diff --git a/newsfragments/5942.added.md b/newsfragments/5942.added.md
new file mode 100644
index 00000000000..ca170d67e23
--- /dev/null
+++ b/newsfragments/5942.added.md
@@ -0,0 +1 @@
+Add FFI definitions `PyObject_GetAIter`, `PyAIter_Check`, `PyMapping_HasKeyWithError`, `PyMapping_HasKeyStringWithError`, `PyMapping_GetOptionalItem`, `PyMapping_GetOptionalItemString`, `PySequence_ITEM`, `PySequence_Fast_GET_SIZE`, `PySequence_Fast_GET_ITEM`, and `PySequence_Fast_ITEMS`.
diff --git a/newsfragments/5942.removed.md b/newsfragments/5942.removed.md
new file mode 100644
index 00000000000..a041c333801
--- /dev/null
+++ b/newsfragments/5942.removed.md
@@ -0,0 +1,3 @@
+Remove private FFI definitions `_PyStack_AsDict`, `_PyObject_CallNoArg`, `_PyObject_FastCall`, `_PyObject_FastCallTstate`. `_PyObject_VectorcallTstate`, `_PyObject_MakeTpCall`, `_Py_CheckFunctionResult`, `_PyObject_CallFunction_SizeT`, `_PyObject_CallMethod_SizeT`, and `_PySequence_IterSearch`.
+
+Remove FFI definitions `PY_ITERSEARCH_COUNT`, `PY_ITERSEARCH_INDEX`, and `PY_ITERSEARCH_CONTAINS`.
diff --git a/pyo3-ffi/src/abstract_.rs b/pyo3-ffi/src/abstract_.rs
index 714e6d0d3f0..c2b141b0c6e 100644
--- a/pyo3-ffi/src/abstract_.rs
+++ b/pyo3-ffi/src/abstract_.rs
@@ -54,21 +54,13 @@ extern_libpython! {
         ...
     ) -> *mut PyObject;
 
-    #[cfg(not(Py_3_13))]
+    #[cfg(all(PyPy, not(Py_3_13)))] // called internally in PyUnicodeDecodeError_Create on PyPy
     #[cfg_attr(PyPy, link_name = "_PyPyObject_CallFunction_SizeT")]
-    pub fn _PyObject_CallFunction_SizeT(
+    pub(crate) fn _PyObject_CallFunction_SizeT(
         callable_object: *mut PyObject,
         format: *const c_char,
         ...
     ) -> *mut PyObject;
-    #[cfg(not(Py_3_13))]
-    #[cfg_attr(PyPy, link_name = "_PyPyObject_CallMethod_SizeT")]
-    pub fn _PyObject_CallMethod_SizeT(
-        o: *mut PyObject,
-        method: *const c_char,
-        format: *const c_char,
-        ...
-    ) -> *mut PyObject;
 
     #[cfg_attr(PyPy, link_name = "PyPyObject_CallFunctionObjArgs")]
     pub fn PyObject_CallFunctionObjArgs(callable: *mut PyObject, ...) -> *mut PyObject;
@@ -78,10 +70,24 @@ extern_libpython! {
         method: *mut PyObject,
         ...
     ) -> *mut PyObject;
+
+    #[cfg(all(Py_3_12, Py_LIMITED_API))] // is an inline function in cpython/abstract.rs on version-specific ABI
+    #[cfg_attr(PyPy, link_name = "PyPyVectorcall_NARGS")]
+    pub fn PyVectorcall_NARGS(nargsf: size_t) -> Py_ssize_t;
+
+    #[cfg_attr(not(any(Py_3_12, PyPy)), link_name = "_PyVectorcall_Call")] // symbol made public in 3.12
+    #[cfg_attr(PyPy, link_name = "PyPyVectorcall_Call")]
+    pub fn PyVectorcall_Call(
+        callable: *mut PyObject,
+        tuple: *mut PyObject,
+        dict: *mut PyObject,
+    ) -> *mut PyObject;
 }
+
 #[cfg(any(Py_3_12, not(Py_LIMITED_API)))]
-pub const PY_VECTORCALL_ARGUMENTS_OFFSET: size_t =
-    1 << (8 * std::mem::size_of::<size_t>() as size_t - 1);
+pub const PY_VECTORCALL_ARGUMENTS_OFFSET: size_t = (1 as size_t)
+    .checked_shl((8 * std::mem::size_of::<size_t>() - 1) as u32)
+    .expect("size_t should fit the flag bits");
 
