Restore the placement vtable to preserve the PyObject layout

Author: jairov4

mypyc/codegen/emitclass.py

@@ -380,9 +380,7 @@ def setter_name(cl: ClassIR, attribute: str, names: NameGenerator) -> str:
 def generate_object_struct(cl: ClassIR, emitter: Emitter) -> None:
     seen_attrs: set[tuple[str, RType]] = set()
     lines: list[str] = []
-    lines += ["typedef struct {", "PyObject_HEAD"]
-    if not cl.is_final_class:
-        lines.append("CPyVTableItem *vtable;")
+    lines += ["typedef struct {", "PyObject_HEAD", "CPyVTableItem *vtable;"]
     if cl.has_method("__call__") and emitter.use_vectorcall():
         lines.append("vectorcallfunc vectorcall;")
     bitmap_attrs = []

mypyc/irbuild/ll_builder.py

@@ -1889,8 +1889,9 @@ def primitive_op(
         # Does this primitive map into calling a Python C API
         # or an internal mypyc C API function?
         if desc.c_function_name:
-            # TODO: Generate PrimitiOps here and transform them into CallC
+            # TODO: Generate PrimitiveOps here and transform them into CallC
             # ops only later in the lowering pass
+            print(f"primitive_op: {desc.name} {desc.c_function_name} {desc.is_pure} -> {result_type}")
             c_desc = CFunctionDescription(
                 desc.name,
                 desc.arg_types,
@@ -1908,7 +1909,7 @@ def primitive_op(
             )
             return self.call_c(c_desc, args, line, result_type)
 
-        # This primitve gets transformed in a lowering pass to
+        # This primitive gets transformed in a lowering pass to
         # lower-level IR ops using a custom transform function.
 
         coerced = []

mypyc/test-data/run-classes.test

@@ -2527,5 +2527,11 @@ class C(B):
     def a(self) -> int:
         return 1
 
+def fn(cl: B) -> int:
+    return cl.a()
+
 def test_class_final_attribute_inherited() -> None:
     assert C().a() == 1
+    assert fn(C()) == 1
+    assert B().a() == 2
+    assert fn(B()) == 2