🚀 go-pugleaf

In the following program, I find that a friend binary operator - and a
member operator - w/ no args cannot co-exist in the same template class;
the result of an attempt is a link error.

Note that if the member minus without args is replaced by a friend
minus with one arg, the problem disappears.

First the compiler:  gcc 2.3.3, original sources, on a sparc (sunos
4.1.2).

The compiler output:
==============================================================================
g++ -v -Wall bug.cc
Reading specs from /blossom/lib/gcc-lib/sun4/2.3.3/specs
gcc version 2.3.3
 /blossom/lib/gcc-lib/sun4/2.3.3/cpp -lang-c++ -v -undef -D__GNUC__=2 -D__GNUG__=2 -D__cplusplus -Dsparc -Dsun -Dunix -D__sparc__ -D__sun__ -D__unix__ -D__sparc -D__sun -D__unix -Wall bug.cc /usr/tmp/cca05901.i
GNU CPP version 2.3.3 (sparc)
 /blossom/lib/gcc-lib/sun4/2.3.3/cc1plus /usr/tmp/cca05901.i -quiet -dumpbase bug.cc -Wall -version -o /usr/tmp/cca05901.s
GNU C++ version 2.3.3 (sparc) compiled by GNU C version 2.3.3.
 as -o /usr/tmp/cca059011.o /usr/tmp/cca05901.s
 /blossom/lib/gcc-lib/sun4/2.3.3/ld -e start -dc -dp /lib/crt0.o -L/blossom/lib/gcc-lib/sun4/2.3.3 -L/blossom/lib /usr/tmp/cca059011.o -lg++ -lgcc -lc -lgcc
ld: Undefined symbol 
   ___mi__FRCt6Number1ZiT0 
collect: /usr/bin/ld returned 2 exit status
==============================================================================

The source:
==============================================================================
template<class T>
class Number
{
public:
friend Number operator- (const Number& src1, const Number& src2);
  Number operator- () const;
  T data;
};

template <class T>
inline Number<T>
operator- (const Number<T>& src1, const Number<T>& src2)
{
  Number<T> dst;
  dst.data = src1.data - src2.data;
  return dst;
}

main()
{
  Number<int> a, b, c;
  b.data = 1;
  c.data = 2;
  a = b - c;
}
==============================================================================

Doug Moore
(dougm@cs.rice.edu)