redundant '+' has no effect

1 files changed, 5 insertions, 0 deletions

diff --git a/sphinx/ext/autodoc/directive.py b/sphinx/ext/autodoc/directive.py
index 32adc342d..2c82122fc 100644
--- a/sphinx/ext/autodoc/directive.py
+++ b/sphinx/ext/autodoc/directive.py
@@ -93,9 +93,14 @@ def process_documenter_options(documenter: "Type[Documenter]", config: Config, o
                         if options[name] is not None and options[name].startswith('+'):
                             options[name] = ','.join([config.autodoc_default_options[name],
                                                       options[name][1:]])
+                            print(options[name])
                 else:
                     options[name] = config.autodoc_default_options[name]
 
+            elif isinstance(options.get(name), str) and options[name].startswith('+'):
+                # remove '+' from option argument if there's nothing to merge it with
+                options[name] = options[name][1:]
+
     return Options(assemble_option_dict(options.items(), documenter.option_spec))