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avoid quadratic behavior in `find_type_var_from`

This commit is contained in:
Ibraheem Ahmed 2025-12-02 16:24:06 -05:00
parent 623210232e
commit be78ea3851
1 changed files with 23 additions and 6 deletions
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29
crates/ty_python_semantic/src/types.rs
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@ -2,6 +2,7 @@ use compact_str::{CompactString, ToCompactString};
use infer::nearest_enclosing_class;
use itertools::{Either, Itertools};
use ruff_diagnostics::{Edit, Fix};
use rustc_hash::FxHashSet;
use std::borrow::Cow;
use std::time::Duration;
@ -1048,6 +1049,16 @@ impl<'db> Type<'db> {
db: &'db dyn Db,
bound_typevar: BoundTypeVarInstance<'db>,
class: ClassLiteral<'db>,
) -> Option<Type<'db>> {
self.find_type_var_from_impl(db, bound_typevar, class, &mut FxHashSet::default())
}
pub(crate) fn find_type_var_from_impl(
self,
db: &'db dyn Db,
bound_typevar: BoundTypeVarInstance<'db>,
class: ClassLiteral<'db>,
visited: &mut FxHashSet<(ClassLiteral<'db>, BoundTypeVarIdentity<'db>)>,
) -> Option<Type<'db>> {
if let Some(specialization) = self.specialization_of(db, class) {
return specialization.get(db, bound_typevar);
@ -1057,19 +1068,25 @@ impl<'db> Type<'db> {
// complex subtyping relationships, e.g., `type[C[T]]` to `Callable[..., T]`, or unions
// containing multiple generic elements.
for base in class.iter_mro(db, None) {
let Some(ClassType::Generic(class)) = base.into_class() else {
let Some((origin, Some(specialization))) =
base.into_class().map(|class| class.class_literal(db))
else {
continue;
};
for (base_typevar, base_ty) in class
.specialization(db)
for (base_typevar, base_ty) in specialization
.generic_context(db)
.variables(db)
.zip(class.specialization(db).types(db))
.zip(specialization.types(db))
{
if *base_ty == Type::TypeVar(bound_typevar) {
// TODO: This is potentially quadratic.
if let Some(ty) = self.find_type_var_from(db, base_typevar, class.origin(db)) {
if !visited.insert((origin, base_typevar.identity(db))) {
return None;
}
if let Some(ty) =
self.find_type_var_from_impl(db, base_typevar, origin, visited)
{
return Some(ty);
}
}