Disable thread-local cleanup on 32-bit MacOS PPC with GCC. This will …

…result in some test failures on that platform, but hopefully solves a crash we were never able to debug when using multiple threads. This is only tested on pre-release versions of an OS that was never released using a compiler available from MacPorts.

CHANGES.rst

@@ -11,6 +11,14 @@
   <https://github.com/python-greenlet/greenlet/issues/422>`_.
 - Remove unnecessary logging sometimes during interpreter shutdown.
   See `issue 426 <https://github.com/python-greenlet/greenlet/issues/426>`_.
+- Fix some crashes on 32-bit PPC MacOS. This is a very old platform,
+  and is only known to be tested on beta versions of an operating
+  system that was never released, using the GCC 14 only provided by
+  MacPorts; it may or may not work on the final MacOS X release that
+  supported 32-bit PowerPC. It has the known issue of leaking memory
+  when greenlets are used in multiple threads. Help debugging this
+  would be appreciated. See `PR 419
+  <https://github.com/python-greenlet/greenlet/pull/419>`_.
 
 3.1.0 (2024-09-10)
 ==================

src/greenlet/TThreadStateDestroy.cpp

@@ -16,6 +16,7 @@
 
 #include "greenlet_thread_support.hpp"
 #include "greenlet_cpython_add_pending.hpp"
+#include "greenlet_compiler_compat.hpp"
 #include "TGreenletGlobals.cpp"
 #include "TThreadState.hpp"
 #include "TThreadStateCreator.hpp"
@@ -32,6 +33,9 @@ struct ThreadState_DestroyNoGIL
     static void
     MarkGreenletDeadAndQueueCleanup(ThreadState* const state)
     {
+#if GREENLET_BROKEN_THREAD_LOCAL_CLEANUP_JUST_LEAK
+        return;
+#endif
         // We are *NOT* holding the GIL. Our thread is in the middle
         // of its death throes and the Python thread state is already
         // gone so we can't use most Python APIs. One that is safe is

src/greenlet/greenlet_compiler_compat.hpp

@@ -83,5 +83,16 @@
 #    define G_NOEXCEPT_WIN32
 #endif
 
+#if defined(__GNUC__) && defined(__POWERPC__) && defined(__APPLE__)
+// 32-bit PPC/MacOSX. Only known to be tested on unreleased versions
+// of macOS 10.6 using a macports build gcc 14. It appears that
+// running C++ destructors of thread-local variables is broken.
+
+// See https://github.com/python-greenlet/greenlet/pull/419
+#     define GREENLET_BROKEN_THREAD_LOCAL_CLEANUP_JUST_LEAK 1
+#else
+#     define GREENLET_BROKEN_THREAD_LOCAL_CLEANUP_JUST_LEAK 0
+#endif
+
 
 #endif

src/greenlet/slp_platformselect.h

@@ -22,7 +22,7 @@ extern "C" {
 #elif defined(__GNUC__) && defined(__PPC__) && (defined(__linux__) || defined(__FreeBSD__))
 # include "platform/switch_ppc_linux.h" /* gcc on PowerPC */
 #elif defined(__GNUC__) && defined(__POWERPC__) && defined(__APPLE__)
-# include "platform/switch_ppc_macosx.h" /* Apple MacOS X on PowerPC */
+# include "platform/switch_ppc_macosx.h" /* Apple MacOS X on 32-bit PowerPC */
 #elif defined(__GNUC__) && defined(__powerpc64__) && defined(_AIX)
 # include "platform/switch_ppc64_aix.h" /* gcc on AIX/PowerPC 64-bit */
 #elif defined(__GNUC__) && defined(_ARCH_PPC) && defined(_AIX)