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fix: a sub-unification bug

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This commit is contained in:
Shunsuke Shibayama 2023-03-18 23:01:17 +09:00
parent 332337efca
commit 988f9f6c99
3 changed files with 18 additions and 4 deletions
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10
crates/erg_compiler/context/unify.rs
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@ -738,6 +738,9 @@ impl Context {
}
Ok(())
}
(Type::FreeVar(lfv), Ref(t)) if lfv.is_unbound() => {
self.sub_unify(maybe_sub, t, loc, param_name)
}
(Type::FreeVar(lfv), _) if lfv.is_unbound() => {
let lfv_ref = unsafe { lfv.as_ptr().as_mut().unwrap() };
match lfv_ref {
@ -752,15 +755,16 @@ impl Context {
// sub <: r, sup :> r => sup = min(sup, r) if min exists
// * sub_unify(?T(:> Never, <: Nat), Int): (/* OK */)
// * sub_unify(?T(:> Nat, <: Obj), Int): (?T(:> Nat, <: Int))
// sup = union(sup, r) if min does not exist
// * sub_unify(?T(:> Never, <: {1}), {0}): (?T(:> Never, <: {0, 1}))
// sup = intersection(sup, r) if min does not exist
// * sub_unify(?T(<: {1}), {0}): (* ?T == Never *)
// * sub_unify(?T(<: Eq and Ord), Show): (?T(<: Eq and Ord and Show))
Constraint::Sandwiched { sub, sup } => {
// REVIEW: correct?
if let Some(new_sup) = self.min(sup, maybe_sup) {
*constraint =
Constraint::new_sandwiched(mem::take(sub), new_sup.clone());
} else {
let new_sup = self.union(sup, maybe_sup);
let new_sup = self.intersection(sup, maybe_sup);
*constraint = Constraint::new_sandwiched(mem::take(sub), new_sup);
}
}