Function compute_with 

pub fn compute_with(
    manifest_path: &Path,
    catalog_path: Option<&Path>,
    rustc_version: &str,
) -> Result<BuildKeyReport, String>

Computes the build key for a manifest. rustc_version is injected rather than probed so the computation is testable without a toolchain; rustc_version is the real probe run uses.

Errors

If the manifest or catalog cannot be read, parsed, validated or resolved, or if the resolved releases carry a duplicate slug.