dec!() procedural macro doesn't work on rust stable (1.30.0)

[zazabe]

It seems that dec!() is not working on the latest rust release.

extern crate rust_decimal;
extern crate rust_decimal_macros;
use rust_decimal_macros::*;
fn main() {
    let num = dec!(3.14);
}

produces this error:

error[E0658]: procedural macros cannot be expanded to expressions (see issue #38356)
 --> examples/decimal.rs:5:15
  |
5 |     let num = dec!(3.14);
  |               ^^^^^^^^^^

error: aborting due to previous error

• rustc 1.30.0 (da5f414c2 2018-10-24)
• rust_decimal = "0.10.2"
• rust_decimal_macros = "0.10.2"

Btw, I tried with #![feature(proc_macro)] with no luck...

Am i missing something?

[zazabe]

Tested on rustc 1.30.1 (1433507eb 2018-11-07), same error.
btw, it should work since https://blog.rust-lang.org/2018/10/25/Rust-1.30.0.html#use-and-macros i guess...

[paupino]

I jumped the gun a bit putting this in stable (i.e. my tests still use the proc_macro_hygiene feature).
This looks like a known blog issue - it also doesn't look like it will be stabalized for the initial release of Rust 2018. It does work on nightly, however only if you also define #![feature(proc_macro_hygiene)].

I may take a look at the proposed alternative solution to see if I can get that working on stable however for the meantime you could feasibly use this macro definition as a workaround.