rustc_private

The tracking issue for this feature is: #27812

This feature allows access to unstable internal compiler crates such as rustc_driver.

The presence of this feature changes the way the linkage format for dylibs is calculated in a way that is necessary for linking against dylibs that statically link std (such as rustc_driver). This makes this feature "viral" in linkage; its use in a given crate makes its use required in dependent crates which link to it (including integration tests, which are built as separate crates).

When using rustc-private with Official Toolchains

When using the rustc_private feature with official toolchains distributed via rustup, you'll need to install:

  1. The rustc-dev component (provides compiler libraries)
  2. The llvm-tools component (provides LLVM libraries needed for linking)

You can install these components using rustup:

rustup component add rustc-dev llvm-tools

Without the llvm-tools component, you may encounter linking errors like:

error: linking with `cc` failed: exit status: 1
  |
  = note: rust-lld: error: unable to find library -lLLVM-{version}

When using rustc-private with Custom Toolchains

For custom-built toolchains or environments not using rustup, different configuration may be required:

  • Ensure LLVM libraries are available in your library search paths
  • You might need to configure library paths explicitly depending on your LLVM installation