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charliermarsh · 2026-05-19T23:45:55Z

Summary

Prior to this change, field synthesis could accidentally follow symbol-table order instead of class-body declaration order in pathological cases like:

from dataclasses import InitVar, dataclass
from ty_extensions import Top

@dataclass
class C:
    a: Top[int]
    int: InitVar[int] = 0

Here, int can be interned before its own declaration because it already appears in Top[int].

This PR carries a stable declaration ordinal through declaration lookup and uses it when building own_fields().

Closes astral-sh/ty#3493.

AlexWaygood

Nice!

AlexWaygood · 2026-05-20T09:31:29Z

+            field_declarations.push((first_declaration_order, symbol_id, result));
+        }
+
+        field_declarations.sort_by_key(|(first_declaration_order, _, _)| *first_declaration_order);


I'm not totally sure if this would be more or less efficient, but you could do this without an additional sort by collecting field_declarations as a BTreeMap instead of a Vec:

diff --git a/crates/ty_python_semantic/src/types/class/static_literal.rs b/crates/ty_python_semantic/src/types/class/static_literal.rs index 2d330f93d3..01e8d69268 100644 --- a/crates/ty_python_semantic/src/types/class/static_literal.rs +++ b/crates/ty_python_semantic/src/types/class/static_literal.rs @@ -7,7 +7,7 @@ use ruff_db::{ use ruff_python_ast as ast; use ruff_python_ast::{PythonVersion, name::Name}; use ruff_text_size::{Ranged, TextRange}; -use std::cell::RefCell; +use std::{cell::RefCell, collections::BTreeMap}; use crate::{ Db, FxIndexMap, FxIndexSet, Program, TypeQualifiers, @@ -1873,7 +1873,7 @@ impl<'db> StaticClassLiteral<'db> { let dataclass_kw_only_default = matches!(field_policy, CodeGeneratorKind::DataclassLike(_)) .then(|| self.has_dataclass_param(db, field_policy, DataclassFlags::KW_ONLY)); let mut kw_only_sentinel_field_seen = false; - let mut field_declarations = Vec::new(); + let mut field_declarations = BTreeMap::default(); for (symbol_id, declarations) in use_def.all_end_of_scope_symbol_declarations() { // Here, we exclude all declarations that are not annotated assignments. We need this because @@ -1911,13 +1911,11 @@ impl<'db> StaticClassLiteral<'db> { }; let result = place_from_declarations(db, declarations.clone()); - field_declarations.push((first_declaration_order, symbol_id, result)); + field_declarations.insert(first_declaration_order, (symbol_id, result)); } - field_declarations.sort_by_key(|(first_declaration_order, _, _)| *first_declaration_order); - let mut attributes = FxIndexMap::default(); - for (_, symbol_id, result) in field_declarations { + for (symbol_id, result) in field_declarations.into_values() { let symbol = table.symbol(symbol_id); let first_declaration = result.first_declaration; let attr = result.ignore_conflicting_declarations();

(I kept it as-is for now.)

AlexWaygood · 2026-05-20T09:35:32Z

             }| {
                DeclarationWithConstraint {
                    declaration: self.all_definitions[*declaration],
+                    declaration_order: declaration.as_u32(),


ScopedDefinitionId is a pub newtype wrapper around a u32 that also defines PartialOrd and Ord -- I'm not sure there's any reason to convert it to a u32 here? That just seems to lose type safety for no real benefit. I think the declaration_order field on DeclarationWithConstraint should just be a ScopedDefinitionId.

It's because it needs to be pub -- it's actually only pub(crate):

pub(crate) use place_state::ScopedDefinitionId;

But, agree and I think it's fine to expose it.

we might want to add something to AGENTS.md about how it's generally fine to just make things pub whenever you need to in this repo. Codex seems to go out of its way to avoid doing that, which is generally good practice in a Rust library but not really necessary here where everything is an implementation detail

Yeah good call.

AlexWaygood · 2026-05-20T09:36:50Z

        )
    }
+
+    fn first_reachable_declaration_order(


Suggested change

fn first_reachable_declaration_order(

/// Return the first reachable declaration that matches the passed in predicate function.

fn first_reachable_declaration_order(

AlexWaygood · 2026-05-20T09:38:12Z

+        let predicates = self.predicates();
+        let reachability_constraints = self.reachability_constraints();
+
+        self.find_map(
+            |DeclarationWithConstraint {
+                 declaration,
+                 declaration_order,
+                 reachability_constraint,
+             }| {
+                (predicate(declaration)
+                    && !reachability_constraints
+                        .evaluate(db, predicates, reachability_constraint)


nit: the term "predicates" is quite overloaded in this function, because there's a parameter named "predicate" and also let predicates = self.predicates(), and they mean two quite different things in the same function 😄

Suggested change

let predicates = self.predicates();

let reachability_constraints = self.reachability_constraints();

self.find_map(

|DeclarationWithConstraint {

declaration,

declaration_order,

reachability_constraint,

}| {

(predicate(declaration)