 extern_libpython! {
     #[cfg_attr(PyPy, link_name = "PyPyObject_Vectorcall")]
@@ -104,14 +110,12 @@ extern_libpython! {
     pub fn PyObject_Type(o: *mut PyObject) -> *mut PyObject;
     #[cfg_attr(PyPy, link_name = "PyPyObject_Size")]
     pub fn PyObject_Size(o: *mut PyObject) -> Py_ssize_t;
-}
 
-#[inline]
-pub unsafe fn PyObject_Length(o: *mut PyObject) -> Py_ssize_t {
-    PyObject_Size(o)
-}
+    // PyObject_Length is a direct alias for PyObject_Size
+    #[cfg_attr(not(PyPy), link_name = "PyObject_Size")]
+    #[cfg_attr(PyPy, link_name = "PyPyObject_Size")]
+    pub fn PyObject_Length(o: *mut PyObject) -> Py_ssize_t;
 
-extern_libpython! {
     #[cfg_attr(PyPy, link_name = "PyPyObject_GetItem")]
     pub fn PyObject_GetItem(o: *mut PyObject, key: *mut PyObject) -> *mut PyObject;
     #[cfg_attr(PyPy, link_name = "PyPyObject_SetItem")]
@@ -120,18 +124,20 @@ extern_libpython! {
     pub fn PyObject_DelItemString(o: *mut PyObject, key: *const c_char) -> c_int;
     #[cfg_attr(PyPy, link_name = "PyPyObject_DelItem")]
     pub fn PyObject_DelItem(o: *mut PyObject, key: *mut PyObject) -> c_int;
-}
 
-extern_libpython! {
     #[cfg_attr(PyPy, link_name = "PyPyObject_Format")]
     pub fn PyObject_Format(obj: *mut PyObject, format_spec: *mut PyObject) -> *mut PyObject;
     #[cfg_attr(PyPy, link_name = "PyPyObject_GetIter")]
     pub fn PyObject_GetIter(arg1: *mut PyObject) -> *mut PyObject;
-}
+    #[cfg(Py_3_10)]
+    #[cfg_attr(PyPy, link_name = "PyPyObject_GetAIter")]
+    pub fn PyObject_GetAIter(arg1: *mut PyObject) -> *mut PyObject;
 
-extern_libpython! {
     #[cfg_attr(PyPy, link_name = "PyPyIter_Check")]
     pub fn PyIter_Check(obj: *mut PyObject) -> c_int;
+    #[cfg(Py_3_10)]
+    #[cfg_attr(PyPy, link_name = "PyPyAIter_Check")]
+    pub fn PyAIter_Check(obj: *mut PyObject) -> c_int;
 
     #[cfg(Py_3_14)]
     #[cfg_attr(PyPy, link_name = "PyPyIter_NextItem")]
@@ -185,20 +191,8 @@ extern_libpython! {
     pub fn PyNumber_Xor(o1: *mut PyObject, o2: *mut PyObject) -> *mut PyObject;
     #[cfg_attr(PyPy, link_name = "PyPyNumber_Or")]
     pub fn PyNumber_Or(o1: *mut PyObject, o2: *mut PyObject) -> *mut PyObject;
-}
-
-// Defined as this macro in Python limited API, but relies on
-// non-limited PyTypeObject. Don't expose this since it cannot be used.
-#[cfg(not(any(Py_LIMITED_API, PyPy)))]
-#[inline]
-pub unsafe fn PyIndex_Check(o: *mut PyObject) -> c_int {
-    let tp_as_number = (*Py_TYPE(o)).tp_as_number;
-    (!tp_as_number.is_null() && (*tp_as_number).nb_index.is_some()) as c_int
-}
 
