It should be an error to have #[inline] on trait methods

[Boscop]

It should be an error to have #[inline] on trait methods because #[inline] should be on the impl.
Otherwise it has no effect and leads people to think they are inlining when they aren't.

[petrochenkov]

*on trait methods without body

[dtolnay]

To clarify: this is asking for an enabled-by-default warning and not a breaking change right?

[Boscop]

Yes, that makes the most sense for now :)

(But it could be a hard error later..)

[etaoins]

This should be fixed by rust-lang/rust-clippy#2367

[Manishearth]

Closing the issue since there's a clippy lint -- the general preference is that aside from deprecation/stability/epoch lints, rustc isn't going to get new lints. If you feel strongly that this should be in rustc, open a new issue for uplifting the clippy lint and make a case specifically for why it belongs in rustc.