From 0f9729c819b39bf02c93407ce82daeae300fef9a Mon Sep 17 00:00:00 2001
From: Antony Polukhin <antoshkka@gmail.com>
Date: Tue, 23 Dec 2025 20:19:29 +0300
Subject: [PATCH 1/2] Check for potential memory leak at runtime rather than on
 compile time

---
 CMakeLists.txt         |  2 +-
 build/Jamfile.v2       |  3 +--
 src/from_exception.cpp | 48 +++++++++++++++++++++++++-----------------
 3 files changed, 31 insertions(+), 22 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a4bde74..3dc5118 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -72,7 +72,7 @@ stacktrace_check(BOOST_STACKTRACE_HAS_WINDBG has_windbg.cpp "" "dbgeng;ole32" ""
 stacktrace_check(BOOST_STACKTRACE_HAS_WINDBG_CACHED has_windbg_cached.cpp "${CMAKE_CURRENT_SOURCE_DIR}/../config/include" "dbgeng;ole32" "")
 
 set(_default_from_exception ON)
-if (NOT CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|AMD64|amd64|i386|i686|x86" OR CMAKE_CXX_PLATFORM_ID MATCHES "Cygwin")
+if (CMAKE_CXX_PLATFORM_ID MATCHES "Cygwin")
   set(_default_from_exception OFF)
 endif()
 
diff --git a/build/Jamfile.v2 b/build/Jamfile.v2
index a7e4615..0af76b9 100644
--- a/build/Jamfile.v2
+++ b/build/Jamfile.v2
@@ -249,8 +249,7 @@ rule build-stacktrace-from-exception ( props * )
         case "off" :  return <build>no ;
     }
 
-    local arch = [ property.select <architecture> : $(props) ] ;
-    if ( $(arch) && ( $(arch:G=) != x86 ) ) || ( <target-os>cygwin in $(props) )
+    if ( <target-os>cygwin in $(props) )
     {
         configure.log-library-search-result "boost.stacktrace.from_exception" : "no" ;
         return <build>no ;
diff --git a/src/from_exception.cpp b/src/from_exception.cpp
index 366ba28..4ad7de7 100644
--- a/src/from_exception.cpp
+++ b/src/from_exception.cpp
@@ -160,29 +160,13 @@ BOOST_SYMBOL_EXPORT void assert_no_pending_traces() noexcept {
 #include <exception>
 #include <dlfcn.h>
 
+
 #if !BOOST_STACKTRACE_ALWAYS_STORE_IN_PADDING
+#include <cstdlib>
 #include <mutex>
 #include <unordered_map>
 
-#ifndef BOOST_STACKTRACE_LIBCXX_RUNTIME_MAY_CAUSE_MEMORY_LEAK
-
-#ifdef BOOST_HAS_THREADS
-
-#error On this platform memory leaks are possible if capturing stacktrace from \
-        exceptions is enabled and exceptions are thrown concurrently \
-        and libc++ runtime is used. \
-        \
-        Define `BOOST_STACKTRACE_LIBCXX_RUNTIME_MAY_CAUSE_MEMORY_LEAK` to \
-        suppress this error if the library would not be used with libc++ \
-        runtime (for example, it would be only used with GCC runtime). \
-        \
-        Otherwise, disable the boost_stacktrace_from_exception library build \
-        (for example by `./b2 boost.stacktrace.from_exception=off` option).
-
-#endif
-
-#endif
-
+#include <unistd.h>
 #endif
 
 namespace {
@@ -297,6 +281,32 @@ void* __cxa_allocate_exception(size_t thrown_size) throw() {
 extern "C" BOOST_SYMBOL_EXPORT
 void __cxa_decrement_exception_refcount(void *thrown_object) throw() {
   BOOST_ASSERT(is_libcpp_runtime());
+
+#if !defined(BOOST_STACKTRACE_LIBCXX_RUNTIME_MAY_CAUSE_MEMORY_LEAK) && defined(BOOST_HAS_THREADS)
+  static const char* leaks_are_fine = std::getenv("BOOST_STACKTRACE_LIBCXX_RUNTIME_MAY_CAUSE_MEMORY_LEAK");
+  if (!leaks_are_fine || leaks_are_fine[0] != '1') {
+        const char* const warning =
+            "\n\n"
+            "=======================================================================================\n"
+            "\n"
+            "On this platform, memory leaks may occur if capturing stacktrace from exceptions is\n"
+            "enabled and exceptions are thrown concurrently by libc++ runtime (libc++abi).\n"
+            "\n"
+            "A proper workaround is to use libstdc++ runtime (libgcc_s) instead.\n"
+            "\n"
+            "Alternatively, if you are willing to accept potential MEMORY LEAKS, set the environment\n"
+            "variable `BOOST_STACKTRACE_LIBCXX_RUNTIME_MAY_CAUSE_MEMORY_LEAK=1` to proceed. You can\n"
+            "also define the `BOOST_STACKTRACE_LIBCXX_RUNTIME_MAY_CAUSE_MEMORY_LEAK` macro when\n"
+            "building the `boost_stacktrace_from_exception` library to disable this warning and to\n"
+            "get the MEMORY LEAKS silently on libc++ runtime.\n"
+            "\n"
+            "=======================================================================================\n"
+        ;
+        write(STDERR_FILENO, warning, strlen(warning));
+        std::abort();
+  }
+#endif
+
   if (!thrown_object) {
     return;
   }

From 544c34063dfb5ae05fc376641428dcab29726a8d Mon Sep 17 00:00:00 2001
From: Antony Polukhin <antoshkka@gmail.com>
Date: Wed, 24 Dec 2025 13:33:07 +0300
Subject: [PATCH 2/2] minor fixes

---
 src/from_exception.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/from_exception.cpp b/src/from_exception.cpp
index 4ad7de7..18f3001 100644
--- a/src/from_exception.cpp
+++ b/src/from_exception.cpp
@@ -163,6 +163,7 @@ BOOST_SYMBOL_EXPORT void assert_no_pending_traces() noexcept {
 
 #if !BOOST_STACKTRACE_ALWAYS_STORE_IN_PADDING
 #include <cstdlib>
+#include <cstring>
 #include <mutex>
 #include <unordered_map>
 
@@ -302,7 +303,7 @@ void __cxa_decrement_exception_refcount(void *thrown_object) throw() {
             "\n"
             "=======================================================================================\n"
         ;
-        write(STDERR_FILENO, warning, strlen(warning));
+        write(STDERR_FILENO, warning, std::strlen(warning));
         std::abort();
   }
 #endif