Int? {
+        guard utf8Offset != 0 else {
+            return 0
+        }
+        guard utf8Offset > 0, utf8Offset < lengthOfBytes(using: .utf8) else {
+            return nil
+        }
+        for (offset, index) in indices.enumerated() where self[...index].lengthOfBytes(using: .utf8) == utf8Offset {
+            return offset + 1
+        }
+        return nil
+    }
 }

Source/SwiftLintCore/Extensions/SwiftLintFile+Regex.swift

@@ -36,7 +36,7 @@ extension SwiftLintFile {
                 break
             }
 
-            let start = Location(file: path, line: command.line, character: command.character)
+            let start = Location(file: path, line: command.line, character: command.range?.upperBound)
             let end = endOf(next: nextCommand)
             guard start < end else { continue }
             var didSetRegion = false
@@ -67,7 +67,7 @@ extension SwiftLintFile {
         let rangeEnd = Location(file: self, characterOffset: NSMaxRange(range))
         return commands
             .filter { command in
-                let commandLocation = Location(file: path, line: command.line, character: command.character)
+                let commandLocation = Location(file: path, line: command.line, character: command.range?.upperBound)
                 return rangeStart <= commandLocation && commandLocation <= rangeEnd
             }
             .flatMap { $0.expand() }
@@ -79,7 +79,7 @@ extension SwiftLintFile {
         }
         let nextLine: Int
         let nextCharacter: Int?
-        if let nextCommandCharacter = nextCommand.character {
+        if let nextCommandCharacter = nextCommand.range?.upperBound {
             nextLine = nextCommand.line
             if nextCommandCharacter > 0 {
                 nextCharacter = nextCommandCharacter - 1

Source/SwiftLintCore/Models/Command.swift

@@ -51,8 +51,8 @@ public struct Command: Equatable {
     public let ruleIdentifiers: Set<RuleIdentifier>
     /// The line in the source file where this command is defined.
     public let line: Int
-    /// The character offset within the line in the source file where this command is defined.
-    public let character: Int?
+    /// The range of the command in the line (0-based).
+    public let range: Range<Int>?
     /// This command's modifier, if any.
     public let modifier: Modifier?
     /// The comment following this command's `-` delimiter, if any.
@@ -63,20 +63,19 @@ public struct Command: Equatable {
     /// - parameter action:          This command's action.
     /// - parameter ruleIdentifiers: The identifiers for the rules associated with this command.
     /// - parameter line:            The line in the source file where this command is defined.
-    /// - parameter character:       The character offset within the line in the source file where this command is
-    ///                              defined.
+    /// - parameter range:           The range of the command in the line (0-based).
     /// - parameter modifier:        This command's modifier, if any.
     /// - parameter trailingComment: The comment following this command's `-` delimiter, if any.
     public init(action: Action,
                 ruleIdentifiers: Set<RuleIdentifier> = [],
                 line: Int = 0,
-                character: Int? = nil,
+                range: Range<Int>? = nil,
                 modifier: Modifier? = nil,
                 trailingComment: String? = nil) {
         self.action = action
         self.ruleIdentifiers = ruleIdentifiers
         self.line = line
-        self.character = character
+        self.range = range
         self.modifier = modifier
         self.trailingComment = trailingComment
     }
@@ -85,21 +84,20 @@ public struct Command: Equatable {
     ///
     /// - parameter actionString: The string in the command's definition describing its action.
     /// - parameter line:         The line in the source file where this command is defined.
-    /// - parameter character:    The character offset within the line in the source file where this command is
-    ///                           defined.
-    public init(actionString: String, line: Int, character: Int) {
+    /// - parameter range:        The range of the command in the line (0-based).
+    public init(actionString: String, line: Int, range: Range<Int>) {
         let scanner = Scanner(string: actionString)
         _ = scanner.scanString("swiftlint:")
         // (enable|disable)(:previous|:this|:next)
         guard let actionAndModifierString = scanner.scanUpToString(" ") else {
-            self.init(action: .invalid, line: line, character: character)
+            self.init(action: .invalid, line: line, range: range)
             return
         }
         let actionAndModifierScanner = Scanner(string: actionAndModifierString)
         guard let actionString = actionAndModifierScanner.scanUpToString(":"),
               let action = Action(rawValue: actionString)
         else {
-            self.init(action: .invalid, line: line, character: character)
+            self.init(action: .invalid, line: line, range: range)
             return
         }
 
