Build failing: macro_reexport has been removed

[denysvitali]

With the latest Rust nightly Rocket build fails.

   Compiling rocket_contrib v0.3.9
error[E0557]: feature has been removed
 --> /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/rocket_contrib-0.3.9/src/lib.rs:1:12
  |
1 | #![feature(macro_reexport)]
  |            ^^^^^^^^^^^^^^
  |
note: subsumed by `#![feature(use_extern_macros)]` and `pub use`
 --> /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/rocket_contrib-0.3.9/src/lib.rs:1:12
  |
1 | #![feature(macro_reexport)]
  |            ^^^^^^^^^^^^^^

error[E0658]: The attribute `macro_reexport` is currently unknown to the compiler and may have meaning added to it in the future (see issue #29642)
  --> /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/rocket_contrib-0.3.9/src/lib.rs:47:30
   |
47 | #[cfg_attr(feature = "json", macro_reexport(json_internal))]
   |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: add #![feature(custom_attribute)] to the crate attributes to enable

error: aborting due to 2 previous errors

Some errors occurred: E0557, E0658.
For more information about an error, try `rustc --explain E0557`.
error: Could not compile `rocket_contrib`.
warning: build failed, waiting for other jobs to finish...
error: build failed

The problem is that macro_reexport feature has been removed (see rust-lang/rust#49982)

[denysvitali]

There is already a PR available (#624) and #625 is tracking this aswell, but was closed before the PR has been merged.

[SergioBenitez]

Fixed in v0.3.10. 🎉

[denysvitali]

Thank you! ❤️