From ede3706ca8f1c1606117b5a6507fc595157afba3 Mon Sep 17 00:00:00 2001
From: pca006132 <jl@m-labs.hk>
Date: Mon, 21 Feb 2022 18:41:42 +0800
Subject: [PATCH] type_inferencer: special case tuple index error message

---
 nac3core/src/typecheck/type_inferencer/mod.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/nac3core/src/typecheck/type_inferencer/mod.rs b/nac3core/src/typecheck/type_inferencer/mod.rs
index 9762fe04..4abcb9d0 100644
--- a/nac3core/src/typecheck/type_inferencer/mod.rs
+++ b/nac3core/src/typecheck/type_inferencer/mod.rs
@@ -1028,6 +1028,10 @@ impl<'a> Inferencer<'a> {
                 Ok(ty)
             }
             _ => {
+                if let TypeEnum::TTuple { .. } = &*self.unifier.get_ty(value.custom.unwrap())
+                {
+                    return report_error("Tuple index must be a constant (KernelInvariant is also not supported)", slice.location)
+                }
                 // the index is not a constant, so value can only be a list
                 self.constrain(slice.custom.unwrap(), self.primitives.int32, &slice.location)?;
                 let list = self.unifier.add_ty(TypeEnum::TList { ty });