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fix(typechecker): type generalization & dereference bugs

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* `Context::subtype_of` now has `allow_cast` param. If this is `false`, cast-aware comparisons are not performed.
This commit is contained in:
Shunsuke Shibayama 2023-02-21 17:04:52 +09:00
parent 3fea50f8bc
commit 4dcca2b06d
18 changed files with 689 additions and 247 deletions
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30
crates/erg_compiler/context/generalize.rs
View file

@ -456,11 +456,12 @@ impl Context {
qnames: &Set<Str>,
loc: &impl Locational,
) -> TyCheckResult<Type> {
let allow_cast = true;
if self.is_trait(&super_t) {
self.check_trait_impl(&sub_t, &super_t, &set! {}, loc)?;
}
// REVIEW: Even if type constraints can be satisfied, implementation may not exist
if self.subtype_of(&sub_t, &super_t) {
if self.subtype_of(&sub_t, &super_t, allow_cast) {
let sub_t = if cfg!(feature = "debug") {
sub_t
} else {
@ -476,7 +477,7 @@ impl Context {
Variance::Contravariant => Ok(super_t),
Variance::Invariant => {
// need to check if sub_t == super_t
if self.supertype_of(&sub_t, &super_t) {
if self.supertype_of(&sub_t, &super_t, allow_cast) {
Ok(sub_t)
} else {
Err(TyCheckErrors::from(TyCheckError::subtyping_error(
@ -754,8 +755,9 @@ impl Context {
}
pub(crate) fn trait_impl_exists(&self, class: &Type, trait_: &Type) -> bool {
let allow_cast = true;
// `Never` implements any trait
if self.subtype_of(class, &Type::Never) {
if self.subtype_of(class, &Type::Never, allow_cast) {
return true;
}
if class.is_monomorphic() {
@ -766,10 +768,11 @@ impl Context {
}
fn mono_class_trait_impl_exist(&self, class: &Type, trait_: &Type) -> bool {
let allow_cast = true;
let mut super_exists = false;
for inst in self.get_trait_impls(trait_).into_iter() {
if self.supertype_of(&inst.sub_type, class)
&& self.supertype_of(&inst.sup_trait, trait_)
if self.supertype_of(&inst.sub_type, class, allow_cast)
&& self.supertype_of(&inst.sup_trait, trait_, allow_cast)
{
super_exists = true;
break;
@ -779,10 +782,11 @@ impl Context {
}
fn poly_class_trait_impl_exists(&self, class: &Type, trait_: &Type) -> bool {
let allow_cast = true;
let mut super_exists = false;
for inst in self.get_trait_impls(trait_).into_iter() {
if self.supertype_of(&inst.sub_type, class)
&& self.supertype_of(&inst.sup_trait, trait_)
if self.supertype_of(&inst.sub_type, class, allow_cast)
&& self.supertype_of(&inst.sup_trait, trait_, allow_cast)
{
super_exists = true;
break;
@ -1030,18 +1034,14 @@ impl Context {
Ok(())
}
hir::Expr::Def(def) => {
*def.sig.ref_mut_t() = self.deref_tyvar(
mem::take(def.sig.ref_mut_t()),
Covariant,
&set! {},
&def.sig,
)?;
let qnames = if let Type::Quantified(quant) = def.sig.ref_t() {
let Ok(subr) = <&SubrType>::try_from(quant.as_ref()) else { unreachable!() };
subr.essential_qnames()
} else {
set! {}
};
*def.sig.ref_mut_t() =
self.deref_tyvar(mem::take(def.sig.ref_mut_t()), Covariant, &qnames, &def.sig)?;
if let Some(params) = def.sig.params_mut() {
self.resolve_params_t(params, &qnames)?;
}
@ -1051,14 +1051,14 @@ impl Context {
Ok(())
}
hir::Expr::Lambda(lambda) => {
lambda.t =
self.deref_tyvar(mem::take(&mut lambda.t), Covariant, &set! {}, lambda)?;
let qnames = if let Type::Quantified(quant) = lambda.ref_t() {
let Ok(subr) = <&SubrType>::try_from(quant.as_ref()) else { unreachable!() };
subr.essential_qnames()
} else {
set! {}
};
lambda.t =
self.deref_tyvar(mem::take(&mut lambda.t), Covariant, &qnames, lambda)?;
self.resolve_params_t(&mut lambda.params, &qnames)?;
for chunk in lambda.body.iter_mut() {
self.resolve_expr_t(chunk)?;