-extern_libpython! {
-    #[cfg(any(Py_LIMITED_API, PyPy))]
-    #[link_name = "PyPyIndex_Check"]
+    #[cfg_attr(PyPy, link_name = "PyPyIndex_Check")]
     pub fn PyIndex_Check(o: *mut PyObject) -> c_int;
 
     #[cfg_attr(PyPy, link_name = "PyPyNumber_Index")]
@@ -246,18 +240,11 @@ extern_libpython! {
     #[cfg_attr(PyPy, link_name = "PyPySequence_Size")]
     pub fn PySequence_Size(o: *mut PyObject) -> Py_ssize_t;
 
-    #[cfg(PyPy)]
-    #[link_name = "PyPySequence_Length"]
+    // PySequence_Length is a direct alias for PySequence_Size
+    #[cfg_attr(not(PyPy), link_name = "PySequence_Size")]
+    #[cfg_attr(PyPy, link_name = "PyPySequence_Size")]
     pub fn PySequence_Length(o: *mut PyObject) -> Py_ssize_t;
-}
 
-#[inline]
-#[cfg(not(PyPy))]
-pub unsafe fn PySequence_Length(o: *mut PyObject) -> Py_ssize_t {
-    PySequence_Size(o)
-}
-
-extern_libpython! {
     #[cfg_attr(PyPy, link_name = "PyPySequence_Concat")]
     pub fn PySequence_Concat(o1: *mut PyObject, o2: *mut PyObject) -> *mut PyObject;
     #[cfg_attr(PyPy, link_name = "PyPySequence_Repeat")]
@@ -285,20 +272,15 @@ extern_libpython! {
     pub fn PySequence_List(o: *mut PyObject) -> *mut PyObject;
     #[cfg_attr(PyPy, link_name = "PyPySequence_Fast")]
     pub fn PySequence_Fast(o: *mut PyObject, m: *const c_char) -> *mut PyObject;
-    // skipped PySequence_Fast_GET_SIZE
-    // skipped PySequence_Fast_GET_ITEM
-    // skipped PySequence_Fast_GET_ITEMS
     pub fn PySequence_Count(o: *mut PyObject, value: *mut PyObject) -> Py_ssize_t;
     #[cfg_attr(PyPy, link_name = "PyPySequence_Contains")]
     pub fn PySequence_Contains(seq: *mut PyObject, ob: *mut PyObject) -> c_int;
-}
 
-#[inline]
-pub unsafe fn PySequence_In(o: *mut PyObject, value: *mut PyObject) -> c_int {
-    PySequence_Contains(o, value)
-}
+    // PySequence_In is a direct alias for PySequence_Contains
+    #[cfg_attr(not(PyPy), link_name = "PySequence_Contains")]
+    #[cfg_attr(PyPy, link_name = "PyPySequence_Contains")]
+    pub fn PySequence_In(o: *mut PyObject, value: *mut PyObject) -> c_int;
 
-extern_libpython! {
     #[cfg_attr(PyPy, link_name = "PyPySequence_Index")]
     pub fn PySequence_Index(o: *mut PyObject, value: *mut PyObject) -> Py_ssize_t;
     #[cfg_attr(PyPy, link_name = "PyPySequence_InPlaceConcat")]
@@ -310,17 +292,12 @@ extern_libpython! {
     #[cfg_attr(PyPy, link_name = "PyPyMapping_Size")]
     pub fn PyMapping_Size(o: *mut PyObject) -> Py_ssize_t;
 
-    #[cfg(PyPy)]
-    #[link_name = "PyPyMapping_Length"]
+    // PyMapping_Length is a direct alias for PyMapping_Size
+    #[cfg_attr(not(PyPy), link_name = "PyMapping_Size")]
+    #[cfg_attr(PyPy, link_name = "PyPyMapping_Size")]
     pub fn PyMapping_Length(o: *mut PyObject) -> Py_ssize_t;
 }
 
