From f5b8b588267696cec1b399065a0440f314515886 Mon Sep 17 00:00:00 2001
From: pca006132 <john.lck40@gmail.com>
Date: Sat, 21 Aug 2021 15:11:01 +0800
Subject: [PATCH] added tuple assignment check

---
 nac3core/src/typecheck/function_check.rs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/nac3core/src/typecheck/function_check.rs b/nac3core/src/typecheck/function_check.rs
index 92509ccc..23cd80e2 100644
--- a/nac3core/src/typecheck/function_check.rs
+++ b/nac3core/src/typecheck/function_check.rs
@@ -1,3 +1,5 @@
+use crate::typecheck::typedef::TypeEnum;
+
 use super::type_inferencer::Inferencer;
 use super::typedef::Type;
 use rustpython_parser::ast::{self, Expr, ExprKind, Stmt, StmtKind};
@@ -22,6 +24,17 @@ impl<'a> Inferencer<'a> {
                 }
                 Ok(())
             }
+            ExprKind::Subscript { value, slice, .. } => {
+                self.check_expr(value, defined_identifiers)?;
+                self.check_expr(slice, defined_identifiers)?;
+                if let TypeEnum::TTuple { .. } = &*self.unifier.get_ty(value.custom.unwrap()) {
+                    return Err(format!(
+                        "Error at {}: cannot assign to tuple element",
+                        value.location
+                    ));
+                }
+                Ok(())
+            }
             _ => self.check_expr(pattern, defined_identifiers),
         }
     }