Document how to transition imports of procedural macros about edition-guide

[vks]

@petrochenkov

Serialize is a macro with the same name as a trait.

I think this is not something that users of procedural macros necessarily know. That it is not mentioned in the docs does not help.

[vks]

This works:

use serde_derive::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
...

[eminence]

hi @vks, this seems to be covered in the "Macro changes" section of the guide: https://rust-lang-nursery.github.io/edition-guide/2018/transitioning/modules/macros.html

Was there anything in particular about this section that was confusing, or that you think could be improved? I guess one of the problems is that in Rust 2015, you didn't have to explicitly name the macro (or derive) you want to use, but in Rust 2018 you have to name them.

[vks]

It was not clear to me you should import the trait you want to derive. If you look at the the docs, there is no macro called `Serialize` , only one called `derive_Serialize`. Importing it does not work. The transition guide states you have to name the macro, which seems inaccurate in this case. It should mention that in the case of procedural macros, you have to mention the trait you want to derive.

…

On Fri, Jul 27, 2018, 06:32 Andrew Chin ***@***.***> wrote: hi @vks <https://github.com/vks>, this seems to be covered in the "Macro changes" section of the guide: https://rust-lang-nursery.github.io/edition-guide/2018/transitioning/modules/macros.html Was there anything in particular about this section that was confusing, or that you think could be improved? I guess one of the problems is that in Rust 2015, you didn't have to explicitly name the macro (or derive) you want to use, but in Rust 2018 you have to name them. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#66 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AACCtGlV15vOVSanUuzkKYpjKINvqTD-ks5uKpfVgaJpZM4VhWj5> .

[petrochenkov]

@vks

The transition guide states you have to name the macro, which seems
inaccurate in this case. It should mention that in the case of procedural
macros, you have to mention the trait you want to derive.

Serialize is a macro with the same name as a trait.
The docs mentioning derive_Serialize are wrong in this case, derive_Serialize is some naming scheme used only for unstable legacy syntax extensions, it doesn't apply to stable "modern" proc macros.