clang/test/SemaCXX/GH83461.cpp

   1 // RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
   2
   3 struct S {
   4   template<typename Ty = int>
   5   friend void foo(auto){}
   6
   7   template<typename Ty = int, typename Tz>
   8   friend void foo2(){}
   9 };
  10
  11 template<typename T>
  12 struct TemplS {
  13   template<typename Ty = int>
  14   friend void foo3(auto){}
  15
  16   template<typename Ty = int, typename Tz>
  17   friend void foo4(){}
  18 };
  19
  20 void Inst() {
  21   TemplS<int>();
  22 }
  23 // expected-error@+2{{template parameter missing a default argument}}
  24 // expected-note@+1{{previous default template argument defined here}}
  25 template<typename T = int, typename U>
  26 struct ClassTempl{};
  27
  28 struct HasFriendClassTempl {
  29   // expected-error@+1{{default template argument not permitted on a friend template}}
  30   template<typename T = int, typename U>
  31   friend struct Friend;
  32
  33   // expected-error@+3{{cannot define a type in a friend declaration}}
  34   // expected-error@+1{{default template argument not permitted on a friend template}}
  35   template<typename T = int, typename U>
  36   friend struct Friend2{};
  37 };
  38
  39 template<typename Ty>
  40 struct HasFriendClassTempl2 {
  41   // expected-error@+3{{template parameter missing a default argument}}
  42   // expected-note@+2{{previous default template argument defined here}}
  43   // expected-note@#INST2{{in instantiation of template class}}
  44   template<typename T = int, typename U>
  45   friend struct Friend;
  46 };
  47
  48 void Inst2() {
  49   HasFriendClassTempl2<int>(); // #INST2
  50 }
  51
  52 // expected-error@+2{{template parameter missing a default argument}}
  53 // expected-note@+1{{previous default template argument defined here}}
  54 template<typename T = int, typename U>
  55 static constexpr U VarTempl;
  56
  57 // expected-error@+2{{template parameter missing a default argument}}
  58 // expected-note@+1{{previous default template argument defined here}}
  59 template<typename T = int, typename U>
  60 using TypeAlias = U;