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fix Subscripting on classes should attempt to invoke dunder methods #259 #2282

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fix Subscripting on classes should attempt to invoke dunder methods #259 #2282

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724332e
fix
asukaminato0721 Feb 1, 2026
68f30ee
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asukaminato0721 Feb 1, 2026
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8 changes: 4 additions & 4 deletions conformance/third_party/conformance.exp
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Original file line number Diff line number Diff line change
Expand Up @@ -9910,7 +9910,7 @@
"code": -2,
"column": 1,
"concise_description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA1, type[type[Any]]] (trying to access unknown)",
"description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA1, type[type[Any]]] (trying to access unknown)\n Sorry, Pyrefly encountered an internal error, this is always a bug in Pyrefly itself\n Please report the bug at https://fb.workplace.com/groups/pyreqa",
"description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA1, type[type[Any]]] (trying to access unknown)\n Sorry, Pyrefly encountered an internal error, this is always a bug in Pyrefly itself\n Please report the bug at https://github.com/facebook/pyrefly/issues/new",
"line": 143,
"name": "internal-error",
"severity": "error",
Expand All @@ -9921,7 +9921,7 @@
"code": -2,
"column": 1,
"concise_description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA2, type[type[Any]]] (trying to access unknown)",
"description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA2, type[type[Any]]] (trying to access unknown)\n Sorry, Pyrefly encountered an internal error, this is always a bug in Pyrefly itself\n Please report the bug at https://fb.workplace.com/groups/pyreqa",
"description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA2, type[type[Any]]] (trying to access unknown)\n Sorry, Pyrefly encountered an internal error, this is always a bug in Pyrefly itself\n Please report the bug at https://github.com/facebook/pyrefly/issues/new",
"line": 144,
"name": "internal-error",
"severity": "error",
Expand All @@ -9932,7 +9932,7 @@
"code": -2,
"column": 1,
"concise_description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA3, type[type[Any]]] (trying to access unknown)",
"description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA3, type[type[Any]]] (trying to access unknown)\n Sorry, Pyrefly encountered an internal error, this is always a bug in Pyrefly itself\n Please report the bug at https://fb.workplace.com/groups/pyreqa",
"description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA3, type[type[Any]]] (trying to access unknown)\n Sorry, Pyrefly encountered an internal error, this is always a bug in Pyrefly itself\n Please report the bug at https://github.com/facebook/pyrefly/issues/new",
"line": 145,
"name": "internal-error",
"severity": "error",
Expand All @@ -9943,7 +9943,7 @@
"code": -2,
"column": 1,
"concise_description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA4, type[type[Any]]] (trying to access unknown)",
"description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA4, type[type[Any]]] (trying to access unknown)\n Sorry, Pyrefly encountered an internal error, this is always a bug in Pyrefly itself\n Please report the bug at https://fb.workplace.com/groups/pyreqa",
"description": "TODO: Expr::attr_infer_for_type attribute base undefined for type: TypeAlias[TA4, type[type[Any]]] (trying to access unknown)\n Sorry, Pyrefly encountered an internal error, this is always a bug in Pyrefly itself\n Please report the bug at https://github.com/facebook/pyrefly/issues/new",
"line": 146,
"name": "internal-error",
"severity": "error",
Expand Down
24 changes: 19 additions & 5 deletions pyrefly/lib/alt/expr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2014,11 +2014,11 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
}
Type::ClassDef(cls) => {
let metadata = self.get_metadata_for_class(&cls);
let class_getitem_result = if self.get_class_tparams(&cls).is_empty()
let class_ty = Type::ClassDef(cls.dupe());
let allow_dunder_lookup = self.get_class_tparams(&cls).is_empty()
&& !metadata.has_base_any()
&& !metadata.is_new_type()
{
let class_ty = Type::ClassDef(cls.dupe());
&& !metadata.is_new_type();
let class_getitem_result = if allow_dunder_lookup {
// TODO(stroxler): Add a new API, similar to `type_of_attr_get` but returning a
// LookupResult or an Optional type, that we could use here to avoid the double lookup.
if self.has_attr(&class_ty, &dunder::CLASS_GETITEM) {
Expand All @@ -2039,7 +2039,21 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
} else {
None
};
if let Some(result) = class_getitem_result {
let metaclass_getitem_result =
if class_getitem_result.is_none() && allow_dunder_lookup {
self.call_magic_dunder_method(
&class_ty,
&dunder::GETITEM,
range,
&[CallArg::expr(slice)],
&[],
errors,
Some(&|| ErrorContext::Index(self.for_display(class_ty.clone()))),
)
} else {
None
};
if let Some(result) = class_getitem_result.or(metaclass_getitem_result) {
result
} else {
Type::type_form(self.specialize(
Expand Down
16 changes: 16 additions & 0 deletions pyrefly/lib/test/simple.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1882,6 +1882,22 @@ assert_type(Foo[0], str)
"#,
);

testcase!(
test_class_metaclass_getitem,
r#"
from typing import assert_type

class Meta(type):
def __getitem__(self, item: int) -> str:
return str(item)

class Foo(metaclass=Meta):
pass

assert_type(Foo[0], str)
"#,
);

testcase!(test_panic_docstring, "\"\"\" F\n\u{85}\"\"\"",);

testcase!(
Expand Down
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