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Merged
youknowone merged 2 commits into from
Jul 30, 2026
Merged

Allow lone-surrogate keyword keys in f(**d) #8409

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daf72d7
Allow lone-surrogate keyword keys in f(**d)
HyoJongPark Jul 28, 2026
de4f2d1
Avoid cloning kwargs keys in _ast, borrow via as_ref instead
HyoJongPark Jul 30, 2026
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4 changes: 3 additions & 1 deletion crates/capi/src/abstract_.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,9 +25,11 @@ fn dict_to_kwargs(vm: &VirtualMachine, dict: &Py<PyDict>) -> PyResult<KwArgs> {
dict.items_vec()
.into_iter()
.map(|(key, value)| {
// `to_string()` would replace lone surrogates with U+FFFD; keep the
// raw WTF-8 so surrogate keys round-trip (issue #8228).
let key = key
.downcast_ref::<PyStr>()
.map(|s| s.to_string())
.map(|s| s.as_wtf8().to_owned())
.ok_or_else(|| vm.new_type_error("keywords must be strings"))?;
Ok((key, value))
})
Expand Down
8 changes: 4 additions & 4 deletions crates/stdlib/src/_asyncio.rs
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Expand Up @@ -566,7 +566,7 @@ pub(crate) mod _asyncio {
let args = if let Some(ctx) = context {
FuncArgs::new(
vec![callback, future_arg],
KwArgs::new(core::iter::once(("context".to_owned(), ctx)).collect()),
KwArgs::new(core::iter::once((Wtf8Buf::from("context"), ctx)).collect()),
)
} else {
FuncArgs::new(vec![callback, future_arg], KwArgs::default())
Expand Down Expand Up @@ -1498,7 +1498,7 @@ pub(crate) mod _asyncio {
let args = if let Some(ctx) = context {
FuncArgs::new(
vec![callback, task_arg],
KwArgs::new(core::iter::once(("context".to_owned(), ctx)).collect()),
KwArgs::new(core::iter::once((Wtf8Buf::from("context"), ctx)).collect()),
)
} else {
FuncArgs::new(vec![callback, task_arg], KwArgs::default())
Expand Down Expand Up @@ -1527,7 +1527,7 @@ pub(crate) mod _asyncio {
let cancel_args = if let Some(ref m) = msg_value {
FuncArgs::new(
vec![],
KwArgs::new(core::iter::once(("msg".to_owned(), m.clone())).collect()),
KwArgs::new(core::iter::once((Wtf8Buf::from("msg"), m.clone())).collect()),
)
} else {
FuncArgs::new(vec![], KwArgs::default())
Expand Down Expand Up @@ -2213,7 +2213,7 @@ pub(crate) mod _asyncio {
let cancel_args = if let Some(ref m) = cancel_msg {
FuncArgs::new(
vec![],
KwArgs::new(core::iter::once(("msg".to_owned(), m.clone())).collect()),
KwArgs::new(core::iter::once((Wtf8Buf::from("msg"), m.clone())).collect()),
)
} else {
FuncArgs::new(vec![], KwArgs::default())
Expand Down
11 changes: 9 additions & 2 deletions crates/vm/src/builtins/function.rs
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Expand Up @@ -337,8 +337,13 @@ impl PyFunction {
let mut posonly_passed_as_kwarg = Vec::new();
// Handle keyword arguments
for (name, value) in func_args.kwargs {
// Parameter names are plain identifiers, so a non-UTF-8 (surrogate) key
// can never match one and just falls through to **kwargs / the error path.
let name_str = name.as_str().ok();
// Check if we have a parameter with this name:
if let Some(pos) = arg_pos(code.posonlyarg_count as usize..total_args, &name) {
if let Some(pos) =
name_str.and_then(|s| arg_pos(code.posonlyarg_count as usize..total_args, s))
{
let slot = &mut fastlocals[pos];
if slot.is_some() {
return Err(vm.new_type_error(format!(
Expand All @@ -350,7 +355,9 @@ impl PyFunction {
*slot = Some(value);
} else if let Some(kwargs) = kwargs.as_ref() {
kwargs.set_item(&name, value, vm)?;
} else if arg_pos(0..code.posonlyarg_count as usize, &name).is_some() {
} else if name_str
.is_some_and(|s| arg_pos(0..code.posonlyarg_count as usize, s).is_some())
{
posonly_passed_as_kwarg.push(name);
} else {
return Err(vm.new_type_error(format!(
Expand Down
3 changes: 3 additions & 0 deletions crates/vm/src/builtins/function/jit.rs
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Expand Up @@ -184,6 +184,9 @@ pub(crate) fn get_jit_args<'a>(
for (name, value) in &func_args.kwargs {
let arg_pos =
|args: &[&PyStrInterned], name: &str| args.iter().position(|arg| arg.as_str() == name);
// Parameter names are plain identifiers, so a non-UTF-8 (surrogate) key
// can never match one.
let name = name.as_str().map_err(|_| ArgsError::NotAKeywordArg)?;
if let Some(arg_idx) = arg_pos(arg_names.args, name) {
if jit_args.is_set(arg_idx) {
return Err(ArgsError::ArgPassedMultipleTimes);
Expand Down
6 changes: 4 additions & 2 deletions crates/vm/src/frame.rs
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Expand Up @@ -7112,11 +7112,13 @@ impl ExecutingFrame<'_> {
let func_str = Self::object_function_str(callable, vm);

