libcxx/test/std/concepts/concepts.callable/concept.equiv/equivalence_relation.subsumption.compile.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14, c++17
  10
  11 // template<class F, class... Args>
  12 // concept equivalence_relation;
  13
  14 #include <concepts>
  15
  16 struct S1 {};
  17 struct S2 {};
  18
  19 struct R {
  20   bool operator()(S1, S1) const;
  21   bool operator()(S1, S2) const;
  22   bool operator()(S2, S1) const;
  23   bool operator()(S2, S2) const;
  24 };
  25
  26 // clang-format off
  27 template<class F, class T, class U>
  28 requires std::relation<F, T, U>
  29 constexpr bool check_equivalence_relation_subsumes_relation() {
  30   return false;
  31 }
  32
  33 template<class F, class T, class U>
  34 requires std::equivalence_relation<F, T, U> && true
  35 constexpr bool check_equivalence_relation_subsumes_relation() {
  36   return true;
  37 }
  38 // clang-format on
  39
  40 static_assert(check_equivalence_relation_subsumes_relation<int (*)(int, int), int, int>());
  41 static_assert(check_equivalence_relation_subsumes_relation<int (*)(int, double), int, double>());
  42 static_assert(check_equivalence_relation_subsumes_relation<R, S1, S1>());
  43 static_assert(check_equivalence_relation_subsumes_relation<R, S1, S2>());
  44
  45 // clang-format off
  46 template<class F, class T, class U>
  47 requires std::relation<F, T, U> && true
  48 constexpr bool check_relation_subsumes_equivalence_relation() {
  49   return true;
  50 }
  51
  52 template<class F, class T, class U>
  53 requires std::equivalence_relation<F, T, U>
  54 constexpr bool check_relation_subsumes_equivalence_relation() {
  55   return false;
  56 }
  57 // clang-format on
  58
  59 static_assert(check_relation_subsumes_equivalence_relation<int (*)(int, int), int, int>());
  60 static_assert(check_relation_subsumes_equivalence_relation<int (*)(int, double), int, double>());
  61 static_assert(check_relation_subsumes_equivalence_relation<R, S1, S1>());
  62 static_assert(check_relation_subsumes_equivalence_relation<R, S1, S2>());
  63
  64 // clang-format off
  65 template<class F, class T, class U>
  66 requires std::equivalence_relation<F, T, T> && std::equivalence_relation<F, U, U>
  67 constexpr bool check_equivalence_relation_subsumes_itself() {
  68   return false;
  69 }
  70
  71 template<class F, class T, class U>
  72 requires std::equivalence_relation<F, T, U>
  73 constexpr bool check_equivalence_relation_subsumes_itself() {
  74   return true;
  75 }
  76 // clang-format on
  77
  78 static_assert(
  79     check_equivalence_relation_subsumes_itself<int (*)(int, int), int, int>());
  80 static_assert(check_equivalence_relation_subsumes_itself<R, S1, S1>());