From 19b64150a2031089f5a957d445a35030c666ae46 Mon Sep 17 00:00:00 2001
From: Ary Borenszweig <asterite@gmail.com>
Date: Mon, 28 Oct 2024 06:54:24 -0300
Subject: [PATCH] fix: remove assumed parent traits

---
 compiler/noirc_frontend/src/node_interner.rs | 25 ++++++++++++++++++++
 compiler/noirc_frontend/src/tests/traits.rs  | 21 ++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/compiler/noirc_frontend/src/node_interner.rs b/compiler/noirc_frontend/src/node_interner.rs
index 2183cfba0ef..5fe88ed4e23 100644
--- a/compiler/noirc_frontend/src/node_interner.rs
+++ b/compiler/noirc_frontend/src/node_interner.rs
@@ -1875,8 +1875,33 @@ impl NodeInterner {
 
     /// Removes all TraitImplKind::Assumed from the list of known impls for the given trait
     pub fn remove_assumed_trait_implementations_for_trait(&mut self, trait_id: TraitId) {
+        self.remove_assumed_trait_implementations_for_trait_and_parents(trait_id, trait_id);
+    }
+
+    fn remove_assumed_trait_implementations_for_trait_and_parents(
+        &mut self,
+        trait_id: TraitId,
+        starting_trait_id: TraitId,
+    ) {
         let entries = self.trait_implementation_map.entry(trait_id).or_default();
         entries.retain(|(_, kind)| matches!(kind, TraitImplKind::Normal(_)));
+
+        // Also remove assumed implementations for the parent traits, if any
+        if let Some(trait_bounds) =
+            self.try_get_trait(trait_id).map(|the_trait| the_trait.trait_bounds.clone())
+        {
+            for parent_trait_bound in trait_bounds {
+                // Avoid looping forever in case there are cycles
+                if parent_trait_bound.trait_id == starting_trait_id {
+                    continue;
+                }
+
+                self.remove_assumed_trait_implementations_for_trait_and_parents(
+                    parent_trait_bound.trait_id,
+                    starting_trait_id,
+                );
+            }
+        }
     }
 
     /// Tags the given identifier with the selected trait_impl so that monomorphization
diff --git a/compiler/noirc_frontend/src/tests/traits.rs b/compiler/noirc_frontend/src/tests/traits.rs
index 88138ecde4d..dd6430a94cc 100644
--- a/compiler/noirc_frontend/src/tests/traits.rs
+++ b/compiler/noirc_frontend/src/tests/traits.rs
@@ -261,3 +261,24 @@ fn errors_if_impl_trait_constraint_is_not_satisfied() {
     assert_eq!(typ, "SomeGreeter");
     assert_eq!(impl_trait, "Foo");
 }
+
+#[test]
+fn removes_assumed_parent_traits_after_function_ends() {
+    let src = r#"
+    trait Foo {}
+    trait Bar: Foo {}
+
+    pub fn foo<T>()
+    where
+        T: Bar,
+    {}
+
+    pub fn bar<T>()
+    where
+        T: Foo,
+    {}
+
+    fn main() {}
+    "#;
+    assert_no_errors(src);
+}