Self::iterate_mapping_keys(vm, &kw_obj, &func_str, |key| {
// `PyStr`, not `PyUtf8Str`: CPython only checks that the key is a
// `str`, not that it is valid UTF-8, so surrogate keys are accepted.
let key_str = key
.downcast_ref::<PyUtf8Str>()
.downcast_ref::<PyStr>()
.ok_or_else(|| vm.new_type_error("keywords must be strings"))?;
let value = kw_obj.get_item(&*key, vm)?;
kwargs.insert(key_str.as_str().to_owned(), value);
kwargs.insert(key_str.as_wtf8().to_owned(), value);
Ok(())
})?
};
Expand Down
60 changes: 45 additions & 15 deletions crates/vm/src/function/argument.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
use crate::{
AsObject, PyObjectRef, PyPayload, PyRef, PyResult, TryFromObject, VirtualMachine,
builtins::{PyBaseExceptionRef, PyTupleRef, PyTypeRef},
common::wtf8::{Wtf8, Wtf8Buf},
convert::ToPyObject,
object::{Traverse, TraverseFn},
};
Expand Down Expand Up @@ -155,10 +156,12 @@ impl FuncArgs {
.iter()
.zip(&args[nargs..nargs + names.len()])
.map(|(name, val)| {
// `PyStr`, not `PyUtf8Str`: a surrogate key is a valid str and
// must survive as WTF-8 rather than panic.
let key = name
.downcast_ref::<crate::builtins::PyUtf8Str>()
.downcast_ref::<crate::builtins::PyStr>()
.expect("kwnames must be strings")
.as_str()
.as_wtf8()
.to_owned();
(key, val.clone())
})
Expand Down Expand Up @@ -187,9 +190,9 @@ impl FuncArgs {
.zip(args.drain(nargs..nargs + kw_count))
.map(|(name, val)| {
let key = name
.downcast_ref::<crate::builtins::PyUtf8Str>()
.downcast_ref::<crate::builtins::PyStr>()
.expect("kwnames must be strings")
.as_str()
.as_wtf8()
.to_owned();
(key, val)
})
Expand Down Expand Up @@ -268,7 +271,7 @@ impl FuncArgs {
self.kwargs.swap_remove(name)
}

pub fn remaining_keywords(&mut self) -> impl Iterator<Item = (String, PyObjectRef)> + '_ {
pub fn remaining_keywords(&mut self) -> impl Iterator<Item = (Wtf8Buf, PyObjectRef)> + '_ {
self.kwargs.drain(..)
}

