print=crate-root-lint-levels

The tracking issue for this feature is: #139180.

This option of the --print flag print the list of lints with print out all the lints and their associated levels (allow, warn, deny, forbid) based on the regular Rust rules at crate root, that is (roughly):

  • command line args (-W, -A, --force-warn, --cap-lints, ...)
  • crate root attributes (#![allow], #![warn], #[expect], ...)
  • the special warnings lint group
  • the default lint level

The output format is LINT_NAME=LINT_LEVEL, e.g.:

unknown_lint=warn
arithmetic_overflow=deny

To be used like this:

rustc --print=crate-root-lint-levels -Zunstable-options lib.rs