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[ty] Enforce typing.Final (#19178)

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## Summary

Emit a diagnostic when a `Final`-qualified symbol is modified. This
first iteration only works for name targets. Tests with TODO comments
were added for attribute assignments as well.

related ticket: https://github.com/astral-sh/ty/issues/158

## Ecosystem impact

Correctly identified [modification of a `Final`
symbol](7b4164a5f2/sphinx/__init__.py (L44))
(behind a `# type: ignore`):
```diff
- warning[unused-ignore-comment] sphinx/__init__.py:44:56: Unused blanket `type: ignore` directive
```
And the same
[here](5471a37e82/src/trio/_core/_run.py (L128)):
```diff
- warning[unused-ignore-comment] src/trio/_core/_run.py:128:45: Unused blanket `type: ignore` directive
```

## Test Plan

New Markdown tests
This commit is contained in:
David Peter 2025-07-08 16:26:09 +02:00 • committed by GitHub
parent 6a42d28867
commit 149350bf39
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GPG key ID: B5690EEEBB952194
6 changed files with 252 additions and 40 deletions
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9
crates/ty_python_semantic/src/semantic_index/definition.rs
View file

@ -618,6 +618,15 @@ impl DefinitionKind<'_> {
}
}
pub(crate) fn is_import(&self) -> bool {
matches!(
self,
DefinitionKind::Import(_)
| DefinitionKind::ImportFrom(_)
| DefinitionKind::StarImport(_)
)
}
/// Returns the [`TextRange`] of the definition target.
///
/// A definition target would mainly be the node representing the place being defined i.e.,

26
crates/ty_python_semantic/src/semantic_index/use_def.rs
View file

@ -306,7 +306,10 @@ pub(crate) struct UseDefMap<'db> {
/// If the definition is both a declaration and a binding -- `x: int = 1` for example -- then
/// we don't actually need anything here, all we'll need to validate is that our own RHS is a
/// valid assignment to our own annotation.
bindings_by_declaration: FxHashMap<Definition<'db>, Bindings>,
///
/// If we see a binding to a `Final`-qualified symbol, we also need this map to find previous
/// bindings to that symbol. If there are any, the assignment is invalid.
bindings_by_definition: FxHashMap<Definition<'db>, Bindings>,
/// [`PlaceState`] visible at end of scope for each place.
end_of_scope_places: IndexVec<ScopedPlaceId, PlaceState>,
@ -448,12 +451,12 @@ impl<'db> UseDefMap<'db> {
}
}
pub(crate) fn bindings_at_declaration(
pub(crate) fn bindings_at_definition(
&self,
declaration: Definition<'db>,
definition: Definition<'db>,
) -> BindingWithConstraintsIterator<'_, 'db> {
self.bindings_iterator(
&self.bindings_by_declaration[&declaration],
&self.bindings_by_definition[&definition],
BoundnessAnalysis::BasedOnUnboundVisibility,
)
}
@ -744,8 +747,8 @@ pub(super) struct UseDefMapBuilder<'db> {
/// Live declarations for each so-far-recorded binding.
declarations_by_binding: FxHashMap<Definition<'db>, Declarations>,
/// Live bindings for each so-far-recorded declaration.
bindings_by_declaration: FxHashMap<Definition<'db>, Bindings>,
/// Live bindings for each so-far-recorded definition.
bindings_by_definition: FxHashMap<Definition<'db>, Bindings>,
/// Currently live bindings and declarations for each place.
place_states: IndexVec<ScopedPlaceId, PlaceState>,
@ -772,7 +775,7 @@ impl<'db> UseDefMapBuilder<'db> {
reachability: ScopedReachabilityConstraintId::ALWAYS_TRUE,
node_reachability: FxHashMap::default(),
declarations_by_binding: FxHashMap::default(),
bindings_by_declaration: FxHashMap::default(),
bindings_by_definition: FxHashMap::default(),
place_states: IndexVec::new(),
reachable_definitions: IndexVec::new(),
eager_snapshots: EagerSnapshots::default(),
@ -808,6 +811,9 @@ impl<'db> UseDefMapBuilder<'db> {
binding: Definition<'db>,
is_place_name: bool,
) {
self.bindings_by_definition
.insert(binding, self.place_states[place].bindings().clone());
let def_id = self.all_definitions.push(DefinitionState::Defined(binding));
let place_state = &mut self.place_states[place];
self.declarations_by_binding
@ -942,7 +948,7 @@ impl<'db> UseDefMapBuilder<'db> {
.all_definitions
.push(DefinitionState::Defined(declaration));
let place_state = &mut self.place_states[place];
self.bindings_by_declaration
self.bindings_by_definition
.insert(declaration, place_state.bindings().clone());
place_state.record_declaration(def_id, self.reachability);
@ -1119,7 +1125,7 @@ impl<'db> UseDefMapBuilder<'db> {
self.bindings_by_use.shrink_to_fit();
self.node_reachability.shrink_to_fit();
self.declarations_by_binding.shrink_to_fit();
self.bindings_by_declaration.shrink_to_fit();
self.bindings_by_definition.shrink_to_fit();
self.eager_snapshots.shrink_to_fit();
UseDefMap {
@ -1132,7 +1138,7 @@ impl<'db> UseDefMapBuilder<'db> {
end_of_scope_places: self.place_states,
reachable_definitions: self.reachable_definitions,
declarations_by_binding: self.declarations_by_binding,
bindings_by_declaration: self.bindings_by_declaration,
bindings_by_definition: self.bindings_by_definition,
eager_snapshots: self.eager_snapshots,
end_of_scope_reachability: self.reachability,
}

