compilation error with function template parameter
 

The following quesion is NOT a HOMEWORK problem.

Consider the following x.cpp:

#include <cstdlib>
#include <iostream>

using namespace std;

template<class T>
inline void fn(void (T::*memfnPtr)())
{
return;
}

class Test
{
public:
void member();
void member() const;
};

inline void Test::member(void)
{
cout << "Test::member() called" << endl;

return;
}

inline void Test::member(void) const
{
cout << "Test::member() const called" << endl;

return;
}

int main()
{
fn(&Test::member);

return EXIT_SUCCESS;
}

When I compile this program with g++3.4.3 as
g++ -std=c++98 -pedantic -Wall -Wextra x.cpp

I get the following compilation error:
x.cpp: In function `int main()':
x.cpp:35: error: no matching function for call to `fn(<unknown type>)'

Why do I get this compilation error ? Kindly explan. Please help to
fix this error. I do not get the compilation error, if I have the
function template 'fn()' as follows:
template<class T>
inline void fn(void (T::*memfnPtr)() const)
{
return;
}

Note that in the above modified version of 'fn()', I have added
'const' to the parameter. Why don't I get the compilation error
for this version but I do get for the earlier version ?

Thanks
V.Subramanian

Re: compilation error with function template parameter
 

On 8/27/2010 8:09 AM, subramanian100in@yahoo.com, India wrote:
> The following quesion is NOT a HOMEWORK problem.
>
> Consider the following x.cpp:
>
> #include<cstdlib>
> #include<iostream>
>
> using namespace std;
>
> template<class T>
> inline void fn(void (T::*memfnPtr)())
> {
> return;
> }
>
> class Test
> {
> public:
> void member();
> void member() const;
> };
>
> inline void Test::member(void)
> {
> cout<< "Test::member() called"<< endl;
>
> return;
> }
>
> inline void Test::member(void) const
> {
> cout<< "Test::member() const called"<< endl;
>
> return;
> }
>
> int main()
> {
> fn(&Test::member);
>
> return EXIT_SUCCESS;
> }
>
> When I compile this program with g++3.4.3 as
> g++ -std=c++98 -pedantic -Wall -Wextra x.cpp
>
> I get the following compilation error:
> x.cpp: In function `int main()':
> x.cpp:35: error: no matching function for call to `fn(<unknown type>)'
>
> Why do I get this compilation error ? Kindly explan. Please help to
> fix this error. I do not get the compilation error, if I have the
> function template 'fn()' as follows:
> template<class T>
> inline void fn(void (T::*memfnPtr)() const)
> {
> return;
> }
>
> Note that in the above modified version of 'fn()', I have added
> 'const' to the parameter. Why don't I get the compilation error
> for this version but I do get for the earlier version ?

Most likely a bug in the compiler. Comeau C++ accepts the code without
a hiccup. So does Visual C++ 2008 (it points out that the argument of
the template 'fn' is unused, but it's a warning).

V
--
I do not respond to top-posted replies, please don't ask

Re: compilation error with function template parameter
 

On Aug 27, 8:24*pm, Victor Bazarov <v.baza...@comcast.invalid> wrote:
> On 8/27/2010 8:09 AM, subramanian10...@yahoo.com, India wrote:
>
>
>
>
>
> > The following quesion is NOT a HOMEWORK problem.
>
> > Consider the following x.cpp:
>
> > #include<cstdlib>
> > #include<iostream>
>
> > using namespace std;
>
> > template<class T>
> > inline void fn(void (T::*memfnPtr)())
> > {
> > * * * * *return;
> > }
>
> > class Test
> > {
> > public:
> > * * *void member();
> > * * *void member() const;
> > };
>
> > inline void Test::member(void)
> > {
> > * * * * *cout<< *"Test::member() called"<< *endl;
>
> > * * * * *return;
> > }
>
> > inline void Test::member(void) const
> > {
> > * * * * *cout<< *"Test::member() const called"<< *endl;
>
> > * * * * *return;
> > }
>
> > int main()
> > {
> > * * * * *fn(&Test::member);
>
> > * * * * *return EXIT_SUCCESS;
> > }
>
> > When I compile this program with g++3.4.3 as
> > g++ -std=c++98 -pedantic -Wall -Wextra x.cpp
>
> > I get the following compilation error:
> > x.cpp: In function `int main()':
> > x.cpp:35: error: no matching function for call to `fn(<unknown type>)'
>
> > Why do I get this compilation error ? Kindly explan. Please help to
> > fix this error. I do not get the compilation error, if I have the
> > function template 'fn()' as follows:
> > template<class T>
> > inline void fn(void (T::*memfnPtr)() const)
> > {
> > * * * * *return;
> > }
>
> > Note that in the above modified version of 'fn()', I have added
> > 'const' to the parameter. Why don't I get the compilation error
> > for this version but I do get for the earlier version ?
>
> Most likely a bug in the compiler. *Comeau C++ accepts the code without
> a hiccup. *So does Visual C++ 2008 (it points out that the argument of
> the template 'fn' is unused, but it's a warning).
>
> V
> --
> I do not respond to top-posted replies, please don't ask


Additional info: On g++ 4.4.3-4ubuntu5, the above code is fine too.

3.4.3 was released in November 4, 2004, probably it's too old to
differentiate the pointers to member functions overloaded by const?