Untrack classes with managed dicts in dealloc; Fix compat function return val

p-sawicki · p-sawicki · commit fc8bd70efd98 · 2026-04-23T14:59:52.000+02:00
diff --git a/mypyc/codegen/emitclass.py b/mypyc/codegen/emitclass.py
@@ -945,16 +945,20 @@ def generate_dealloc_for_class(
         emitter.emit_line("if (res < 0) {")
         emitter.emit_line("goto done;")
         emitter.emit_line("}")
+    if not cl.is_acyclic:
+        emitter.emit_line("PyObject_GC_UnTrack(self);")
     if cl.builtin_base:
+        emitter.emit_line(f"{clear_func_name}(self);")
         # For native subclasses of builtins such as dict, the base deallocator
         # is responsible for tearing down base-owned storage and freeing memory.
-        emitter.emit_line(f"{clear_func_name}(self);")
-        emitter.emit_base_tp_function_call(cl, "tp_dealloc", "(PyObject *)self")
+        # Re-track self if base is GC-aware to match cpython's subtype_dealloc.
+        base = f"{emitter.type_struct_name(cl)}->tp_base"
+        base_arg = "(PyObject *)self"
+        emitter.emit_line(f"if (PyType_IS_GC({base})) PyObject_GC_Track({base_arg});")
+        emitter.emit_base_tp_function_call(cl, "tp_dealloc", base_arg)
         emitter.emit_line("done: ;")
         emitter.emit_line("}")
         return
-    if not cl.is_acyclic:
-        emitter.emit_line("PyObject_GC_UnTrack(self);")
     if cl.reuse_freed_instance:
         emit_reuse_dealloc(cl, emitter)
     # The trashcan is needed to handle deep recursive deallocations
diff --git a/mypyc/lib-rt/pythoncapi_compat.h b/mypyc/lib-rt/pythoncapi_compat.h
@@ -922,7 +922,8 @@ PyObject_VisitManagedDict(PyObject *obj, visitproc visit, void *arg)
 {
     PyObject **dict = _PyObject_GetDictPtr(obj);
     if (dict == NULL || *dict == NULL) {
-        return -1;
+        // Nothing to do.
+        return 0;
     }
     Py_VISIT(*dict);
     return 0;

Original file line number	Diff line number	Diff line change
`@@ -922,7 +922,8 @@ PyObject_VisitManagedDict(PyObject obj, visitproc visit, void arg)`
`922`	`922`	`{`
`923`	`923`	`PyObject **dict = _PyObject_GetDictPtr(obj);`
`924`	`924`	`if (dict == NULL \|\| *dict == NULL) {`
`925`		`- return -1;`
	`925`	`+ // Nothing to do.`
	`926`	`+ return 0;`
`926`	`927`	`}`
`927`	`928`	`Py_VISIT(*dict);`
`928`	`929`	`return 0;`