@@ -137,7 +135,7 @@ public struct Command: Equatable {
             action: action,
             ruleIdentifiers: ruleIdentifiers,
             line: line,
-            character: character,
+            range: range,
             modifier: modifier,
             trailingComment: trailingComment
         )
@@ -155,17 +153,17 @@ public struct Command: Equatable {
         case .previous:
             return [
                 Self(action: action, ruleIdentifiers: ruleIdentifiers, line: line - 1),
-                Self(action: action.inverse(), ruleIdentifiers: ruleIdentifiers, line: line - 1, character: Int.max),
+                Self(action: action.inverse(), ruleIdentifiers: ruleIdentifiers, line: line - 1, range: 0..<Int.max),
             ]
         case .this:
             return [
                 Self(action: action, ruleIdentifiers: ruleIdentifiers, line: line),
-                Self(action: action.inverse(), ruleIdentifiers: ruleIdentifiers, line: line, character: Int.max),
+                Self(action: action.inverse(), ruleIdentifiers: ruleIdentifiers, line: line, range: 0..<Int.max),
             ]
         case .next:
             return [
                 Self(action: action, ruleIdentifiers: ruleIdentifiers, line: line + 1),
-                Self(action: action.inverse(), ruleIdentifiers: ruleIdentifiers, line: line + 1, character: Int.max),
+                Self(action: action.inverse(), ruleIdentifiers: ruleIdentifiers, line: line + 1, range: 0..<Int.max),
             ]
         case .invalid:
             return []

Source/SwiftLintCore/Visitors/CommandVisitor.swift

@@ -13,37 +13,34 @@ final class CommandVisitor: SyntaxVisitor {
     }
 
     override func visitPost(_ node: TokenSyntax) {
-        let leadingCommands = node.leadingTrivia.commands(offset: node.position,
-                                                          locationConverter: locationConverter)
-        let trailingCommands = node.trailingTrivia.commands(offset: node.endPositionBeforeTrailingTrivia,
-                                                            locationConverter: locationConverter)
-        self.commands.append(contentsOf: leadingCommands + trailingCommands)
+        collectCommands(in: node.leadingTrivia, offset: node.position)
+        collectCommands(in: node.trailingTrivia, offset: node.endPositionBeforeTrailingTrivia)
     }
-}
-
-// MARK: - Private Helpers
 
-private extension Trivia {
-    func commands(offset: AbsolutePosition, locationConverter: SourceLocationConverter) -> [Command] {
-        var triviaOffset = SourceLength.zero
-        var results: [Command] = []
-        for trivia in self {
-            triviaOffset += trivia.sourceLength
-            switch trivia {
+    private func collectCommands(in trivia: Trivia, offset: AbsolutePosition) {
+        var position = offset
+        for piece in trivia {
+            switch piece {
             case .lineComment(let comment):
-                guard let lower = comment.range(of: "swiftlint:")?.lowerBound else {
+                guard let lower = comment.range(of: "swiftlint:")?.lowerBound.samePosition(in: comment.utf8) else {
                     break
                 }
-
-                let actionString = String(comment[lower...])
-                let end = locationConverter.location(for: offset + triviaOffset)
-                let command = Command(actionString: actionString, line: end.line, character: end.column)
-                results.append(command)
+                let offset = comment.utf8.distance(from: comment.utf8.startIndex, to: lower)
+                let location = locationConverter.location(for: position.advanced(by: offset))
+                let line = locationConverter.sourceLines[location.line - 1]
+                guard let character = line.characterPosition(of: location.column) else {
+                    break
+                }
+                let command = Command(
+                    actionString: String(comment[lower...]),
+                    line: location.line,
+                    range: character..<(character + piece.sourceLength.utf8Length - offset)
+                )
+                commands.append(command)
             default:
                 break
             }
+            position += piece.sourceLength
         }
-
-        return results
     }
 }