1ndahous3 · Oct 1, 2026 · Oct 2, 2026
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
@@ -1865,7 +1865,6 @@ class D(C):
         self.assertEqual(b.foo, 3)
         self.assertEqual(b.__class__, D)
 
-    @unittest.expectedSuccess  # TODO: RUSTPYTHON; The `expectedFailure` here is from CPython, so this test must fail
     @unittest.expectedFailure
     def test_bad_new(self):
         self.assertRaises(TypeError, object.__new__)

diff --git a/Lib/test/test_gc.py b/Lib/test/test_gc.py
@@ -236,7 +236,6 @@ def test_function(self):
         # is 3 because it includes f's code object.
         self.assertIn(gc.collect(), (2, 3))
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; - weakref clear ordering differs from 3.15+
     def test_function_tp_clear_leaves_consistent_state(self):
         # https://github.com/python/cpython/issues/91636
         code = """if 1:

diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py
@@ -751,7 +751,6 @@ class D:
         del c1, c2, C, D
         gc.collect()
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test_callback_in_cycle_resurrection(self):
         import gc
 
@@ -798,7 +797,6 @@ def C_went_away(ignore):
         gc.collect()
         self.assertEqual(alist, [])
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test_callbacks_on_callback(self):
         import gc
 

diff --git a/benches/execution.rs b/benches/execution.rs
@@ -39,17 +39,23 @@ fn bench_rustpython_code(b: &mut Bencher<'_>, name: &str, source: &str) {
     settings.write_bytecode = false;
     settings.user_site_directory = false;
     let builder = Interpreter::builder(settings);
-    let defs = rustpython_stdlib::stdlib_module_defs(&builder.ctx);
-    builder.add_native_modules(&defs).build().enter(|vm| {
-        // Note: bench_cpython is both compiling and executing the code.
-        // As such we compile the code in the benchmark loop as well.
-        b.iter(|| {
-            let code = vm.compile(source, Mode::Exec, name).unwrap();
-            let scope = vm.new_scope_with_builtins();
-            let res: PyResult = vm.run_code_obj(code, scope);
-            vm.unwrap_pyresult(res);
-        })
-    })
+    let defs = rustpython_stdlib::stdlib_module_defs(unsafe { builder.context() });
+    // SAFETY: compilation and execution retain no objects beyond this entry.
+    unsafe {
+        builder
+            .add_native_modules(&defs)
+            .build()
+            .enter_unchecked(|vm| {
+                // Note: bench_cpython is both compiling and executing the code.
+                // As such we compile the code in the benchmark loop as well.
+                b.iter(|| {
+                    let code = vm.compile(source, Mode::Exec, name).unwrap();
+                    let scope = vm.new_scope_with_builtins();
+                    let res: PyResult = vm.run_code_obj(code, scope);
+                    vm.unwrap_pyresult(res);
+                })
+            })
+    }
 }
 
 pub fn benchmark_file_execution(

diff --git a/benches/microbenchmarks.rs b/benches/microbenchmarks.rs
@@ -111,58 +111,61 @@ fn bench_rustpython_code(group: &mut BenchmarkGroup<'_, WallTime>, bench: &Micro
     settings.user_site_directory = false;
 
     let builder = Interpreter::builder(settings);
-    let defs = rustpython_stdlib::stdlib_module_defs(&builder.ctx);
-    let interp = builder.add_native_modules(&defs).build();
-    interp.enter(|vm| {
-        let setup_code = vm
-            .compile(&bench.setup, Mode::Exec, &bench.name)
-            .expect("Error compiling setup code");
-        let bench_code = vm
-            .compile(&bench.code, Mode::Exec, &bench.name)
-            .expect("Error compiling bench code");
-
-        let bench_func = |scope| {
-            let res: PyResult = vm.run_code_obj(bench_code.clone(), scope);
-            vm.unwrap_pyresult(res);
-        };
+    let defs = rustpython_stdlib::stdlib_module_defs(unsafe { builder.context() });
+    let interp = unsafe { builder.add_native_modules(&defs) }.build();
+    // SAFETY: benchmark scopes and code objects are released before leaving.
+    unsafe {
+        interp.enter_unchecked(|vm| {
+            let setup_code = vm
+                .compile(&bench.setup, Mode::Exec, &bench.name)
+                .expect("Error compiling setup code");
+            let bench_code = vm
+                .compile(&bench.code, Mode::Exec, &bench.name)
+                .expect("Error compiling bench code");
+
+            let bench_func = |scope| {
+                let res: PyResult = vm.run_code_obj(bench_code.clone(), scope);
+                vm.unwrap_pyresult(res);
+            };
 
