template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(const basic_string<charT, traits, Allocator>& lhs,
const basic_string<charT, traits, Allocator>& rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(const basic_string<charT, traits, Allocator>& lhs, const charT* rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(basic_string<charT, traits, Allocator>&& lhs,
const basic_string<charT, traits, Allocator>& rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(basic_string<charT, traits, Allocator>&& lhs, const charT* rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(basic_string<charT, traits, Allocator>&& lhs,
basic_string<charT, traits, Allocator>&& rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(const basic_string<charT, traits, Allocator>& lhs,
basic_string<charT, traits, Allocator>&& rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(const charT* lhs, basic_string<charT, traits, Allocator>&& rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(const charT* lhs, const basic_string<charT, traits, Allocator>& rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(charT lhs, const basic_string<charT, traits, Allocator>& rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(charT lhs, basic_string<charT, traits, Allocator>&& rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(const basic_string<charT, traits, Allocator>& lhs, charT rhs);
template<class charT, class traits, class Allocator>
constexpr basic_string<charT, traits, Allocator>
operator+(basic_string<charT, traits, Allocator>&& lhs, charT rhs);
template<class charT, class traits, class Allocator>
constexpr bool
operator==(const basic_string<charT, traits, Allocator>& lhs,
const basic_string<charT, traits, Allocator>& rhs) noexcept;
template<class charT, class traits, class Allocator>
constexpr bool operator==(const basic_string<charT, traits, Allocator>& lhs,
const charT* rhs);
template<class charT, class traits, class Allocator>
constexpr see below operator<=>(const basic_string<charT, traits, Allocator>& lhs,
const basic_string<charT, traits, Allocator>& rhs) noexcept;
template<class charT, class traits, class Allocator>
constexpr see below operator<=>(const basic_string<charT, traits, Allocator>& lhs,
const charT* rhs);
template<class charT, class traits, class Allocator>
constexpr void
swap(basic_string<charT, traits, Allocator>& lhs,
basic_string<charT, traits, Allocator>& rhs)
noexcept(noexcept(lhs.swap(rhs)));
template<class charT, class traits, class Allocator>
basic_istream<charT, traits>&
operator>>(basic_istream<charT, traits>& is, basic_string<charT, traits, Allocator>& str);
template<class charT, class traits, class Allocator>
basic_ostream<charT, traits>&
operator<<(basic_ostream<charT, traits>& os,
const basic_string<charT, traits, Allocator>& str);
template<class charT, class traits, class Allocator>
basic_istream<charT, traits>&
getline(basic_istream<charT, traits>& is,
basic_string<charT, traits, Allocator>& str,
charT delim);
template<class charT, class traits, class Allocator>
basic_istream<charT, traits>&
getline(basic_istream<charT, traits>&& is,
basic_string<charT, traits, Allocator>& str,
charT delim);
template<class charT, class traits, class Allocator>
basic_istream<charT, traits>&
getline(basic_istream<charT, traits>& is,
basic_string<charT, traits, Allocator>& str);
template<class charT, class traits, class Allocator>
basic_istream<charT, traits>&
getline(basic_istream<charT, traits>&& is,
basic_string<charT, traits, Allocator>& str);
template<class charT, class traits, class Allocator, class U>
constexpr typename basic_string<charT, traits, Allocator>::size_type
erase(basic_string<charT, traits, Allocator>& c, const U& value);
template<class charT, class traits, class Allocator, class Predicate>
constexpr typename basic_string<charT, traits, Allocator>::size_type
erase_if(basic_string<charT, traits, Allocator>& c, Predicate pred);