libcxx/test/std/utilities/meta/meta.trans/meta.trans.ref/add_lvalue_ref.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 // add_lvalue_reference
  12 // If T names a referenceable type then the member typedef type
  13 //    shall name T&; otherwise, type shall name T.
  14
  15 #include <type_traits>
  16 #include "test_macros.h"
  17
  18 template <class T, class U>
  19 void test_add_lvalue_reference()
  20 {
  21     ASSERT_SAME_TYPE(U, typename std::add_lvalue_reference<T>::type);
  22 #if TEST_STD_VER > 11
  23     ASSERT_SAME_TYPE(U, std::add_lvalue_reference_t<T>);
  24 #endif
  25 }
  26
  27 template <class F>
  28 void test_function0()
  29 {
  30     ASSERT_SAME_TYPE(F&, typename std::add_lvalue_reference<F>::type);
  31 #if TEST_STD_VER > 11
  32     ASSERT_SAME_TYPE(F&, std::add_lvalue_reference_t<F>);
  33 #endif
  34 }
  35
  36 template <class F>
  37 void test_function1()
  38 {
  39     ASSERT_SAME_TYPE(F, typename std::add_lvalue_reference<F>::type);
  40 #if TEST_STD_VER > 11
  41     ASSERT_SAME_TYPE(F, std::add_lvalue_reference_t<F>);
  42 #endif
  43 }
  44
  45 struct Foo {};
  46
  47 int main(int, char**)
  48 {
  49     test_add_lvalue_reference<void, void>();
  50     test_add_lvalue_reference<int, int&>();
  51     test_add_lvalue_reference<int[3], int(&)[3]>();
  52     test_add_lvalue_reference<int&, int&>();
  53     test_add_lvalue_reference<const int&, const int&>();
  54     test_add_lvalue_reference<int*, int*&>();
  55     test_add_lvalue_reference<const int*, const int*&>();
  56     test_add_lvalue_reference<Foo, Foo&>();
  57
  58 //  LWG 2101 specifically talks about add_lvalue_reference and functions.
  59 //  The term of art is "a referenceable type", which a cv- or ref-qualified function is not.
  60     test_function0<void()>();
  61     test_function1<void() const>();
  62     test_function1<void() &>();
  63     test_function1<void() &&>();
  64     test_function1<void() const &>();
  65     test_function1<void() const &&>();
  66
  67 //  But a cv- or ref-qualified member function *is* "a referenceable type"
  68     test_function0<void (Foo::*)()>();
  69     test_function0<void (Foo::*)() const>();
  70     test_function0<void (Foo::*)() &>();
  71     test_function0<void (Foo::*)() &&>();
  72     test_function0<void (Foo::*)() const &>();
  73     test_function0<void (Foo::*)() const &&>();
  74
  75   return 0;
  76 }