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Correctly introduce new recursion variables at the correct rank

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Ayaz Hafiz 2023-04-20 17:30:04 -05:00
parent 7beee4e1f3
commit 5ec2715820
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4 changed files with 56 additions and 12 deletions
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23
crates/compiler/unify/src/unify.rs
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@ -1449,8 +1449,8 @@ fn separate_union_lambdas<M: MetaCollector>(
// code generator, we have not yet observed a case where they must
// collapsed to the type checker of the surface syntax.
// It is possible this assumption will be invalidated!
maybe_mark_union_recursive(env, var1);
maybe_mark_union_recursive(env, var2);
maybe_mark_union_recursive(env, pool, var1);
maybe_mark_union_recursive(env, pool, var2);
}
// Check whether the two type variables in the closure set are
@ -2972,7 +2972,7 @@ enum OtherTags2 {
/// Promotes a non-recursive tag union or lambda set to its recursive variant, if it is found to be
/// recursive.
fn maybe_mark_union_recursive(env: &mut Env, union_var: Variable) {
fn maybe_mark_union_recursive(env: &mut Env, pool: &mut Pool, union_var: Variable) {
let subs = &mut env.subs;
'outer: while let Err((_, chain)) = subs.occurs(union_var) {
// walk the chain till we find a tag union or lambda set, starting from the variable that
@ -2981,7 +2981,9 @@ fn maybe_mark_union_recursive(env: &mut Env, union_var: Variable) {
let description = subs.get(v);
match description.content {
Content::Structure(FlatType::TagUnion(tags, ext_var)) => {
subs.mark_tag_union_recursive(v, tags, ext_var);
let rec_var = subs.mark_tag_union_recursive(v, tags, ext_var);
pool.push(rec_var);
continue 'outer;
}
LambdaSet(self::LambdaSet {
@ -2990,7 +2992,14 @@ fn maybe_mark_union_recursive(env: &mut Env, union_var: Variable) {
unspecialized,
ambient_function: ambient_function_var,
}) => {
subs.mark_lambda_set_recursive(v, solved, unspecialized, ambient_function_var);
let rec_var = subs.mark_lambda_set_recursive(
v,
solved,
unspecialized,
ambient_function_var,
);
pool.push(rec_var);
continue 'outer;
}
_ => { /* fall through */ }
@ -3119,8 +3128,8 @@ fn unify_shared_tags<M: MetaCollector>(
// since we're expanding tag unions to equal depths as described above,
// we'll always pass through this branch. So, we promote tag unions to recursive
// ones here if it turns out they are that.
maybe_mark_union_recursive(env, actual);
maybe_mark_union_recursive(env, expected);
maybe_mark_union_recursive(env, pool, actual);
maybe_mark_union_recursive(env, pool, expected);
let mut outcome = Outcome::<M>::default();