RustPython · bschoenmaeckers · Apr 4, 2026 · Apr 5, 2026 · Apr 5, 2026 · Apr 5, 2026
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
@@ -49,7 +49,7 @@
 flamescope = { version = "0.1.2", optional = true }

 rustls = { workspace = true, optional = true }
 rustls-graviola = { workspace = true, optional = true }

 [target.'cfg(windows)'.dependencies]
 libc = { workspace = true }
@@ -119,6 +119,7 @@
 
 [patch.crates-io]
 parking_lot_core = { git = "https://github.com/youknowone/parking_lot", branch = "rustpython" }
+pyo3-ffi = { git = "https://github.com/PyO3/pyo3" }
 # REDOX START, Uncomment when you want to compile/check with redoxer
 # REDOX END
 
@@ -270,7 +271,7 @@
 proc-macro2 = "1.0.105"
 psm = "0.1"
 pymath = { version = "0.2.0", features = ["mul_add", "malachite-bigint", "complex"] }
-pyo3 = "0.28"
+pyo3 = { git = "https://github.com/PyO3/pyo3" }
 quote = "1.0.45"
 radium = "1.1.1"
 rand = "0.9"

diff --git a/Lib/test/test_ctypes/test_python_api.py b/Lib/test/test_ctypes/test_python_api.py
@@ -7,7 +7,6 @@
 
 
 class PythonAPITestCase(unittest.TestCase):
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; - requires pythonapi (Python C API)
     def test_PyBytes_FromStringAndSize(self):
         PyBytes_FromStringAndSize = pythonapi.PyBytes_FromStringAndSize
 

diff --git a/crates/capi/Cargo.toml b/crates/capi/Cargo.toml
@@ -21,6 +21,10 @@ rustpython-stdlib = {workspace = true, features = ["threading"] }
 [dev-dependencies]
 pyo3 = { workspace = true, features = ["auto-initialize", "abi3"] }
 
+[features]
+# Enable PyObject_CallMethodObjArgs variadic function, which is only available on nightly Rust.
-# Enable PyObject_CallMethodObjArgs variadic function, which is only available on nightly Rust.
+# Enable PyObject_CallMethodObjArgs variadic function, which is only available on nightly Rust.
+# TODO: remove this when the `c_variadic` feature is stabilized (https://github.com/rust-lang/rust/issues/44930)
-# Enable PyObject_CallMethodObjArgs variadic function, which is only available on nightly Rust.
+# Enable PyObject_CallMethodObjArgs variadic function, which is only available on nightly Rust.
+# TODO: remove this when the `c_variadic` feature is stabilized (https://github.com/rust-lang/rust/issues/44930)
+nightly = []
+
 [lints]
 workspace = true
 