-        let bench_setup = |iterations| {
-            let scope = vm.new_scope_with_builtins();
-            if let Some(idx) = iterations {
+            let bench_setup = |iterations| {
+                let scope = vm.new_scope_with_builtins();
+                if let Some(idx) = iterations {
+                    scope
+                        .locals
+                        .as_ref()
+                        .expect("new_scope_with_builtins always provides locals")
+                        .as_object()
+                        .set_item("ITERATIONS", vm.new_pyobj(idx), vm)
+                        .expect("Error adding ITERATIONS local variable");
+                }
+                let setup_result = vm.run_code_obj(setup_code.clone(), scope.clone());
+                vm.unwrap_pyresult(setup_result);
                 scope
-                    .locals
-                    .as_ref()
-                    .expect("new_scope_with_builtins always provides locals")
-                    .as_object()
-                    .set_item("ITERATIONS", vm.new_pyobj(idx), vm)
-                    .expect("Error adding ITERATIONS local variable");
-            }
-            let setup_result = vm.run_code_obj(setup_code.clone(), scope.clone());
-            vm.unwrap_pyresult(setup_result);
-            scope
-        };
+            };
 
-        if bench.iterate {
-            for idx in iteration_counts() {
-                group.throughput(Throughput::Elements(idx as u64));
-                group.bench_with_input(
-                    BenchmarkId::new("rustpython", &bench.name),
-                    &idx,
-                    |b, idx| {
-                        b.iter_batched(
-                            || bench_setup(Some(*idx)),
-                            bench_func,
-                            BatchSize::LargeInput,
-                        );
-                    },
-                );
+            if bench.iterate {
+                for idx in iteration_counts() {
+                    group.throughput(Throughput::Elements(idx as u64));
+                    group.bench_with_input(
+                        BenchmarkId::new("rustpython", &bench.name),
+                        &idx,
+                        |b, idx| {
+                            b.iter_batched(
+                                || bench_setup(Some(*idx)),
+                                bench_func,
+                                BatchSize::LargeInput,
+                            );
+                        },
+                    );
+                }
+            } else {
+                group.bench_function(BenchmarkId::new("rustpython", &bench.name), move |b| {
+                    b.iter_batched(|| bench_setup(None), bench_func, BatchSize::LargeInput);
+                });
             }
-        } else {
-            group.bench_function(BenchmarkId::new("rustpython", &bench.name), move |b| {
-                b.iter_batched(|| bench_setup(None), bench_func, BatchSize::LargeInput);
-            });
-        }
-    })
+        })
+    }
 }
 
 /// `true` when the benchmarks are executed by the CodSpeed runner.

diff --git a/crates/capi/src/bytearrayobject.rs b/crates/capi/src/bytearrayobject.rs
@@ -59,7 +59,9 @@ pub unsafe extern "C" fn PyByteArray_Size(bytearray: *mut PyObject) -> isize {
 pub unsafe extern "C" fn PyByteArray_AsString(bytearray: *mut PyObject) -> *mut c_char {
     with_vm(|vm| {
         let bytearray = unsafe { bytearray.assume_borrowed_and_cast::<PyByteArray>(vm) }?;
-        Ok(bytearray.borrow_buf_mut().as_mut_ptr())
+        // SAFETY: the C caller owns the PyByteArray_AsString lifetime and
+        // synchronization contract; no resizable Rust Vec escapes this API.
+        Ok(unsafe { bytearray.as_mut_ptr_unchecked() })
     })
 }
 

