Macro tool_check_step

macro_rules! tool_check_step {
    (
        $name:ident {
            // The part of this path after the final '/' is also used as a display name.
            path: $path:literal
            $(, alt_path: $alt_path:literal )*
            // Closure that returns `Mode` based on the passed `&Builder<'_>`
            , mode: $mode:expr
            // Subset of nightly features that are allowed to be used when checking
            $(, allow_features: $allow_features:expr )?
            // Features that should be enabled when checking
            $(, enable_features: [$($enable_features:expr),*] )?
            $(, default: $default:literal )?
            $( , )?
        }
    ) => { ... };
}