From d368998120aec845ff5bdffb4a14a03fcdb09e1a Mon Sep 17 00:00:00 2001
From: Tyler Veness <calcmogul@gmail.com>
Date: Sat, 23 Aug 2025 22:25:52 +0000
Subject: [PATCH] Fix MSVC error about missing std::bit_cast

---
 Eigen/Core | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Eigen/Core b/Eigen/Core
index 90bcbc391..4b35b6c3d 100644
--- a/Eigen/Core
+++ b/Eigen/Core
@@ -103,6 +103,11 @@
 #include <thread>
 #endif
 
+// for std::bit_cast()
+#if defined(__cpp_lib_bit_cast) && __cpp_lib_bit_cast >= 201806L
+#include <bit>
+#endif
+
 // for outputting debug info
 #ifdef EIGEN_DEBUG_ASSIGN
 #include <iostream>