Fix function attribute tests: __defaults__ del, __code__ free vars check, bound method dir()

- Support `del func.__defaults__` and `del func.__kwdefaults__` by changing
  setter signatures to `PySetterValue<Option<...>>` so Delete is treated as
  setting the value to None (matching CPython behaviour)
- Validate free-variable count when assigning to `func.__code__`: raise
  ValueError when the new code object's freevars count doesn't match the
  existing closure size
- Add `__dir__` to `PyBoundMethod` that delegates to the underlying
  function's dir(), so attributes set on the function show up in
  `dir(bound_method)`
- Remove `@unittest.expectedFailure` from the four tests that now pass:
  test_blank_func_defaults, test_func_default_args, test___code__,
  test_dir_includes_correct_attrs

Author: ever0de

Lib/test/test_funcattrs.py

@@ -50,7 +50,6 @@ class FunctionPropertiesTest(FuncAttrsTest):
     def test_module(self):
         self.assertEqual(self.b.__module__, __name__)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test_dir_includes_correct_attrs(self):
         self.b.known_attr = 7
         self.assertIn('known_attr', dir(self.b),
@@ -238,7 +237,6 @@ def not_generic(): pass
                 func.__type_params__ = (T,)
                 self.assertEqual(func.__type_params__, (T,))
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test___code__(self):
         num_one, num_two = 7, 8
         def a(): pass
@@ -269,13 +267,11 @@ def e(): return num_one, num_two
             self.fail("__code__ with different numbers of free vars should "
                       "not be possible")
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test_blank_func_defaults(self):
         self.assertEqual(self.b.__defaults__, None)
         del self.b.__defaults__
         self.assertEqual(self.b.__defaults__, None)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test_func_default_args(self):
         def first_func(a, b):
             return a+b

crates/vm/src/builtins/function.rs

@@ -2,8 +2,8 @@
 mod jit;
 
 use super::{
-    PyAsyncGen, PyCode, PyCoroutine, PyDictRef, PyGenerator, PyModule, PyStr, PyStrRef, PyTuple,
-    PyTupleRef, PyType, object,
+    PyAsyncGen, PyCode, PyCoroutine, PyDictRef, PyGenerator, PyList, PyModule, PyStr, PyStrRef,
+    PyTuple, PyTupleRef, PyType, object,
 };
 use crate::common::hash::PyHash;
 use crate::common::lock::PyMutex;
@@ -788,7 +788,17 @@ impl PyFunction {
     }
 
     #[pygetset(setter)]
-    fn set___code__(&self, code: PyRef<PyCode>, vm: &VirtualMachine) {
+    fn set___code__(&self, code: PyRef<PyCode>, vm: &VirtualMachine) -> PyResult<()> {
+        let nfree = code.freevars.len();
+        let nclosure = self.closure.as_ref().map_or(0, |c| c.len());
+        if nclosure != nfree {
+            return Err(vm.new_value_error(format!(
+                "{}() requires a code object with {} free vars, not {}",
+                self.qualname.lock(),
+                nclosure,
+                nfree,
+            )));
+        }
         #[cfg(feature = "jit")]
         let mut jit_guard = self.jitted_code.lock();
         self.code.swap_to_temporary_refs(code, vm);
@@ -797,15 +807,19 @@ impl PyFunction {
             *jit_guard = None;
         }
         self.func_version.store(0, Relaxed);
+        Ok(())
     }
 
     #[pygetset]
     fn __defaults__(&self) -> Option<PyTupleRef> {
         self.defaults_and_kwdefaults.lock().0.clone()
     }
     #[pygetset(setter)]
-    fn set___defaults__(&self, defaults: Option<PyTupleRef>) {
-        self.defaults_and_kwdefaults.lock().0 = defaults;
+    fn set___defaults__(&self, defaults: PySetterValue<Option<PyTupleRef>>) {
+        self.defaults_and_kwdefaults.lock().0 = match defaults {
+            PySetterValue::Assign(d) => d,
+            PySetterValue::Delete => None,
+        };
         self.func_version.store(0, Relaxed);
     }
 
@@ -814,8 +828,11 @@ impl PyFunction {
         self.defaults_and_kwdefaults.lock().1.clone()
     }
     #[pygetset(setter)]
-    fn set___kwdefaults__(&self, kwdefaults: Option<PyDictRef>) {
-        self.defaults_and_kwdefaults.lock().1 = kwdefaults;
+    fn set___kwdefaults__(&self, kwdefaults: PySetterValue<Option<PyDictRef>>) {
+        self.defaults_and_kwdefaults.lock().1 = match kwdefaults {
+            PySetterValue::Assign(d) => d,
+            PySetterValue::Delete => None,
+        };
         self.func_version.store(0, Relaxed);
     }
 
@@ -1308,6 +1325,11 @@ impl PyBoundMethod {
     fn __module__(&self, vm: &VirtualMachine) -> Option<PyObjectRef> {
         self.function.get_attr("__module__", vm).ok()
     }
+
+    #[pymethod]
+    fn __dir__(&self, vm: &VirtualMachine) -> PyResult<PyList> {
+        vm.dir(Some(self.function.clone()))
+    }
 }
 
 impl PyPayload for PyBoundMethod {