std::variant is implemented with variadic templates; but C++ doesn't have a "variadic switch" statement.
So std::visit cannot directly use a switch statement. Instead it's usually implemented as a recursive function with the hope that the compiler will unroll the recursion and optimize it into a switch.
This hope usually doesn't work out in practice.
AFAIK the usual implementation is statically generating an array of function pointers and dispatching based on the type discriminator. This works even less for inlining.
On my phone so cannot check, but I thought this was mostly a solved problem? Inlining/folding a jump table should be easy enough especially since the table can be const
edit: For a short while libc++ adopted mpark's variant visit, which AFAIK compiles down to switch case with some hand coding. AFAIK it had other problems so they rolled back to the constexpr array of function pointers.
