Re: Help on class templates + friendship

[patrick <patrick at mail dot boxsoft dot com>]

Try a patch similar to this:

(note: my source is different than yours since i had to re-type it.
       Hence this patch will not work properly on your source.  It
       is meant only for demonstration purpose)

// begin
--- tf.cc-orig  Sat Oct 30 11:28:09 1999
+++ tf.cc       Sat Oct 30 11:28:44 1999
@@ -18,7 +18,7 @@
 class C
 {
  public:
-   template< typename TS, TV> friend class B;   // gcc chokes here?
+   template< typename TS, typename TV> friend class B;   // fixed now!
    C( int j = 0 ) : j_(j) { };
 
  private:
// end


This changed applied, the source compiles fine under:

% g++ -v
Reading specs from
/usr/local/egcs-1.1.2/lib/gcc-lib/i686-pc-linux-gnulibc1/egcs-2.91.66/specs
gcc version egcs-2.91.66 19990314 (egcs-1.1.2 release)





* Frederic Perez (frederic@ima.udg.es) [991030 10:48]:
> Hello everyone,
> 
> While porting a program to Linux using GCC (from SGI using MIPSpro) 
> I'm having troubles trying to establish a friendship between 
> two class templates, and I still don't know if this is due to 
> a restriction on the GCC compiler or to a wrong use of notation. 
> 
> What follows is an over-simplified version of the code that fails 
> to compile:
> 
> --------------------
> 
> template<typename TV> class C; // forward declaration
> 
> template<typename TS, typename TV>
> class B {
> public:
>   B(int i=0) : i_(i) {}
>   B& operator+=(const B& rhs) { i_ += rhs.i_; return *this; }
>   B& operator+=(const C<TV>& rhs) { i_ += rhs.j_; return *this; }
> private:
>   int i_;
> };
> 
> template<typename TV>
> class C {
> public:
>   template<typename TS, TV> friend class B; //makes it crash using gcc-2.51.1
>   C(int j=0) : j_(j) {}
> private:
>   int j_;
> };
> 
> int main() {
>   B<int, float> foo;
>   C<float> bar;
>   foo += bar;
> }

patrick
--
two guys walk into a bar... one of them goes "ouch!"