Fix handling of annotated varargs in commands

When we have something like "*values: str" in :config-cycle, we get a list of
values, but the type converter assumes it's a string.

We could implement proper conversion of *args, but for now, let's just make
sure it's always a string.

qutebrowser/commands/command.py

@@ -333,13 +333,18 @@ class Command:
             param: The inspect.Parameter to look at.
         """
         arginfo = self.get_arg_info(param)
-        if param.annotation is not inspect.Parameter.empty:
+        if arginfo.value:
+            # Filled values are passed 1:1
+            return None
+        elif param.kind in [inspect.Parameter.VAR_POSITIONAL,
+                            inspect.Parameter.VAR_KEYWORD]:
+            # For *args/**kwargs we only support strings
+            assert param.annotation in [inspect.Parameter.empty, str], param
+            return None
+        elif param.annotation is not inspect.Parameter.empty:
             return param.annotation
         elif param.default not in [None, inspect.Parameter.empty]:
             return type(param.default)
-        elif arginfo.value or param.kind in [inspect.Parameter.VAR_POSITIONAL,
-                                             inspect.Parameter.VAR_KEYWORD]:
-            return None
         else:
             return str
 

tests/unit/api/test_cmdutils.py

@@ -154,6 +154,15 @@ class TestRegister:
         args, kwargs = cmd._get_call_args(win_id=0)
         fun(*args, **kwargs)
 
+    def test_star_args_optional_annotated(self):
+        @cmdutils.register(star_args_optional=True)
+        def fun(*args: str):
+            """Blah."""
+
+        cmd = objects.commands['fun']
+        cmd.namespace = cmd.parser.parse_args([])
+        cmd._get_call_args(win_id=0)
+
     @pytest.mark.parametrize('inp, expected', [
         (['--arg'], True), (['-a'], True), ([], False)])
     def test_flag(self, inp, expected):