gcc -pthread -c -Wno-unused-result -Wsign-compare -DDYNAMIC_ANNOTATIONS_ENABLED=1 -g -Og -Wall    -std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers -Werror=implicit-function-declaration  -I./Include/internal  -I. -I./Include    -DPy_BUILD_CORE -o Objects/memoryobject.o Objects/memoryobject.c
Objects/memoryobject.c:3112:21: warning: cast between incompatible function types from 'PyObject * (*)(PyMemoryViewObject *, PyObject *, PyObject *)' {aka 'struct _object * (*)(struct <anonymous> *, struct _object *, struct _object *)'} to 'PyObject * (*)(PyObject *, PyObject *)' {aka 'struct _object * (*)(struct _object *, struct _object *)'} [-Wcast-function-type]
     {"tobytes",     (PyCFunction)memory_tobytes, METH_VARARGS|METH_KEYWORDS, memory_tobytes_doc},


I am preparing a small PR for this issue.

Fix an other warning in the same PR

_collections._tuplegetter.__reduce__

I prefer to reuse bpo-33012.

This is not correct fix for tuplegetter_reduce. tuplegetter_reduce should have two parameters, just the second is unused.

Hi @serhiy,

Thank you for your PR, I prefer your patch, just because you have just added the PyObject *Py_UNUSED(ignored) to the tuplegetter_reduce function. And in this case, you don't need to cast to (void(*)(void)).

I will use this tip for the next time.

Thank

This is only for methods with METH_NOARGS. The code that calls such method, calls it with two arguments, passing NULL as the second argument. So the signature of the C function should have two parameters. Functions for methods with METH_KEYWORDS or METH_FASTCALL should have different corresponding signatures.

New changeset adfffc7343ce7ebc88ec734a803d3247ba8927fb by Serhiy Storchaka in branch 'master':
Fix the C function signature for _collections._tuplegetter.__reduce__. (GH-12180)
https://github.com/python/cpython/commit/adfffc7343ce7ebc88ec734a803d3247ba8927fb