> Ok, I wrote PR 9122 to add %t format and modify %T format:

Nice!

I agree that it is easy to use _PyType_Name() directly. But using _PyType_FullName() instead of tp_name can be cumbersome because it returns a new object and needs error handling.

> Or do you want to add a new formatter to type.__format__() to expose %T at the Python level, f"{type(obj).__module__}.{type(obj).__qualname__}"?

Yes, I think we need a convenient way of formatting fully qualified name that omits the module name for types in the builtins module. It is equivalent to Py_TYPE(obj)->tp_name for extension types which is the most popular way to format a type name in error messages for now.

There are several open issues for inconsistency in error messages for Python and C implementations, because the former use type(obj).__name__ or obj.__class__.__name__, and the latter use Py_TYPE(obj)->tp_name. I hope finally we will fix this.