Re: function template specialization used with default parameter

From:
Victor Bazarov <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Wed, 07 Jan 2009 10:24:29 -0500
Message-ID:
<gk2hfd$soj$2@news.datemas.de>
Leandro Melo wrote:

On 7 jan, 11:57, Peter K?mmel <syntheti...@gmx.net> wrote:

What's wrong with this code:

template<typename T>
void foo(T * = 0) {}

template<>
void foo<int>(int*) {}

void fo(){
    foo<int>();

}

MSVC couldn't convert the default parameter from T* to int*.
A compiler bug?


The code below compiled (and ran) fine with GCC 4.1.2 (from codepad)
and MSVC 2002 (the version I have hands-on right now). It also
compiled fine in comeau online. Which version of MSVC are you using?

template<typename T>
void foo(T * = 0){std::cout << "T";}

template<>
void foo<int>(int*){std::cout << "int";}

int main()
{
    foo<int>();
}


So, which one would be used? BTW, VC++ 2008 (v14 I guess) complains
about conversion from T* to int*. Adding (T*) in front of the 0 fixes
it (as Michael DOUBEZ suggested). And it outputs 'int', not 'T', which
is a bit perplexing -- how does the default argument in the original
template get applied in the specialisation? If the specialisation is to
be called, the the argument is missing, isn't it?

V
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