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From: "rdiezmail-gcc at yahoo dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/107500] Useless atexit entry for ~constant_init in
 eh_globals.cc
Date: Wed, 02 Nov 2022 12:46:06 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107500

--- Comment #4 from R. Diez <rdiezmail-gcc at yahoo dot de> ---
The 'constant_init' wrapper with the 'union' inside is a contrived hack, is=
n't
it? We may as well use a different hack then.

How about a combination of '__attribute__ constructor' and 'placement new' =
like
this?

uint8_t some_buffer[ sizeof( __cxa_eh_globals ) ];

// All objects with an init_priority attribute are constructed before any
// object with no init_priority attribute.
#define SOME_INIT_PRIORITY  200  // Priority range [101, 65535].

static __attribute__ ((constructor (SOME_INIT_PRIORITY))) void
MyHackForInitWithoutAtExitDestructor ( void ) throw()
{
  // Placement new.
  new ( some_buffer ) __cxa_eh_globals();
}

You would then need a 'get_eh_globals()' wrapper to return a pointer or a
reference to a '__cxa_eh_globals' object from 'some_buffer', by doing a type
cast. Everybody should then use the wrapper to access that singleton object=
.=