diff --git a/Include/pyport.h b/Include/pyport.h
@@ -538,18 +538,19 @@ extern "C" {
 //
 // Example: _Py_TYPEOF(x) x_copy = (x);
 //
-// On C23, use typeof(). On C++11, use decltype(). Otherwise, use __typeof__()
-// if on GCC, clang or MSVC 17.9 and newer.
+// On C23, use typeof(). Otherwise, use __typeof__() if on GCC, clang or
+// MSVC 17.9 and newer.
 //
-// On MSVC, check also _MSVC_LANG since __cplusplus is 199711L unless
-// the /Zc:__cplusplus flag is used.
-#if defined (__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
-#  define _Py_TYPEOF(expr) typeof(expr)
-#elif defined(__cplusplus) && (__cplusplus >= 201103L ||  _MSVC_LANG >= 201103L)
-#  define _Py_TYPEOF(expr) decltype(expr)
-#elif defined(__GNUC__) || defined(__clang__) || \
-    (defined(_MSC_VER) && _MSC_VER >= 1939)
-#  define _Py_TYPEOF(expr) __typeof__(expr)
+// In C++, decltype() can produce a reference type for an lvalue expression,
+// making a refcount macro's temporary alias its destination (gh-157649).
+// Leave _Py_TYPEOF undefined to use the existing memcpy() implementations.
+#if !defined(__cplusplus)
+#  if defined (__STDC_VERSION__) && __STDC_VERSION__ >= 202311L
+#    define _Py_TYPEOF(expr) typeof(expr)
+#  elif defined(__GNUC__) || defined(__clang__) || \
+        (defined(_MSC_VER) && _MSC_VER >= 1939)
+#    define _Py_TYPEOF(expr) __typeof__(expr)
+#  endif
 #endif
 
 

diff --git a/Lib/test/test_cppext/extension.cpp b/Lib/test/test_cppext/extension.cpp
@@ -256,6 +256,85 @@ test_datetime(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
     Py_RETURN_NONE;
 }
 
+// gh-157649: Py_SETREF(), Py_XSETREF(), and Py_CLEAR() must copy the old
+// pointer, not bind to an array item or reference the macro overwrites.
+static int
+test_refcount_lvalues(void)
+{
+    PyObject *old_obj = PyList_New(0);
+    if (old_obj == _Py_NULL) {
+        return -1;
+    }
+    PyObject *new_obj = PyList_New(0);
+    if (new_obj == _Py_NULL) {
+        Py_DECREF(old_obj);
+        return -1;
+    }
+    PyObject *slots[2] = {Py_NewRef(old_obj), _Py_NULL};
+
+#ifndef Py_LIMITED_API
+    Py_SETREF(slots[0], Py_NewRef(new_obj));
+    assert(slots[0] == new_obj);
+    assert(Py_REFCNT(old_obj) == 1);
+    assert(Py_REFCNT(new_obj) == 2);
+
+    Py_XSETREF(slots[0], Py_NewRef(old_obj));
+    assert(slots[0] == old_obj);
+    assert(Py_REFCNT(old_obj) == 2);
+    assert(Py_REFCNT(new_obj) == 1);
+#endif
+
+    int index = 0;
+    Py_CLEAR(slots[index++]);
+    assert(index == 1);
+    assert(slots[0] == _Py_NULL);
+    assert(Py_REFCNT(old_obj) == 1);
+    Py_CLEAR(slots[0]);
+
+    slots[0] = Py_NewRef(old_obj);
+    PyObject *&slot = slots[0];
+    Py_CLEAR(slot);
+    assert(slots[0] == _Py_NULL);
+    assert(Py_REFCNT(old_obj) == 1);
+
+#ifndef Py_LIMITED_API
+    slot = Py_NewRef(old_obj);
+    Py_SETREF(slot, Py_NewRef(new_obj));
+    assert(slots[0] == new_obj);
+    assert(Py_REFCNT(old_obj) == 1);
+    assert(Py_REFCNT(new_obj) == 2);
+
+    Py_XSETREF((slot), Py_NewRef(old_obj));
+    assert(slots[0] == old_obj);
+    assert(Py_REFCNT(old_obj) == 2);
+    assert(Py_REFCNT(new_obj) == 1);
+    Py_CLEAR(slot);
+
+    // Both arguments must be evaluated once, including a NULL destination.
+    index = 0;
+    Py_XSETREF(slots[index++], Py_NewRef(new_obj));
+    assert(index == 1);
+    assert(slots[0] == new_obj);
+    assert(Py_REFCNT(new_obj) == 2);
+    Py_CLEAR(slots[0]);
+
+    // Preserve support for pointers to concrete object types.
+    PyListObject *lists[1] = {(PyListObject *)Py_NewRef(old_obj)};
+    Py_SETREF(lists[0], (PyListObject *)Py_NewRef(new_obj));
+    assert((PyObject *)lists[0] == new_obj);
+    assert(Py_REFCNT(old_obj) == 1);
+    assert(Py_REFCNT(new_obj) == 2);
+    Py_CLEAR(lists[0]);
+    assert(lists[0] == _Py_NULL);
+#endif
+
+    assert(Py_REFCNT(old_obj) == 1);
+    assert(Py_REFCNT(new_obj) == 1);
+    Py_DECREF(old_obj);
+    Py_DECREF(new_obj);
+    return 0;
+}
+
 static PyMethodDef _testcppext_methods[] = {
     {"add", _testcppext_add, METH_VARARGS, _testcppext_add_doc},
     {"test_api_casts", test_api_casts, METH_NOARGS, _Py_NULL},
@@ -298,6 +377,10 @@ _testcppext_exec(PyObject *module)
     if (!result) return -1;
     Py_DECREF(result);
 
+    if (test_refcount_lvalues() < 0) {
+        return -1;
+    }
+
     // test Py_BUILD_ASSERT() and Py_BUILD_ASSERT_EXPR()
     Py_BUILD_ASSERT(sizeof(int) == sizeof(unsigned int));
     assert(Py_BUILD_ASSERT_EXPR(sizeof(int) == sizeof(unsigned int)) == 0);

diff --git a/Misc/NEWS.d/next/C_API/2026-09-18-00-00-00.gh-issue-157649.CppRef.rst b/Misc/NEWS.d/next/C_API/2026-09-18-00-00-00.gh-issue-157649.CppRef.rst
@@ -0,0 +1,3 @@
+Fix a C++ regression in :c:macro:`Py_CLEAR`, :c:macro:`Py_SETREF` and
+:c:macro:`Py_XSETREF` when the destination is an array item or a reference.
+The macros could decrement the wrong object's reference count or crash.