Add the xcissues Swift package

Package.resolved

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+{
+  "object": {
+    "pins": [
+      {
+        "package": "swift-argument-parser",
+        "repositoryURL": "https://github.com/apple/swift-argument-parser.git",
+        "state": {
+          "branch": null,
+          "revision": "82905286cc3f0fa8adc4674bf49437cab65a8373",
+          "version": "1.1.1"
+        }
+      }
+    ]
+  },
+  "version": 1
+}

Package.swift

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+// swift-tools-version:5.5
+import PackageDescription
+
+let package = Package(
+    name: "SwiftLint",
+    platforms: [.macOS(.v12)],
+    products: [
+        .executable(name: "xcissues", targets: ["xcissues"]),
+    ],
+    dependencies: [
+        .package(name: "swift-argument-parser", url: "https://github.com/apple/swift-argument-parser.git", .upToNextMinor(from: "1.1.1")),
+    ],
+    targets: [
+        .executableTarget(
+            name: "xcissues",
+            dependencies: [
+                "XcodeIssues",
+            ]
+        ),
+        .target(
+            name: "XcodeIssues",
+            dependencies: [
+                .product(name: "ArgumentParser", package: "swift-argument-parser"),
+            ]
+        ),
+    ]
+)

Source/XcodeIssues/ReviewDogJSON.swift

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+import Foundation
+
+struct DiagnosticResult: Codable, Hashable {
+    var diagnostics: [Diagnostic]
+}
+
+struct Diagnostic: Codable, Hashable {
+    struct Position: Codable, Hashable {
+        var line: Int
+        var column: Int
+    }
+
+    struct Range: Codable, Hashable {
+        var start: Position
+        var end: Position?
+    }
+
+    struct Location: Codable, Hashable {
+        var path: String
+        var range: Range
+    }
+
+    enum Severity: String, Codable, Hashable {
+        case unknown = "UNKNOWN_SEVERITY"
+        case error = "ERROR"
+        case info = "INFO"
+        case warning = "WARNING"
+    }
+
+    var message: String
+    var location: Location
+    var severity: Severity
+}

Source/XcodeIssues/XcodeIssues.swift

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+import ArgumentParser
+import Foundation
+
+public struct XcodeIssues: AsyncParsableCommand {
+    public static var configuration = CommandConfiguration(
+        commandName: "xcissues",
+        abstract: "A utility for reporting xcode issues in reviewdog JSON Format.")
+
+    @Argument(help: "The path of the xcresult JSON file to process. If omitted, stdin is used instead.")
+    var input: String?
+
+    public init() {
+    }
+
+    public func run() throws {
+        let fileHandle = input.flatMap(FileHandle.init(forReadingAtPath:)) ?? .standardInput
+
+        guard let fileData = try fileHandle.readToEnd() else {
+            return // TODO: throw an error?
+        }
+
+        let invocationRecord = try JSONDecoder().decode(ActionsInvocationRecord.self, from: fileData)
+        let errorDiagnostics = invocationRecord.issues.errorSummaries?.values.compactMap { Diagnostic(issueSummary: $0, severity: .error) } ?? []
+        let warningDiagnostics = invocationRecord.issues.warningSummaries?.values.compactMap { Diagnostic(issueSummary: $0, severity: .warning) } ?? []
+        let allDiagnostics = errorDiagnostics + warningDiagnostics
+        let result = DiagnosticResult(diagnostics: allDiagnostics)
+        let jsonData = try JSONEncoder().encode(result)
+
+        try FileHandle.standardOutput.write(contentsOf: jsonData)
+    }
+}
+
+extension Diagnostic {
+    init?(issueSummary: IssueSummary, severity: Severity) {
+        guard let location = issueSummary.documentLocationInCreatingWorkspace,
+              let startingLineNumber = location.startingLineNumber,
+              let startingColumnNumber = location.startingColumnNumber
+        else {
+            return nil
+        }
+
+        // `DocumentLocation` uses zero-indexed line/column numbers, while rdjson uses 1-indexed line/column numbers.
+        // Add 1 to each of the line/column numbers here to account for this.
+        let endPosition: Position?
+        if let endingLineNumber = location.endingLineNumber,
+           let endingColumnNumber = location.endingColumnNumber {
+            endPosition = .init(
+                line: endingLineNumber + 1,
+                column: endingColumnNumber + 1
+            )
+        } else {
+            endPosition = nil
+        }
+
+        self.init(
+            message: issueSummary.message.value,
+            location: .init(
+                path: location.path,
+                range: .init(
+                    start: .init(
+                        line: startingLineNumber + 1,
+                        column: startingColumnNumber + 1
+                    ),
+                    end: endPosition
+                )
+            ),
+            severity: severity
+        )
+    }
+}

