[docs,io] Clarify that isDirectory is not meaningful for FileSystemDe…

…leteEvent.

Bug: #55130
Change-Id: I43c95218cd9f6b87ab242affa8cc2b9d42df7d96
CoreLibraryReviewExempt: documentation-only change
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/357663
Reviewed-by: Lasse Nielsen <[email protected]>
Reviewed-by: Brian Quinlan <[email protected]>
Commit-Queue: Brian Quinlan <[email protected]>

CHANGELOG.md

@@ -41,6 +41,9 @@ advantage of these improvements, set your package's
   `stderr`. Classes that `implement Stdout` must define the `lineTerminator`
   field. The default semantics of `stdout` and `stderr` are not changed.
 
+- Deprecates `FileSystemDeleteEvent.isDirectory`, which always returns
+  `false`.
+
 [#53863]: https://github.com/dart-lang/sdk/issues/53863
 
 #### `dart:js_interop`

sdk/lib/io/file_system_entity.dart

@@ -897,11 +897,13 @@ sealed class FileSystemEvent {
   /// relative.
   final String path;
 
-  /// Is `true` if the event target was a directory.
+  /// Whether the event target is a directory.
   ///
-  /// Note that if the file has been deleted by the time the event has arrived,
-  /// this will always be `false` on Windows. In particular, it will always be
-  /// `false` for `delete` events.
+  /// The value will always be `false` for [FileSystemDeleteEvent].
+  ///
+  /// On Windows, the value may also be `false` for a create, move or
+  /// modify event on a directory, if that directory was deleted
+  /// soon after this create, modify or move event occured.
   final bool isDirectory;
 
   FileSystemEvent._(this.type, this.path, this.isDirectory);
@@ -936,10 +938,15 @@ final class FileSystemModifyEvent extends FileSystemEvent {
 final class FileSystemDeleteEvent extends FileSystemEvent {
   /// Constructs a new [FileSystemDeleteEvent].
   FileSystemDeleteEvent(String path, bool isDirectory)
-      : super._(FileSystemEvent.delete, path, isDirectory);
+      : super._(FileSystemEvent.delete, path, false);
 
-  String toString() =>
-      "FileSystemDeleteEvent('$path', isDirectory=$isDirectory)";
+  String toString() => "FileSystemDeleteEvent('$path')";
+
+  /// Whether the file system object was a directory.
+  ///
+  /// The value will always be `false` for [FileSystemDeleteEvent].
+  @Deprecated('always false for FileSystemDeleteEvent')
+  bool get isDirectory => false;
 }
 
 /// File system event for moving of file system objects.