I completely agree with @lukasa.
This feature may be really useful, but there are probably others that also would. And a common thing between a lot of proposals is that it probably could be done with a good macro system. Even if ti's not a priority it would mean that we could do things like this ourselves without relaying on the language/compiler to implement it. Rust has some interesting features that rely on the macro system and it powers a lot of cool libs in the ecosystem, I can't imagine what the burden on the compiler would be if everything would need to be implemented in it.
I personally would love to see Run Swift code at compile time being considered at some point.