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fix Contextual typing works only with the first element in a union #793 #1392

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fix Contextual typing works only with the first element in a union #793 #1392

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482f77e
fix?
asukaminato0721 Oct 26, 2025
601bc7c
fix todo
asukaminato0721 Oct 26, 2025
c15af9a
fix
asukaminato0721 Nov 24, 2025
035682a
impl?
asukaminato0721 Nov 25, 2025
20798d5
fmt
asukaminato0721 Nov 25, 2025
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24 changes: 24 additions & 0 deletions pyrefly/lib/alt/answers_solver.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -857,4 +857,28 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
pub fn error_swallower(&self) -> ErrorCollector {
ErrorCollector::new(self.module().dupe(), ErrorStyle::Never)
}

pub fn prefer_union_branch_without_vars(&self, ty: &Type) -> Option<Type> {
if let Type::Union(options) = ty {
let mut reordered = options.clone();
reordered.sort_by_key(|option| self.type_contains_var(option));
if reordered == *options {
None
} else {
Some(Type::Union(reordered))
}
} else {
None
}
}

pub(crate) fn type_contains_var(&self, ty: &Type) -> bool {
let mut has_var = false;
ty.universe(&mut |t| {
if matches!(t, Type::Var(_)) {
has_var = true;
}
});
has_var
}
}
2 changes: 1 addition & 1 deletion pyrefly/lib/alt/call.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1293,7 +1293,7 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
None,
)
}
})
})
}
}

Expand Down
88 changes: 70 additions & 18 deletions pyrefly/lib/alt/callable.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -312,6 +312,7 @@ impl CallArgPreEval<'_> {
solver: &AnswersSolver<Ans>,
callable_name: Option<&FunctionKind>,
hint: &Type,
use_hint: bool,
param_name: Option<&Name>,
vararg: bool,
range: TextRange,
Expand All @@ -334,11 +335,16 @@ impl CallArgPreEval<'_> {
}
Self::Expr(x, done) => {
*done = true;
solver.expr_with_separate_check_errors(
x,
Some((hint, call_errors, tcc)),
arg_errors,
);
if use_hint && !hint.is_any() {
solver.expr_with_separate_check_errors(
x,
Some((hint, call_errors, tcc)),
arg_errors,
);
} else {
let ty = solver.expr_infer(x, arg_errors);
solver.check_type(&ty, hint, range, call_errors, tcc);
}
}
Self::Star(ty, done) => {
*done = vararg;
Expand Down Expand Up @@ -541,17 +547,39 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
// We ignore positional-only parameters because they can't be passed in by name.
seen_names.insert(name, ty);
}
let ty = if let Some(reordered) = self.prefer_union_branch_without_vars(ty)
{
type_owner.push(reordered)
} else {
ty
};
let expanded = self.solver().expand_vars((*ty).clone());
let (hint_ty, mut use_hint) = if expanded == *ty {
(ty, false)
} else {
(type_owner.push(expanded), true)
};
if !use_hint {
if !self.type_contains_var(hint_ty) {
use_hint = true;
} else if let Type::Union(options) = hint_ty {
if options.iter().any(|option| !self.type_contains_var(option)) {
use_hint = true;
}
}
}
arg_pre.post_check(
self,
callable_name,
ty,
hint_ty,
use_hint,
name,
false,
arg.range(),
arg_errors,
call_errors,
context,
)
);
}
Some(PosParam {
ty,
Expand All @@ -568,17 +596,41 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
ty,
name,
kind: PosParamKind::Variadic,
}) => arg_pre.post_check(
self,
callable_name,
ty,
name,
true,
arg.range(),
arg_errors,
call_errors,
context,
),
}) => {
let ty = if let Some(reordered) = self.prefer_union_branch_without_vars(ty)
{
type_owner.push(reordered)
} else {
ty
};
let expanded = self.solver().expand_vars((*ty).clone());
let (hint_ty, mut use_hint) = if expanded == *ty {
(ty, false)
} else {
(type_owner.push(expanded), true)
};
if !use_hint {
if !self.type_contains_var(hint_ty) {
use_hint = true;
} else if let Type::Union(options) = hint_ty {
if options.iter().any(|option| !self.type_contains_var(option)) {
use_hint = true;
}
}
}
arg_pre.post_check(
self,
callable_name,
hint_ty,
use_hint,
name,
true,
arg.range(),
arg_errors,
call_errors,
context,
)
}
None => {
arg_pre.post_infer(self, arg_errors);
if !arg_pre.is_star() {
Expand Down
9 changes: 3 additions & 6 deletions pyrefly/lib/alt/class/typed_dict.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,6 @@ use crate::alt::class::class_field::ClassField;
use crate::alt::types::class_metadata::ClassMetadata;
use crate::alt::types::class_metadata::ClassSynthesizedField;
use crate::alt::types::class_metadata::ClassSynthesizedFields;
use crate::alt::unwrap::HintRef;
use crate::binding::binding::ClassFieldDefinition;
use crate::config::error_kind::ErrorKind;
use crate::error::collector::ErrorCollector;
Expand Down Expand Up @@ -149,11 +148,9 @@ impl<'a, Ans: LookupAnswer> AnswersSolver<'a, Ans> {
// This is an unpacked item (`**some_dict`).
has_expansion = true;
let partial_td_ty = Type::PartialTypedDict(typed_dict.clone());
let item_ty = self.expr_infer_with_hint(
&x.value,
Some(HintRef::soft(&partial_td_ty)),
item_errors,
);
let partial_hint = self.hint_from_type(partial_td_ty.clone(), None);
let item_ty =
self.expr_infer_with_hint(&x.value, Some(partial_hint.as_ref()), item_errors);
let subset_result = self.is_subset_eq_with_reason(&item_ty, &partial_td_ty);
if let Some(subset_error) = subset_result.err() {
let tcc: &dyn Fn() -> TypeCheckContext =
Expand Down
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