Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is an older version of Boost and was released in 2018. The current version is 1.89.0.

flat_static_buffer::max_size

Return the maximum sum of the input and output sequence sizes.

std::size_t constexpr
max_size() const;