-#[inline]
-#[cfg(not(PyPy))]
-pub unsafe fn PyMapping_Length(o: *mut PyObject) -> Py_ssize_t {
-    PyMapping_Size(o)
-}
-
 #[inline]
 pub unsafe fn PyMapping_DelItemString(o: *mut PyObject, key: *mut c_char) -> c_int {
     PyObject_DelItemString(o, key)
@@ -336,6 +313,12 @@ extern_libpython! {
     pub fn PyMapping_HasKeyString(o: *mut PyObject, key: *const c_char) -> c_int;
     #[cfg_attr(PyPy, link_name = "PyPyMapping_HasKey")]
     pub fn PyMapping_HasKey(o: *mut PyObject, key: *mut PyObject) -> c_int;
+    #[cfg(Py_3_13)]
+    #[cfg_attr(PyPy, link_name = "PyPyMapping_HasKeyWithError")]
+    pub fn PyMapping_HasKeyWithError(o: *mut PyObject, key: *mut PyObject) -> c_int;
+    #[cfg(Py_3_13)]
+    #[cfg_attr(PyPy, link_name = "PyPyMapping_HasKeyStringWithError")]
+    pub fn PyMapping_HasKeyStringWithError(o: *mut PyObject, key: *const c_char) -> c_int;
     #[cfg_attr(PyPy, link_name = "PyPyMapping_Keys")]
     pub fn PyMapping_Keys(o: *mut PyObject) -> *mut PyObject;
     #[cfg_attr(PyPy, link_name = "PyPyMapping_Values")]
@@ -344,6 +327,20 @@ extern_libpython! {
     pub fn PyMapping_Items(o: *mut PyObject) -> *mut PyObject;
     #[cfg_attr(PyPy, link_name = "PyPyMapping_GetItemString")]
     pub fn PyMapping_GetItemString(o: *mut PyObject, key: *const c_char) -> *mut PyObject;
+    #[cfg(Py_3_13)]
+    #[cfg_attr(PyPy, link_name = "PyPyMapping_GetOptionalItem")]
+    pub fn PyMapping_GetOptionalItem(
+        o: *mut PyObject,
+        key: *mut PyObject,
+        result: *mut *mut PyObject,
+    ) -> c_int;
+    #[cfg(Py_3_13)]
+    #[cfg_attr(PyPy, link_name = "PyPyMapping_GetOptionalItemString")]
+    pub fn PyMapping_GetOptionalItemString(
+        o: *mut PyObject,
+        key: *const c_char,
+        result: *mut *mut PyObject,
+    ) -> c_int;
     #[cfg_attr(PyPy, link_name = "PyPyMapping_SetItemString")]
     pub fn PyMapping_SetItemString(
         o: *mut PyObject,
diff --git a/pyo3-ffi/src/cpython/abstract_.rs b/pyo3-ffi/src/cpython/abstract_.rs
index b6358f854ff..aea3740ed3c 100644
--- a/pyo3-ffi/src/cpython/abstract_.rs
+++ b/pyo3-ffi/src/cpython/abstract_.rs
@@ -1,29 +1,31 @@
-use crate::{PyObject, Py_ssize_t};
-#[cfg(any(not(PyPy), not(Py_3_11)))]
+use crate::{vectorcallfunc, PyObject, Py_TYPE, Py_ssize_t};
+#[cfg(all(any(not(PyPy), not(Py_3_11)), not(Py_3_12)))]
 use std::ffi::c_char;
+#[cfg(not(Py_3_11))]
 use std::ffi::c_int;
 
+#[cfg(not(any(PyPy, GraalPy)))]
+use crate::{
+    PyListObject, PyList_Check, PyList_GET_ITEM, PyList_GET_SIZE, PyTupleObject, PyTuple_GET_ITEM,
+    PyTuple_GET_SIZE,
+};
+
 #[cfg(not(Py_3_11))]
 use crate::Py_buffer;
 
