From 8fdbbf8b18f1405abe677d0e04874c1c86ccdb4a Mon Sep 17 00:00:00 2001
From: Amit Lavon <amitlavon1.spam@gmail.com>
Date: Sat, 7 Jun 2025 14:08:44 -0700
Subject: GH-131798: Type-propagate string/list/tuple slices (GH-134671)

---
 Python/optimizer_bytecodes.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

(limited to 'Python/optimizer_bytecodes.c')

diff --git a/Python/optimizer_bytecodes.c b/Python/optimizer_bytecodes.c
index 12efaacd8f0..fbf4dfd3db6 100644
--- a/Python/optimizer_bytecodes.c
+++ b/Python/optimizer_bytecodes.c
@@ -1237,6 +1237,20 @@ dummy_func(void) {
         sym_set_const(callable, list_append);
     }
 
+    op(_BINARY_SLICE, (container, start, stop -- res)) {
+        // Slicing a string/list/tuple always returns the same type.
+        PyTypeObject *type = sym_get_type(container);
+        if (type == &PyUnicode_Type ||
+            type == &PyList_Type ||
+            type == &PyTuple_Type)
+        {
+            res = sym_new_type(ctx, type);
+        }
+        else {
+            res = sym_new_not_null(ctx);
+        }
+    }
+
 // END BYTECODES //
 
 }
-- 
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