Infer native keyword dispatch from argument metadata

Replace no_keywords annotations with registration-time inference from FromArgs::PARAMS, including nested parameter metadata. Forward arguments with keyword-capable parameters to the binder, preserving min/max body validation and descriptor self checks. Add regressions for raw arguments, keyword argument structs, and list.sort. Tested: C-API tests, workspace and C-API Clippy, VM without doc, both keyword regression snippets, and test_call/test_extcall/test_builtin/test_list. Workspace tests reported eight _opcode snapshot failures. The full snippet suite reported 477 passes and seven failures: six CPython-side failures and one RustPython failure due to the missing optional SQLite module. Assisted-by: Codex:GPT-6
youknowone · Oct 9, 2026 · Oct 4, 2026 · Oct 4, 2026 · Oct 6, 2026 · Oct 8, 2026
commit 4575883f447fbfdb6314227d6fc96a2136391b59
diff --git a/crates/derive-impl/src/pyclass.rs b/crates/derive-impl/src/pyclass.rs
@@ -2,7 +2,7 @@ use super::Diagnostic;
 use crate::util::{
     ALL_ALLOWED_NAMES, ClassItemMeta, ContentItem, ContentItemInner, ErrorVec, ExceptionItemMeta,
     ItemMeta, ItemMetaInner, ItemNursery, SimpleItemMeta, internal_doc_tokens,
-    pyclass_ident_and_attrs, pyexception_ident_and_attrs,
+    keyword_dispatch_tokens, pyclass_ident_and_attrs, pyexception_ident_and_attrs,
 };
 use core::str::FromStr;
 use proc_macro2::{Delimiter, Group, Span, TokenStream, TokenTree};
@@ -1290,7 +1290,6 @@ where
         }
 
         let raw = item_meta.raw()?;
-        let no_keywords = item_meta.inner()._bool("no_keywords")?;
         let has_receiver = func
             .sig()
             .inputs
@@ -1308,6 +1307,12 @@ where
                 _ => None,
             }
         };
+        let keyword_dispatch = keyword_dispatch_tokens(
+            func.sig(),
+            implicit_self,
+            args.context.self_ty_subst.as_ref(),
+        );
+
         // Add #[allow(non_snake_case)] for setter methods like set___name__
         let method_name = ident.to_string();
         if method_name.starts_with("set_") && method_name.contains("__") {
@@ -1337,7 +1342,7 @@ where
             doc,
             doc_body_pending,
             raw,
-            no_keywords,
+            keyword_dispatch,
             coexist,
             attr_name: self.inner.attr_name,
         });
@@ -1532,7 +1537,7 @@ struct MethodNurseryItem {
     cfgs: Vec<Attribute>,
     ident: Ident,
     raw: bool,
-    no_keywords: bool,
+    keyword_dispatch: TokenStream,
     coexist: bool,
     doc: TokenStream,
     doc_body_pending: TokenStream,
@@ -1564,11 +1569,7 @@ impl ToTokens for MethodNursery {
             let cfgs = &item.cfgs;
             let doc = &item.doc;
             let doc_body_pending = &item.doc_body_pending;
-            let keyword_dispatch = if item.no_keywords {
-                quote!(rustpython_vm::function::KeywordDispatch::RejectNonempty)
-            } else {
-                quote!(rustpython_vm::function::KeywordDispatch::PassToBinder)
-            };
+            let keyword_dispatch = &item.keyword_dispatch;
             let binding_flags = match &item.attr_name {
                 AttrName::Method => {
                     quote! { rustpython_vm::function::PyMethodFlags::METHOD }
@@ -1739,7 +1740,7 @@ impl ToTokens for GetSetNursery {
 struct MethodItemMeta(ItemMetaInner);
 
 impl ItemMeta for MethodItemMeta {
-    const ALLOWED_NAMES: &'static [&'static str] = &["name", "raw", "coexist", "no_keywords"];
+    const ALLOWED_NAMES: &'static [&'static str] = &["name", "raw", "coexist"];
 
     fn from_inner(inner: ItemMetaInner) -> Self {
         Self(inner)

diff --git a/crates/derive-impl/src/pymodule.rs b/crates/derive-impl/src/pymodule.rs
@@ -3,7 +3,7 @@ use crate::pystructseq::PyStructSequenceMeta;
 use crate::util::{
     ALL_ALLOWED_NAMES, AttrItemMeta, AttributeExt, ClassItemMeta, ContentItem, ContentItemInner,
     ErrorVec, ItemMeta, ItemMetaInner, ItemNursery, ModuleItemMeta, SimpleItemMeta,
-    internal_doc_tokens, iter_use_idents, pyclass_ident_and_attrs,
+    internal_doc_tokens, iter_use_idents, keyword_dispatch_tokens, pyclass_ident_and_attrs,
 };
 use core::str::FromStr;
 use proc_macro2::{Delimiter, Group, TokenStream, TokenTree};
@@ -536,7 +536,7 @@ struct FunctionNurseryItem {
     ident: Ident,
     /// One internal doc per [`py_names`](Self::py_names) entry.
     docs: Vec<TokenStream>,
-    no_keywords: bool,
+    keyword_dispatch: TokenStream,
 }
 
