Cannot install on mac

[RazrFalcon]

I've already installed necessary components:

> rustup component add rust-src rustc-dev llvm-tools-preview
info: component 'rust-src' is up to date
info: component 'rustc-dev' for target 'aarch64-apple-darwin' is up to date
info: component 'llvm-tools-preview' for target 'aarch64-apple-darwin' is up to date

> cargo install cargo-typesize
    Updating crates.io index
  Installing cargo-typesize v0.1.0
   Compiling cargo-typesize v0.1.0
error[E0554]: `#![feature]` may not be used on the stable release channel
 --> /Users/razr/.cargo/registry/src/gitpro.ttaallkk.top-1ecc6299db9ec823/cargo-typesize-0.1.0/src/driver.rs:1:1
  |
1 | #![feature(rustc_private)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0554]: `#![feature]` may not be used on the stable release channel
 --> /Users/razr/.cargo/registry/src/gitpro.ttaallkk.top-1ecc6299db9ec823/cargo-typesize-0.1.0/src/driver.rs:2:1
  |
2 | #![feature(once_cell)]
  | ^^^^^^^^^^^^^^^^^^^^^^

error[E0554]: `#![feature]` may not be used on the stable release channel
 --> /Users/razr/.cargo/registry/src/gitpro.ttaallkk.top-1ecc6299db9ec823/cargo-typesize-0.1.0/src/driver.rs:2:12
  |
2 | #![feature(once_cell)]
  |            ^^^^^^^^^

> cargo +nightly install cargo-typesize
    Updating crates.io index
  Installing cargo-typesize v0.1.0
   Compiling cargo-typesize v0.1.0
error[E0463]: can't find crate for `rustc_driver`
  --> /Users/razr/.cargo/registry/src/gitpro.ttaallkk.top-1ecc6299db9ec823/cargo-typesize-0.1.0/src/driver.rs:11:1
   |
11 | extern crate rustc_driver;
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^ can't find crate
   |
   = help: maybe you need to install the missing components with: `rustup component add rust-src rustc-dev llvm-tools-preview`

Should I somehow install nightly components?

[hazelutf8]

On windows I had to:
rustup default nightly
rustup component add rust-src rustc-dev llvm-tools-preview

[RazrFalcon]

Thanks! It seems that it works only on nightly channel. Readme worth updating.

[davidrusu]

Hey, yes I had to gone through this earlier when first setting up, but subsequently forgot about these steps!

The rust devs don't want folks linking against rustc on stable since these API's may be unstable, see: rust-lang/rust#27812

Hence the need for #[feature(rustc_private)] and nightly.

I've updated the README with a note and instructions, thanks for the report!