WIP

Sources/SwiftFormat/API/Configuration.swift

@@ -472,17 +472,3 @@ public struct NoAssignmentInExpressionsConfiguration: Codable, Equatable {
 
   public init() {}
 }
-
-fileprivate extension URL {
-  var isRoot: Bool {
-    #if os(Windows)
-    // FIXME: We should call into Windows' native check to check if this path is a root once https://github.com/swiftlang/swift-foundation/issues/976 is fixed.
-    // https://github.com/swiftlang/swift-format/issues/844
-    return self.pathComponents.count <= 1
-    #else
-    // On Linux, we may end up with an string for the path due to https://github.com/swiftlang/swift-foundation/issues/980
-    // TODO: Remove the check for "" once https://github.com/swiftlang/swift-foundation/issues/980 is fixed.
-    return self.path == "/" || self.path == ""
-    #endif
-  }
-}

Sources/SwiftFormat/CMakeLists.txt

@@ -97,7 +97,8 @@ add_library(SwiftFormat
   Rules/UseTripleSlashForDocumentationComments.swift
   Rules/UseWhereClausesInForLoops.swift
   Rules/ValidateDocumentationComments.swift
-  Utilities/FileIterator.swift)
+  Utilities/FileIterator.swift
+  Utilities/URL+isRoot.swift)
 target_link_libraries(SwiftFormat PUBLIC
   SwiftMarkdown::Markdown
   SwiftSyntax::SwiftSyntax

Sources/SwiftFormat/Utilities/FileIterator.swift

@@ -153,15 +153,12 @@ public struct FileIterator: Sequence, IteratorProtocol {
         // if the user passes paths that are relative to the current working directory, they will
         // be displayed as relative paths. Otherwise, they will still be displayed as absolute
         // paths.
-        #if os(Windows)
-        let relativePath = path
-        #else
         let relativePath =
-          path.hasPrefix(workingDirectory.path)
-            && !URL(fileURLWithPath: FileManager.default.currentDirectoryPath).isRoot
-          ? String(path.dropFirst(workingDirectory.path.count + 1))
-          : path
-        #endif
+          if !workingDirectory.isRoot, path.hasPrefix(workingDirectory.path) {
+            String(path.dropFirst(workingDirectory.path.count).drop(while: { $0 == "/" || $0 == #"\"# }))
+          } else {
+            path
+          }
         output =
           URL(fileURLWithPath: relativePath, isDirectory: false, relativeTo: workingDirectory)
 
@@ -183,16 +180,3 @@ private func fileType(at url: URL) -> FileAttributeType? {
   // Linux.
   return try? FileManager.default.attributesOfItem(atPath: url.path)[.type] as? FileAttributeType
 }
-
-fileprivate extension URL {
-  var isRoot: Bool {
-    guard isFileURL else { return false }
-    #if os(macOS)
-    return self.path == NSOpenStepRootDirectory()
-    #elseif os(Windows)
-    return self.path.withCString(encodedAs: UTF16.self, PathCchIsRoot)
-    #else
-    return self.path == "/"
-    #endif
-  }
-}

Sources/SwiftFormat/Utilities/URL+isRoot.swift

@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import Foundation
+
+extension URL {
+  @_spi(Testing) public var isRoot: Bool {
+    #if os(Windows)
+    // FIXME: We should call into Windows' native check to check if this path is a root once https://github.com/swiftlang/swift-foundation/issues/976 is fixed.
+    // https://github.com/swiftlang/swift-format/issues/844
+    return self.pathComponents.count <= 1
+    #else
+    // On Linux, we may end up with an string for the path due to https://github.com/swiftlang/swift-foundation/issues/980
+    // TODO: Remove the check for "" once https://github.com/swiftlang/swift-foundation/issues/980 is fixed.
+    return self.path == "/" || self.path == ""
+    #endif
+  }
+}

