MAINT: Make keyword arrays static

[alexhenrie]

These arrays never change, and making them static will avoid having to reinitialize them on every function call.

[eric-wieser]

I'm not convinced by this change - isn't it sufficient to mark them const?

[alexhenrie]

Sadly, marking them const produces compiler warnings because PyArg_ParseTupleAndKeywords takes a non-const array even though it doesn't actually modify the array. git grep -F 'char *kwlist[]' shows that most of these arrays were already marked static in NumPy, and none are marked const. I'm just proposing that we be consistent and add static to the ones that didn't have it already.

[eric-wieser]

I just concluded the same thing. The approach seems odd, but it's even how CPython itself does it. I'll maybe play around with godbolt to see if const is ultimately better, but at the end of the day consistency matters more than microoptimization here.

[eric-wieser]

takes a non-const array even though it doesn't actually modify the array

As far as I remember this is due to a shortcoming in C (fixed in C++), where a T const* const argument cannot legally be passed a T*.

[seberg]

Sorry, forgot about these. Adding static uniformly seems great to me (some of this might cause me a merge conflict, but that is trivial). Thanks @alexhenrie.

[alexhenrie]

Thank you!