Unsafe derives and attributes

[joshtriplett]

Allow declaring proc macro attributes and derive macros as unsafe, and
requiring unsafe to invoke them.

Rendered

[clarfonthey]

Just my 2¢, but I think that the shorthand for derive(..., unsafe(Trait), ...) is a bit unprecedented.

You have to separate out derive traits any time there's some different requirement, e.g. cfg_attr(feature = "serde", derive(Serialize, Deserialize)), and by keeping unsafe at the top level you can easily grep for #!?\[unsafe\( whereas unsafe( will catch any call to method_unsafe(.

Sure, it's likely it won't make a difference, but I think that only having to check attributes at the top level for unsafe to verify safety is best.

[carbotaniuman]

The greppability is already broken by things like #[cfg_attr(all(), unsafe(no_mangle)], and can be restored by just grepping unsafe( I think putting the unsafe with the trait makes syntactic sense as it discharges the safety obligation of each trait derive.

[clarfonthey]

The greppability is already broken by things like #[cfg_attr(all(), unsafe(no_mangle)], and can be restored by just grepping unsafe( I think putting the unsafe with the trait makes syntactic sense as it discharges the safety obligation of each trait derive.

I feel kind of silly for literally alluding to this point in my post and missing it somehow. You're right and I retract my original claim.