Source/XcodeIssues/XcodeResultTypes.swift

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+import Foundation
+
+public struct XcodeObject<Value: Decodable>: Decodable {
+    enum CodingKeys: String, CodingKey {
+        case value = "_value"
+    }
+
+    public let value: Value
+}
+
+public struct XcodeArray<Value: Decodable>: Decodable {
+    enum CodingKeys: String, CodingKey {
+        case values = "_values"
+    }
+
+    public let values: [Value]
+}
+
+public struct ActionsInvocationRecord: Decodable {
+    public let issues: ResultIssueSummaries
+}
+
+public struct ResultIssueSummaries: Decodable {
+    public var errorSummaries: XcodeArray<IssueSummary>?
+    public var warningSummaries: XcodeArray<IssueSummary>?
+    public var testFailureSummaries: XcodeArray<TestFailureIssueSummary>?
+}
+
+public struct IssueSummary: Decodable {
+    public let documentLocationInCreatingWorkspace: DocumentLocation?
+    public var message: XcodeObject<String>
+}
+
+public struct TestFailureIssueSummary: Decodable {
+    public let documentLocationInCreatingWorkspace: DocumentLocation?
+    public var message: XcodeObject<String>
+    public var producingTarget: XcodeObject<String>
+    public var testCaseName: XcodeObject<String>
+}
+
+public struct DocumentLocation: Decodable {
+    public let path: String
+    public let startingLineNumber: Int?
+    public let endingLineNumber: Int?
+    public let startingColumnNumber: Int?
+    public let endingColumnNumber: Int?
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        let url = try container.decode(XcodeObject<URL>.self, forKey: .url)
+        guard var urlComponents = URLComponents(url: url.value, resolvingAgainstBaseURL: true) else {
+            throw DecodingError.dataCorruptedError(forKey: .url, in: container, debugDescription: "Invalid URL")
+        }
+
+        urlComponents.query = urlComponents.fragment
+        let fragmentQueryItem = { name in
+            urlComponents
+                .fragmentQueryItems?
+                .last(where: { $0.name == name })?
+                .value
+        }
+
+        self.path = urlComponents.path
+        self.startingLineNumber = fragmentQueryItem("StartingLineNumber").flatMap(Int.init)
+        self.endingLineNumber = fragmentQueryItem("EndingLineNumber").flatMap(Int.init)
+        self.startingColumnNumber = fragmentQueryItem("StartingColumnNumber").flatMap(Int.init)
+        self.endingColumnNumber = fragmentQueryItem("EndingColumnNumber").flatMap(Int.init)
+    }
+
+    enum CodingKeys: String, CodingKey {
+        case url = "url"
+    }
+}
+
+extension URLComponents {
+    var fragmentQueryItems: [URLQueryItem]? {
+        var newComponents = URLComponents()
+        newComponents.query = fragment
+        return newComponents.queryItems
+    }
+}

Source/xcissues/MainApp.swift

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+import XcodeIssues
+
+@main
+struct MainApp {
+    static func main() {
+        XcodeIssues.main()
+    }
+}