diff --git a/crates/capi/src/ceval.rs b/crates/capi/src/ceval.rs
@@ -180,7 +180,7 @@ mod tests {
     #[pyfunction]
     fn legacy_locals_is_frame_mapping() -> bool {
         let locals = super::PyEval_GetLocals();
-        rustpython_vm::vm::thread::with_current_vm(|vm| {
+        crate::pystate::with_current_vm(|vm| {
             let frame = vm.current_frame().unwrap();
             core::ptr::eq(
                 locals.cast_const(),

diff --git a/crates/capi/src/descrobject.rs b/crates/capi/src/descrobject.rs
@@ -5,7 +5,7 @@ use crate::pystate::with_vm;
 use crate::util::{CStrExt, FfiPtrExt};
 use core::ffi::{c_char, c_int, c_void};
 use rustpython_vm::builtins::{
-    DescriptorMemberDef, MemberAccess, MemberKind, PyDescriptorOwned, PyGetSet, PyMappingProxy,
+    DescriptorMemberDef, MemberAccess, MemberKind, PyDescriptor, PyGetSet, PyMappingProxy,
     PyMemberDescriptor, PyMemberFlags, PyType,
 };
 use rustpython_vm::common::lock::PyRwLock;
@@ -144,7 +144,7 @@ impl PyMemberDef {
         });
 
         let descriptor = PyMemberDescriptor {
-            common: PyDescriptorOwned {
+            common: PyDescriptor {
                 typ: ty.to_owned(),
                 name: vm.ctx.intern_str(name),
                 qualname: PyRwLock::new(None),

diff --git a/crates/capi/src/lib.rs b/crates/capi/src/lib.rs
@@ -61,7 +61,7 @@ pub fn init_main_interpreter(interpreter: Interpreter) {
     let mut interp = get_main_interpreter();
     assert!(interp.is_none(), "Main interpreter is already set");
     // Safety: Interpreter was not initialized before, so we can safely assume the statics are not used
-    unsafe { init_exception_statics(&Context::genesis().exceptions) };
+    unsafe { init_exception_statics(&Context::genesis_unchecked().exceptions) };
     *interp = Some(interpreter);
     MAIN_INTERP_PTR.store(
         interp.as_ref().unwrap() as *const _ as *mut _,

diff --git a/crates/capi/src/object/pytype.rs b/crates/capi/src/object/pytype.rs
@@ -27,7 +27,7 @@ pub unsafe extern "C" fn Py_IS_TYPE(op: *mut PyObject, ty: *mut PyTypeObject) ->
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn PyType_GetFlags(ptr: *mut PyTypeObject) -> c_ulong {
     let ty = unsafe { ptr.assume_borrowed() };
-    ty.slots.flags.bits() as u32 as c_ulong
+    ty.effective_flags().bits() as u32 as c_ulong
 }
 
 #[unsafe(no_mangle)]

diff --git a/crates/capi/src/objimpl.rs b/crates/capi/src/objimpl.rs
@@ -10,7 +10,10 @@ pub unsafe extern "C" fn PyObject_GC_Track(op: *mut PyObject) {
     with_vm(|_vm| {
         let obj = unsafe { op.assume_borrowed() };
         if !obj.is_gc_tracked() {
-            unsafe { gc_state::gc_state().track_object(obj.into(), gc_state::current_owner()) };
+            unsafe {
+                gc_state::gc_state_unchecked()
+                    .track_object(obj.into(), gc_state::current_owner_unchecked())
+            };
         }
     })
 }
@@ -20,7 +23,7 @@ pub unsafe extern "C" fn PyObject_GC_UnTrack(op: *mut PyObject) {
     with_vm(|_vm| {
         let obj = unsafe { op.assume_borrowed() };
         if obj.is_gc_tracked() {
-            unsafe { gc_state::gc_state().untrack_object(obj.into()) };
+            unsafe { gc_state::gc_state_unchecked().untrack_object(obj.into()) };
         }
     })
 }

diff --git a/crates/capi/src/pyframe.rs b/crates/capi/src/pyframe.rs
@@ -41,7 +41,7 @@ mod tests {
     use rustpython_vm::AsObject;
 
     fn current_frame_ptr() -> *mut super::PyFrameObject {
-        rustpython_vm::vm::thread::with_current_vm(|vm| {
+        crate::pystate::with_current_vm(|vm| {
             vm.current_frame()
                 .unwrap()
                 .as_object()
@@ -83,7 +83,7 @@ mod tests {
 
