fix(tvix/eval): catchable-aware `elem` r/7405

`elem` did not catch the list being a catchable.
This surfaced during Nixpkgs evaluation.

Change-Id: Icf19b94e914e35a435c4412d769ee63ba59ab7b0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10599
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 4 insertions, 0 deletions

diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs
index 2070f6591e47..eb24c0559f30 100644
--- a/tvix/eval/src/builtins/mod.rs
+++ b/tvix/eval/src/builtins/mod.rs
@@ -397,6 +397,10 @@ mod pure_builtins {
 
     #[builtin("elem")]
     async fn builtin_elem(co: GenCo, x: Value, xs: Value) -> Result<Value, ErrorKind> {
+        if xs.is_catchable() {
+            return Ok(xs);
+        }
+
         for val in xs.to_list()? {
             match generators::check_equality(&co, x.clone(), val, PointerEquality::AllowAll).await?
             {