Tests/SwiftFormatTests/Utilities/FileIteratorTests.swift

@@ -1,6 +1,31 @@
-@_spi(Internal) import SwiftFormat
+@_spi(Internal) @_spi(Testing) import SwiftFormat
 import XCTest
 
+extension URL {
+  /// Assuming this is a file URL, resolves all symlinks in the path.
+  ///
+  /// - Note: We need this because `URL.resolvingSymlinksInPath()` not only resolves symlinks but also standardizes the
+  ///   path by stripping away `private` prefixes. Since sourcekitd is not performing this standardization, using
+  ///   `resolvingSymlinksInPath` can lead to slightly mismatched URLs between the sourcekit-lsp response and the test
+  ///   assertion.
+  var realpath: URL {
+    #if canImport(Darwin)
+    return self.path.withCString { path in
+      guard let realpath = Darwin.realpath(path, nil) else {
+        return self
+      }
+      let result = URL(fileURLWithPath: String(cString: realpath))
+      free(realpath)
+      return result
+    }
+    #else
+    // Non-Darwin platforms don't have the `/private` stripping issue, so we can just use `self.resolvingSymlinksInPath`
+    // here.
+    return self.resolvingSymlinksInPath()
+    #endif
+  }
+}
+
 final class FileIteratorTests: XCTestCase {
   private var tmpdir: URL!
 
@@ -10,7 +35,7 @@ final class FileIteratorTests: XCTestCase {
       in: .userDomainMask,
       appropriateFor: FileManager.default.temporaryDirectory,
       create: true
-    )
+    ).realpath
 
     // Create a simple file tree used by the tests below.
     try touch("project/real1.swift")
@@ -73,26 +98,22 @@ final class FileIteratorTests: XCTestCase {
   }
 
   func testDoesNotTrimFirstCharacterOfPathIfRunningInRoot() throws {
-    #if os(Windows) && compiler(<5.10)
-    try XCTSkipIf(true, "Testing issues with Foundation inserting extra slashes.")
-    #endif
-    // Make sure that we don't drop the begining of the path if we are running in root.
+    // Find the root of tmpdir. On Unix systems, this is always `/`. On Windows it is the drive.
+    var root = tmpdir!
+    while !root.isRoot {
+      root.deleteLastPathComponent()
+    }
+    // Make sure that we don't drop the beginning of the path if we are running in root.
     // https://github.com/swiftlang/swift-format/issues/862
-    FileManager.default.changeCurrentDirectoryPath("/")
-    let seen = allFilesSeen(iteratingOver: [tmpdir], followSymlinks: false)
-    XCTAssertEqual(seen.count, 2)
-    XCTAssertTrue(seen.contains { $0.path.hasPrefix("/") })
-    XCTAssertTrue(seen.contains { $0.path.hasPrefix("/") })
+    let seen = allFilesSeen(iteratingOver: [tmpdir], followSymlinks: false, workingDirectory: root)
+    XCTAssertTrue(seen.allSatisfy { $0.relativePath.hasPrefix(root.path) }, "\(seen) does not contain root directory")
   }
 
   func testShowsRelativePaths() throws {
     // Make sure that we still show the relative path if using them.
     // https://github.com/swiftlang/swift-format/issues/862
-    FileManager.default.changeCurrentDirectoryPath(tmpdir.path)
-    let seen = allFilesSeen(iteratingOver: [URL(fileURLWithPath: ".")], followSymlinks: false)
-    XCTAssertEqual(seen.count, 2)
-    XCTAssertTrue(seen.contains { $0.relativePath == "project/real1.swift" })
-    XCTAssertTrue(seen.contains { $0.relativePath == "project/real2.swift" })
+    let seen = allFilesSeen(iteratingOver: [tmpdir], followSymlinks: false, workingDirectory: tmpdir)
+    XCTAssertEqual(Set(seen.map(\.relativePath)), ["project/real1.swift", "project/real2.swift"])
   }
 }