Expand Down Expand Up @@ -406,8 +409,12 @@ impl<T: TryFromObject> FromArgOptional for T {
/// KwArgs is only for functions that accept arbitrary keyword arguments. For
/// functions that accept only *specific* named arguments, a rust struct with
/// an appropriate FromArgs implementation must be created.
// Keys are stored as `Wtf8Buf`, not `String`, so that a lone-surrogate keyword
// name coming through `f(**d)` is preserved instead of being rejected (see
// issue #8228). `PyStr` is WTF-8 backed, and CPython only requires that a
// keyword key be a `str`, not that it be valid UTF-8.
#[derive(Clone, Debug)]
pub struct KwArgs<T = PyObjectRef>(IndexMap<String, T>);
pub struct KwArgs<T = PyObjectRef>(IndexMap<Wtf8Buf, T>);

impl<T> Default for KwArgs<T> {
fn default() -> Self {
Expand All @@ -416,7 +423,7 @@ impl<T> Default for KwArgs<T> {
}

impl<T> Deref for KwArgs<T> {
type class="x x-first x-last">String, T>;
type class="x x-first x-last">Wtf8Buf, T>;

fn deref(&self) -> &Self::Target {
&self.0
Expand All @@ -440,33 +447,56 @@ where

impl<T> KwArgs<T> {
#[must_use]
pub const fn new(map: IndexMap<String, T>) -> Self {
pub const fn new(map: IndexMap<Wtf8Buf, T>) -> Self {
Self(map)
}

// `String` keys accepted `&str` lookups for free via `Borrow<str>`; `Wtf8Buf`
// borrows only as `Wtf8`, so these inherent methods restore the `&str` interface
// via the zero-cost `Wtf8::new` cast, keeping every call site unchanged.
#[must_use]
pub fn get(&self, name: &str) -> Option<&T> {
self.0.get(Wtf8::new(name))
}

#[must_use]
pub fn contains_key(&self, name: &str) -> bool {
self.0.contains_key(Wtf8::new(name))
}

pub fn swap_remove(&mut self, name: &str) -> Option<T> {
self.0.swap_remove(Wtf8::new(name))
}

pub fn shift_remove(&mut self, name: &str) -> Option<T> {
self.0.shift_remove(Wtf8::new(name))
}

pub fn pop_kwarg(&mut self, name: &str) -> Option<T> {
self.swap_remove(name)
}
}

impl<T> FromIterator<(String, T)> for KwArgs<T> {
fn from_iter<I: IntoIterator<Item = (String, T)>>(iter: I) -> Self {
Self(iter.into_iter().collect())
// Accept any key that converts into `Wtf8Buf` (notably `String`), so existing
// call sites that build kwargs from string literals keep compiling unchanged.
impl<K: Into<Wtf8Buf>, T> FromIterator<(K, T)> for KwArgs<T> {
fn from_iter<I: IntoIterator<Item = (K, T)>>(iter: I) -> Self {
Self(iter.into_iter().map(|(k, v)| (k.into(), v)).collect())
}
}

impl<'a, T> IntoIterator for &'a KwArgs<T> {
type Item = (&'a String, &'a T);
type IntoIter = indexmap::map::Iter<'a, String, T>;
type Item = (&'a Wtf8Buf, &'a T);
type IntoIter = indexmap::map::Iter<'a, Wtf8Buf, T>;

fn into_iter(self) -> Self::IntoIter {
self.0.iter()
}
}

impl<T> IntoIterator for KwArgs<T> {
type Item = (String, T);
type IntoIter = indexmap::map::IntoIter<String, T>;
type Item = (Wtf8Buf, T);
type IntoIter = indexmap::map::IntoIter<Wtf8Buf, T>;

fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
Expand Down
13 changes: 7 additions & 6 deletions crates/vm/src/stdlib/_ast/python.rs
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Expand Up @@ -8,8 +8,9 @@ use super::{
pub(crate) mod _ast {
use crate::{
AsObject, Context, Py, PyObject, PyObjectRef, PyPayload, PyRef, PyResult, VirtualMachine,
builtins::{PyDictRef, PySet, PyStr, PyTupleRef, PyType, PyTypeRef, PyUtf8Str},
builtins::{PyDictRef, PySet, PyStr, PyTupleRef, PyType, PyTypeRef},
class::{PyClassImpl, StaticType},
common::wtf8::Wtf8Buf,
function::{ArgIterable, FuncArgs, KwArgs, PyMethodDef, PyMethodFlags},
stdlib::_ast::repr,
types::{Constructor, Initializer},
Expand Down Expand Up @@ -229,7 +230,7 @@ pub(crate) mod _ast {
ast_replace_set_update(&expecting, attributes.as_ref(), vm)?;

for (key, _value) in &args.kwargs {
let key_obj: PyObjectRef = vm.ctx.new_str(key.as_str()).into();
let key_obj: PyObjectRef = vm.ctx.new_str(key.clone()).into();

@youknowone youknowone Jul 29, 2026

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there must be a way not to use clone here. could you check? I will find out one if there isn't any way to do it yet.

