tiny::optional is a header-only C++ library for x86/x64 intended to be a drop-in replacement for std::optional with the twist that it does not require additional memory for bools, floats, doubles and raw pointers. For example, a standard optional double has twice the size of a raw double because of 7 padding bytes after the internal bool. These wasted bytes can have a notable impact on performance in memory bound applications. On the other hand, a tiny::optional double has the size of a double by exploiting unused bit patterns.For other types such as integers, it allows to specify a "sentinel" value that represents the empty state, again causing the optional to have the same size as the underlying type.
Quick example: https://godbolt.org/z/83xo9hdxT