FileManager: Add missing replaceItemAt(_:withItemAt:backupItemName:options:)

- This just wraps replaceItem(at:withItemAt:backupItemName:options:)

Author: spevans

Foundation/FileManager.swift

@@ -1045,10 +1045,20 @@ open class FileManager : NSObject {
     open func replaceItem(at originalItemURL: URL, withItemAt newItemURL: URL, backupItemName: String?, options: ItemReplacementOptions = []) throws -> URL? {
         NSUnimplemented()
     }
+
+    @available(Windows, deprecated, message: "Not yet implemented")
+    public func replaceItemAt(_ originalItemURL: URL, withItemAt newItemURL: URL, backupItemName: String? = nil, options: ItemReplacementOptions = []) throws -> URL? {
+        NSUnimplemented()
+    }
+
     #else
     open func replaceItem(at originalItemURL: URL, withItemAt newItemURL: URL, backupItemName: String?, options: ItemReplacementOptions = []) throws -> URL? {
         return try _replaceItem(at: originalItemURL, withItemAt: newItemURL, backupItemName: backupItemName, options: options)
     }
+
+    public func replaceItemAt(_ originalItemURL: URL, withItemAt newItemURL: URL, backupItemName: String? = nil, options: ItemReplacementOptions = []) throws -> URL? {
+        return try _replaceItem(at: originalItemURL, withItemAt: newItemURL, backupItemName: backupItemName, options: options)
+    }
     #endif
 
     @available(*, unavailable, message: "Returning an object through an autoreleased pointer is not supported in swift-corelibs-foundation. Use replaceItem(at:withItemAt:backupItemName:options:) instead.", renamed: "replaceItem(at:withItemAt:backupItemName:options:)")
@@ -1064,17 +1074,7 @@ open class FileManager : NSObject {
 
         return _appendSymlinkDestination(destination, toPath: path)
     }
-    
 
-}
-
-extension FileManager {
-    public func replaceItemAt(_ originalItemURL: URL, withItemAt newItemURL: URL, backupItemName: String? = nil, options: ItemReplacementOptions = []) throws -> NSURL? {
-        NSUnimplemented()
-    }
-}
-
-extension FileManager {
     open var homeDirectoryForCurrentUser: URL {
         return homeDirectory(forUser: NSUserName())!
     }

TestFoundation/TestFileManager.swift

@@ -1701,13 +1701,18 @@ VIDEOS=StopgapVideos
             try runSingleTest(aIsDirectory: true, bIsDirectory: false, options: [.withoutDeletingBackupItem, .usingNewMetadataOnly])
         }
 
+        print("Testing Darwin Foundation compatible replace", to: &stderr)
+        try testReplaceMethod { (a, b, backupItemName, options) -> URL? in
+            try fm.replaceItemAt(a, withItemAt: b, backupItemName: backupItemName, options: options)
+        }
+
         #if !DARWIN_COMPATIBILITY_TESTS
         print("note: Testing platform-specific replace implementation.", to: &stderr)
         try testReplaceMethod { (a, b, backupItemName, options) -> URL? in
             try fm.replaceItem(at: a, withItemAt: b, backupItemName: backupItemName, options: options)
         }
         #endif
-        
+
         #if NS_FOUNDATION_ALLOWS_TESTABLE_IMPORT
         print("note: Testing cross-platform replace implementation.", to: &stderr)
         try testReplaceMethod { (a, b, backupItemName, options) -> URL? in