From e246f9cb68d07e8f15c60a2404ac9a625c349223 Mon Sep 17 00:00:00 2001
From: Charles Schlosser <cs.schlosser@gmail.com>
Date: Thu, 22 Jan 2026 01:01:26 +0000
Subject: [PATCH] Use memset if !NumTraits<Scalar>::RequireInitialization

libeigen/eigen!2113

Closes #3019
---
 Eigen/src/Core/Fill.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Eigen/src/Core/Fill.h b/Eigen/src/Core/Fill.h
index 779ef26ab..6f4593589 100644
--- a/Eigen/src/Core/Fill.h
+++ b/Eigen/src/Core/Fill.h
@@ -93,8 +93,10 @@ struct eigen_fill_impl<Xpr, /*use_fill*/ true> {
 
 template <typename Xpr>
 struct eigen_memset_helper {
-  static constexpr bool value =
-      std::is_trivially_copyable<typename Xpr::Scalar>::value && eigen_fill_helper<Xpr>::value;
+  using Scalar = typename Xpr::Scalar;
+  static constexpr bool value = std::is_trivially_copyable<Scalar>::value &&
+                                !static_cast<bool>(NumTraits<Scalar>::RequireInitialization) &&
+                                eigen_fill_helper<Xpr>::value;
 };
 
 template <typename Xpr>