Usually non-string keyword names are rejected.

>>> def f(**kwargs): pass                                                                                                                                                                                                                    
...                                                                                                                                                                                                                                          
>>> f(**{0:0})
Traceback (most recent call last):                                                                                                                                                                                                           
  File "<stdin>", line 1, in <module>                                                                                                                                                                                                        
TypeError: f() keywords must be strings                                                                                                                                                                                                      
>>> dict(**{0:0})
Traceback (most recent call last):                                                                                                                                                                                                           
  File "<stdin>", line 1, in <module>                                                                                                                                                                                                        
TypeError: keywords must be strings                                                                                                                                                                                                          

There are checks in multiple places that satisfy this: in _PyEval_EvalCodeWithName(), PyArg_ValidateKeywordArguments(), PyArg_ParseTupleAndKeywords(), etc.

But SimpleNamespace is an exception.

>>> from types import SimpleNamespace
>>> SimpleNamespace(**{0:0})
namespace()

Non-string keys are omitted in the repr. Wouldn't be better to add also the check that keyword names for SimpleNamespace constructor are strings?

I don't know how classify this issue, as a bug or an enhancement.

Based on the StackOverflow question: https://stackoverflow.com/questions/46164770/accepting-integers-as-keys-of-kwargs.