clang/test/Parser/cxx2a-concept-declaration.cpp

   1 // Support parsing of concepts
   2
   3 // RUN:  %clang_cc1 -std=c++20 -verify %s
   4 template<typename T> concept C1 = true; // expected-note 2{{previous}}
   5
   6 template<typename T> concept C1 = true; // expected-error{{redefinition}}
   7
   8 template<concept T> concept D1 = true;
   9 // expected-error@-1{{expected template parameter}}
  10 // expected-error@-2{{concept template parameter list must have at least one parameter; explicit specialization of concepts is not allowed}}
  11
  12 template<template<typename> concept T> concept D2 = true;
  13 // expected-error@-1{{expected identifier}}
  14 // expected-error@-2{{template template parameter requires 'class' or 'typename' after the parameter list}}
  15 // expected-error@-3{{concept template parameter list must have at least one parameter; explicit specialization of concepts is not allowed}}
  16
  17 struct S1 {
  18   template<typename T> concept C1 = true; // expected-error {{concept declarations may only appear in global or namespace scope}}
  19 };
  20
  21 extern "C++" {
  22   template<typename T> concept C1 = true; // expected-error{{redefinition}}
  23 }
  24
  25 template<typename A>
  26 template<typename B>
  27 concept C2 = true; // expected-error {{extraneous template parameter list in concept definition}}
  28
  29 template<typename T> concept C3 = true; // expected-note {{previous}} expected-note {{previous}}
  30 int C3; // expected-error {{redefinition}}
  31 struct C3 {}; // expected-error {{redefinition}}
  32
  33 struct C4 {}; // expected-note{{previous definition is here}}
  34 template<typename T> concept C4 = true;
  35 // expected-error@-1{{redefinition of 'C4' as different kind of symbol}}
  36
  37 // TODO: Add test to prevent explicit specialization, partial specialization
  38 // and explicit instantiation of concepts.
  39
  40 template<typename T, T v>
  41 struct integral_constant { static constexpr T value = v; };
  42
  43 namespace N {
  44   template<typename T> concept C5 = true;
  45 }
  46 using N::C5;
  47
  48 template <bool word> concept C6 = integral_constant<bool, wor>::value;
  49 // expected-error@-1{{use of undeclared identifier 'wor'; did you mean 'word'?}}
  50 // expected-note@-2{{'word' declared here}}
  51
  52 template<typename T> concept bool C7 = true;
  53 // expected-warning@-1{{ISO C++20 does not permit the 'bool' keyword after 'concept'}}
  54
  55 template<> concept C8 = false;
  56 // expected-error@-1{{concept template parameter list must have at least one parameter; explicit specialization of concepts is not allowed}}
  57
  58 template<> concept C7<int> = false;
  59 // expected-error@-1{{name defined in concept definition must be an identifier}}
  60
  61 template<typename T> concept N::C9 = false;
  62 // expected-error@-1{{name defined in concept definition must be an identifier}}
  63
  64 class A { };
  65 // expected-note@-1{{'A' declared here}}
  66
  67 template<typename T> concept A::C10 = false;
  68 // expected-error@-1{{expected namespace name}}
  69
  70 template<typename T> concept operator int = false;
  71 // expected-error@-1{{name defined in concept definition must be an identifier}}
  72
  73 template<bool x> concept C11 = 2; // expected-error {{atomic constraint must be of type 'bool' (found 'int')}}
  74 template<bool x> concept C12 = 2 && x; // expected-error {{atomic constraint must be of type 'bool' (found 'int')}}
  75 template<bool x> concept C13 = x || 2 || x; // expected-error {{atomic constraint must be of type 'bool' (found 'int')}}
  76 template<bool x> concept C14 = 8ull && x || x; // expected-error {{atomic constraint must be of type 'bool' (found 'unsigned long long')}}
  77 template<typename T> concept C15 = sizeof(T); // expected-error {{atomic constraint must be of type 'bool'}}
  78 template<typename T> concept C16 = true && (0 && 0); // expected-error {{atomic constraint must be of type 'bool' (found 'int')}}
  79 // expected-warning@-1{{use of logical '&&' with constant operand}}
  80 // expected-note@-2{{use '&' for a bitwise operation}}
  81 // expected-note@-3{{remove constant to silence this warning}}
  82 template<typename T> concept C17 = T{};
  83 static_assert(!C17<bool>);
  84 template<typename T> concept C18 = (bool&&)true;
  85 static_assert(C18<int>);
  86 template<typename T> concept C19 = (const bool&)true;
  87 static_assert(C19<int>);
  88 template<typename T> concept C20 = (const bool)true;
  89 static_assert(C20<int>);
  90 template <bool c> concept C21 = integral_constant<bool, c>::value && true;
  91 static_assert(C21<true>);
  92 static_assert(!C21<false>);
  93 template <bool c> concept C22 = integral_constant<bool, c>::value;
  94 static_assert(C22<true>);
  95 static_assert(!C22<false>);
  96
  97 template <bool word> concept C23 = integral_constant<bool, wor>::value;
  98 // expected-error@-1{{use of undeclared identifier 'wor'; did you mean 'word'?}}
  99 // expected-note@-2{{'word' declared here}}
 100