Wrap cypclass methods only when all args can be converted *from* python

Cython/Compiler/CypclassWrapper.py

@@ -378,7 +378,7 @@ class CypclassWrapperInjection(Visitor.CythonTransform):
             return # skip c methods with Python-incompatible return types
 
         for argtype in cfunc_type.args:
-            if not argtype.type.can_coerce_to_pyobject(self.module_scope):
+            if not argtype.type.can_coerce_from_pyobject(self.module_scope):
                 return # skip c methods with Python-incompatible argument types
 
         # > name of the wrapping method: same name as in the original code

Cython/Compiler/PyrexTypes.py

@@ -4241,6 +4241,10 @@ class CypClassType(CppClassType):
     def can_coerce_to_pyobject(self, env):
         return self.wrapper_type is not None
 
+    # allow conversion from Python only when there is a wrapper type
+    def can_coerce_from_pyobject(self, env):
+        return self.wrapper_type is not None
+
     def create_to_py_utility_code(self, env):
         if not self.wrapper_type:
             return False