Macro query_regex 

macro_rules! query_regex {
    ($label_type:path: $($regex:tt)*) => { ... };
}

query_regex is a wrapper around compile_regex that should be used when you’re using the resulting regex only once, inline. This is often the case in scope graph queries.

compile_regex generates a type, which when instantiated can match a string. This macro avoids the need to instantiate, and combines the compiling and instantiation.