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Fix false positive on attribute access for TypeVar bounded by type #2672

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yangdanny97 wants to merge 1 commit into from
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Fix false positive on attribute access for TypeVar bounded by type #2672

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19 changes: 15 additions & 4 deletions pyrefly/lib/alt/attr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1870,6 +1870,17 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
}
}

/// Extract the ClassType to use for attribute lookup on a quantified (TypeVar)
/// type from the attribute base of its bound.
fn quantified_bound_class(&self, base: AttributeBase1) -> Option<ClassType> {
match base {
AttributeBase1::ClassInstance(cls) => Some(cls),
// Handle `type[Any]`, which happens for TypeVars w/ `bound=type`
AttributeBase1::TypeAny(_) => Some(self.stdlib.builtins_type().clone()),
_ => None,
}
}

fn as_attribute_base(&self, ty: Type) -> Option<AttributeBase> {
let mut acc = Vec::new();
self.as_attribute_base1(ty, &mut acc);
Expand Down Expand Up @@ -1979,7 +1990,7 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
let mut use_fallback = false;
if let Some(base) = self.as_attribute_base(ty.clone()) {
for base1 in base.0 {
if let AttributeBase1::ClassInstance(cls) = base1 {
if let Some(cls) = self.quantified_bound_class(base1) {
acc.push(AttributeBase1::ClassObject(ClassBase::Quantified(
(*quantified).clone(),
cls,
Expand All @@ -2001,7 +2012,7 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
for ty in constraints {
if let Some(base) = self.as_attribute_base(ty.clone()) {
for base1 in base.0 {
if let AttributeBase1::ClassInstance(cls) = base1 {
if let Some(cls) = self.quantified_bound_class(base1) {
acc.push(AttributeBase1::ClassObject(ClassBase::Quantified(
(*quantified).clone(),
cls,
Expand Down Expand Up @@ -2185,7 +2196,7 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
let mut use_fallback = false;
if let Some(base) = self.as_attribute_base(ty.clone()) {
for base1 in base.0 {
if let AttributeBase1::ClassInstance(cls) = base1 {
if let Some(cls) = self.quantified_bound_class(base1) {
acc.push(AttributeBase1::Quantified((*quantified).clone(), cls));
} else {
use_fallback = true;
Expand All @@ -2204,7 +2215,7 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
for ty in constraints {
if let Some(base) = self.as_attribute_base(ty.clone()) {
for base1 in base.0 {
if let AttributeBase1::ClassInstance(cls) = base1 {
if let Some(cls) = self.quantified_bound_class(base1) {
acc.push(AttributeBase1::Quantified(
(*quantified).clone(),
cls,
Expand Down
11 changes: 11 additions & 0 deletions pyrefly/lib/test/generic_restrictions.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -247,6 +247,17 @@ def func(c: T) -> C:
"#,
);

testcase!(
test_bounded_typevar_type_attribute_access,
r#"
from typing import TypeVar, assert_type
T = TypeVar('T', bound=type)
def get_class_name(cls: T) -> str:
assert_type(cls.__name__, str)
return cls.__name__
"#,
);

testcase!(
test_instantiate_default_typevar,
r#"
Expand Down