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Date: Fri, 10 Jul 2009 12:44:00 -0000
Message-ID: <84fc9c000907100544n6d0a3d6u3927eb9925d1110@mail.gmail.com>
Subject: Re: Possible bug in g++ - template specialization
From: Richard Guenther <richard.guenther@gmail.com>
To: Maciej Cencora <m.cencora@gmail.com>
Cc: gcc@gcc.gnu.org
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On Fri, Jul 10, 2009 at 1:48 PM, Maciej Cencora<m.cencora@gmail.com> wrote:
> Hi,
>
> I think I've found a bug in g++. Let's say we have following files:
>
> // a.hpp
>
> template<typename T>
> void func1()
> {
> =A0 =A0 =A0 =A0// general code
> }
>
> // a.cpp
>
> #include "a.hpp"
>
> template<>
> void func1<int>()
> {
> =A0 =A0 =A0 =A0// specialized code
> }
>
> // main.cpp
>
> #include "a.hpp"
>
> int main(void)
> {
> =A0 =A0 =A0 =A0func1<int>();
>
> =A0 =A0 =A0 =A0return 0;
> }
>
>
> Now when we run the program compiled with: g++ main.cpp a.cpp -o main
> specialized version of func1 will be called, but when compiled with
> -Os flag the general version will be called.
> I'm not an expert but I believe the -Os behaviour is the correct one.

By not making the specialized version available at the point of
instantiation you are violating the one-definition rule (ODR, no need
to diagnose it) and the behavior is undefined.

Richard.