From 0686e83f4c8fd91c657d3fa5e73a074043474fa7 Mon Sep 17 00:00:00 2001
From: pca006132 <jl@m-labs.hk>
Date: Fri, 25 Feb 2022 20:01:11 +0800
Subject: [PATCH] nac3core/typecheck: fixed incorrect rollback

---
 nac3core/src/typecheck/typedef/mod.rs       | 2 ++
 nac3core/src/typecheck/unification_table.rs | 1 +
 2 files changed, 3 insertions(+)

diff --git a/nac3core/src/typecheck/typedef/mod.rs b/nac3core/src/typecheck/typedef/mod.rs
index 0af37127..6246dc21 100644
--- a/nac3core/src/typecheck/typedef/mod.rs
+++ b/nac3core/src/typecheck/typedef/mod.rs
@@ -427,6 +427,7 @@ impl Unifier {
         let mut all_names: Vec<_> = signature.args.iter().map(|v| (v.name, v.ty)).rev().collect();
         for (i, t) in posargs.iter().enumerate() {
             if signature.args.len() <= i {
+                self.restore_snapshot();
                 return Err(TypeError::new(
                     TypeErrorKind::TooManyArguments { expected: signature.args.len(), got: i },
                     *loc,
@@ -483,6 +484,7 @@ impl Unifier {
         }
         self.unify_cache.clear();
         if self.unification_table.unioned(a, b) {
+            self.discard_snapshot(snapshot);
             Ok(())
         } else {
             let result = self.unify_impl(a, b, false);
diff --git a/nac3core/src/typecheck/unification_table.rs b/nac3core/src/typecheck/unification_table.rs
index 70864154..43ef0637 100644
--- a/nac3core/src/typecheck/unification_table.rs
+++ b/nac3core/src/typecheck/unification_table.rs
@@ -61,6 +61,7 @@ impl<V> UnificationTable<V> {
         if self.ranks[a] < self.ranks[b] {
             std::mem::swap(&mut a, &mut b);
         }
+        self.log.push(Action::Parent { key: b, original_parent: a });
         self.parents[b] = a;
         if self.ranks[a] == self.ranks[b] {
             self.log.push(Action::Rank { key: a, original_rank: self.ranks[a] });