@HyoJongPark HyoJongPark Jul 30, 2026

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         for (key, _value) in &args.kwargs {
-            let key_obj: PyObjectRef = vm.ctx.new_str(key.clone()).into();
+            let key_obj: PyObjectRef = vm.ctx.new_str(key.as_ref()).into();

Replaced the clone with as_ref() to avoid an unnecessary copy.
new_str only needs a &Wtf8, so instead of cloning the key into an owned Wtf8Buf, I pass key.as_ref() to borrow it instead.

Does this match what you had in mind?

if !ast_replace_set_discard(&expecting, &key_obj, vm)? {
return Err(vm.new_type_error(format!(
"{}.__replace__ got an unexpected keyword argument '{}'.",
Expand Down Expand Up @@ -290,11 +291,11 @@ pub(crate) mod _ast {
.into_iter()
.map(|(key, value)| {
let key = key
.downcast::<PyUtf8Str>()
.downcast::<PyStr>()
.map_err(|_| vm.new_type_error("keywords must be strings"))?;
Ok((key.as_str().to_owned(), value))
Ok((key.as_wtf8().to_owned(), value))
})
.collect::<PyResult<IndexMap<String, PyObjectRef>>>()?;
.collect::<PyResult<IndexMap<Wtf8Buf, PyObjectRef>>>()?;
let result = type_obj.call(FuncArgs::new(vec![], KwArgs::new(kwargs)), vm)?;
Ok(result)
}
Expand Down Expand Up @@ -418,7 +419,7 @@ pub(crate) mod _ast {
ast_replace_set_discard(&remaining_fields, &name, vm)?;
}
for (key, value) in args.kwargs {
let key_obj: PyObjectRef = vm.ctx.new_str(key.as_str()).into();
let key_obj: PyObjectRef = vm.ctx.new_str(key.clone()).into();

@youknowone youknowone Jul 29, 2026

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another clone here

let contains = fields_seq.contains(&key_obj, vm)?;
if contains {
if !ast_replace_set_discard(&remaining_fields, &key_obj, vm)? {
Expand Down
9 changes: 5 additions & 4 deletions crates/vm/src/stdlib/_ctypes/structure.rs
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@@ -1,5 +1,6 @@
use super::base::{CDATA_BUFFER_METHODS, PyCData, PyCField, StgInfo, StgInfoFlags};
use crate::builtins::{PyList, PyStr, PyTuple, PyType, PyTypeRef, PyUtf8Str};
use crate::common::wtf8::Wtf8Buf;
use crate::convert::ToPyObject;
use crate::function::{FuncArgs, OptionalArg, PySetterValue};
use crate::protocol::{BufferDescriptor, PyBuffer, PyNumberMethods};
Expand Down Expand Up @@ -712,7 +713,7 @@ impl PyCStructure {
self_obj: &Py<Self>,
type_obj: &Py<PyType>,
args: &[PyObjectRef],
kwargs: &indexmap::IndexMap<String, PyObjectRef>,
kwargs: &indexmap::IndexMap<Wtf8Buf, PyObjectRef>,
index: usize,
vm: &VirtualMachine,
) -> PyResult<usize> {
Expand Down Expand Up @@ -746,7 +747,7 @@ impl PyCStructure {
&& let Some(name) = tuple.first()
&& let Some(name_str) = name.downcast_ref::<PyUtf8Str>()
{
let field_name = name_str.as_str().to_owned();
let field_name = name_str.as_wtf8().to_owned();
// Check for duplicate in kwargs
if kwargs.contains_key(&field_name) {
return Err(
Expand Down Expand Up @@ -784,9 +785,9 @@ impl Initializer for PyCStructure {
}

