> If you're constructing invalid `str` you already have severely fucked up.

Presumably it'd be better to know this immediately on initialization of the variable rather than at some point in the program that actually expects valid utf8—god forbid you transmit or persist the data before this happens.

That's why str::from_utf8 returns Result<&str, FromUtf8Error>. And if you know the string is UTF-8 encoded and don't want to pay the cost, there's `from_utf8_unchecked`, which is marked unsafe.

Ah, I thought you were referring to the benefits of such a system as compared to zig and blithely passing the responsibility of input validation on to the programmer. Rust of course demonstrates the benefit of checking validity at initialization.