Narrowing conversion

Posted Jul 22, 2021 1:21 UTC (Thu) by roc (subscriber, #30627)
In reply to: Narrowing conversion by Gaelan
Parent article: The Sequoia seq_file vulnerability

From and TryFrom let you express infallible and fallible scalar conversions. There probably should be a third trait+method to explicitly request a truncating/sign-modifying conversion. But "as" for scalar conversions is a footgun.

I'm not sure what the best way to proceed from here is. One option would be to introduce that trait+method for truncating conversions, and deprecate or ban lossy "as" scalar conversions in a future edition. But obviously a lot of existing code would be affected.

Narrowing conversion

Posted Jul 23, 2021 0:47 UTC (Fri) by khim (subscriber, #9252) [Link] (2 responses)

> But obviously a lot of existing code would be affected.

Isn't it something Rust editions are supposed to cover?

Narrowing conversion

Posted Jul 23, 2021 7:50 UTC (Fri) by Fowl (subscriber, #65667) [Link] (1 responses)

The code still would want to be upgraded to a newer edition at some point.

Narrowing conversion

Posted Jul 23, 2021 9:54 UTC (Fri) by khim (subscriber, #9252) [Link]

Not really. In Rust, unlike in C++, editions are supposed to coexist. You can write one crate in Rust 2015, another in Rust 2018, and third in Rust 2021.

Sure, if you are actively developing your code then you would probably want to upgrade it, but there are no pressure to do that ASAP.