Provide guidance when called with a YouTube ID starting with a dash.

Reported at https://news.ycombinator.com/item?id=8648121

1 files changed, 4 insertions, 3 deletions

diff --git a/youtube_dl/__init__.py b/youtube_dl/__init__.py
index c1323b4f3..f519fae3e 100644
--- a/youtube_dl/__init__.py
+++ b/youtube_dl/__init__.py
@@ -334,11 +334,12 @@ def _real_main(argv=None):
 
         # Maybe do nothing
         if (len(all_urls) < 1) and (opts.load_info_filename is None):
-            if not (opts.update_self or opts.rm_cachedir):
-                parser.error('you must provide at least one URL')
-            else:
+            if opts.update_self or opts.rm_cachedir:
                 sys.exit()
 
+            ydl.warn_if_short_id(sys.argv[1:] if argv is None else argv)
+            parser.error('you must provide at least one URL')
+
         try:
             if opts.load_info_filename is not None:
                 retcode = ydl.download_with_info_file(opts.load_info_filename)