[mypyc] Fix object finalization (#19749)

Fixes mypyc/mypyc#1127

Author: cdce8p

mypy/test/helpers.py

@@ -233,6 +233,9 @@ def clean_up(a: list[str]) -> list[str]:
         for p in prefix, prefix.replace(os.sep, "/"):
             if p != "/" and p != "//" and p != "\\" and p != "\\\\":
                 ss = ss.replace(p, "")
+        # Replace memory address with zeros
+        if "at 0x" in ss:
+            ss = re.sub(r"(at 0x)\w+>", r"\g<1>000000000000>", ss)
         # Ignore spaces at end of line.
         ss = re.sub(" +$", "", ss)
         # Remove pwd from driver.py's path

mypyc/codegen/emitclass.py

@@ -889,8 +889,21 @@ def generate_dealloc_for_class(
     emitter.emit_line(f"{dealloc_func_name}({cl.struct_name(emitter.names)} *self)")
     emitter.emit_line("{")
     if has_tp_finalize:
-        emitter.emit_line("if (!PyObject_GC_IsFinalized((PyObject *)self)) {")
-        emitter.emit_line("Py_TYPE(self)->tp_finalize((PyObject *)self);")
+        emitter.emit_line("PyObject *type, *value, *traceback;")
+        emitter.emit_line("PyErr_Fetch(&type, &value, &traceback);")
+        emitter.emit_line("int res = PyObject_CallFinalizerFromDealloc((PyObject *)self);")
+        # CPython interpreter uses PyErr_WriteUnraisable: https://docs.python.org/3/c-api/exceptions.html#c.PyErr_WriteUnraisable
+        # However, the message is slightly different due to the way mypyc compiles classes.
+        # CPython interpreter prints: Exception ignored in: <function F.__del__ at 0x100aed940>
+        # mypyc prints: Exception ignored in: <slot wrapper '__del__' of 'F' objects>
+        emitter.emit_line("if (PyErr_Occurred() != NULL) {")
+        # Don't untrack instance if error occurred
+        emitter.emit_line("PyErr_WriteUnraisable((PyObject *)self);")
+        emitter.emit_line("res = -1;")
+        emitter.emit_line("}")
+        emitter.emit_line("PyErr_Restore(type, value, traceback);")
+        emitter.emit_line("if (res < 0) {")
+        emitter.emit_line("goto done;")
         emitter.emit_line("}")
     emitter.emit_line("PyObject_GC_UnTrack(self);")
     if cl.reuse_freed_instance:
@@ -900,6 +913,7 @@ def generate_dealloc_for_class(
     emitter.emit_line(f"{clear_func_name}(self);")
     emitter.emit_line("Py_TYPE(self)->tp_free((PyObject *)self);")
     emitter.emit_line("CPy_TRASHCAN_END(self)")
+    emitter.emit_line("done: ;")
     emitter.emit_line("}")
 
 
@@ -930,30 +944,13 @@ def generate_finalize_for_class(
     emitter.emit_line("static void")
     emitter.emit_line(f"{finalize_func_name}(PyObject *self)")
     emitter.emit_line("{")
-    emitter.emit_line("PyObject *type, *value, *traceback;")
-    emitter.emit_line("PyErr_Fetch(&type, &value, &traceback);")
     emitter.emit_line(
         "{}{}{}(self);".format(
             emitter.get_group_prefix(del_method.decl),
             NATIVE_PREFIX,
             del_method.cname(emitter.names),
         )
     )
-    emitter.emit_line("if (PyErr_Occurred() != NULL) {")
-    emitter.emit_line('PyObject *del_str = PyUnicode_FromString("__del__");')
-    emitter.emit_line(
-        "PyObject *del_method = (del_str == NULL) ? NULL : _PyType_Lookup(Py_TYPE(self), del_str);"
-    )
-    # CPython interpreter uses PyErr_WriteUnraisable: https://docs.python.org/3/c-api/exceptions.html#c.PyErr_WriteUnraisable
-    # However, the message is slightly different due to the way mypyc compiles classes.
-    # CPython interpreter prints: Exception ignored in: <function F.__del__ at 0x100aed940>
-    # mypyc prints: Exception ignored in: <slot wrapper '__del__' of 'F' objects>
-    emitter.emit_line("PyErr_WriteUnraisable(del_method);")
-    emitter.emit_line("Py_XDECREF(del_method);")
-    emitter.emit_line("Py_XDECREF(del_str);")
-    emitter.emit_line("}")
-    # PyErr_Restore also clears exception raised in __del__.
-    emitter.emit_line("PyErr_Restore(type, value, traceback);")
     emitter.emit_line("}")
 
 

mypyc/test-data/run-classes.test

@@ -3110,7 +3110,7 @@ f = native.F()
 del f
 
 [out]
-Exception ignored in: <slot wrapper '__del__' of 'F' objects>
+Exception ignored in: <native.F object at 0x000000000000>
 Traceback (most recent call last):
   File "native.py", line 5, in __del__
     raise Exception("e2")