From 7176ae16238ded7fb5ed30a7f5215825b3abd134 Mon Sep 17 00:00:00 2001
From: Antonio Sanchez <cantonios@google.com>
Date: Mon, 16 Oct 2023 15:38:25 -0700
Subject: [PATCH] Make 3.4.1 compatible with c++03

---
 Eigen/src/Core/util/Meta.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/Eigen/src/Core/util/Meta.h b/Eigen/src/Core/util/Meta.h
index 8751ed23e..b7635f985 100755
--- a/Eigen/src/Core/util/Meta.h
+++ b/Eigen/src/Core/util/Meta.h
@@ -470,9 +470,8 @@ template<typename T, std::size_t N> struct array_size<std::array<T,N> > {
   */
 #if EIGEN_COMP_CXXVER < 20
 template <typename T>
-EIGEN_CONSTEXPR auto index_list_size(const T& x) {
-  using R = std::common_type_t<std::ptrdiff_t, std::make_signed_t<decltype(x.size())>>;
-  return static_cast<R>(x.size());
+EIGEN_CONSTEXPR std::ptrdiff_t index_list_size(const T& x) {
+  return static_cast<std::ptrdiff_t>(x.size());
 }
 
 template<typename T, std::ptrdiff_t N>