Rust to_int() and related method do not check for overflow

[DaGenix]

The rust to_int() and related methods on integers do not check for overflow in the current Rust codebase. Either update the library to work around this, or create a patch against Rust to do these checks.

[l0kod]

Like for add_bytes_to_bits, std:num:Checked{Add,Sub,Mul,Div} could help.

cc rust-lang/rust#8635
cc rust-lang/rust#16446

[thestinger]

This seems to work fine:

> 255u.to_u8()
None

[DaGenix]

I believe that when I opened this issue last October that those functions didn't check for overlfow. Or, maybe they did and I misread them. Regardless, they certainly do now. I'll close this issue since this doesn't seem to be a problem.

Thanks @thestinger and @l0kod!