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author | Jonathan Wakely <jwakely@redhat.com> | 2023-01-12 10:40:49 +0000 |
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committer | Jonathan Wakely <jwakely@redhat.com> | 2023-01-13 13:34:20 +0000 |
commit | e2fc12a5dafadf15d804e1d2541528296e97a847 (patch) | |
tree | e4d9e046e730a5a3b7ebb417d85ae1fa772c5c9f /libgcc | |
parent | 57d104ab0f515d12ba12270a415a76f55c235574 (diff) | |
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libstdc++: Fix unintended layout change to std::basic_filebuf [PR108331]
GCC 13 has a new implementation of gthr-win32.h which supports C++11
mutexes, threads etc. but this causes an unintended ABI break. The
__gthread_mutex_t type is always used in std::basic_filebuf even in
C++98, so independent of whether C++11 sync primitives work or not.
Because that type changed for the win32 thread model, we have a layout
change in std::basic_filebuf. The member is completely unused, it just
gets passed to the std::__basic_file constructor and ignored. So we
don't need that mutex to actually work, we just need its layout to not
change.
Introduce a new __gthr_win32_legacy_mutex_t struct in gthr-win32.h with
the old layout, and conditionally use that in std::basic_filebuf.
PR libstdc++/108331
libgcc/ChangeLog:
* config/i386/gthr-win32.h (__gthr_win32_legacy_mutex_t): New
struct matching the previous __gthread_mutex_t struct.
(__GTHREAD_LEGACY_MUTEX_T): Define.
libstdc++-v3/ChangeLog:
* config/io/c_io_stdio.h (__c_lock): Define as a typedef for
__GTHREAD_LEGACY_MUTEX_T if defined.
Diffstat (limited to 'libgcc')
-rw-r--r-- | libgcc/config/i386/gthr-win32.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/libgcc/config/i386/gthr-win32.h b/libgcc/config/i386/gthr-win32.h index 146357f..050c7a2 100644 --- a/libgcc/config/i386/gthr-win32.h +++ b/libgcc/config/i386/gthr-win32.h @@ -381,6 +381,14 @@ typedef struct timespec __gthread_time_t; #define __GTHREAD_COND_INIT_FUNCTION __gthread_cond_init_function #define __GTHREAD_TIME_INIT {0, 0} +// Libstdc++ std::basic_filebuf needs the old definition of __gthread_mutex_t +// for layout purposes, but doesn't actually use it. +typedef struct { + long __unused1; + void *__unused2; +} __gthr_win32_legacy_mutex_t; +#define __GTHREAD_LEGACY_MUTEX_T __gthr_win32_legacy_mutex_t + #if defined (_WIN32) && !defined(__CYGWIN__) #define MINGW32_SUPPORTS_MT_EH 1 /* Mingw runtime >= v0.3 provides a magic variable that is set to nonzero |