From 37968845284501a536a96b9fdafab83d43dd9b9d Mon Sep 17 00:00:00 2001
From: Victor Stinner <vstinner@python.org>
Date: Thu, 27 Mar 2025 10:03:58 +0100
Subject: gh-111178: Skip undefined behavior checks in _PyPegen_lookahead()
 (#131714)

For example, expression_rule() return type is 'expr_ty', whereas
_PyPegen_lookahead() uses 'void*'.
---
 Parser/pegen.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/Parser/pegen.c b/Parser/pegen.c
index 592269e..75fdd46 100644
--- a/Parser/pegen.c
+++ b/Parser/pegen.c
@@ -406,11 +406,14 @@ _PyPegen_lookahead_with_int(int positive, Token *(func)(Parser *, int), Parser *
     return (res != NULL) == positive;
 }
 
-int
+// gh-111178: Use _Py_NO_SANITIZE_UNDEFINED to disable sanitizer checks on
+// undefined behavior (UBsan) in this function, rather than changing 'func'
+// callback API.
+int _Py_NO_SANITIZE_UNDEFINED
 _PyPegen_lookahead(int positive, void *(func)(Parser *), Parser *p)
 {
     int mark = p->mark;
-    void *res = (void*)func(p);
+    void *res = func(p);
     p->mark = mark;
     return (res != NULL) == positive;
 }
-- 
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