[spoiler]

You can write Rust macros in Rust too, if you wish, but it's a bit more involved (https://doc.rust-lang.org/reference/procedural-macros.html). I realise this isn't the same as constexpr, but I'd argue it's nicer.

Rust also has const generics (but they are still a bit shabby in places last time I used them).

I for one never liked the constexpr semantic and syntax. Always felt like a... Little pebble in my shoe. Didn't quite annoy me enough not to use it since it was useful, but it was never a comfortable experience.