Thank you, Mr. Nagler for your comments and testing. My compiler is
Metrowerks C++ Pro. 5. I post the results of these cases again :

case 3:

  template<class T> int f( T a, T b =3D 1 );  // a declaration from header
  template<class T> int f( T a, T b ) {
    return a + b;
  }

  int main() {
    f( 1 );
    return 0;
  }

case 4:

  template<class T> int f( T a, T b =3D 1 ); // a declaration from header
  template<class T> int f( T a, T b =3D 1 ) {
    return a + b;
  }

  int main() {
    f( 1 );
    return 0;
  }

results:
         Metrowerks C++ Pro5, C++Builder4&5FT, Watcom C++, Visual C++ 6
case 3:         error               ok           error       error
case 4:          ok                error          ok         error

If the rule of default arguments for non-template function can be
applied to template functions, it seems that the compilers have a bug
except for C++Builder. Do all members of committee of C++ standard
agree with this conclusion?

in article Z7mjOAV=tpdLnzM0C=xLSnKkDmmX@4ax.com, Eric Nagler at
epn@eric-nagler.com wrote on 00.2.11 7:03 PM:

>> Thank you and please forgive my poor English.
>
> What poor English? I never saw it.

Thanks!

Masanori Ohshiro

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Hi,

    I have a question about function template and default arguments. May I
ask about the question?

1) The rule of default arguments says that a default argument shall not be
   redefined by a later declaration. Therefore, my compiler's behavior is
   as follows:

case 1:

  typedef int T;
  int f( T a, T b = 1 ); // a declaration from header
  int f( T a, T b ) // ok
  {
    return a + b;
  }

case 2:

  typedef int T;
  int f( T a, T b = 1 ); // a declaration from header
  int f( T a, T b = 1 )  // error!
  {
    return a + b;
  }

Sounds good, but...


2) On the other hand, my complier's behavior with function template is as
   follows:

case 3:

  template<class T> int f( T a, T b = 1 );  // a declaration from header
  template<class T> int f( T a, T b )
  {
    return a + b;
  }

  int main()
  {
    f( 1 ); // error! The complier says "function call f( int )
            // does not match 'f(T0, T0)'"
    return 0;
  }

case 4:

  template<class T> int f( T a, T b = 1 ); // a declaration from header
  template<class T> int f( T a, T b = 1 )
  {
    return a + b;
  }

  int main()
  {
    f( 1 ); // ok!
    return 0;
  }

I'm confused by these results of declaration for function template. Are
the results valid as standard C++?  Or dose my compiler have a bug? Do
you have any idea?

Thank you and please forgive my poor English.

Masanori Oshiro

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On Mon, 7 Feb 2000 03:30:28 CST, Masanori Ohshiro
<osilo@vision.tp.chiba-u.ac.jp> wrote:

>case 3:
>
>  template<class T> int f( T a, T b = 1 );  // a declaration from header
>  template<class T> int f( T a, T b )
>  {
>    return a + b;
>  }
>
>  int main()
>  {
>    f( 1 ); // error! The complier says "function call f( int )
>            // does not match 'f(T0, T0)'"
>    return 0;
>  }

Yes, VC++ 6.0 gives the error, but BCB4 and Comeau compile it OK. In
this case it certainly appears to be a Microsoft bug.

>  template<class T> int f( T a, T b = 1 ); // a declaration from header
>  template<class T> int f( T a, T b = 1 )
>  {
>    return a + b;
>  }
>
>  int main()
>  {
>    f( 1 ); // ok!
>    return 0;
>  }

In this case all 3 compilers yield an error. Which compiler are you
using?

>Thank you and please forgive my poor English.

What poor English? I never saw it.


EriC++

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