Ensure directory URL enumerator error handler block is invoked with non-nil URL

apinotes/Foundation.apinotes

@@ -659,6 +659,9 @@ Classes:
   - Selector: 'URLForPublishingUbiquitousItemAtURL:expirationDate:error:'
     SwiftName: url(forPublishingUbiquitousItemAt:expiration:)
     MethodKind: Instance
+  - Selector: 'enumeratorAtURL:includingPropertiesForKeys:options:errorHandler:'
+    MethodKind: Instance
+    SwiftPrivate: true
 - Name: NSFileVersion
   Methods:
   - Selector: 'versionOfItemAtURL:forPersistentIdentifier:'

stdlib/public/SDK/Foundation/FileManager.swift

@@ -21,6 +21,13 @@ internal func NS_Swift_NSFileManager_replaceItemAtURL_withItemAtURL_backupItemNa
     _ options: FileManager.ItemReplacementOptions,
     _ error: NSErrorPointer) -> NSURL?
 
+@_silgen_name("NS_Swift_NSFileManager_enumeratorAt_includingPropertiesForKeys_options_errorHandler")
+internal func NS_Swift_NSFileManager_enumeratorAt_includingPropertiesForKeys_options_errorHandler(
+    _ self_ : AnyObject,
+    _ url: AnyObject,
+    _ keys: NSArray?,
+    _ options: FileManager.DirectoryEnumerationOptions,
+    _ errorHandler: @escaping @convention(block) (NSURL, NSError) -> Bool) -> FileManager.DirectoryEnumerator?
 
 extension FileManager {
     /*
@@ -45,4 +52,16 @@ extension FileManager {
         }
         throw error!
     }
+
+    @available(OSX 10.6, iOS 4.0, *)
+    public func enumerator(at url: URL, includingPropertiesForKeys keys: [URLResourceKey]?, options mask: FileManager.DirectoryEnumerationOptions = [], errorHandler handler: ((URL, Error) -> Bool)? = nil) -> FileManager.DirectoryEnumerator? {
+        return NS_Swift_NSFileManager_enumeratorAt_includingPropertiesForKeys_options_errorHandler(self, url as NSURL, keys as NSArray?, mask, { (url, error) in
+            var errorResult = true;
+            if let h = handler {
+                errorResult = h(url as URL, error)
+            }
+            return errorResult
+        })
+    }
+
 }

stdlib/public/SDK/Foundation/FileManagerThunks.m

@@ -33,3 +33,31 @@
   [backupItemName release];
   return success ? [result retain] : nil;
 }
+
+extern /*"C"*/ NS_RETURNS_RETAINED id
+NS_Swift_NSFileManager_enumeratorAt_includingPropertiesForKeys_options_errorHandler(
+    NSFileManager *NS_RELEASES_ARGUMENT _Nonnull self_,
+    NSURL *NS_RELEASES_ARGUMENT _Nonnull url,
+    NSArray *NS_RELEASES_ARGUMENT _Nullable keys,
+    NSUInteger options,
+    BOOL (^_Nonnull errorHandler)(NSURL * _Nonnull url, NSError * _Nonnull error) ) {
+
+  NSDirectoryEnumerator *result = [self_ enumeratorAtURL:url
+                              includingPropertiesForKeys:keys
+                                                 options:(NSDirectoryEnumerationOptions)options
+                                            errorHandler:^(NSURL * url, NSError *error) {
+
+    NSURL *realURL = url ?: error.userInfo[NSURLErrorKey];
+    if (!realURL) {
+      NSString *path = error.userInfo[NSFilePathErrorKey];
+      realURL = [NSURL fileURLWithPath:path];
+    }
+    return errorHandler(realURL, error);
+
+  }];
+  [self_ release];
+  [url release];
+  [keys release];
+  [errorHandler release];
+  return [result retain];
+}

test/stdlib/TestFileManager.swift

@@ -72,12 +72,68 @@ class TestFileManager : TestFileManagerSuper {
         expectTrue(threw, "Should have thrown")
 
     }
+
+    func testDirectoryEnumerator_error() {
+        let fm = FileManager.default
+        let nonexistantURL = URL(fileURLWithPath: "\(NSTemporaryDirectory())/nonexistant")
+
+        var invoked = false
+        let e = fm.enumerator(at: nonexistantURL, includingPropertiesForKeys: []) { (url, err) in
+            invoked = true
+            expectEqual(nonexistantURL, url)
+            expectEqual((err as NSError).code, NSFileReadNoSuchFileError)
+            return true
+        }
+
+        let url = e?.nextObject()
+        expectTrue(invoked)
+        expectTrue(url == nil)
+
+    }
+
+    func testDirectoryEnumerator_error_noHandler() {
+        let fm = FileManager.default
+        let nonexistantURL = URL(fileURLWithPath: "\(NSTemporaryDirectory())/nonexistant")
+
+        let e = fm.enumerator(at: nonexistantURL, includingPropertiesForKeys: [])
+        let url = e?.nextObject()
+        expectTrue(url == nil)
+
+    }
+
+    func testDirectoryEnumerator_simple() {
+        let fm = FileManager.default
+        let dirPath = (NSTemporaryDirectory() as NSString).appendingPathComponent(NSUUID().uuidString)
+        try! fm.createDirectory(atPath: dirPath, withIntermediateDirectories: true, attributes: nil)
+        defer { try! FileManager.default.removeItem(atPath: dirPath) }
+
+        let item1 = URL(fileURLWithPath: "\(dirPath)/1", isDirectory: false)
+        let item2 = URL(fileURLWithPath: "\(dirPath)/2", isDirectory: false)
+
+        try! Data().write(to: item1)
+        try! Data().write(to: item2)
+
+        let e = fm.enumerator(at: URL(fileURLWithPath: dirPath, isDirectory: true), includingPropertiesForKeys: [])
+        let result1 = e?.nextObject()
+        let result2 = e?.nextObject()
+        let result3 = e?.nextObject()
+
+        // Avoid potential symlink discrepancy between the result and the original URL
+        expectEqual((result1! as! URL).lastPathComponent, item1.lastPathComponent)
+        expectEqual((result2! as! URL).lastPathComponent, item2.lastPathComponent)
+        expectTrue(result3 == nil)
+
+    }
+
 }
 
 #if !FOUNDATION_XCTEST
 var FMTests = TestSuite("TestFileManager")
 FMTests.test("testReplaceItem") { TestFileManager().testReplaceItem() }
 FMTests.test("testReplaceItem_error") { TestFileManager().testReplaceItem_error() }
+FMTests.test("testDirectoryEnumerator_error") { TestFileManager().testDirectoryEnumerator_error() }
+FMTests.test("testDirectoryEnumerator_error_noHandler") { TestFileManager().testDirectoryEnumerator_error_noHandler() }
+FMTests.test("testDirectoryEnumerator_simple") { TestFileManager().testDirectoryEnumerator_simple() }
 
 runAllTests()
 #endif