zero-sized arrays not allowed within templated struct definitions?

[Seapig6@aol.com]

[if you need to reply to me directly, please use the kosak@cs.cmu.edu address]

Is there a reason why the g++ extension that permits zero-length arrays is not
permitted within templated structs?  It does seem to be permitted within 
templated functions:

% cat zero.cc && g++ -v && g++ zero.cc
void func()
{
  int a[0]; //permitted
}


template<int N> void tfunc()
{
   int a[N]; //permitted
}


struct cow {
  int a[0]; //permitted
};


template<int N> struct tcow {
  int a[N]; //NOT permitted
};

int main()
{
   func();
   tfunc<0>();
   cow x;
   tcow<0> tx;
}
Reading specs from 
/afs/cs.cmu.edu/project/cmcl-kosak/various-gcc/egcs-19990517/i386_linux3/lib/g
cc-lib/i686-pc-linux-gnu/egcs-2.93.22/specs
gcc version egcs-2.93.22 19990517 (gcc2 ss-980929 experimental)
zero.cc: In instantiation of `tcow<0>':
zero.cc:27:   instantiated from here
zero.cc:19: creating array with size `0'