Make warnings fail CI about druid HOT 4 CLOSED

This could be pretty easily implemented by adding #![deny(warnings)] to the top of lib.rs.
That way we enforce the policy locally as well, which might reduce the time newcomers spend trying to figure out why the CI is failing. Thoughts?

from druid.

Hmm, I'm not sure. It seems more fragile, like if a brand-new rustc starts throwing a warning (for example, as happened with dyn Trait). One of the crates I work on has a no-warnings policy, but I can't remember which one; sadly, there's very little consistency in CI setups :/

from druid.

A fair point. Steve Klabnik suggests cargo rustc -- -D warnings on the command line for the same behavior here, which I think is the cleanest alternative.

But that doesn't really solve the problem, unless we start pinning that CI template to versions (as opposed to stable/nightly).

from druid.

The reason not to like #![deny(warnings)] is because warnings are totally reasonable during development; we just don't want them in code we commit. I think that cargo rustc -- -D warnings (only on stable) is the correct approach; if we have to fix some warnings every six weeks that's manageable.

from druid.