From 1682c6048380f7b2b523ce45218bb91454b58e11 Mon Sep 17 00:00:00 2001
From: Antonio Sanchez <cantonios@google.com>
Date: Mon, 27 Oct 2025 16:04:41 -0700
Subject: [PATCH] Allow user to configure if `free` is allowed at runtime.

Fixes #2983.
---
 Eigen/src/Core/util/Memory.h | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/Eigen/src/Core/util/Memory.h b/Eigen/src/Core/util/Memory.h
index d1f2bf3ed..f8d3c42ec 100644
--- a/Eigen/src/Core/util/Memory.h
+++ b/Eigen/src/Core/util/Memory.h
@@ -91,6 +91,9 @@ namespace internal {
 EIGEN_DEVICE_FUNC inline void check_that_malloc_is_allowed() {
   eigen_assert(false && "heap allocation is forbidden (EIGEN_NO_MALLOC is defined)");
 }
+EIGEN_DEVICE_FUNC inline void check_that_free_is_allowed() {
+  eigen_assert(false && "heap deallocation is forbidden (EIGEN_NO_MALLOC is defined)");
+}
 #elif defined EIGEN_RUNTIME_NO_MALLOC
 EIGEN_DEVICE_FUNC inline bool is_malloc_allowed_impl(bool update, bool new_value = false) {
   EIGEN_MALLOC_CHECK_THREAD_LOCAL static bool value = true;
@@ -101,10 +104,22 @@ EIGEN_DEVICE_FUNC inline bool is_malloc_allowed() { return is_malloc_allowed_imp
 EIGEN_DEVICE_FUNC inline bool set_is_malloc_allowed(bool new_value) { return is_malloc_allowed_impl(true, new_value); }
 EIGEN_DEVICE_FUNC inline void check_that_malloc_is_allowed() {
   eigen_assert(is_malloc_allowed() &&
-               "heap allocation is forbidden (EIGEN_RUNTIME_NO_MALLOC is defined and g_is_malloc_allowed is false)");
+               "heap allocation is forbidden (EIGEN_RUNTIME_NO_MALLOC is defined and set_is_malloc_allowed is false)");
+}
+EIGEN_DEVICE_FUNC inline bool is_free_allowed_impl(bool update, bool new_value = false) {
+  EIGEN_MALLOC_CHECK_THREAD_LOCAL static bool value = true;
+  if (update == 1) value = new_value;
+  return value;
+}
+EIGEN_DEVICE_FUNC inline bool is_free_allowed() { return is_free_allowed_impl(false); }
+EIGEN_DEVICE_FUNC inline bool set_is_free_allowed(bool new_value) { return is_free_allowed_impl(true, new_value); }
+EIGEN_DEVICE_FUNC inline void check_that_free_is_allowed() {
+  eigen_assert(is_malloc_allowed() &&
+               "heap deallocation is forbidden (EIGEN_RUNTIME_NO_MALLOC is defined and set_is_free_allowed is false)");
 }
 #else
 EIGEN_DEVICE_FUNC inline void check_that_malloc_is_allowed() {}
+EIGEN_DEVICE_FUNC inline void check_that_free_is_allowed() {}
 #endif
 
 EIGEN_DEVICE_FUNC inline void throw_std_bad_alloc() {
@@ -161,7 +176,7 @@ EIGEN_DEVICE_FUNC inline void handmade_aligned_free(void* ptr) {
     std::size_t offset = static_cast<std::size_t>(*(static_cast<uint8_t*>(ptr) - 1)) + 1;
     void* original = static_cast<void*>(static_cast<uint8_t*>(ptr) - offset);
 
-    check_that_malloc_is_allowed();
+    check_that_free_is_allowed();
     EIGEN_USING_STD(free)
     free(original);
   }
@@ -227,7 +242,7 @@ EIGEN_DEVICE_FUNC inline void aligned_free(void* ptr) {
 #if (EIGEN_DEFAULT_ALIGN_BYTES == 0) || EIGEN_MALLOC_ALREADY_ALIGNED
 
   if (ptr != nullptr) {
-    check_that_malloc_is_allowed();
+    check_that_free_is_allowed();
     EIGEN_USING_STD(free)
     free(ptr);
   }
@@ -299,7 +314,7 @@ EIGEN_DEVICE_FUNC inline void conditional_aligned_free(void* ptr) {
 template <>
 EIGEN_DEVICE_FUNC inline void conditional_aligned_free<false>(void* ptr) {
   if (ptr != nullptr) {
-    check_that_malloc_is_allowed();
+    check_that_free_is_allowed();
     EIGEN_USING_STD(free)
     free(ptr);
   }
-- 
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