Numeric .into() should not require everyone to support 16-bit and 128-bit usize

language design
7

.try_into().unwrap() sort of works, but not quite:

  • it’s a run-time check, not a compile-time check. If the conversion unexpectedly becomes lossy (e.g. a library interface changes), the compiler won’t warn you about the breakage.

  • .into() syntax is already second-class compared to as, and .try_into().unwrap() is even more verbose. Explicit integer conversions are needed sometimes even multiple times in a single expression, so verbosity matters here a lot. It’d be better if TryInto had a syntax sugar, e.g. as!.