-#[cfg(not(PyPy))]
-use crate::{
-    vectorcallfunc, PyCallable_Check, PyThreadState, PyThreadState_GET, PyTuple_Check,
-    PyType_HasFeature, Py_TPFLAGS_HAVE_VECTORCALL,
-};
+#[cfg(not(any(PyPy, Py_3_11)))]
+use crate::{PyCallable_Check, PyType_HasFeature, Py_TPFLAGS_HAVE_VECTORCALL};
+#[cfg(not(any(Py_3_12, PyPy)))]
+use crate::{PyThreadState, PyThreadState_GET, PyTuple_Check};
 use libc::size_t;
 
-extern_libpython! {
-    #[cfg(not(any(PyPy, GraalPy)))]
-    pub fn _PyStack_AsDict(values: *const *mut PyObject, kwnames: *mut PyObject) -> *mut PyObject;
-}
-
-#[cfg(not(any(PyPy, GraalPy)))]
-const _PY_FASTCALL_SMALL_STACK: size_t = 5;
+// skipped private _PyObject_CallMethodId
+// skipped private _PyStack_AsDict
 
+#[cfg(not(Py_3_12))]
 extern_libpython! {
     #[cfg(not(PyPy))]
-    pub fn _Py_CheckFunctionResult(
+    fn _Py_CheckFunctionResult(
         tstate: *mut PyThreadState,
         callable: *mut PyObject,
         result: *mut PyObject,
@@ -31,7 +33,7 @@ extern_libpython! {
     ) -> *mut PyObject;
 
     #[cfg(not(PyPy))]
-    pub fn _PyObject_MakeTpCall(
+    fn _PyObject_MakeTpCall(
         tstate: *mut PyThreadState,
         callable: *mut PyObject,
         args: *const *mut PyObject,
@@ -40,8 +42,13 @@ extern_libpython! {
     ) -> *mut PyObject;
 }
 
-const PY_VECTORCALL_ARGUMENTS_OFFSET: size_t =
-    1 << (8 * std::mem::size_of::<size_t>() as size_t - 1);
+#[cfg(not(Py_3_12))]
+const PY_VECTORCALL_ARGUMENTS_OFFSET: size_t = (1 as size_t)
+    .checked_shl((8 * std::mem::size_of::<size_t>() - 1) as u32)
+    .expect("size_t should fit the flag bits");
+
+#[cfg(Py_3_12)] // public API from 3.12
+use crate::PY_VECTORCALL_ARGUMENTS_OFFSET;
 
 #[inline(always)]
 pub unsafe fn PyVectorcall_NARGS(n: size_t) -> Py_ssize_t {
@@ -49,7 +56,13 @@ pub unsafe fn PyVectorcall_NARGS(n: size_t) -> Py_ssize_t {
     n.try_into().expect("cannot fail due to mask")
 }
 
-#[cfg(not(PyPy))]
+#[cfg(any(PyPy, Py_3_11))]
+extern_libpython! {
+    #[cfg_attr(PyPy, link_name = "PyPyVectorcall_Function")]
+    pub fn PyVectorcall_Function(callable: *mut PyObject) -> Option<vectorcallfunc>;
+}
+
+#[cfg(not(any(PyPy, Py_3_11)))]
 #[inline(always)]
 pub unsafe fn PyVectorcall_Function(callable: *mut PyObject) -> Option<vectorcallfunc> {
     assert!(!callable.is_null());
@@ -64,9 +77,10 @@ pub unsafe fn PyVectorcall_Function(callable: *mut PyObject) -> Option<vectorcal
     *ptr
 }
 
