[v638][CPyCppyy] Correctly handle static method calls via derived instance

bindings/pyroot/cppyy/CPyCppyy/src/CPPClassMethod.cxx

@@ -34,8 +34,8 @@ PyObject* CPyCppyy::CPPClassMethod::Call(CPPInstance*&
     int nargs = (int)CPyCppyy_PyArgs_GET_SIZE(args, nargsf);
     if ((!self || (PyObject*)self == Py_None) && nargs) {
         PyObject* arg0 = CPyCppyy_PyArgs_GET_ITEM(args, 0);
-        if ((CPPInstance_Check(arg0) && ((CPPInstance*)arg0)->ObjectIsA() == GetScope()) && \
-                (fArgsRequired <= nargs-1)) {
+        if (CPPInstance_Check(arg0) && fArgsRequired <= nargs - 1 &&
+            Cppyy::IsSubtype(reinterpret_cast<CPPInstance *>(arg0)->ObjectIsA(), GetScope())) {
             args   += 1;     // drops first argument
             nargsf -= 1;
         }

bindings/pyroot/cppyy/cppyy/test/test_overloads.py

@@ -1,4 +1,4 @@
 import py, pytest, os
 from pytest import raises, skip, mark
 from support import setup_make, ispypy, IS_WINDOWS, IS_MAC_ARM
 
@@ -73,7 +73,7 @@
         import cppyy
         more_overloads = cppyy.gbl.more_overloads
         aa_ol = cppyy.gbl.aa_ol
         bb_ol = cppyy.gbl.bb_ol
         cc_ol = cppyy.gbl.cc_ol
         dd_ol = cppyy.gbl.dd_ol
 
@@ -130,13 +130,13 @@
     def test07_mean_overloads(self):
         """Adapted test for array overloading"""
 
         import cppyy, array
         cmean = cppyy.gbl.calc_mean
 
         numbers = [8, 2, 4, 2, 4, 2, 4, 4, 1, 5, 6, 3, 7]
         mean, median = 4.0, 4.0
 
         for l in ['f', 'd', 'i', 'h', 'l']:
             a = array.array(l, numbers)
             assert round(cmean(len(a), a) - mean, 8) == 0
 
@@ -158,7 +158,7 @@
         assert m.slice(0)          == 'non-const'
         assert m,slice(0, 0)       == 'non-const'
         assert m.slice_const(0)    ==     'const'
         assert m,slice_const(0, 0) ==     'const'
 
     def test09_bool_int_overloads(self):
         """Check bool/int overloaded calls"""
@@ -377,5 +377,33 @@
         assert cppyy.gbl.test12_foo(1) == cppyy.gbl.call_test12_foo()
         assert cppyy.gbl.test12_bar(1) == cppyy.gbl.call_test12_bar()
 
+
+    def test13_static_call_from_derived_instance(self):
+        """Test calling a static member function via a derived instance."""
+
+        import cppyy
+
+        cppyy.cppdef("""
+            class Base {
+            public:
+                static int StaticMethod() {
+                    return 42;
+                }
+            };
+
+            class Derived : public Base {
+            };
+        """)
+
+        d = cppyy.gbl.Derived()
+
+        # Call static method through base class directly
+        result_direct = cppyy.gbl.Base.StaticMethod()
+
+        # Call static method through instance
+        result_instance = d.StaticMethod()
+
+        assert result_instance == result_direct
+
 if __name__ == "__main__":
     exit(pytest.main(args=['-sv', '-ra', __file__]))