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 // <string_view>
10 
11 // template<class charT, class traits, class Allocator>
12 //   basic_ostream<charT, traits>&
13 //   operator<<(basic_ostream<charT, traits>& os,
14 //              const basic_string_view<charT,traits> str);
15 
16 #include <string_view>
17 #include <iosfwd>
18 
19 template <class SV, class = void>
20 struct HasDecl : std::false_type {};
21 template <class SV>
22 struct HasDecl<SV, decltype(static_cast<void>(std::declval<std::ostream&>() << std::declval<SV&>()))> : std::true_type {};
23 
24 static_assert(HasDecl<std::string_view>::value, "streaming operator declaration not present");
25