libcxx/test/std/utilities/meta/meta.unary/meta.unary.prop/is_empty.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 // type_traits
  10
  11 // is_empty
  12
  13 // T is a non-union class type with:
  14 //  no non-static data members,
  15 //  no unnamed bit-fields of non-zero length,
  16 //  no virtual member functions,
  17 //  no virtual base classes,
  18 //  and no base class B for which is_empty_v<B> is false.
  19
  20
  21 #include <type_traits>
  22 #include "test_macros.h"
  23
  24 template <class T>
  25 void test_is_empty()
  26 {
  27     static_assert( std::is_empty<T>::value, "");
  28     static_assert( std::is_empty<const T>::value, "");
  29     static_assert( std::is_empty<volatile T>::value, "");
  30     static_assert( std::is_empty<const volatile T>::value, "");
  31 #if TEST_STD_VER > 14
  32     static_assert( std::is_empty_v<T>, "");
  33     static_assert( std::is_empty_v<const T>, "");
  34     static_assert( std::is_empty_v<volatile T>, "");
  35     static_assert( std::is_empty_v<const volatile T>, "");
  36 #endif
  37 }
  38
  39 template <class T>
  40 void test_is_not_empty()
  41 {
  42     static_assert(!std::is_empty<T>::value, "");
  43     static_assert(!std::is_empty<const T>::value, "");
  44     static_assert(!std::is_empty<volatile T>::value, "");
  45     static_assert(!std::is_empty<const volatile T>::value, "");
  46 #if TEST_STD_VER > 14
  47     static_assert(!std::is_empty_v<T>, "");
  48     static_assert(!std::is_empty_v<const T>, "");
  49     static_assert(!std::is_empty_v<volatile T>, "");
  50     static_assert(!std::is_empty_v<const volatile T>, "");
  51 #endif
  52 }
  53
  54 class Empty {};
  55 struct NotEmpty { int foo; };
  56
  57 class VirtualFn
  58 {
  59     virtual ~VirtualFn();
  60 };
  61
  62 union Union {};
  63
  64 struct EmptyBase    : public Empty {};
  65 struct VirtualBase  : virtual Empty {};
  66 struct NotEmptyBase : public NotEmpty {};
  67
  68 struct StaticMember    { static int foo; };
  69 struct NonStaticMember {        int foo; };
  70
  71 struct bit_zero
  72 {
  73     int :  0;
  74 };
  75
  76 struct bit_one
  77 {
  78     int :  1;
  79 };
  80
  81 int main(int, char**)
  82 {
  83     test_is_not_empty<void>();
  84     test_is_not_empty<int&>();
  85     test_is_not_empty<int>();
  86     test_is_not_empty<double>();
  87     test_is_not_empty<int*>();
  88     test_is_not_empty<const int*>();
  89     test_is_not_empty<char[3]>();
  90     test_is_not_empty<char[]>();
  91     test_is_not_empty<Union>();
  92     test_is_not_empty<NotEmpty>();
  93     test_is_not_empty<VirtualFn>();
  94     test_is_not_empty<VirtualBase>();
  95     test_is_not_empty<NotEmptyBase>();
  96     test_is_not_empty<NonStaticMember>();
  97 //    test_is_not_empty<bit_one>();
  98
  99     test_is_empty<Empty>();
 100     test_is_empty<EmptyBase>();
 101     test_is_empty<StaticMember>();
 102     test_is_empty<bit_zero>();
 103
 104   return 0;
 105 }