Lint against indexing and slicing

[aochagavia]

Some projects (e.g. operating systems) need to be very careful about panics. Since indexing and slicing panic when indices are out of bounds, I think it would be useful to have a lint for that (allowed by default).

Does this fit the scope of clippy?

[oli-obk]

This would be one of the "restrictions" mentioned in #632

Hard to do cross crate though

[Manishearth]

THis goes under the "restrictions" thing. Completely avoiding panics is global thing, and hard to do, but blacklisting certain operations is a good step.

[aochagavia]

Does the "restrictions" thing require refactoring of clippy or could this particular lint be implemented without major changes?

[Manishearth]

It requires refactoring of the lint groups machinery in the python script to be able to create more non-pedantic Allow groups.

[aochagavia]

Hmmm... I am not familiar with the architecture of clippy, so I guess I would rather wait until those changes are in place before implementing this.

[Manishearth]

Feel free to implement this as a regular pedantic Allow lint.

[aochagavia]

Ok!