mp_units::operator+

[[nodiscard]]
constexpr
basic_fixed_string<CharT, 1 + N>
operator+(
    CharT const lhs,
    basic_fixed_string const& rhs) noexcept;

[[nodiscard]]
constexpr
basic_fixed_string<CharT, N + 1>
operator+(
    basic_fixed_string const& lhs,
    CharT rhs) noexcept;

[[nodiscard]]
constexpr
basic_fixed_string<CharT, N + N2>
operator+(
    basic_fixed_string const& lhs,
    basic_fixed_string<CharT, N2> const& rhs) noexcept;

[[nodiscard]]
consteval
basic_fixed_string<CharT, N + N2 ‐ 1>
operator+(
    basic_fixed_string const& lhs,
    CharT const(& rhs)[N2]) noexcept;

[[nodiscard]]
constexpr
symbol_text<N + N2, M + M2>
operator+(
    symbol_text const& lhs,
    symbol_text<N2, M2> const& rhs);

[[nodiscard]]
consteval
basic_fixed_string<CharT, N1 + N ‐ 1>
operator+(
    CharT const(& lhs)[N1],
    basic_fixed_string const& rhs) noexcept;