From 2e9acb3035d93e36c315fe3068b7f52ff57b09aa Mon Sep 17 00:00:00 2001
From: jfh <jfh@imijmi.eu>
Date: Thu, 17 Jun 2021 12:25:59 +0300
Subject: [PATCH] Make tuple() return empty_tuple

---
 vm/src/builtins/tuple.rs | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/vm/src/builtins/tuple.rs b/vm/src/builtins/tuple.rs
index 9f82122eb..0940271e0 100644
--- a/vm/src/builtins/tuple.rs
+++ b/vm/src/builtins/tuple.rs
@@ -258,10 +258,16 @@ impl PyTuple {
             vm.extract_elements(&iterable)?
         } else {
             vec![]
+        };
+        // Return empty tuple only for exact tuple types if the iterable is empty.
+        if elements.is_empty() && cls.is(&vm.ctx.types.tuple_type) {
+            Ok(vm.ctx.empty_tuple.clone())
+        } else {
+            Self {
+                elements: elements.into_boxed_slice(),
+            }
+            .into_ref_with_type(vm, cls)
         }
-        .into_boxed_slice();
-
-        Self { elements }.into_ref_with_type(vm, cls)
     }
 }