Re: [boost] Â [type_traits] MSVC rejects typename -- why?

Subject: Re: [boost]  [type_traits] MSVC rejects typename -- why?
From: lcaminiti (lorcaminiti_at_[hidden])
Date: 2011-03-24 11:31:26

Vicente Botet wrote:
> 
> > Message du 24/03/11 01:01
> > De : "Lorenzo Caminiti" 
> > A : boost_at_[hidden]
> > Copie à : 
> > Objet : [boost] Â [type_traits] MSVC rejects typename -- why?
> > 
> > Hello all,
> > 
> > The following code compiles on GCC (v3.4.3) but it does not on MSVC
> > (cl.exe v14):
> > 
> > #include 
> > 
> > template
> > void f(T& x) {
> > struct s {
> > T g() {
> > // GCC needs this typename but MSVC does not -- why??
> > typename boost::remove_reference::type i = 0;
> > return i;
> > }
> > };
> > x = s().g();
> > }
> > 
> > MSVC does not accept the `typename` inside `s::g` because it says
> it's
> > not within a template (but I think it is within a template...). GCC
> > instead requires that `typename`.
> > 
> > Which compiler is right? (What does the standard say?) How do I
> > program this code so it works on all compilers?
> 
> 
> here is a macro BOOST_TYPENAME in Boost.Config that was used for this
> purposes with old compilers. 
> 

I tried BOOST_DEDUCED_TYPENAME but it still does not work on my MSVC
compiler... is this a problem with Boost.Config?

#include <boost/type_traits.hpp>
#include <boost/config.hpp>

template
void f(T& x) {
    struct s {
        T g() {
            BOOST_DEDUCED_TYPENAME
boost::remove_reference<T&>::type i = 0;
            return i;
        }
    };
    x = s().g();
}

int main() {
    int x;
    f(x);
    return 0;
}

E:\sandbox\boost-sandbox-local\libs\local\example>cl /EHs /I..\..\..
/I"c:\Progr
am Files\boost\boost_1_46_1" 02.cpp
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.42 for
80x86
Copyright (C) Microsoft Corporation.  All rights reserved.

02.cpp
02.cpp(9) : error C2899: typename cannot be used outside a template
declaration

Thanks.
--Lorenzo

--
View this message in context: http://boost.2283326.n4.nabble.com/type-traits-MSVC-rejects-typename-why-tp3401175p3402842.html
Sent from the Boost - Dev mailing list archive at Nabble.com.