From 68fabb1a8ec6b734e1493fa8836f64886fc3edc1 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Mon, 11 May 2026 21:23:29 +0300
Subject: [PATCH] Do not throw an exception when hashing valueless std::variant
 values

---
 include/boost/container_hash/hash.hpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/boost/container_hash/hash.hpp b/include/boost/container_hash/hash.hpp
index 1fe3f2f..7eb2755 100644
--- a/include/boost/container_hash/hash.hpp
+++ b/include/boost/container_hash/hash.hpp
@@ -455,7 +455,11 @@ namespace boost
         std::size_t seed = 0;
 
         hash_combine( seed, v.index() );
-        std::visit( [&seed](auto&& x) { hash_combine(seed, x); }, v );
+
+        if( !v.valueless_by_exception() )
+        {
+            std::visit( [&seed](auto&& x) { hash_combine(seed, x); }, v );
+        }
 
         return seed;
     }