Macro rustc_middle::query::plumbing::query_if_arena

macro_rules! query_if_arena {
    ([] $arena:tt $no_arena:tt) => { ... };
    ([(arena_cache) $($rest:tt)*] $arena:tt $no_arena:tt) => { ... };
    ([$other:tt $($modifiers:tt)*]$($args:tt)*) => { ... };
}