libcxx/test/std/strings/string.view/string.view.io/stream_insert_decl_present.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: !stdlib=libc++ && (c++03 || c++11 || c++14)
  10
  11 // <string_view>
  12
  13 // template<class charT, class traits, class Allocator>
  14 //   basic_ostream<charT, traits>&
  15 //   operator<<(basic_ostream<charT, traits>& os,
  16 //              const basic_string_view<charT,traits> str);
  17
  18 #include <iosfwd>
  19 #include <string_view>
  20 #include <utility>
  21
  22 template <class SV, class = void>
  23 struct HasDecl : std::false_type {};
  24 template <class SV>
  25 struct HasDecl<SV, decltype(static_cast<void>(std::declval<std::ostream&>() << std::declval<SV&>()))> : std::true_type {
  26 };
  27
  28 static_assert(HasDecl<std::string_view>::value, "streaming operator declaration not present");