bpo-37540: vectorcall: keyword names must be strings (GH-14682)
The fact that keyword names are strings is now part of the vectorcall and `METH_FASTCALL` protocols. The biggest concrete change is that `_PyStack_UnpackDict` now checks that and raises `TypeError` if not.
CC @markshannon @vstinner
https://bugs.python.org/issue37540
diff --git a/Doc/c-api/structures.rst b/Doc/c-api/structures.rst
index 5184ad5..d4e65af 100644
--- a/Doc/c-api/structures.rst
+++ b/Doc/c-api/structures.rst
@@ -204,6 +204,7 @@
Keyword arguments are passed the same way as in the vectorcall protocol:
there is an additional fourth :c:type:`PyObject\*` parameter
which is a tuple representing the names of the keyword arguments
+ (which are guaranteed to be strings)
or possibly *NULL* if there are no keywords. The values of the keyword
arguments are stored in the *args* array, after the positional arguments.