 impl FunctionNursery {
@@ -566,11 +566,7 @@ impl ToTokens for ValidatedFunctionNursery {
             let ident = &item.ident;
             let cfgs = &item.cfgs;
             let cfgs = quote!(#(#cfgs)*);
-            let keyword_dispatch = if item.no_keywords {
-                quote!(rustpython_vm::function::KeywordDispatch::RejectNonempty)
-            } else {
-                quote!(rustpython_vm::function::KeywordDispatch::PassToBinder)
-            };
+            let keyword_dispatch = &item.keyword_dispatch;
             for (py_name, doc) in item.py_names.iter().zip(&item.docs) {
                 inner_tokens.extend(quote![
                     #cfgs
@@ -677,7 +673,6 @@ impl ModuleItem for FunctionItem {
 
         let item_attr = args.attrs.remove(self.index());
         let item_meta = FunctionItemMeta::from_attr(ident.clone(), &item_attr)?;
-        let no_keywords = item_meta.inner()._bool("no_keywords")?;
 
         let py_name = item_meta.simple_name()?;
         let mut py_names = vec![py_name];
@@ -716,13 +711,14 @@ impl ModuleItem for FunctionItem {
                 internal_doc_tokens(func.sig(), py_name, None, doc, None, Some("$module"))
             })
             .collect();
+        let keyword_dispatch = keyword_dispatch_tokens(func.sig(), None, None);
 
         args.context.function_items.add_item(FunctionNurseryItem {
             ident: ident.to_owned(),
             py_names,
             cfgs: args.cfgs.to_vec(),
             docs,
-            no_keywords,
+            keyword_dispatch,
         });
         Ok(())
     }
@@ -1094,7 +1090,7 @@ impl ModuleItem for AttributeItem {
 struct FunctionItemMeta(ItemMetaInner);
 
 impl ItemMeta for FunctionItemMeta {
-    const ALLOWED_NAMES: &'static [&'static str] = &["name", "no_keywords"];
+    const ALLOWED_NAMES: &'static [&'static str] = &["name"];
 
     fn from_inner(inner: ItemMetaInner) -> Self {
         Self(inner)

diff --git a/crates/derive-impl/src/util.rs b/crates/derive-impl/src/util.rs
@@ -936,3 +936,19 @@ pub(crate) fn internal_doc_tokens(
         }
     }
 }
+
+pub(crate) fn keyword_dispatch_tokens(
+    sig: &Signature,
+    implicit_self: Option<&str>,
+    self_ty: Option<&Type>,
+) -> TokenStream {
+    let args = args_const(&sig_pieces(sig, implicit_self, self_ty, None));
+    quote! {
+        {
+            #args
+            const POLICY: ::rustpython_vm::function::KeywordDispatch =
+                ::rustpython_vm::function::keyword_dispatch(ARGS);
+            POLICY
+        }
+    }
+}
diff --git a/crates/vm/src/builtins/list.rs b/crates/vm/src/builtins/list.rs
@@ -420,7 +420,7 @@ impl PyList {
     flags(BASETYPE, SEQUENCE, _MATCH_SELF)
 )]
 impl Py<PyList> {
-    #[pymethod(no_keywords)]
+    #[pymethod]
     pub(crate) fn append(&self, object: PyObjectRef) {
         self.payload.append(object)
     }
@@ -497,7 +497,7 @@ impl Py<PyList> {
         elements.insert(index, object);
     }
 
-    #[pymethod(no_keywords)]
+    #[pymethod]
     fn clear(&self) {
         let removed = core::mem::take(self.borrow_vec_mut().deref_mut());
         removed.into_iter().rev().for_each(drop);

diff --git a/crates/vm/src/function/mod.rs b/crates/vm/src/function/mod.rs
@@ -40,7 +40,8 @@ pub use number::{
 pub use protocol::{ArgCallable, ArgIterable, ArgMapping, ArgSequence};
 pub use signature::{
     DefaultRepr, Param, ParamKind, SigArg, choose_class_params, has_signature, internal_doc_bytes,
-    internal_doc_len, real_signature, signature_prefix_bytes, signature_prefix_len,
+    internal_doc_len, keyword_dispatch, real_signature, signature_prefix_bytes,
+    signature_prefix_len,
 };
 pub use time::TimeoutSeconds;
 

diff --git a/crates/vm/src/function/signature.rs b/crates/vm/src/function/signature.rs
@@ -210,6 +210,38 @@ const fn count_param(
     }
 }
 
+/// Determine keyword dispatch from each argument's binding metadata.
+///
+/// Inspect arguments separately: a tuple's `PARAMS` can erase leaf metadata.
+#[must_use]
+pub const fn keyword_dispatch(args: &[SigArg]) -> super::KeywordDispatch {
+    let mut i = 0;
+    while i < args.len() {
+        if let Some(params) = args[i].params
+            && params_accept_keywords(params)
+        {
+            return super::KeywordDispatch::PassToBinder;
+        }
+        i += 1;
+    }
+    super::KeywordDispatch::RejectNonempty
+}
+
+const fn params_accept_keywords(params: &[Param]) -> bool {
+    let mut i = 0;
+    while i < params.len() {
+        match params[i].kind {
+            ParamKind::PositionalOrKeyword | ParamKind::KeywordOnly | ParamKind::VarKeyword => {
+                return true;
+            }
+            ParamKind::Flatten(Some(inner)) if params_accept_keywords(inner) => return true,
+            _ => {}
+        }
+        i += 1;
+    }
+    false
+}
+
 const fn name_eq(name: &str, bytes: &[u8]) -> bool {
     let got = name.as_bytes();
     if got.len() != bytes.len() {