+#[cfg(not(Py_3_12))]
 #[cfg(not(PyPy))]
 #[inline(always)]
-pub unsafe fn _PyObject_VectorcallTstate(
+unsafe fn _PyObject_VectorcallTstate(
     tstate: *mut PyThreadState,
     callable: *mut PyObject,
     args: *const *mut PyObject,
@@ -112,56 +126,9 @@ extern_libpython! {
         nargsf: size_t,
         kwdict: *mut PyObject,
     ) -> *mut PyObject;
-
-    #[cfg_attr(not(any(Py_3_9, PyPy)), link_name = "_PyVectorcall_Call")]
-    #[cfg_attr(PyPy, link_name = "PyPyVectorcall_Call")]
-    pub fn PyVectorcall_Call(
-        callable: *mut PyObject,
-        tuple: *mut PyObject,
-        dict: *mut PyObject,
-    ) -> *mut PyObject;
-}
-
-#[cfg(not(any(PyPy, GraalPy)))]
-#[inline(always)]
-pub unsafe fn _PyObject_FastCallTstate(
-    tstate: *mut PyThreadState,
-    func: *mut PyObject,
-    args: *const *mut PyObject,
-    nargs: Py_ssize_t,
-) -> *mut PyObject {
-    _PyObject_VectorcallTstate(tstate, func, args, nargs as size_t, std::ptr::null_mut())
-}
-
-#[cfg(not(any(PyPy, GraalPy)))]
-#[inline(always)]
-pub unsafe fn _PyObject_FastCall(
-    func: *mut PyObject,
-    args: *const *mut PyObject,
-    nargs: Py_ssize_t,
-) -> *mut PyObject {
-    _PyObject_FastCallTstate(PyThreadState_GET(), func, args, nargs)
-}
-
-#[cfg(not(PyPy))]
-#[inline(always)]
-pub unsafe fn _PyObject_CallNoArg(func: *mut PyObject) -> *mut PyObject {
-    _PyObject_VectorcallTstate(
-        PyThreadState_GET(),
-        func,
-        std::ptr::null_mut(),
-        0,
-        std::ptr::null_mut(),
-    )
-}
-
-extern_libpython! {
-    #[cfg(PyPy)]
-    #[link_name = "_PyPyObject_CallNoArg"]
-    pub fn _PyObject_CallNoArg(func: *mut PyObject) -> *mut PyObject;
 }
 
-#[cfg(not(PyPy))]
+#[cfg(not(any(Py_3_12, PyPy)))]
 #[inline(always)]
 pub unsafe fn PyObject_CallOneArg(func: *mut PyObject, arg: *mut PyObject) -> *mut PyObject {
     assert!(!arg.is_null());
@@ -172,6 +139,12 @@ pub unsafe fn PyObject_CallOneArg(func: *mut PyObject, arg: *mut PyObject) -> *m
     _PyObject_VectorcallTstate(tstate, func, args, nargsf, std::ptr::null_mut())
 }
 
+extern_libpython! {
+    #[cfg(any(Py_3_12, PyPy))]
+    #[cfg_attr(PyPy, link_name = "PyPyObject_CallOneArg")]
+    pub fn PyObject_CallOneArg(func: *mut PyObject, arg: *mut PyObject) -> *mut PyObject;
+}
+
 #[cfg(all(Py_3_9, not(PyPy)))]
 #[inline(always)]
 pub unsafe fn PyObject_CallMethodNoArgs(
@@ -203,12 +176,6 @@ pub unsafe fn PyObject_CallMethodOneArg(
     )
 }
 
-// skipped _PyObject_VectorcallMethodId
-// skipped _PyObject_CallMethodIdNoArgs
-// skipped _PyObject_CallMethodIdOneArg
-
-// skipped _PyObject_HasLen
-
 extern_libpython! {
     #[cfg_attr(PyPy, link_name = "PyPyObject_LengthHint")]
     pub fn PyObject_LengthHint(o: *mut PyObject, arg1: Py_ssize_t) -> Py_ssize_t;
@@ -273,31 +240,37 @@ extern_libpython! {
     pub fn PyBuffer_Release(view: *mut Py_buffer);
 }
 
-// skipped PySequence_ITEM
-
-pub const PY_ITERSEARCH_COUNT: c_int = 1;
-pub const PY_ITERSEARCH_INDEX: c_int = 2;
-pub const PY_ITERSEARCH_CONTAINS: c_int = 3;
-
-extern_libpython! {
-    #[cfg(not(any(PyPy, GraalPy)))]
-    pub fn _PySequence_IterSearch(
-        seq: *mut PyObject,
-        obj: *mut PyObject,
-        operation: c_int,
-    ) -> Py_ssize_t;
+#[inline(always)]
+pub unsafe fn PySequence_ITEM(seq: *mut PyObject, i: Py_ssize_t) -> *mut PyObject {
+    (*(*Py_TYPE(seq)).tp_as_sequence).sq_item.unwrap_unchecked()(seq, i)
 }
 
