Re: c++/10112: static data member is not correctly initialized

[Gabriel Dos Reis <gdr@integrable-solutions.net>]

The following reply was made to PR c++/10112; it has been noted by GNATS.

From: Gabriel Dos Reis <gdr@integrable-solutions.net>
To: "Giovanni Bajo" <giovannibajo@libero.it>
Cc: "Wolfgang Bangerth" <bangerth@ticam.utexas.edu>, <gcc-gnats@gcc.gnu.org>,
   <gcc-bugs@gcc.gnu.org>, <o.kullmann@swansea.ac.uk>, <nathan@gcc.gnu.org>
Subject: Re: c++/10112: static data member is not correctly initialized
Date: 18 Mar 2003 03:34:23 +0100

 "Giovanni Bajo" <giovannibajo@libero.it> writes:
 
 | ----- Original Message -----
 | From: "Gabriel Dos Reis" <gdr@integrable-solutions.net>
 | To: "Giovanni Bajo" <giovannibajo@libero.it>
 | Cc: "Wolfgang Bangerth" <bangerth@ticam.utexas.edu>;
 | <gcc-gnats@gcc.gnu.org>; <gcc-bugs@gcc.gnu.org>; <o.kullmann@swansea.ac.u=
 k>;
 | <nathan@gcc.gnu.org>
 | Sent: Tuesday, March 18, 2003 2:46 AM
 | Subject: Re: c++/10112: static data member is not correctly initialized
 |=20
 |=20
 | >From which parts of the standard did read that?
 |=20
 | I was reading =A73.6.2p1 <<before any other initialization takes place>> =
 in
 | this way.
 
 That paragraph speaks about initialisation of objects.  It says
 nothing about the order of template instantiations and the order
 
 
 | Anyway, the bug is about the order of initialization between two static d=
 ata
 | members. Since instantiation of class templates does not affect
 | initialization of static data members (as per quoted paragraph), even if =
 you
 | instantiate the class templates before inizializing the data members, you
 | should respect the order of inizialization of the data members.
 
 Unless the instantiation of the class template uses the static data
 members.=20
 
 | It seems to me that GCC is initializing the static data members because t=
 he
 | templates are instantiated, but this violates =A714.7.1p8.
 
 What you're missing is  that your expression in the assertion
 introduces an indeterminism in the order of instantiation.  It is the
 instantiation of the static data members that defines them, not just
 their mere -template- definition.
 
 What is happening is not far from the following scenario:=20
 
    struct A {=20
       int p;
 =20
       A(int x) : p(x) { }
    };=20
 
    struct B {
       static A a;
       static int p1;
    };
 
     int B::p1 =3D a.p;
     A B::a(123);
 
   int main()
   {
     assert (B::a.p =3D=3D B::p1);
   }=20
 
 -- Gaby