module-level `rustfmt::skip` fails with confusing error

[andrewbanchich]

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=73768e89fe43b087349454c8cf2bf2c9

i would have expected / liked to disable rustfmt for the entire module instead of needing to place it on every item.

also, the error seems pretty confusing.

[bjorn3]

A #[foo] attribute is called an outer attribute and a #![foo] attribute is called an inner attribute. Inner attributes that are not built into the compiler are unstable as macro expansion for inner attributes at the crate root has weird semantics. I guess it would be fine to make inner attributes stable for inert (not expanding to anything) tool attributes like rustfmt::skip though as no macro expansion is involved there. It was originally made unstable before tool attributes were introduced. As such I think it was only ever intended to apply to macro attributes and not to inert tool attributes.

[andrewbanchich]

thanks for the explanation! i'll look into making a PR for this.

do you think changing the existing message to be "inner attributes defined outside the compiler are unstable" would be good? "custom" made me think it thought i had created it or that it was unrecognized.