This is a very interesting feature, especially if comptime can become a true language superset with features such as the ability for seamless type-level programming, leveraging `const fn` code throughout. This would unlock the potential for having true dependent types in (the comptime portion of) Rust programs, and write arbitrary end-to-end compiler-verified proofs about code that will ultimately run in the final program.
Oh my gosh, that would be incredible! In one of my rust projects, I used enum dispatch so simple functions could be inlined, but it used a slightly hacky macro that couldn't do static dispatch. One of those things that comptime matches very well.
Love this. Borrow all the good ideas! Would also enjoy compile-time trig functions, exponents etc so we are not invoking lazy/static/once-cell/lazy-cell etc.