Explicitly specify the encoding when loading a string with contents from a file

This fixes a deprecation warning on Linux about `String(contentsOf:)` being deprecated.

Author: ahoppen

Sources/Diagnose/MergeSwiftFiles.swift

@@ -23,7 +23,8 @@ extension RequestInfo {
     progressUpdate: (_ progress: Double, _ message: String) -> Void
   ) async throws -> RequestInfo? {
     let swiftFilePaths = compilerArgs.filter { $0.hasSuffix(".swift") }
-    let mergedFile = try swiftFilePaths.map { try String(contentsOfFile: $0) }.joined(separator: "\n\n\n\n")
+    let mergedFile = try swiftFilePaths.map { try String(contentsOfFile: $0, encoding: .utf8) }
+      .joined(separator: "\n\n\n\n")
 
     progressUpdate(0, "Merging all .swift files into a single file")
 

Sources/Diagnose/ReduceCommand.swift

@@ -78,7 +78,7 @@ package struct ReduceCommand: AsyncParsableCommand {
 
     let progressBar = PercentProgressAnimation(stream: stderrStreamConcurrencySafe, header: "Reducing sourcekitd issue")
 
-    let request = try String(contentsOfFile: sourcekitdRequestPath)
+    let request = try String(contentsOfFile: sourcekitdRequestPath, encoding: .utf8)
     let requestInfo = try RequestInfo(request: request)
 
     let executor = OutOfProcessSourceKitRequestExecutor(

Sources/Diagnose/RequestInfo.swift

@@ -104,7 +104,7 @@ package struct RequestInfo: Sendable {
 
     self.requestTemplate = requestTemplate
 
-    fileContents = try String(contentsOf: URL(fileURLWithPath: sourceFilePath))
+    fileContents = try String(contentsOf: URL(fileURLWithPath: sourceFilePath), encoding: .utf8)
   }
 
   /// Create a `RequestInfo` that is used to reduce a `swift-frontend issue`
@@ -126,7 +126,7 @@ package struct RequestInfo: Sendable {
         guard let fileList = iterator.next() else {
           throw ReductionError("Expected file path after -filelist command line argument")
         }
-        frontendArgsWithFilelistInlined += try String(contentsOfFile: fileList)
+        frontendArgsWithFilelistInlined += try String(contentsOfFile: fileList, encoding: .utf8)
           .split(separator: "\n")
           .map { String($0) }
       default:

Sources/Diagnose/RunSourcekitdRequestCommand.swift

@@ -42,7 +42,7 @@ package struct RunSourceKitdRequestCommand: AsyncParsableCommand {
   package init() {}
 
   package func run() async throws {
-    var requestString = try String(contentsOf: URL(fileURLWithPath: sourcekitdRequestPath))
+    var requestString = try String(contentsOf: URL(fileURLWithPath: sourcekitdRequestPath), encoding: .utf8)
 
     let installPath = try AbsolutePath(validating: Bundle.main.bundlePath)
     let sourcekitdPath =

Sources/SourceKitLSP/DocumentSnapshot+FromFileContents.swift

@@ -29,7 +29,7 @@ package extension DocumentSnapshot {
   ///
   /// Throws an error if the file could not be read.
   init(withContentsFromDisk url: URL, language: Language) throws {
-    let contents = try String(contentsOf: url)
+    let contents = try String(contentsOf: url, encoding: .utf8)
     self.init(uri: DocumentURI(url), language: language, version: 0, lineTable: LineTable(contents))
   }
 }

Tests/SourceKitLSPTests/BackgroundIndexingTests.swift

@@ -1199,7 +1199,7 @@ final class BackgroundIndexingTests: XCTestCase {
     )
     let packageResolvedURL = project.scratchDirectory.appendingPathComponent("Package.resolved")
 
-    let originalPackageResolvedContents = try String(contentsOf: packageResolvedURL)
+    let originalPackageResolvedContents = try String(contentsOf: packageResolvedURL, encoding: .utf8)
 
     // First check our setup to see that we get the expected hover response before changing the dependency project.
     let (uri, positions) = try project.openDocument("Test.swift")
@@ -1234,7 +1234,7 @@ final class BackgroundIndexingTests: XCTestCase {
       ])
     )
     try await project.testClient.send(PollIndexRequest())
-    XCTAssertEqual(try String(contentsOf: packageResolvedURL), originalPackageResolvedContents)
+    XCTAssertEqual(try String(contentsOf: packageResolvedURL, encoding: .utf8), originalPackageResolvedContents)
 
     // Simulate a package update which goes as follows:
     //  - The user runs `swift package update`
@@ -1248,7 +1248,7 @@ final class BackgroundIndexingTests: XCTestCase {
       ],
       workingDirectory: nil
     )
-    XCTAssertNotEqual(try String(contentsOf: packageResolvedURL), originalPackageResolvedContents)
+    XCTAssertNotEqual(try String(contentsOf: packageResolvedURL, encoding: .utf8), originalPackageResolvedContents)
     project.testClient.send(
       DidChangeWatchedFilesNotification(changes: [
         FileEvent(uri: DocumentURI(project.scratchDirectory.appendingPathComponent("Package.resolved")), type: .changed)