clang/test/CXX/temp/temp.arg/temp.arg.template/p3-2a.cpp

   1 // RUN:  %clang_cc1 -std=c++2a -frelaxed-template-template-args -verify %s
   2
   3 template<typename T> concept C = T::f(); // #C
   4 template<typename T> concept D = C<T> && T::g();
   5 template<typename T> concept F = T::f(); // #F
   6 template<template<C> class P> struct S1 { }; // #S1
   7
   8 template<C> struct X { };
   9
  10 template<D> struct Y { }; // #Y
  11 template<typename T> struct Z { };
  12 template<F> struct W { }; // #W
  13 S1<X> s11;
  14 S1<Y> s12;
  15 // expected-error@-1 {{template template argument 'Y' is more constrained than template template parameter 'P'}}
  16 // expected-note@#S1 {{'P' declared here}}
  17 // expected-note@#Y {{'Y' declared here}}
  18 S1<Z> s13;
  19 S1<W> s14;
  20 // expected-error@-1 {{template template argument 'W' is more constrained than template template parameter 'P'}}
  21 // expected-note@#S1 {{'P' declared here}}
  22 // expected-note@#W {{'W' declared here}}
  23 // expected-note@#F 1-2{{similar constraint expressions not considered equivalent}}
  24 // expected-note@#C 1-2{{similar constraint}}
  25
  26 template<template<typename> class P> struct S2 { };
  27
  28 S2<X> s21;
  29 S2<Y> s22;
  30 S2<Z> s23;
  31
  32 template <template <typename...> class C>
  33 struct S3;
  34
  35 template <C T>
  36 using N = typename T::type;
  37
  38 using s31 = S3<N>;
  39 using s32 = S3<Z>;
  40
  41 template<template<typename T> requires C<T> class P> struct S4 { }; // #S4
  42
  43 S4<X> s41;
  44 S4<Y> s42;
  45 // expected-error@-1 {{template template argument 'Y' is more constrained than template template parameter 'P'}}
  46 // expected-note@#S4 {{'P' declared here}}
  47 // expected-note@#Y {{'Y' declared here}}
  48 S4<Z> s43;
  49 S4<W> s44;
  50 // expected-error@-1 {{template template argument 'W' is more constrained than template template parameter 'P'}}
  51 // expected-note@#S4 {{'P' declared here}}
  52 // expected-note@#W {{'W' declared here}}
  53
  54 template<template<typename T> requires C<T> typename U> struct S5 {
  55   template<typename T> static U<T> V;
  56 };
  57
  58 struct Nothing {};
  59
  60 // FIXME: Wait the standard to clarify the intent.
  61 template<> template<> Z<Nothing> S5<Z>::V<Nothing>;