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From: "iains at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug modula2/108183] wrong code generated in the modula2 scaffold
 mechanism
Date: Sat, 24 Dec 2022 17:19:16 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108183

--- Comment #14 from Iain Sandoe <iains at gcc dot gnu.org> ---
coming back to this code:
=3D=3D=3D

extern "C" void
_M2_termios_init (int, char *[], char *[])
{
}

extern "C" void
_M2_termios_fini (int, char *[], char *[])
{
}

extern "C" void
_M2_termios_dep (void)
{
}

struct _M2_termios_ctor { _M2_termios_ctor (); } _M2_termios_ctor;

_M2_termios_ctor::_M2_termios_ctor (void)
{
//  M2RTS_RegisterModule ("termios", _M2_termios_init, _M2_termios_fini,
//                      _M2_termios_dep);
}

=3D=3D=3D=3D

I think this is not currently doing what is expected (it's certainly
inconsistent with the compiler's PoV .. from my debugging).

----

The declaration in the compiler thinks that _M2_termios_ctor is the symbol =
for
a function.  Where (because of the way this shim is written) it's actually =
the
name of a static variable.  Which means if it was ever called "boom".=20

However, my current understanding us that M2_link() is just a mechanism to
ensure that all the library code is pulled in (so perhaps it would never be
called).  Actually, that should not be necessary if the decls are correctly
marked as "used".

Furthermore, the initialisation code for the static instance will be entered
automatically into the startup (so it's out of your control).

=3D=3D=3D=3D=3D

What about, instead:

extern "C" void
_M2_termios_init (int, char *[], char *[])
{
}

extern "C" void
_M2_termios_fini (int, char *[], char *[])
{
}

extern "C" void
_M2_termios_dep (void)
{
}

extern "C" void
_M2_termios_ctor (void)
{
  M2RTS_RegisterModule ("termios", _M2_termios_init, _M2_termios_fini,
                        _M2_termios_dep);
}

=3D=3D now the symbol will indeed refer to the CTOR that causes the module =
to be
registered.  As it is written that CTOR will not be called unless you do it.

IFF you want it to be called "automatically" at program startup .. you can =
mark
it
__attribute__((constructor))=