Macro define_queries 

macro_rules! define_queries {
    (
        // Note: `$K` and `$V` are unused but present so this can be called by
        // `rustc_with_all_queries`.
        queries {
            $(
                $(#[$attr:meta])*
                fn $name:ident($K:ty) -> $V:ty
                {
                    // Search for (QMODLIST) to find all occurrences of this query modifier list.
                    anon: $anon:literal,
                    arena_cache: $arena_cache:literal,
                    cache_on_disk: $cache_on_disk:literal,
                    cycle_error_handling: $cycle_error_handling:ident,
                    depth_limit: $depth_limit:literal,
                    eval_always: $eval_always:literal,
                    feedable: $feedable:literal,
                    no_hash: $no_hash:literal,
                    returns_error_guaranteed: $returns_error_guaranteed:literal,
                    separate_provide_extern: $separate_provide_extern:literal,
                }
            )*
        }
        // Non-queries are unused here.
        non_queries { $($_:tt)* }
    ) => { ... };
}