&& !reachability_constraints

.evaluate(db, predicates, reachability_constraint)

let reachability_predicates = self.predicates();

let reachability_constraints = self.reachability_constraints();

self.find_map(

|DeclarationWithConstraint {

declaration,

declaration_order,

reachability_constraint,

}| {

(predicate(declaration)

&& !reachability_constraints

.evaluate(db, reachability_predicates, reachability_constraint)

astral-sh-bot · 2026-05-20T09:54:34Z

Typing conformance results

No changes detected ✅

Current numbers

The percentage of diagnostics emitted that were expected errors held steady at 89.36%. The percentage of expected errors that received a diagnostic held steady at 85.49%. The number of fully passing files held steady at 88/134.

astral-sh-bot · 2026-05-20T09:55:09Z

Memory usage report

Memory usage unchanged ✅

astral-sh-bot · 2026-05-20T09:56:51Z

`ecosystem-analyzer` results

No diagnostic changes detected ✅

Full report with detailed diff (timing results)

## Summary See: #25249 (comment).

…l-sh#25249) ## Summary Prior to this change, field synthesis could accidentally follow symbol-table order instead of class-body declaration order in pathological cases like: ```python from dataclasses import InitVar, dataclass from ty_extensions import Top @DataClass class C: a: Top[int] int: InitVar[int] = 0 ``` Here, `int` can be interned before its own declaration because it already appears in `Top[int]`. This PR carries a stable declaration ordinal through declaration lookup and uses it when building `own_fields()`. Closes astral-sh/ty#3493.

## Summary See: astral-sh#25249 (comment).

…l-sh#25249) ## Summary Prior to this change, field synthesis could accidentally follow symbol-table order instead of class-body declaration order in pathological cases like: ```python from dataclasses import InitVar, dataclass from ty_extensions import Top @DataClass class C: a: Top[int] int: InitVar[int] = 0 ``` Here, `int` can be interned before its own declaration because it already appears in `Top[int]`. This PR carries a stable declaration ordinal through declaration lookup and uses it when building `own_fields()`. Closes astral-sh/ty#3493.

## Summary See: astral-sh#25249 (comment).

## Summary I fixed astral-sh/ty#3493 in #25249, but missed the case of deferred evaluation for annotations... For deferred evaluation, when we then checked whether that field was a descriptor, `class_member_with_policy` attempted meta-type lookup on the cycle marker itself and panicked. E.g., on Python 3.14, where annotations are deferred by default: ```python from dataclasses import InitVar, dataclass from ty_extensions import Top @DataClass class C: a: Top[int] int: InitVar[int] = 0 C() ``` We now apply the materialized divergent fallback before class-member lookup, consistent with the other lookup and descriptor operations. (The example reports the expected missing argument for `a` instead of panicking, and is covered under Python 3.14.) Closes astral-sh/ty#3493.

charliermarsh added bug Something isn't working ty Multi-file analysis & type inference labels May 19, 2026

charliermarsh force-pushed the charlie/declaration-order branch 2 times, most recently from bba1d8c to 33a711c Compare May 20, 2026 00:03

charliermarsh marked this pull request as ready for review May 20, 2026 09:08

charliermarsh requested review from AlexWaygood, carljm, dcreager, ibraheemdev and sharkdp as code owners May 20, 2026 09:08

astral-sh-bot Bot assigned oconnor663 May 20, 2026

astral-sh-bot Bot requested a review from oconnor663 May 20, 2026 09:08

AlexWaygood approved these changes May 20, 2026

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charliermarsh added 2 commits May 20, 2026 10:42

[ty] Preserve declaration order when synthesizing class fields

8c0f842

Review feedback

020bc64

charliermarsh force-pushed the charlie/declaration-order branch from 33a711c to 020bc64 Compare May 20, 2026 09:52

charliermarsh enabled auto-merge (squash) May 20, 2026 09:55

charliermarsh merged commit f242f37 into main May 20, 2026
58 checks passed

charliermarsh deleted the charlie/declaration-order branch May 20, 2026 09:57

charliermarsh mentioned this pull request May 20, 2026

Add visibility guidance to AGENTS.md #25275

Merged

charliermarsh added a commit that referenced this pull request May 20, 2026

Add visibility guidance to AGENTS.md (#25275)

8228322

## Summary See: #25249 (comment).

thejchap pushed a commit to thejchap/ruff that referenced this pull request May 23, 2026

Add visibility guidance to AGENTS.md (astral-sh#25275)

ca13471

## Summary See: astral-sh#25249 (comment).

anishgirianish pushed a commit to anishgirianish/ruff that referenced this pull request May 28, 2026

Add visibility guidance to AGENTS.md (astral-sh#25275)

430626d

## Summary See: astral-sh#25249 (comment).

charliermarsh mentioned this pull request May 29, 2026

[ty] Avoid panic for deferred dataclass field annotations #25444

Merged

	fn first_reachable_declaration_order(
	/// Return the first reachable declaration that matches the passed in predicate function.
	fn first_reachable_declaration_order(

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charliermarsh commented May 19, 2026

Summary

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astral-sh-bot Bot commented May 20, 2026

No changes detected ✅

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astral-sh-bot Bot commented May 20, 2026

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