[Please CC me as I am not subscribed to this list.] [This patch is only a draft and has not been tested at all.]
Some details have been discussed in [1]. mingw-w64 has got an implementation [2] [3] for static libraries, but it takes a destructor using the `__thiscall` convention. As both functions have C linkage, they should agree with each other and should behave simliarily. Considerations: 0) This is going to be an ABI breakage for i?86. I am not sure whether people would expect the old, broken behavior. 1) GCC doesn't provide `__cxa_atexit()`, but it would suffer from the same problem. At the moment GCC calls `atexit()` to register destructors so it appears to work. 2) There is an explicit reference to `__cxa_atexit` in 'gcc/cp/decl.c' and it probably be changed, unless it is not used by 1?86-w64-mingw32 targets. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83562 [2] https://sourceforge.net/p/mingw-w64/mingw-w64/ci/master/tree/mingw-w64-crt/crt/cxa_thread_atexit.c [3] https://sourceforge.net/p/mingw-w64/mingw-w64/ci/f3e0fbb40cbc9f8821db8bd8a0c4dae8ff671e9f/ [4] https://github.com/msys2/MINGW-packages/issues/7071 -- Best regards, LH_Mouse
From ac325bdcd6e3fa522f8b59d436cd4b3ab663de5c Mon Sep 17 00:00:00 2001 From: Liu Hao <lh_mo...@126.com> Date: Thu, 8 Oct 2020 10:26:13 +0800 Subject: [PATCH] libsupc++: Make the destructor parameter to `__cxa_thread_atexit()` use the `__thiscall` calling convention for i686-w64-mingw32 The mingw-w64 implementations of `__cxa_thread_atexit()` and `__cxa_atexit()` have been using `__thiscall` since two years ago. Using the default calling convention (which is `__cdecl`) causes crashes as explained in PR83562. Calling conventions have no effect on x86_64-w64-mingw32. Reference: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83562 Reference: https://sourceforge.net/p/mingw-w64/mingw-w64/ci/master/tree/mingw-w64-crt/crt/cxa_thread_atexit.c Reference: https://sourceforge.net/p/mingw-w64/mingw-w64/ci/f3e0fbb40cbc9f8821db8bd8a0c4dae8ff671e9f/ Reference: https://github.com/msys2/MINGW-packages/issues/7071 Signed-off-by: Liu Hao <lh_mo...@126.com> --- libstdc++-v3/libsupc++/atexit_thread.cc | 14 ++++++++++---- libstdc++-v3/libsupc++/cxxabi.h | 8 ++++++++ 2 files changed, 18 insertions(+), 4 deletions(-) diff --git a/libstdc++-v3/libsupc++/atexit_thread.cc b/libstdc++-v3/libsupc++/atexit_thread.cc index e97644f8cd4..4f7f982ac6b 100644 --- a/libstdc++-v3/libsupc++/atexit_thread.cc +++ b/libstdc++-v3/libsupc++/atexit_thread.cc @@ -30,16 +30,21 @@ #include <windows.h> #endif +// Simplify it a little for this file. +#ifndef _GLIBCXX_CDTOR_CALLABI +# define _GLIBCXX_CDTOR_CALLABI +#endif + #if _GLIBCXX_HAVE___CXA_THREAD_ATEXIT // Libc provides __cxa_thread_atexit definition. #elif _GLIBCXX_HAVE___CXA_THREAD_ATEXIT_IMPL -extern "C" int __cxa_thread_atexit_impl (void (*func) (void *), +extern "C" int __cxa_thread_atexit_impl (void (_GLIBCXX_CDTOR_CALLABI *func) (void *), void *arg, void *d); extern "C" int -__cxxabiv1::__cxa_thread_atexit (void (*dtor)(void *), +__cxxabiv1::__cxa_thread_atexit (void (_GLIBCXX_CDTOR_CALLABI *dtor)(void *), void *obj, void *dso_handle) _GLIBCXX_NOTHROW { @@ -52,7 +57,7 @@ namespace { // One element in a singly-linked stack of cleanups. struct elt { - void (*destructor)(void *); + void (_GLIBCXX_CDTOR_CALLABI *destructor)(void *); void *object; elt *next; #ifdef _GLIBCXX_THREAD_ATEXIT_WIN32 @@ -116,7 +121,8 @@ namespace { } extern "C" int -__cxxabiv1::__cxa_thread_atexit (void (*dtor)(void *), void *obj, void */*dso_handle*/) +__cxxabiv1::__cxa_thread_atexit (void (_GLIBCXX_CDTOR_CALLABI *dtor)(void *), + void *obj, void */*dso_handle*/) _GLIBCXX_NOTHROW { // Do this initialization once. diff --git a/libstdc++-v3/libsupc++/cxxabi.h b/libstdc++-v3/libsupc++/cxxabi.h index 000713ecdf8..3d6217a6fac 100644 --- a/libstdc++-v3/libsupc++/cxxabi.h +++ b/libstdc++-v3/libsupc++/cxxabi.h @@ -125,14 +125,22 @@ namespace __cxxabiv1 // DSO destruction. int +#ifdef _GLIBCXX_CDTOR_CALLABI + __cxa_atexit(void (_GLIBCXX_CDTOR_CALLABI *)(void*), void*, void*) _GLIBCXX_NOTHROW; +#else __cxa_atexit(void (*)(void*), void*, void*) _GLIBCXX_NOTHROW; +#endif void __cxa_finalize(void*); // TLS destruction. int +#ifdef _GLIBCXX_CDTOR_CALLABI + __cxa_thread_atexit(void (_GLIBCXX_CDTOR_CALLABI *)(void*), void*, void *) _GLIBCXX_NOTHROW; +#else __cxa_thread_atexit(void (*)(void*), void*, void *) _GLIBCXX_NOTHROW; +#endif // Pure virtual functions. void -- 2.20.1
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