gcc/testsuite/g++.dg/cpp2a/concepts-requires31.C

   1 // PR c++/107179
   2 // { dg-do compile { target c++20 } }
   3
   4 template<bool B> struct bool_constant { static constexpr bool value = B; };
   5
   6 template<typename T>
   7   struct is_implicitly_default_constructible
   8   : bool_constant<requires { T(); }>
   9   { };
  10
  11 struct X { private: X(); };
  12 struct Y { };
  13
  14 static_assert( !is_implicitly_default_constructible<X>::value );
  15 static_assert(  is_implicitly_default_constructible<Y>::value );