diff --git a/crates/capi/capi_todo.md b/crates/capi/capi_todo.md
@@ -0,0 +1,141 @@
+# Unimplemented C API functions
+
+Mapping source: `pyo3-ffi/src/*.rs`, which mirrors the CPython header split used by the C API.
+
+## `abstract.h`
+
+RustPython C API target: `crates/capi/src/abstract_.rs`
+
+- `PyIter_Check`
+- `PyIter_NextItem`
+- `PyIter_Send`
+- `PyObject_GetIter`
+- `PyObject_Size`
+
+## `descrobject.h`
+
+RustPython C API target: `crates/capi/src/descrobject.rs` (not present yet)
+
+- `PyDictProxy_New`
+
+## `dictobject.h`
+
+RustPython C API target: `crates/capi/src/dictobject.rs`
+
+- `PyDict_Contains`
+- `PyDict_Copy`
+- `PyDict_DelItem`
+- `PyDict_Items`
+- `PyDict_Keys`
+- `PyDict_Merge`
+- `PyDict_MergeFromSeq2`
+- `PyDict_Update`
+- `PyDict_Values`
+
+## `genericaliasobject.h`
+
+RustPython C API target: `crates/capi/src/genericaliasobject.rs` (not present yet)
+
+- `Py_GenericAlias`
+
+## `import.h`
+
+RustPython C API target: `crates/capi/src/import.rs`
+
+- `PyImport_ExecCodeModuleEx`
+
+## `listobject.h`
+
+RustPython C API target: `crates/capi/src/listobject.rs`
+
+- `PyList_AsTuple`
+- `PyList_GetSlice`
+- `PyList_SetSlice`
+- `PyList_Sort`
+
+## `longobject.h`
+
+RustPython C API target: `crates/capi/src/longobject.rs`
+
+- `PyLong_AsUnsignedLongLongMask`
+
+## `modsupport.h`
+
+RustPython C API target: `crates/capi/src/modsupport.rs` (not present yet)
+
+- `PyModule_ExecDef`
+- `PyModule_FromDefAndSpec2`
+
+## `moduleobject.h`
+
+RustPython C API target: `crates/capi/src/moduleobject.rs`
+
+- `PyModule_GetFilenameObject`
+- `PyModule_NewObject`
+
+## `object.h`
+
+RustPython C API target: `crates/capi/src/object.rs`
+
+- `PyCallable_Check`
+- `PyObject_ClearWeakRefs`
+- `PyObject_Dir`
+- `PyObject_GenericGetAttr`
+- `PyObject_GetOptionalAttr`
+- `PyObject_RichCompare`
+- `PyType_GetModuleName`
+
+## `osmodule.h`
+
+RustPython C API target: `crates/capi/src/osmodule.rs` (not present yet)
+
+- `PyOS_FSPath`
+
+## `pybuffer.h`
+
+RustPython C API target: `crates/capi/src/pybuffer.rs` (not present yet)
+
+- `PyBuffer_FromContiguous`
+- `PyBuffer_GetPointer`
+- `PyBuffer_IsContiguous`
+- `PyBuffer_Release`
+- `PyBuffer_ToContiguous`
+- `PyObject_GetBuffer`
+
+## `pyerrors.h`
+
+RustPython C API target: `crates/capi/src/pyerrors.rs`
+
+- `PyException_SetContext`
+- `PyUnicodeDecodeError_Create`
+
+## `pystate.h`
+
+RustPython C API target: `crates/capi/src/pystate.rs`
+
+- `PyInterpreterState_Get`
+- `PyInterpreterState_GetID`
+
+## `sliceobject.h`
+
+RustPython C API target: `crates/capi/src/sliceobject.rs` (not present yet)
+
+- `PySlice_AdjustIndices`
+- `PySlice_New`
+- `PySlice_Unpack`
+
+## `unicodeobject.h`
+
+RustPython C API target: `crates/capi/src/unicodeobject.rs`
+
+- `PyUnicode_AsUTF8String`
+- `PyUnicode_DecodeFSDefaultAndSize`
+- `PyUnicode_EncodeFSDefault`
+- `PyUnicode_FromEncodedObject`
+
+## `warnings.h`
+
+RustPython C API target: `crates/capi/src/warnings.rs` (not present yet)
+
+- `PyErr_WarnEx`
+- `PyErr_WarnExplicit`
diff --git a/crates/capi/pyo3-rustpython.config b/crates/capi/pyo3-rustpython.config
@@ -1,4 +1,4 @@
-implementation=CPython
+implementation=RustPython
 version=3.14
 shared=true
 abi3=true

diff --git a/crates/capi/src/abstract_.rs b/crates/capi/src/abstract_.rs
@@ -2,11 +2,13 @@ use crate::{PyObject, pystate::with_vm};
 use alloc::slice;
 use core::ffi::c_int;
 pub use mapping::*;
+pub use number::*;
 use rustpython_vm::builtins::{PyDict, PyStr, PyTuple};
 use rustpython_vm::function::{FuncArgs, KwArgs, PosArgs};
 use rustpython_vm::{AsObject, Py, PyObjectRef, PyResult, VirtualMachine};
 
 mod mapping;
+mod number;
 
 const PY_VECTORCALL_ARGUMENTS_OFFSET: usize = 1usize << (usize::BITS as usize - 1);
 
