A sketch for an adaptors module

Author: glessard

Package.swift

@@ -135,12 +135,27 @@ let package = Package(
       exclude: filesToExclude,
       cSettings: cSettings,
       swiftSettings: swiftSettings),
+    .target(
+      name: "SystemCompatibilityAdaptors",
+      dependencies: ["SystemPackage"],
+      path: "Sources/SystemCompatibilityAdaptors",
+      exclude: [],
+      cSettings: cSettings,
+      swiftSettings: swiftSettings
+    ),
     .testTarget(
       name: "SystemTests",
       dependencies: ["SystemPackage"],
       exclude: testsToExclude,
       cSettings: cSettings,
       swiftSettings: swiftSettings),
+    .testTarget(
+      name: "SystemCompatibilityAdaptorTests",
+      dependencies: ["SystemCompatibilityAdaptors", "SystemPackage"],
+      exclude: [],
+      cSettings: cSettings,
+      swiftSettings: swiftSettings
+    ),
   ],
   swiftLanguageVersions: [.v5]
 )

Sources/SystemCompatibilityAdaptors/CompatibilityAdaptors.swift

@@ -0,0 +1,36 @@
+#if canImport(System) && canImport(SystemPackage)
+import System
+import SystemPackage
+
+@available(System 0.0.2, *)
+extension SystemPackage.FilePath {
+  @available(System 0.0.2, *)
+  public init(converting path: System.FilePath) {
+    self = path.withPlatformString(Self.init(platformString:))
+  }
+}
+
+@available(System 0.0.2, *)
+extension System.FilePath {
+  @available(System 0.0.2, *)
+  public init(converting path: SystemPackage.FilePath) {
+    self = path.withPlatformString(Self.init(platformString:))
+  }
+}
+
+@available(System 0.0.1, *)
+extension SystemPackage.FileDescriptor {
+  @available(System 0.0.1, *)
+  public init(converting descriptor: System.FileDescriptor) {
+    self.init(rawValue: descriptor.rawValue)
+  }
+}
+
+@available(System 0.0.1, *)
+extension System.FileDescriptor {
+  @available(System 0.0.1, *)
+  public init(converting descriptor: SystemPackage.FileDescriptor) {
+    self.init(rawValue: descriptor.rawValue)
+  }
+}
+#endif // canImport(System) && canImport(SystemPackage)

Tests/SystemCompatibilityAdaptorTests/AdaptorTests.swift

@@ -0,0 +1,30 @@
+#if canImport(System) && canImport(SystemPackage)
+
+import XCTest
+
+import SystemPackage
+import System
+
+import SystemCompatibilityAdaptors
+
+final class SystemCompatibilityAdaptorTests: XCTestCase {
+
+  func testFilePathAdaptor() {
+    let fp = SystemPackage.FilePath("/bar")
+
+    let sfp = System.FilePath(converting: fp)
+
+    // If we had access to the underlying array as API, this would look less silly
+    XCTAssertEqual(fp, SystemPackage.FilePath(converting: sfp))
+  }
+
+  func testFileDescriptorAdaptor() throws {
+    let fd = try SystemPackage.FileDescriptor.standardInput.duplicate()
+
+    let sfd: System.FileDescriptor = System.FileDescriptor(converting: fd)
+
+    print(fd.rawValue)
+    XCTAssertEqual(fd.rawValue, sfd.rawValue)
+  }
+}
+#endif // canImport(System) && canImport(SystemPackage)