-// skipped _PyObject_RealIsInstance
-// skipped _PyObject_RealIsSubclass
-
-// skipped _PySequence_BytesToCharpArray
-
-// skipped _Py_FreeCharPArray
-
-// skipped _Py_add_one_to_index_F
-// skipped _Py_add_one_to_index_C
+#[inline(always)]
+#[cfg(not(any(PyPy, GraalPy)))]
+pub unsafe fn PySequence_Fast_GET_SIZE(seq: *mut PyObject) -> Py_ssize_t {
+    if PyList_Check(seq) == 1 {
+        PyList_GET_SIZE(seq)
+    } else {
+        PyTuple_GET_SIZE(seq)
+    }
+}
 
-// skipped _Py_convert_optional_to_ssize_t
+#[inline(always)]
+#[cfg(not(any(PyPy, GraalPy)))]
+pub unsafe fn PySequence_Fast_GET_ITEM(seq: *mut PyObject, i: Py_ssize_t) -> *mut PyObject {
+    if PyList_Check(seq) == 1 {
+        PyList_GET_ITEM(seq, i)
+    } else {
+        PyTuple_GET_ITEM(seq, i)
+    }
+}
 
-// skipped _PyNumber_Index(*mut PyObject o)
+#[inline(always)]
+#[cfg(not(any(PyPy, GraalPy)))]
+pub unsafe fn PySequence_Fast_ITEMS(seq: *mut PyObject) -> *mut *mut PyObject {
+    if PyList_Check(seq) == 1 {
+        (*seq.cast::<PyListObject>()).ob_item
+    } else {
+        (*seq.cast::<PyTupleObject>()).ob_item.as_mut_ptr()
+    }
+}
diff --git a/pyo3-ffi/src/impl_/macros.rs b/pyo3-ffi/src/impl_/macros.rs
index c493157186c..be3b0418866 100644
--- a/pyo3-ffi/src/impl_/macros.rs
+++ b/pyo3-ffi/src/impl_/macros.rs
@@ -38,30 +38,12 @@ macro_rules! extern_libpython_maybe_private_fn {
     ) => {
         extern_libpython_cpython_private_fn! { $(#[$attrs])* $vis $name($($args)*) $(-> $ret)? }
     };
-    (
-        [_PyObject_CallMethod_SizeT]
-        $(#[$attrs:meta])* $vis:vis fn $name:ident($($args:tt)*) $(-> $ret:ty)?
-    ) => {
-        extern_libpython_cpython_private_fn! { $(#[$attrs])* $vis $name($($args)*) $(-> $ret)? }
-    };
     (
         [_PyObject_MakeTpCall]
         $(#[$attrs:meta])* $vis:vis fn $name:ident($($args:tt)*) $(-> $ret:ty)?
     ) => {
         extern_libpython_cpython_private_fn! { $(#[$attrs])* $vis $name($($args)*) $(-> $ret)? }
     };
-    (
-        [_PySequence_IterSearch]
-        $(#[$attrs:meta])* $vis:vis fn $name:ident($($args:tt)*) $(-> $ret:ty)?
-    ) => {
-        extern_libpython_cpython_private_fn! { $(#[$attrs])* $vis $name($($args)*) $(-> $ret)? }
-    };
-    (
-        [_PyStack_AsDict]
-        $(#[$attrs:meta])* $vis:vis fn $name:ident($($args:tt)*) $(-> $ret:ty)?
-    ) => {
-        extern_libpython_cpython_private_fn! { $(#[$attrs])* $vis $name($($args)*) $(-> $ret)? }
-    };
     (
         [_Py_CheckFunctionResult]
         $(#[$attrs:meta])* $vis:vis fn $name:ident($($args:tt)*) $(-> $ret:ty)?