2 files changed, 14 insertions, 3 deletions
diff --git a/tvix/eval/src/value/attrs.rs b/tvix/eval/src/value/attrs.rs
index adf56567fb0d..a41e7ce58a12 100644
--- a/tvix/eval/src/value/attrs.rs
+++ b/tvix/eval/src/value/attrs.rs
@@ -173,6 +173,17 @@ impl NixAttrs {
         Self(AttrsRep::Empty)
     }
 
+    /// Compare two attribute sets by pointer equality. Only makes
+    /// sense for some attribute set reprsentations, i.e. returning
+    /// `false` does not mean that the two attribute sets do not have
+    /// equal *content*.
+    pub fn ptr_eq(&self, other: &Self) -> bool {
+        match (&self.0, &other.0) {
+            (AttrsRep::Im(lhs), AttrsRep::Im(rhs)) => lhs.ptr_eq(rhs),
+            _ => false,
+        }
+    }
+
     /// Return an attribute set containing the merge of the two
     /// provided sets. Keys from the `other` set have precedence.
     pub fn update(self, other: Self) -> Self {
diff --git a/tvix/eval/src/value/mod.rs b/tvix/eval/src/value/mod.rs
index 7791a4a8c33d..b5585923a301 100644
--- a/tvix/eval/src/value/mod.rs
+++ b/tvix/eval/src/value/mod.rs
@@ -39,7 +39,7 @@ pub enum Value {
     Float(f64),
     String(NixString),
     Path(PathBuf),
-    Attrs(Rc<NixAttrs>),
+    Attrs(Box<NixAttrs>),
     List(NixList),
     Closure(Rc<Closure>), // must use Rc<Closure> here in order to get proper pointer equality
     Builtin(Builtin),
@@ -154,7 +154,7 @@ where
 impl Value {
     /// Construct a [`Value::Attrs`] from a [`NixAttrs`].
     pub fn attrs(attrs: NixAttrs) -> Self {
-        Self::Attrs(Rc::new(attrs))
+        Self::Attrs(Box::new(attrs))
     }
 }
 
@@ -303,7 +303,7 @@ impl Value {
     gen_cast!(as_int, i64, "int", Value::Integer(x), *x);
     gen_cast!(as_float, f64, "float", Value::Float(x), *x);
     gen_cast!(to_str, NixString, "string", Value::String(s), s.clone());
-    gen_cast!(to_attrs, Rc<NixAttrs>, "set", Value::Attrs(a), a.clone());
+    gen_cast!(to_attrs, Box<NixAttrs>, "set", Value::Attrs(a), a.clone());
     gen_cast!(to_list, NixList, "list", Value::List(l), l.clone());
     gen_cast!(
         as_closure,