#![rustfmt::skip]: non-builtin inner attributes are unstable

[WalterSmuts]

I'm a bit new to rust so please bear with me here :) I'm trying to use the protobuf library but can only get it to compile when I add the +nightly flag to cargo:

wssmts@laptop:~/Programs/rust-ipc/rust-protobuf > cargo +nightly build
    Finished dev [unoptimized + debuginfo] target(s) in 0.09s

Everything works fine using the nightly compiler, but I am a bit hesitant using this in a production system with the nightly compiler building using actual unstable features.

So I looked around in the documentation, the github readme and the the issues mentioning nightly and couldn't find anything refering to having to use the nightly compiler to use the protobuf crate.

So I guess the question is, do I have to use the nightly compiler if I need this library?

If not, and I almost assume not, what am I doing wrong?

My setup

My repo
Versions etc

wssmts@laptop:~/Programs/rust-ipc/rust-protobuf > cargo -V
cargo 1.41.0 (626f0f40e 2019-12-03)
wssmts@laptop:~/Programs/rust-ipc/rust-protobuf > rustc -V
rustc 1.41.0 (5e1a79984 2020-01-27)
wssmts@laptop:~/Programs/rust-ipc/rust-protobuf > rustup show
Default host: x86_64-unknown-linux-gnu
rustup home:  /home/ANT.AMAZON.COM/wssmts/.rustup

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu
1.38.0-x86_64-unknown-linux-gnu
1.41.0-x86_64-unknown-linux-gnu (default)

installed targets for active toolchain
--------------------------------------

aarch64-unknown-linux-musl
x86_64-unknown-linux-gnu
x86_64-unknown-linux-musl

active toolchain
----------------

1.41.0-x86_64-unknown-linux-gnu (default)
rustc 1.41.0 (5e1a79984 2020-01-27)

Error output without compiling using nightly

wssmts@laptop:~/Programs/rust-ipc/rust-protobuf > cargo build
   Compiling protobuf v2.18.1
error[E0658]: non-builtin inner attributes are unstable
 --> /home/ANT.AMAZON.COM/wssmts/.cargo/registry/src/github.jparrowsec.cn-1ecc6299db9ec823/protobuf-2.18.1/src/descriptor.rs:9:1
  |
9 | #![rustfmt::skip]
  | ^^^^^^^^^^^^^^^^^
  |
  = note: for more information, see https://github.com/rust-lang/rust/issues/54726

<SNIP> Basically repeats the same error </SNIP>

[stepancheg]

Can you please check with the latest rust? Version 1.41.0 you are using is 10 months old.

Alternatively, try using some older version of rust-protobuf.

I don't know what's the official minimum supported rust version of rust-protobuf because I accidentally broke CI testing with older versions.

[stepancheg]

Just checked, latest stable version works with rust versions starting with 1.44.1.

[stepancheg]

OK, it's actually even mentioned in changelog.

Closing the issue now, please reopen or create another one if the issue still exists or something other help is needed.