Clear frame locals and stack on generator close

youknowone · youknowone · commit 15bbe370eebf · 2026-02-25T18:02:15.000+09:00
Add Frame::clear_locals_and_stack() to release references held by
closed generators/coroutines, matching _PyFrame_ClearLocals behavior.
Call it from Coro::close() after marking the coroutine as closed.

Update test_generators.py expectedFailure markers accordingly.
diff --git a/Lib/test/test_generators.py b/Lib/test/test_generators.py
@@ -660,7 +660,6 @@ def f():
         with self.assertRaises(RuntimeError):
             gen.close()
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; no deterministic GC finalization
     def test_close_releases_frame_locals(self):
         # See gh-118272
 
@@ -684,6 +683,7 @@ def genfn():
 
 # See https://github.com/python/cpython/issues/125723
 class GeneratorDeallocTest(unittest.TestCase):
+    @unittest.expectedFailure  # TODO: RUSTPYTHON; frame uses shared Arc, no ownership transfer
     def test_frame_outlives_generator(self):
         def g1():
             a = 42
diff --git a/crates/vm/src/coroutine.rs b/crates/vm/src/coroutine.rs
@@ -207,6 +207,9 @@ impl Coro {
             )
         });
         self.closed.store(true);
+        // Release frame locals and stack to free references held by the
+        // closed generator, matching gen_send_ex2 with close_on_completion.
+        self.frame.clear_locals_and_stack();
         match result {
             Ok(ExecutionResult::Yield(_)) => {
                 Err(vm.new_runtime_error(format!("{} ignored GeneratorExit", gen_name(jen, vm))))
diff --git a/crates/vm/src/frame.rs b/crates/vm/src/frame.rs
@@ -223,6 +223,16 @@ impl Frame {
         self.state.lock().stack.clear();
     }
 
+    /// Clear locals and stack after generator/coroutine close.
+    /// Releases references held by the frame, matching _PyFrame_ClearLocals.
+    pub(crate) fn clear_locals_and_stack(&self) {
+        self.state.lock().stack.clear();
+        let mut fastlocals = self.fastlocals.lock();
+        for slot in fastlocals.iter_mut() {
+            *slot = None;
+        }
+    }
+
     /// Store a borrowed back-reference to the owning generator/coroutine.
     /// The caller must ensure the generator outlives the frame.
     pub fn set_generator(&self, generator: &PyObject) {
