From: Dino Viehland <dinoviehland@meta.com>
Date: Sat, 1 Nov 2025 16:23:58 +0000 (-0400)
Subject: gh-140868: Don't rely on undefined left shift behavior in assert (#140869)
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b1554146c29182803d1df23d6367c07a429d21ba;p=thirdparty%2FPython%2Fcpython.git

gh-140868: Don't rely on undefined left shift behavior in assert (#140869)

Don't rely on undefined left shift behavior in assert
---

diff --git a/Include/internal/pycore_stackref.h b/Include/internal/pycore_stackref.h
index 94fcb1d8aee5..15a703a08204 100644
--- a/Include/internal/pycore_stackref.h
+++ b/Include/internal/pycore_stackref.h
@@ -403,7 +403,8 @@ PyStackRef_IsTaggedInt(_PyStackRef i)
 static inline _PyStackRef
 PyStackRef_TagInt(intptr_t i)
 {
-    assert(Py_ARITHMETIC_RIGHT_SHIFT(intptr_t, (i << Py_TAGGED_SHIFT), Py_TAGGED_SHIFT) == i);
+    assert(Py_ARITHMETIC_RIGHT_SHIFT(intptr_t, (intptr_t)(((uintptr_t)i) << Py_TAGGED_SHIFT),
+                                     Py_TAGGED_SHIFT) == i);
     return (_PyStackRef){ .bits = ((((uintptr_t)i) << Py_TAGGED_SHIFT) | Py_INT_TAG) };
 }