Rust製のエディタをビルドするのに1時間ぐらいハマったのでメモしておく ref: https://qiita.com/object-kazuAtGitHub/items/a24cc8a833f4663ad4b2

file0.txt

% > cargo build                                                                                                                                                                
   Compiling orbclient v0.3.17
error[E0554]: #![feature] may not be used on the stable release channel
 --> /Users/xxx/.cargo/registry/src/github.com-1ecc6299db9ec823/orbclient-0.3.17/src/lib.rs:3:1
  |
3 | #![feature(alloc)]
  | ^^^^^^^^^^^^^^^^^^

error[E0554]: #![feature] may not be used on the stable release channel
 --> /Users/xxx/.cargo/registry/src/github.com-1ecc6299db9ec823/orbclient-0.3.17/src/lib.rs:4:1
  |
4 | #![feature(asm)]
  | ^^^^^^^^^^^^^^^^

error[E0554]: #![feature] may not be used on the stable release channel
 --> /Users/xxx/.cargo/registry/src/github.com-1ecc6299db9ec823/orbclient-0.3.17/src/lib.rs:5:1
  |
5 | #![feature(const_fn)]
  | ^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0554`.
error: Could not compile `orbclient`.

file1.txt

> brew install sdl2
> rustup update
> rustup override set nightly
> rustup update nightly

file2.txt

> cargo -V
cargo 1.30.0-nightly (a5d829494 2018-09-13)