From ce8ef4f19ea1212adde4d87103fc4dfaebf703a0 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Mon, 6 Oct 2025 20:34:13 +0000
Subject: [PATCH] Add mutex to warning.cpp for thread safety

Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com>
---
 src/util/warning.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/util/warning.cpp b/src/util/warning.cpp
index 033c93780..c7becf49f 100644
--- a/src/util/warning.cpp
+++ b/src/util/warning.cpp
@@ -24,6 +24,10 @@ Revision History:
 #include "util/buffer.h"
 #include "util/vector.h"
 
+#ifndef SINGLE_THREAD
+#include <mutex>
+#endif
+
 #ifdef _WINDOWS
 #if defined( __MINGW32__ ) && ( defined( __GNUG__ ) || defined( __clang__ ) )
 #include <crtdbg.h>
@@ -67,6 +71,10 @@ static bool g_use_std_stdout = false;
 static std::ostream* g_error_stream = nullptr;
 static std::ostream* g_warning_stream = nullptr;
 
+#ifndef SINGLE_THREAD
+static std::mutex g_warning_mutex;
+#endif
+
 void send_warnings_to_stdout(bool flag) {
     g_use_std_stdout = flag;
 }
@@ -129,6 +137,9 @@ void print_msg(std::ostream * out, const char* prefix, const char* msg, va_list
 
 void warning_msg(const char * msg, ...) {
     if (g_warning_msgs) {
+#ifndef SINGLE_THREAD
+        std::lock_guard<std::mutex> lock(g_warning_mutex);
+#endif
         va_list args;
         va_start(args, msg);
         print_msg(g_warning_stream, "WARNING: ", msg, args);