error[E0463]: can't find crate for `rustc_ast`
  --> /home/liangzi/.cargo/registry/src/rsproxy.cn-8f6827c7555bfaf8/racer-2.2.2/src/racer/lib.rs:16:1
   |
16 | extern crate rustc_ast;
   | ^^^^^^^^^^^^^^^^^^^^^^^ can't find crate
   |
   = help: maybe you need to install the missing components with: `rustup component add rust-src rustc-dev llvm-tools-preview`

error[E0463]: can't find crate for `rustc_ast_pretty`
  --> /home/liangzi/.cargo/registry/src/rsproxy.cn-8f6827c7555bfaf8/racer-2.2.2/src/racer/lib.rs:17:1
   |
17 | extern crate rustc_ast_pretty;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate
   |
   = help: maybe you need to install the missing components with: `rustup component add rust-src rustc-dev llvm-tools-preview`

error[E0463]: can't find crate for `rustc_data_structures`
  --> /home/liangzi/.cargo/registry/src/rsproxy.cn-8f6827c7555bfaf8/racer-2.2.2/src/racer/lib.rs:18:1
   |
18 | extern crate rustc_data_structures;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate
   |
   = help: maybe you need to install the missing components with: `rustup component add rust-src rustc-dev llvm-tools-preview`

error[E0463]: can't find crate for `rustc_errors`
  --> /home/liangzi/.cargo/registry/src/rsproxy.cn-8f6827c7555bfaf8/racer-2.2.2/src/racer/lib.rs:19:1
   |
19 | extern crate rustc_errors;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate
   |
   = help: maybe you need to install the missing components with: `rustup component add rust-src rustc-dev llvm-tools-preview`

error[E0463]: can't find crate for `rustc_parse`
  --> /home/liangzi/.cargo/registry/src/rsproxy.cn-8f6827c7555bfaf8/racer-2.2.2/src/racer/lib.rs:20:1
   |
20 | extern crate rustc_parse;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate
   |
   = help: maybe you need to install the missing components with: `rustup component add rust-src rustc-dev llvm-tools-preview`

error[E0463]: can't find crate for `rustc_session`
  --> /home/liangzi/.cargo/registry/src/rsproxy.cn-8f6827c7555bfaf8/racer-2.2.2/src/racer/lib.rs:21:1
   |
21 | extern crate rustc_session;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate
   |
   = help: maybe you need to install the missing components with: `rustup component add rust-src rustc-dev llvm-tools-preview`

error[E0463]: can't find crate for `rustc_span`
  --> /home/liangzi/.cargo/registry/src/rsproxy.cn-8f6827c7555bfaf8/racer-2.2.2/src/racer/lib.rs:22:1
   |
22 | extern crate rustc_span;
   | ^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate
   |
   = help: maybe you need to install the missing components with: `rustup component add rust-src rustc-dev llvm-tools-preview`

For more information about this error, try `rustc --explain E0463`.
error: could not compile `racer` (lib) due to 7 previous errors
warning: build failed, waiting for other jobs to finish...
error: failed to compile `racer v2.2.2`, intermediate artifacts can be found at `/tmp/cargo-install2PlMTx`.
To reuse those artifacts with a future compilation, set the environment variable `CARGO_TARGET_DIR` to that path.