From 337ee5c47e3485d2ad4eefe5a83734751f1bb7d2 Mon Sep 17 00:00:00 2001
From: Stan Ulbrych <stan@python.org>
Date: Wed, 30 Sep 2026 15:45:37 +0100
Subject: [PATCH] Avoid Clang bug in UBSan CI (GH-157958) (cherry picked from
 commit c57c8772b0b133c5580e94006e8b084f78753f49)

Co-authored-by: Stan Ulbrych <stan@python.org>
Co-authored-by: Victor Stinner <vstinner@python.org>
---
 .github/workflows/reusable-san.yml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/.github/workflows/reusable-san.yml b/.github/workflows/reusable-san.yml
index 6b4a43b259638e2..ad3232743874d6b 100644
--- a/.github/workflows/reusable-san.yml
+++ b/.github/workflows/reusable-san.yml
@@ -90,10 +90,14 @@ jobs:
         --openssl="${OPENSSL_VER}"
         --system=Linux
         --tsan
+    # gh-157958: -O2 instead of the pydebug default -Og to avoid a clang 21
+    # compile-time blowup on some interpreter files.
+    # (https://github.com/llvm/llvm-project/issues/179695)
     - name: Configure CPython
       run: >-
         ./configure
         --config-cache
+        OPT="-O2 -g"
         ${{
           inputs.sanitizer == 'TSan'
           && '--with-thread-sanitizer'