[gcc r12-8848] libstdc++: eh_globals: gthreads: reset _S_init before deleting key

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:362e56d042f2d37337eea50b97b993f5ac6db86d

commit r12-8848-g362e56d042f2d37337eea50b97b993f5ac6db86d
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Tue Jun 21 23:11:02 2022 -0300

    libstdc++: eh_globals: gthreads: reset _S_init before deleting key
    
    Clear __eh_globals_init's _S_init in the dtor before deleting the
    gthread key.
    
    This ensures that, in case any code involved in deleting the key
    interacts with eh_globals, the key that is being deleted won't be
    used, and the non-thread-specific eh_globals fallback will.
    
    for  libstdc++-v3/ChangeLog
    
            * libsupc++/eh_globals.cc [!_GLIBCXX_HAVE_TLS]
            (__eh_globals_init::~__eh_globals_init): Clear _S_init first.
    
    (cherry picked from commit a33dda016e5acf9c6325ce8a72a1b0238130374e)

Diff:
---
 libstdc++-v3/libsupc++/eh_globals.cc | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/libsupc++/eh_globals.cc b/libstdc++-v3/libsupc++/eh_globals.cc
index 768425c0f40..0aadb692a96 100644
--- a/libstdc++-v3/libsupc++/eh_globals.cc
+++ b/libstdc++-v3/libsupc++/eh_globals.cc
@@ -119,8 +119,13 @@ struct __eh_globals_init
   ~__eh_globals_init()
   {
     if (_S_init)
-      __gthread_key_delete(_M_key);
-    _S_init = false;
+      {
+	/* Set it before the call, so that, should
+	   __gthread_key_delete throw an exception, it won't rely on
+	   the key being deleted.  */
+	_S_init = false;
+	__gthread_key_delete(_M_key);
+      }
   }
 
   __eh_globals_init(const __eh_globals_init&) = delete;