Rust error[E0554]： #！[feature] may not be used on the stable release channel Couldn't install racer using cargo

我试图使用cargo安装racer，所以我在终端执行了命令cargo install racer，结果出现了错误:

error[E0554]: #![feature] may not be used on the stable release channel
--> /home/rajkumar/.cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:47:34
|
47 | #![cfg_attr(feature = "nightly", feature(macro_vis_matcher))]
|                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0554]: #![feature] may not be used on the stable release channel
--> /home/rajkumar/.cargo/registry/src/github.com-1ecc6299db9ec823/scoped-tls-0.1.2/src/lib.rs:48:34
|
48 | #![cfg_attr(feature = "nightly", feature(allow_internal_unstable))]
|                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0554`.
error: failed to compile `racer v2.1.10`, intermediate artifacts can be found at `/tmp/cargo-install5YWPWW`

Caused by:
Could not compile `scoped-tls`.

To learn more, run the command again with --verbose.

以下是我的详细信息:

$rustc --version
rustc 1.30.0 (da5f414c2 2018-10-24)

> rustup --version 
rustup 1.14.0 (1e51b07cc 2018-10-04)

> cargo --version 
cargo 1.30.0 (36d96825d 2018-10-24)

以下是我的opensuse版本详细信息:

> cat /usr/lib/os-release 
NAME="openSUSE Tumbleweed"
# VERSION="20181029"
ID="opensuse-tumbleweed"
ID_LIKE="opensuse suse"
VERSION_ID="20181029"
PRETTY_NAME="openSUSE Tumbleweed"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:opensuse:tumbleweed:20181029"
BUG_REPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org/"

为什么我不能使用cargo安装racer？我错过什么了吗？