@@ -51,6 +53,25 @@ pub unsafe extern "C" fn PyObject_CallNoArgs(callable: *mut PyObject) -> *mut Py
     with_vm(|vm| unsafe { &*callable }.call((), vm))
 }
 
+#[unsafe(no_mangle)]
+#[cfg(feature = "nightly")]
+pub unsafe extern "C" fn PyObject_CallMethodObjArgs(
+    receiver: *mut PyObject,
+    name: *mut PyObject,
+    mut args: ...
+) -> *mut PyObject {
+    with_vm(|vm| {
+        let method_name = unsafe { (&*name).try_downcast_ref::<PyStr>(vm)? };
+        let callable = unsafe { (&*receiver).get_attr(method_name, vm)? };
+        let arguments = core::iter::from_fn(|| unsafe {
+            core::ptr::NonNull::new(args.next_arg::<*mut PyObject>())
+                .map(|obj| obj.as_ref().to_owned())
+        })
+        .collect::<Vec<_>>();
+        callable.call(arguments, vm)
+    })
+}
+
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn PyObject_Vectorcall(
     callable: *mut PyObject,
@@ -166,3 +187,71 @@ pub unsafe extern "C" fn PyObject_IsInstance(inst: *mut PyObject, cls: *mut PyOb
         inst.is_instance(cls, vm)
     })
 }
+
+#[unsafe(no_mangle)]
+pub extern "C" fn PySequence_Contains(obj: *mut PyObject, value: *mut PyObject) -> c_int {
+    with_vm(|vm| {
+        let obj = unsafe { &*obj };
+        let value = unsafe { &mut *value };
+        match obj.try_sequence(vm) {
+            Ok(sequence) => sequence.contains(value, vm),
+            Err(type_err) => {
+                // TODO Dict should implement sequence protocol, but for now we can special case it
+                if let Some(dict) = obj.downcast_ref::<PyDict>() {
+                    Ok(dict.contains_key(value, vm))
+                } else {
+                    Err(type_err)
+                }
+            }
+        }
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use pyo3::prelude::*;
+    use pyo3::types::{PyDict, PyString};
+
+    #[test]
+    #[cfg(feature = "nightly")]
+    fn test_call_method0() {
+        Python::attach(|py| {
+            let string = PyString::new(py, "Hello, World!");
+            assert_eq!(
+                string.call_method0("upper").unwrap().str().unwrap(),
+                "HELLO, WORLD!"
+            );
+        })
+    }
+
+    #[test]
+    fn test_call_method1() {
+        Python::attach(|py| {
+            let string = PyString::new(py, "Hello, World!");
+            assert!(
+                string
+                    .call_method1("endswith", ("!",))
+                    .unwrap()
+                    .is_truthy()
+                    .unwrap()
+            );
+        })
+    }
+
+    #[test]
+    fn test_object_set_get_del_item() {
+        Python::attach(|py| {
+            let obj = PyDict::new(py).into_any();
+            obj.set_item("key", "value").unwrap();
+            assert_eq!(
+                obj.get_item("key")
+                    .unwrap()
+                    .cast_into::<PyString>()
+                    .unwrap(),
+                "value"
+            );
+            obj.del_item("key").unwrap();
+            assert!(obj.get_item("key").is_err());
+        })
+    }
+}
diff --git a/crates/capi/src/abstract_/mapping.rs b/crates/capi/src/abstract_/mapping.rs
@@ -37,7 +37,7 @@ pub unsafe extern "C" fn PyMapping_Items(obj: *mut PyObject) -> *mut PyObject {
     })
 }
 
-#[cfg(false)]
+#[cfg(test)]
 mod tests {
     use pyo3::prelude::*;
     use pyo3::types::{PyDict, PyMapping, PyMappingMethods, PyTuple};