Re: Q. about POD with const member (or g++ vs. Comeau)

[Andrew Haley <aph at redhat dot com>]

Stefan Naewe wrote:
> Given the following:
> 
> 
> // ++ CODE
> struct S
> {
>   const int ci;
> };
> 
> int main()
> {
>   S  * s = new S;
> }
> // -- CODE
> 
> 
> Comeau Online gives me:
> 
> // ++ output
> Comeau C/C++ 4.3.10.1 (May 29 2008 09:37:15) for ONLINE_EVALUATION_BETA1
> Copyright 1988-2008 Comeau Computing.  All rights reserved.
> MODE:strict errors C++ C++0x_extensions
> 
> "ComeauTest.c", line 1: warning: class "S" defines no constructor to
> initialize the
>           following:
>             const member "S::ci"
>   struct S
>          ^
> 
> "ComeauTest.c", line 8: error: object has an uninitialized const or
> reference member
>     S  * s = new S;
>                  ^
> 
> 1 error detected in the compilation of "ComeauTest.c".
> 
> // -- output
> 
> 
> Different g++ versions
> 4.2.3
> 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
> gcc version 4.3.1 20080404 (prerelease) [gcc-4_3-branch revision 133917]
>         (Ubuntu 20080404-0ubuntu1)
> 
> give:
> 
> // ++ output
> constmember.cc: In function 'int main()':
> constmember.cc:8: warning: unused variable 's'
> // -- output
> 
> 
> Reading 5.3.4.15 (and 8.5.5) of the holy standard
> I'd say Comeau is right, the program is ill-formed, isn't it?

Yes.

ISO/IEC 14882:1998(E)
12.6.2 Initializing bases and members, Para 4

"If the entity is a nonstatic data member of a const-qualified type,
the entity class shall have a user-declared default constructor."

Andrew.