Error while installing "cargo install racer"

[shehzadaliqadri]

raza@Raza-Ubuntu:~$ cargo install racer Updating crates.io index Installing racer v2.1.19 Compiling semver-parser v0.7.0 Compiling arrayvec v0.4.10 Compiling nodrop v0.1.13 Compiling cfg-if v0.1.7 Compiling libc v0.2.50 Compiling rand_core v0.4.0 Compiling lazy_static v1.3.0 Compiling memoffset v0.2.1 Compiling scopeguard v0.3.3 Compiling stable_deref_trait v1.1.1 Compiling byteorder v1.3.1 Compiling proc-macro2 v0.4.27 Compiling rustc-rayon-core v0.1.2 Compiling smallvec v0.6.9 Compiling rustc-rayon v0.1.2 error[E0554]: #![feature] may not be used on the stable release channel --> /home/raza/.cargo/registry/src/github.com-1ecc6299db9ec823/smallvec-0.6.9/lib.rs:33:32 | 33 | #![cfg_attr(feature = "union", feature(untagged_unions))] | ^^^^^^^^^^^^^^^^^^^^^^^^

error[E0554]: #![feature] may not be used on the stable release channel --> /home/raza/.cargo/registry/src/github.com-1ecc6299db9ec823/smallvec-0.6.9/lib.rs:35:37 | 35 | #![cfg_attr(feature = "may_dangle", feature(dropck_eyepatch))] | ^^^^^^^^^^^^^^^^^^^^^^^^

Compiling unicode-xid v0.1.0 Compiling bitflags v1.0.4 Compiling syn v0.15.29 error: aborting due to 2 previous errors

For more information about this error, try rustc --explain E0554. error: Could not compile smallvec. warning: build failed, waiting for other jobs to finish... error: failed to compile racer v2.1.19, intermediate artifacts can be found at /tmp/cargo-installarnQai

Caused by: build failed

[kngwyu]

We have to type cargo +nightly install racer because it depends on nightly library. See readme for detail.