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can store, but not load recursive fields

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Folkert 2020-08-22 16:01:04 +02:00
parent f4e1aa046d
commit ba186bfe09
8 changed files with 400 additions and 100 deletions
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23
compiler/unify/src/unify.rs
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@ -563,9 +563,12 @@ fn unify_shared_tags(
// > RecursiveTagUnion(rvar, [ Cons a [ Cons a rvar, Nil ], Nil ], ext)
//
// and so on until the whole non-recursive tag union can be unified with it.
let problems = if let Some(rvar) = recursion_var {
let mut problems = Vec::new();
if let Some(rvar) = recursion_var {
if expected == rvar {
unify_pool(subs, pool, actual, ctx.second)
problems.extend(unify_pool(subs, pool, actual, ctx.second));
println!("A");
} else if is_structure(actual, subs) {
// the recursion variable is hidden behind some structure (commonly an Attr
// with uniqueness inference). Thus we must expand the recursive tag union to
@ -578,19 +581,29 @@ fn unify_shared_tags(
// when `actual` is just a flex/rigid variable, the substitution would expand a
// recursive tag union infinitely!
unify_pool(subs, pool, actual, expected)
problems.extend(unify_pool(subs, pool, actual, expected));
println!("B");
} else {
// unification with a non-structure is trivial
unify_pool(subs, pool, actual, expected)
problems.extend(unify_pool(subs, pool, actual, expected));
println!("C");
}
} else {
// we always unify NonRecursive with Recursive, so this should never happen
debug_assert_ne!(Some(actual), recursion_var);
unify_pool(subs, pool, actual, expected)
problems.extend(unify_pool(subs, pool, actual, expected));
println!("D");
};
// TODO this changes some error messages
// but is important for the inference of recursive types
if problems.is_empty() {
problems.extend(unify_pool(subs, pool, expected, actual));
}
if problems.is_empty() {
// debug_assert_eq!(subs.get_root_key(actual), subs.get_root_key(expected));
matching_vars.push(actual);
}
}