1 // PR c++/61745
2 
3 template <typename INT,INT P> class Zp;
4 
5 template <typename INT,INT P>
6 Zp<INT,P> operator-(const Zp<INT,P>& a, const Zp<INT,P>& b);
7 
8 template <typename INT,INT P>
9 class Zp {
10 public:
11   static const INT p = P;
12 private:
13   INT val;
14 public:
Zp()15   Zp() : val(0) {}
Zp(INT x)16   Zp( INT x ) : val(x%p) { if (x < 0 ) x+= p; }
17 
18   // this compiles only if the following definition is moved
19   // AFTER the friend declaration
20   Zp  operator-() const { return Zp(p-val); }
21   // In C++2A, we have an unqualified-id (operator-) followed by
22   // '<', and name lookup found a function.
23   friend Zp<INT,P> operator- <>(const Zp<INT,P>& a, const Zp<INT,P>& b); // { dg-error "20:declaration of .operator\\-. as non-function" "" { target c++17_down } }
24   // { dg-error "expected" "" { target c++17_down } .-1 }
25 };
26