From 13b61529f459eb9cf2ceee23a51bcbd4b7c64e9a Mon Sep 17 00:00:00 2001
From: Rasmus Munk Larsen <4643818-rmlarsen1@users.noreply.gitlab.com>
Date: Thu, 26 Feb 2026 12:35:44 -0800
Subject: [PATCH] Add const to non-mutating member functions in products/ and
 Serializer

libeigen/eigen!2221

Co-authored-by: Rasmus Munk Larsen <rmlarsen@gmail.com>
---
 Eigen/src/Core/products/GeneralMatrixMatrixTriangular.h | 2 +-
 Eigen/src/Core/products/SelfadjointMatrixMatrix.h       | 6 +++---
 Eigen/src/Core/util/Serializer.h                        | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/Eigen/src/Core/products/GeneralMatrixMatrixTriangular.h b/Eigen/src/Core/products/GeneralMatrixMatrixTriangular.h
index adae3dd6c..5a8599ab7 100644
--- a/Eigen/src/Core/products/GeneralMatrixMatrixTriangular.h
+++ b/Eigen/src/Core/products/GeneralMatrixMatrixTriangular.h
@@ -154,7 +154,7 @@ struct tribb_kernel {
 
   enum { BlockSize = meta_least_common_multiple<plain_enum_max(mr, nr), plain_enum_min(mr, nr)>::ret };
   void operator()(ResScalar* res_, Index resIncr, Index resStride, const LhsScalar* blockA, const RhsScalar* blockB,
-                  Index size, Index depth, const ResScalar& alpha) {
+                  Index size, Index depth, const ResScalar& alpha) const {
     typedef blas_data_mapper<ResScalar, Index, ColMajor, Unaligned, ResInnerStride> ResMapper;
     typedef blas_data_mapper<ResScalar, Index, ColMajor, Unaligned> BufferMapper;
     ResMapper res(res_, resStride, resIncr);
diff --git a/Eigen/src/Core/products/SelfadjointMatrixMatrix.h b/Eigen/src/Core/products/SelfadjointMatrixMatrix.h
index 899283dcc..fd66b6093 100644
--- a/Eigen/src/Core/products/SelfadjointMatrixMatrix.h
+++ b/Eigen/src/Core/products/SelfadjointMatrixMatrix.h
@@ -22,7 +22,7 @@ template <typename Scalar, typename Index, int Pack1, int Pack2_dummy, int Stora
 struct symm_pack_lhs {
   template <int BlockRows>
   inline void pack(Scalar* blockA, const const_blas_data_mapper<Scalar, Index, StorageOrder>& lhs, Index cols, Index i,
-                   Index& count) {
+                   Index& count) const {
     // normal copy
     for (Index k = 0; k < i; k++)
       for (Index w = 0; w < BlockRows; w++) blockA[count++] = lhs(i + w, k);  // normal
@@ -40,7 +40,7 @@ struct symm_pack_lhs {
     for (Index k = i + BlockRows; k < cols; k++)
       for (Index w = 0; w < BlockRows; w++) blockA[count++] = numext::conj(lhs(k, i + w));  // transposed
   }
-  void operator()(Scalar* blockA, const Scalar* lhs_, Index lhsStride, Index cols, Index rows) {
+  void operator()(Scalar* blockA, const Scalar* lhs_, Index lhsStride, Index cols, Index rows) const {
     typedef typename unpacket_traits<typename packet_traits<Scalar>::type>::half HalfPacket;
     typedef typename unpacket_traits<typename unpacket_traits<typename packet_traits<Scalar>::type>::half>::half
         QuarterPacket;
@@ -99,7 +99,7 @@ struct symm_pack_lhs {
 template <typename Scalar, typename Index, int nr, int StorageOrder>
 struct symm_pack_rhs {
   enum { PacketSize = packet_traits<Scalar>::size };
-  void operator()(Scalar* blockB, const Scalar* rhs_, Index rhsStride, Index rows, Index cols, Index k2) {
+  void operator()(Scalar* blockB, const Scalar* rhs_, Index rhsStride, Index rows, Index cols, Index k2) const {
     Index end_k = k2 + rows;
     Index count = 0;
     const_blas_data_mapper<Scalar, Index, StorageOrder> rhs(rhs_, rhsStride);
diff --git a/Eigen/src/Core/util/Serializer.h b/Eigen/src/Core/util/Serializer.h
index 72ce6cb59..6de7fe247 100644
--- a/Eigen/src/Core/util/Serializer.h
+++ b/Eigen/src/Core/util/Serializer.h
@@ -46,7 +46,7 @@ class Serializer<T,
    * \param value the value to serialize.
    * \return the next memory address past the end of the serialized data.
    */
-  EIGEN_DEVICE_FUNC uint8_t* serialize(uint8_t* dest, uint8_t* end, const T& value) {
+  EIGEN_DEVICE_FUNC uint8_t* serialize(uint8_t* dest, uint8_t* end, const T& value) const {
     if (EIGEN_PREDICT_FALSE(dest == nullptr)) return nullptr;
     if (EIGEN_PREDICT_FALSE(dest + sizeof(value) > end)) return nullptr;
     EIGEN_USING_STD(memcpy)
@@ -84,7 +84,7 @@ class Serializer<DenseBase<Derived>, void> {
 
   EIGEN_DEVICE_FUNC size_t size(const Derived& value) const { return sizeof(Header) + sizeof(Scalar) * value.size(); }
 
-  EIGEN_DEVICE_FUNC uint8_t* serialize(uint8_t* dest, uint8_t* end, const Derived& value) {
+  EIGEN_DEVICE_FUNC uint8_t* serialize(uint8_t* dest, uint8_t* end, const Derived& value) const {
     if (EIGEN_PREDICT_FALSE(dest == nullptr)) return nullptr;
     if (EIGEN_PREDICT_FALSE(dest + size(value) > end)) return nullptr;
     const size_t header_bytes = sizeof(Header);