Importing Diesel macros (Rust 2018)

[lnicola]

In the 2018 edition, #[macro_use] is going away (kinda'), as use works with macros. Unfortunately, Diesel doesn't seem to play well with that, as a lot of macros are hard to find (e.g. no_arg_sql_function_body), or seem not to work even after being imported (although it's quite possible that I used a wrong path).

https://www.reddit.com/r/rust/comments/8tbah2/my_problems_with_understanding_rust_edition_2018/e166pdp/ suggests a simple work-around, but that might require a minimum compiler version bump.

#[macro_use] is probably still going to be supported, but it might be worth fixing this.

Related: rust-lang/rust#35896 (comment).

[sgrif]

I don't think there's anything actionable that we can do at this point in time. Even the comment you've linked to says "the lang team is looking into this but hasn't made a decision yet". As far as I can tell there's no compiler that demonstrates a concrete problem here, nor is there any change we can currently make that would address this potential problem today.

In a few months, if Diesel is unable to compile with stable Rust (which would be a pretty shocking step for Rust to take), please open a new issue.

[lnicola]

As far as I can tell there's no compiler that demonstrates a concrete problem here

The issue can be observed on nightly, with the use_extern_macros feature enabled: https://play.rust-lang.org/?gist=51baef8107264c2aafaf140c4d045e86&version=nightly&mode=debug, and it affects Diesel in the same way.

I'll post here again if use_extern_macros gets stabilized and it's still hard to use it with Diesel.