13
crates/ty_python_semantic/src/types.rs
View file

@ -2613,7 +2613,7 @@ impl<'db> Type<'db> {
/// See also: [`Type::member`]
fn static_member(&self, db: &'db dyn Db, name: &str) -> Place<'db> {
if let Type::ModuleLiteral(module) = self {
module.static_member(db, name)
module.static_member(db, name).place
} else if let place @ Place::Type(_, _) = self.class_member(db, name.into()).place {
place
} else if let Some(place @ Place::Type(_, _)) =
@ -3067,7 +3067,7 @@ impl<'db> Type<'db> {
Place::bound(Type::IntLiteral(i64::from(bool_value))).into()
}
Type::ModuleLiteral(module) => module.static_member(db, name_str).into(),
Type::ModuleLiteral(module) => module.static_member(db, name_str),
_ if policy.no_instance_fallback() => self.invoke_descriptor_protocol(
db,
@ -7511,15 +7511,14 @@ pub struct ModuleLiteralType<'db> {
impl get_size2::GetSize for ModuleLiteralType<'_> {}
impl<'db> ModuleLiteralType<'db> {
fn static_member(self, db: &'db dyn Db, name: &str) -> Place<'db> {
fn static_member(self, db: &'db dyn Db, name: &str) -> PlaceAndQualifiers<'db> {
// `__dict__` is a very special member that is never overridden by module globals;
// we should always look it up directly as an attribute on `types.ModuleType`,
// never in the global scope of the module.
if name == "__dict__" {
return KnownClass::ModuleType
.to_instance(db)
.member(db, "__dict__")
.place;
.member(db, "__dict__");
}
// If the file that originally imported the module has also imported a submodule
@ -7538,7 +7537,8 @@ impl<'db> ModuleLiteralType<'db> {
full_submodule_name.extend(&submodule_name);
if imported_submodules.contains(&full_submodule_name) {
if let Some(submodule) = resolve_module(db, &full_submodule_name) {
return Place::bound(Type::module_literal(db, importing_file, &submodule));
return Place::bound(Type::module_literal(db, importing_file, &submodule))
.into();
}
}
}
@ -7547,7 +7547,6 @@ impl<'db> ModuleLiteralType<'db> {
.file()
.map(|file| imported_symbol(db, file, name, None))
.unwrap_or_default()
.place
}
}