     #[pyfunction]
     fn frame_globals_is_globals() -> bool {
-        rustpython_vm::vm::thread::with_current_vm(|vm| {
+        crate::pystate::with_current_vm(|vm| {
             let frame = vm.current_frame().unwrap();
             let got = unsafe { super::PyFrame_GetGlobals(current_frame_ptr()) };
             let expected = frame.iframe().globals().as_object().as_raw();
@@ -95,7 +95,7 @@ mod tests {
 
     #[pyfunction]
     fn frame_builtins_is_builtins() -> bool {
-        rustpython_vm::vm::thread::with_current_vm(|vm| {
+        crate::pystate::with_current_vm(|vm| {
             let frame = vm.current_frame().unwrap();
             let got = unsafe { super::PyFrame_GetBuiltins(current_frame_ptr()) };
             let expected = frame.iframe().builtins().as_object().as_raw();

diff --git a/crates/capi/src/pylifecycle.rs b/crates/capi/src/pylifecycle.rs
@@ -4,7 +4,6 @@ use crate::pystate::ensure_thread_has_vm_attached;
 use alloc::ffi::CString;
 use core::ffi::{c_char, c_int, c_ulong};
 use core::sync::atomic::{AtomicPtr, Ordering};
-use rustpython_vm::common::rc::PyRc;
 use rustpython_vm::stdlib::sys;
 use rustpython_vm::version::{MAJOR, MICRO, MINOR, RUSTPYTHON_BUILD_INFO, VERSION_HEX};
 use rustpython_vm::vm::thread::ThreadedVirtualMachine;
@@ -19,7 +18,7 @@ pub(crate) fn request_vm_from_interpreter() -> ThreadedVirtualMachine {
     get_main_interpreter()
         .as_ref()
         .expect("Interpreter not initialized")
-        .enter(|vm| vm.new_thread())
+        .new_thread()
 }
 
 #[unsafe(no_mangle)]
@@ -40,20 +39,21 @@ pub extern "C" fn Py_InitializeEx(_initsigs: c_int) {
     let mut interp = get_main_interpreter();
     if interp.is_none() {
         // Safety: Interpreter was not initialized before, so we can safely assume the statics are not used
-        unsafe { init_exception_statics(&Context::genesis().exceptions) };
+        unsafe { init_exception_statics(&Context::genesis_unchecked().exceptions) };
         let builder = Interpreter::builder(Default::default());
-        let defs = rustpython_stdlib::stdlib_module_defs(&builder.ctx);
-        *interp = builder
-            .add_native_modules(&defs)
-            .init_hook(|vm| {
-                let state = PyRc::get_mut(&mut vm.state).unwrap();
-                let path = rustpython_pylib::LIB_PATH.to_owned();
-
-                state.config.paths.stdlib_dir = Some(path.clone());
-                state.config.paths.module_search_paths.insert(0, path);
-            })
-            .build()
-            .into();
+        let defs = rustpython_stdlib::stdlib_module_defs(unsafe { builder.context() });
+        *interp = unsafe {
+            builder
+                .add_native_modules(&defs)
+                .configure(|config| {
+                    let path = rustpython_pylib::LIB_PATH.to_owned();
+
+                    config.paths.stdlib_dir = Some(path.clone());
+                    config.paths.module_search_paths.insert(0, path);
+                })
+                .build()
+                .into()
+        };
         MAIN_INTERP_PTR.store(
             interp.as_ref().unwrap() as *const _ as *mut _,
             Ordering::Release,