windows: use NtSetInformationFile in DeleteFile.

lib/std/fs/test.zig

@@ -488,10 +488,7 @@ test "deleteDir" {
     dir.close();
 
     // deleting a non-empty directory
-    // TODO: Re-enable this check on Windows, see https://github.com/ziglang/zig/issues/5537
-    if (builtin.os.tag != .windows) {
-        try testing.expectError(error.DirNotEmpty, tmp_dir.dir.deleteDir("test_dir"));
-    }
+    try testing.expectError(error.DirNotEmpty, tmp_dir.dir.deleteDir("test_dir"));
 
     dir = try tmp_dir.dir.openDir("test_dir", .{});
     try dir.deleteFile("test_file");
@@ -1418,3 +1415,22 @@ test "File.PermissionsUnix" {
     try testing.expect(permissions_unix.unixHas(.user, .execute));
     try testing.expect(!permissions_unix.unixHas(.other, .execute));
 }
+
+test "delete a read-only file on windows" {
+    if (builtin.os.tag != .windows) return error.SkipZigTest;
+
+    var tmp = tmpDir(.{});
+    defer tmp.cleanup();
+    const file = try tmp.dir.createFile("test_file", .{ .read = true });
+    // Create a file and make it read-only
+    const metadata = try file.metadata();
+    var permissions = metadata.permissions();
+    permissions.setReadOnly(true);
+    try file.setPermissions(permissions);
+    try testing.expectError(error.AccessDenied, tmp.dir.deleteFile("test_file"));
+    // Now make the file not read-only
+    permissions.setReadOnly(false);
+    try file.setPermissions(permissions);
+    file.close();
+    try tmp.dir.deleteFile("test_file");
+}

lib/std/os/windows.zig

@@ -870,6 +870,7 @@ pub const DeleteFileError = error{
     Unexpected,
     NotDir,
     IsDir,
+    DirNotEmpty,
 };
 
 pub const DeleteFileOptions = struct {
@@ -879,9 +880,9 @@ pub const DeleteFileOptions = struct {
 
 pub fn DeleteFile(sub_path_w: []const u16, options: DeleteFileOptions) DeleteFileError!void {
     const create_options_flags: ULONG = if (options.remove_dir)
-        FILE_DELETE_ON_CLOSE | FILE_DIRECTORY_FILE | FILE_OPEN_REPARSE_POINT
+        FILE_DIRECTORY_FILE | FILE_OPEN_REPARSE_POINT
     else
-        FILE_DELETE_ON_CLOSE | FILE_NON_DIRECTORY_FILE | FILE_OPEN_REPARSE_POINT; // would we ever want to delete the target instead?
+        FILE_NON_DIRECTORY_FILE | FILE_OPEN_REPARSE_POINT; // would we ever want to delete the target instead?
 
     const path_len_bytes = @intCast(u16, sub_path_w.len * 2);
     var nt_name = UNICODE_STRING{
@@ -924,15 +925,36 @@ pub fn DeleteFile(sub_path_w: []const u16, options: DeleteFileOptions) DeleteFil
         0,
     );
     switch (rc) {
-        .SUCCESS => return CloseHandle(tmp_handle),
+        .SUCCESS => {},
         .OBJECT_NAME_INVALID => unreachable,
         .OBJECT_NAME_NOT_FOUND => return error.FileNotFound,
         .OBJECT_PATH_NOT_FOUND => return error.FileNotFound,
         .INVALID_PARAMETER => unreachable,
         .FILE_IS_A_DIRECTORY => return error.IsDir,
         .NOT_A_DIRECTORY => return error.NotDir,
         .SHARING_VIOLATION => return error.FileBusy,
+        .ACCESS_DENIED => return error.AccessDenied,
+        .DELETE_PENDING => return,
+        else => return unexpectedStatus(rc),
+    }
+    var file_dispo = FILE_DISPOSITION_INFORMATION{
+        .DeleteFile = TRUE,
+    };
+    rc = ntdll.NtSetInformationFile(
+        tmp_handle,
+        &io,
+        &file_dispo,
+        @sizeOf(FILE_DISPOSITION_INFORMATION),
+        .FileDispositionInformation,
+    );
+    CloseHandle(tmp_handle);
+    switch (rc) {
+        .SUCCESS => return,
+        .DIRECTORY_NOT_EMPTY => return error.DirNotEmpty,
+        .INVALID_PARAMETER => unreachable,
         .CANNOT_DELETE => return error.AccessDenied,
+        .MEDIA_WRITE_PROTECTED => return error.AccessDenied,
+        .ACCESS_DENIED => return error.AccessDenied,
         else => return unexpectedStatus(rc),
     }
 }
@@ -2470,6 +2492,10 @@ pub const FILE_INFORMATION_CLASS = enum(c_int) {
     FileMaximumInformation,
 };
 
+pub const FILE_DISPOSITION_INFORMATION = extern struct {
+    DeleteFile: BOOLEAN,
+};
+
 pub const FILE_FS_DEVICE_INFORMATION = extern struct {
     DeviceType: DEVICE_TYPE,
     Characteristics: ULONG,