Added test case

tests/test_kwargs_and_defaults.cpp

@@ -322,4 +322,16 @@ TEST_SUBMODULE(kwargs_and_defaults, m) {
             py::pos_only{},
             py::arg("i"),
             py::arg("j"));
+            
+    // Test support for args and kwargs subclasses
+    class ArgsSubclass: public py::args{
+        using py::args::args;
+    }
+    class KWArgsSubclass: public py::kwargs{
+        using py::kwargs::kwargs;
+    }
+    m.def("args_kwargs_subclass_function", [](const ArgsSubclass &args, const KWArgsSubclass &kwargs) {
+        return py::make_tuple(args, kwargs);
+    });
+    
 }

tests/test_kwargs_and_defaults.py

@@ -426,3 +426,8 @@ def test_args_refcount():
     assert m.mixed_args_refcount(myval, myval, myval) == (exp3_3, exp3_3, exp3_3)
 
     assert m.class_default_argument() == "<class 'decimal.Decimal'>"
+    
+    assert m.args_kwargs_subclass_function(7, 8, myval, a=1, b=myval) == (
+        (7, 8, myval),
+        {"a": 1, "b": myval},
+    )