Are you referring to the Py_LOCAL_INLINE macro?
I see that we have no Py_INLINE.  Py_LOCAL_INLINE includes the "static" qualifier, and in fact, if there is no "USE_INLINE" defined, then all that it does is to add "static".

Would having a "Py_INLINE(type)" macro, that is the same, but without the static (except when USE_INLINE is false) make a difference?  It would be a bit odd to have Py_LOCAL_INLINE() functions defined in the headers.

I'm not sure that there is any practical difference between "static inline" and "inline".  But there is a difference between "static" and "inline".

It would be great if we could start writing stuff like the Py_INCREF() and Py_DECREF() as functions rather than macros, but for this to happen we must be able to trust that they are really inlined.