types: count the __call__ and __get__ slot dispatches as recursion

Both wrappers re-enter Python without pushing a frame, so nothing counted the nesting when the special method named the object it was looked up on: class C: pass c = C(); C.__call__ = c c() # native stack overflow, SIGSEGV class D: pass d = D(); D.__get__ = d; D.x = d d.x # the same, through descr_get with_recursion around the two dispatches raises RecursionError instead, the way Py_EnterRecursiveCall bounds a tp_call dispatch. It costs about 5% on a __call__ dispatch and 3% on a __get__ dispatch through these wrappers. Assisted-by: Claude
youknowone · Aug 16, 2026 · Aug 14, 2026 · Aug 14, 2026 · Aug 14, 2026 · Aug 14, 2026
commit 40a839bc89ce80f3313512f77003309581b1665b
diff --git a/crates/vm/src/types/slot.rs b/crates/vm/src/types/slot.rs
@@ -527,7 +527,11 @@ pub fn hash_not_implemented(zelf: &PyObject, vm: &VirtualMachine) -> PyResult<Py
 }
 
 fn call_wrapper(zelf: &PyObject, args: FuncArgs, vm: &VirtualMachine) -> PyResult {
-    vm.call_special_method(zelf, identifier!(vm, __call__), args)
+    // `__call__` can name the object being called, and dispatching it pushes no
+    // Python frame, so nothing else counts the nesting.
+    vm.with_recursion("while calling a Python object", || {
+        vm.call_special_method(zelf, identifier!(vm, __call__), args)
+    })
 }
 
 fn getattro_wrapper(zelf: &PyObject, name: &Py<PyStr>, vm: &VirtualMachine) -> PyResult {
@@ -616,7 +620,11 @@ fn descr_get_wrapper(
     cls: Option<PyObjectRef>,
     vm: &VirtualMachine,
 ) -> PyResult {
-    vm.call_special_method(&zelf, identifier!(vm, __get__), (obj, cls))
+    // A descriptor whose `__get__` is the descriptor itself resolves it by
+    // fetching `__get__` again, and none of that pushes a Python frame.
+    vm.with_recursion("while calling a Python object", || {
+        vm.call_special_method(&zelf, identifier!(vm, __get__), (obj, cls))
+    })
 }
 
 fn descr_set_wrapper(

diff --git a/extra_tests/snippets/recursion.py b/extra_tests/snippets/recursion.py
@@ -11,3 +11,36 @@ class Foo(object):
 # Since the default __str__ implementation calls __repr__ and __repr__ is
 # actually __str__, str(foo) should raise a RecursionError.
 assert_raises(RecursionError, str, foo)
+
+
+# A __call__ that is the object being called dispatches through the call slot
+# again, and none of that pushes a Python frame.
+
+
+class Caller:
+    pass
+
+
+caller = Caller()
+Caller.__call__ = caller
+assert_raises(RecursionError, caller)
+
+
+# The same shape through the descriptor protocol: resolving the attribute
+# fetches __get__, which is the descriptor itself.
+
+
+class Descr:
+    pass
+
+
+descr = Descr()
+Descr.__get__ = descr
+Descr.x = descr
+try:
+    descr.x
+except (RecursionError, TypeError):
+    # RecursionError here, TypeError from the call of a non-callable elsewhere
+    pass
+else:
+    raise AssertionError("descr.x should not resolve")