/*
Using BC++ 4.5 I have run into the following two template code generation
quirks.  Because I don't subscribe to the DWP I though I would ask here
before submitting bug reports to Borland.
*/

// Note the template functions default argument t()
template < class t > void f( const t & = t() ) {}

// Note the lack of a default constructor
struct b { b( int ) {} };

int main()
{
#ifdef thisfails // As expected
 f(); // Could not find a match for 'f()'
#endif
#ifdef thisfailstoo // As expected
 f( 42 );
 f( 56.0 );
 f(); // Ambiguity between 'f(const double &)' and 'f(const int &)'
#endif
 f( 42 );
// Bug or quirk in template code generation rules?
 f(); // finds f( const int & ), understandable but surprising
// Bug or is a default constructor required because of the default argument?
 f( b( 42 ) ); // Could not find a match for 'b::b()'
 return 0;
}

The STL uses = t(), it must be there to enforce the availability
of default constructors then . . .

My apologies if the STL docs cover this, I haven't undertaken
round two of the ghostscript vs STL docs wrestling match yet.

In <gjohnsonD21Jp3.Kq1@netcom.com> gjohnson@netcom.com (Serendipitous Freelance Hacker) writes:
>/*
>Using BC++ 4.5 I have run into the following two template code generation
>quirks.  Because I don't subscribe to the DWP I though I would ask here
>before submitting bug reports to Borland.
>*/

>// Note the template functions default argument t()
>template < class t > void f( const t & = t() ) {}

>// Note the lack of a default constructor
>struct b { b( int ) {} };

>int main()
>{
> f( 42 );
>// Bug or quirk in template code generation rules?
> f(); // finds f( const int & ), understandable but surprising

A function f(const int& = int()) exists. It was created by the f(42) call.
It looks like this is how it should happen.

>// Bug or is a default constructor required because of the default argument?
> f( b( 42 ) ); // Could not find a match for 'b::b()'

If you provide a constructor for a class then the compiler will not generate
a default constructor. The template specifies that a default argument is created
by calling the default constructor. There is no default constructor so it is an
error. I don't think this is a bug, more the way templates work.

Regards,
Chris.