86
crates/ty_python_semantic/src/types/infer.rs
View file

@ -1567,21 +1567,21 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
let place_id = binding.place(self.db());
let place = place_table.place_expr(place_id);
let skip_non_global_scopes = self.skip_non_global_scopes(file_scope_id, place_id);
let declarations = if skip_non_global_scopes {
let (declarations, is_local) = if skip_non_global_scopes {
match self
.index
.place_table(FileScopeId::global())
.place_id_by_expr(&place.expr)
{
Some(id) => global_use_def_map.end_of_scope_declarations(id),
Some(id) => (global_use_def_map.end_of_scope_declarations(id), false),
// This case is a syntax error (load before global declaration) but ignore that here
None => use_def.declarations_at_binding(binding),
None => (use_def.declarations_at_binding(binding), true),
}
} else {
use_def.declarations_at_binding(binding)
(use_def.declarations_at_binding(binding), true)
};
let declared_ty = place_from_declarations(self.db(), declarations)
let (declared_ty, is_modifiable) = place_from_declarations(self.db(), declarations)
.and_then(|place_and_quals| {
Ok(
if matches!(place_and_quals.place, Place::Type(_, Boundness::Bound)) {
@ -1600,8 +1600,10 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
.map(
|PlaceAndQualifiers {
place: resolved_place,
..
qualifiers,
}| {
let is_modifiable = !qualifiers.contains(TypeQualifiers::FINAL);
if resolved_place.is_unbound() && !place_table.place_expr(place_id).is_name() {
if let AnyNodeRef::ExprAttribute(ast::ExprAttribute {
value, attr, ..
@ -1611,7 +1613,8 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
if let Place::Type(ty, Boundness::Bound) =
value_type.member(db, attr).place
{
return ty;
// TODO: also consider qualifiers on the attribute
return (ty, is_modifiable);
}
} else if let AnyNodeRef::ExprSubscript(ast::ExprSubscript {
value,
@ -1623,12 +1626,15 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
let slice_ty = self.infer_expression(slice);
let result_ty =
self.infer_subscript_expression_types(value, value_ty, slice_ty);
return result_ty;
return (result_ty, is_modifiable);
}
}
resolved_place
.ignore_possibly_unbound()
.unwrap_or(Type::unknown())
(
resolved_place
.ignore_possibly_unbound()
.unwrap_or(Type::unknown()),
is_modifiable,
)
},
)
.unwrap_or_else(|(ty, conflicting)| {
@ -1640,8 +1646,46 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
format_enumeration(conflicting.iter().map(|ty| ty.display(db)))
));
}
ty.inner_type()
(
ty.inner_type(),
!ty.qualifiers.contains(TypeQualifiers::FINAL),
)
});
if !is_modifiable {
let mut previous_bindings = use_def.bindings_at_definition(binding);
// An assignment to a local `Final`-qualified symbol is only an error if there are prior bindings
let previous_definition = previous_bindings
.next()
.and_then(|r| r.binding.definition());
if !is_local || previous_definition.is_some() {
let place = place_table.place_expr(binding.place(db));
if let Some(builder) = self.context.report_lint(&INVALID_ASSIGNMENT, node) {
let mut diagnostic = builder.into_diagnostic(format_args!(
"Reassignment of `Final` symbol `{place}` is not allowed"
));
diagnostic.set_primary_message("Reassignment of `Final` symbol");
if let Some(previous_definition) = previous_definition {
// It is not very helpful to show the previous definition if it results from
// an import. Ideally, we would show the original definition in the external
// module, but that information is currently not threaded through attribute
// lookup.
if !previous_definition.kind(db).is_import() {
let range = previous_definition.full_range(self.db(), self.module());
diagnostic.annotate(
self.context.secondary(range).message("Original definition"),
);
}
}
}
}
}
if !bound_ty.is_assignable_to(db, declared_ty) {
report_invalid_assignment(&self.context, node, declared_ty, bound_ty);
// allow declarations to override inference in case of invalid assignment
@ -1721,7 +1765,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
.is_declaration()
);
let use_def = self.index.use_def_map(declaration.file_scope(self.db()));
let prior_bindings = use_def.bindings_at_declaration(declaration);
let prior_bindings = use_def.bindings_at_definition(declaration);
// unbound_ty is Never because for this check we don't care about unbound
let inferred_ty = place_from_bindings(self.db(), prior_bindings)
.with_qualifiers(TypeQualifiers::empty())
@ -3680,7 +3724,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
}
Type::ModuleLiteral(module) => {
if let Place::Type(attr_ty, _) = module.static_member(db, attribute) {
if let Place::Type(attr_ty, _) = module.static_member(db, attribute).place {
let assignable = value_ty.is_assignable_to(db, attr_ty);
if assignable {
true
@ -4427,7 +4471,11 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
// First try loading the requested attribute from the module.
if !import_is_self_referential {
if let Place::Type(ty, boundness) = module_ty.member(self.db(), name).place {
if let PlaceAndQualifiers {
place: Place::Type(ty, boundness),
qualifiers,
} = module_ty.member(self.db(), name)
{
if &alias.name != "*" && boundness == Boundness::PossiblyUnbound {
// TODO: Consider loading _both_ the attribute and any submodule and unioning them
// together if the attribute exists but is possibly-unbound.
@ -4443,7 +4491,13 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
self.add_declaration_with_binding(
alias.into(),
definition,
&DeclaredAndInferredType::AreTheSame(ty),
&DeclaredAndInferredType::MightBeDifferent {
declared_ty: TypeAndQualifiers {
inner: ty,
qualifiers,
},
inferred_ty: ty,
},
);
return;
}