// 2. Process keyword arguments
for (key, value) in &args.kwargs {
for (key, value) in args.kwargs {
zelf.as_object()
.set_attr(vm.ctx.intern_str(key.as_str()), value.clone(), vm)?;
.set_attr(vm.ctx.intern_str(key), value, vm)?;
}

Ok(())
Expand Down
9 changes: 5 additions & 4 deletions crates/vm/src/stdlib/_ctypes/union.rs
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@@ -1,6 +1,7 @@
use super::base::{CDATA_BUFFER_METHODS, StgInfoFlags};
use super::{PyCData, PyCField, StgInfo};
use crate::builtins::{PyList, PyStr, PyTuple, PyType, PyTypeRef, PyUtf8Str};
use crate::common::wtf8::Wtf8Buf;
use crate::convert::ToPyObject;
use crate::function::{ArgBytesLike, FuncArgs, OptionalArg, PySetterValue};
use crate::protocol::{BufferDescriptor, PyBuffer};
Expand Down Expand Up @@ -581,7 +582,7 @@ impl PyCUnion {
self_obj: &Py<Self>,
type_obj: &Py<PyType>,
args: &[PyObjectRef],
kwargs: &indexmap::IndexMap<String, PyObjectRef>,
kwargs: &indexmap::IndexMap<Wtf8Buf, PyObjectRef>,
index: usize,
vm: &VirtualMachine,
) -> PyResult<usize> {
Expand Down Expand Up @@ -617,7 +618,7 @@ impl PyCUnion {
&& let Some(name) = tuple.first()
&& let Some(name_str) = name.downcast_ref::<PyUtf8Str>()
{
let field_name = name_str.as_str().to_owned();
let field_name = name_str.as_wtf8().to_owned();
// Check for duplicate in kwargs
if kwargs.contains_key(&field_name) {
return Err(
Expand Down Expand Up @@ -655,9 +656,9 @@ impl Initializer for PyCUnion {
}

// 2. Process keyword arguments
for (key, value) in &args.kwargs {
for (key, value) in args.kwargs {
zelf.as_object()
.set_attr(vm.ctx.intern_str(key.as_str()), value.clone(), vm)?;
.set_attr(vm.ctx.intern_str(key), value, vm)?;
}

Ok(())
Expand Down
5 changes: 3 additions & 2 deletions crates/vm/src/stdlib/_functools.rs
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Expand Up @@ -373,7 +373,7 @@ mod _functools {

// Add new keywords
for (key, value) in args.kwargs {
final_keywords.set_item(vm.ctx.intern_str(key.as_str()), value, vm)?;
final_keywords.set_item(vm.ctx.intern_str(key), value, vm)?;
}

Ok(Self {
Expand Down Expand Up @@ -436,10 +436,11 @@ mod _functools {

// Add keywords from self.keywords
for (key, value) in &*keywords {
// `expect_str()` would panic on surrogate keys; keep them as WTF-8.
let key_str = key
.downcast_ref::<crate::builtins::PyStr>()
.ok_or_else(|| vm.new_type_error("keywords must be strings"))?;
final_kwargs.insert(key_str.expect_str().to_owned(), value);
final_kwargs.insert(key_str.as_wtf8().to_owned(), value);
}

// Add keywords from args.kwargs (these override self.keywords)
Expand Down
2 changes: 1 addition & 1 deletion crates/vm/src/stdlib/_operator.rs
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Expand Up @@ -610,7 +610,7 @@ mod _operator {
}
for (key, value) in kwargs {
result.push_str(", ");
result.push_str(key);
result.push_wtf8(key);
result.push_char('=');
result.push_wtf8(value.repr(vm)?.as_wtf8());
}
Expand Down
4 changes: 2 additions & 2 deletions crates/vm/src/stdlib/_typing.rs
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Expand Up @@ -353,9 +353,9 @@ pub(crate) mod decl {
// typealias(name, value, *, type_params=())
// name and value are positional-or-keyword; type_params is keyword-only.

// Reject unexpected keyword arguments
// Reject unexpected keyword arguments.
for key in args.kwargs.keys() {
if key != "name" && key != "value" && key != "type_params" {
if !matches!(key.as_str(), Ok("name" | "value" | "type_params")) {
return Err(vm.new_type_error(format!(
"typealias() got an unexpected keyword argument '{key}'"
)));
Expand Down
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