From a4c728e6b36400ce9a6da39f5991702760b4052f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Mon, 24 Mar 2025 14:55:31 +0100
Subject: [PATCH 1/3] fix signature of `anext_awaitable.close`

---
 Lib/test/test_coroutines.py | 11 +++++++++++
 Objects/iterobject.c        | 10 ++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/Lib/test/test_coroutines.py b/Lib/test/test_coroutines.py
index ae3cd3555002ef..d78eaaca2796a6 100644
--- a/Lib/test/test_coroutines.py
+++ b/Lib/test/test_coroutines.py
@@ -1191,6 +1191,17 @@ async def g():
         _, result = run_async(g())
         self.assertIsNone(result.__context__)
 
+    def test_await_17(self):
+        # See https://github.com/python/cpython/issues/131666 for details.
+        class A:
+            async def __anext__(self):
+                raise StopAsyncIteration
+            def __aiter__(self):
+                return self
+
+        anext_awaitable = anext(A(), "a").__await__()
+        self.assertRaises(TypeError, anext_awaitable.close, 1)
+
     def test_with_1(self):
         class Manager:
             def __init__(self, name):
diff --git a/Objects/iterobject.c b/Objects/iterobject.c
index c023f41638f3d3..3291b3898a8f11 100644
--- a/Objects/iterobject.c
+++ b/Objects/iterobject.c
@@ -408,7 +408,9 @@ anextawaitable_proxy(anextawaitableobject *obj, char *meth, PyObject *arg) {
     if (awaitable == NULL) {
         return NULL;
     }
-    PyObject *ret = PyObject_CallMethod(awaitable, meth, "O", arg);
+    PyObject *ret = arg == NULL
+        ? PyObject_CallMethod(awaitable, meth, NULL)
+        : PyObject_CallMethod(awaitable, meth, "O", arg);
     Py_DECREF(awaitable);
     if (ret != NULL) {
         return ret;
@@ -439,8 +441,8 @@ anextawaitable_throw(anextawaitableobject *obj, PyObject *arg) {
 
 
 static PyObject *
-anextawaitable_close(anextawaitableobject *obj, PyObject *arg) {
-    return anextawaitable_proxy(obj, "close", arg);
+anextawaitable_close(anextawaitableobject *obj, PyObject *Py_UNUSED(dummy)) {
+    return anextawaitable_proxy(obj, "close", NULL);
 }
 
 
@@ -466,7 +468,7 @@ PyDoc_STRVAR(close_doc,
 static PyMethodDef anextawaitable_methods[] = {
     {"send",(PyCFunction)anextawaitable_send, METH_O, send_doc},
     {"throw",(PyCFunction)anextawaitable_throw, METH_VARARGS, throw_doc},
-    {"close",(PyCFunction)anextawaitable_close, METH_VARARGS, close_doc},
+    {"close",(PyCFunction)anextawaitable_close, METH_NOARGS, close_doc},
     {NULL, NULL}        /* Sentinel */
 };
 

From f8bac51de5843de6350e18991a6d2e86f8342d2e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Mon, 24 Mar 2025 14:56:07 +0100
Subject: [PATCH 2/3] blurb

---
 .../2025-03-24-14-56-00.gh-issue-131666.q0-a-b.rst               | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2025-03-24-14-56-00.gh-issue-131666.q0-a-b.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-03-24-14-56-00.gh-issue-131666.q0-a-b.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-03-24-14-56-00.gh-issue-131666.q0-a-b.rst
new file mode 100644
index 00000000000000..45ac86e520d929
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-03-24-14-56-00.gh-issue-131666.q0-a-b.rst
@@ -0,0 +1 @@
+Fix signature of ``anext_awaitable.close`` objects. Patch by Bénédikt Tran.

From da35c4ef7b98678f1bb681238a15df375c067c4e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Mon, 24 Mar 2025 15:55:35 +0100
Subject: [PATCH 3/3] update comment

---
 Objects/iterobject.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Objects/iterobject.c b/Objects/iterobject.c
index dddf8f20f78eb5..5712e02ae828ab 100644
--- a/Objects/iterobject.c
+++ b/Objects/iterobject.c
@@ -414,6 +414,8 @@ anextawaitable_proxy(anextawaitableobject *obj, char *meth, PyObject *arg)
     if (awaitable == NULL) {
         return NULL;
     }
+    // When specified, 'arg' may be a tuple (if coming from a METH_VARARGS
+    // method) or a single object (if coming from a METH_O method).
     PyObject *ret = arg == NULL
         ? PyObject_CallMethod(awaitable, meth, NULL)
         : PyObject_CallMethod(awaitable, meth, "O", arg);