Macro try_validation 

macro_rules! try_validation {
    ($e:expr, $where:expr,
    $( $( $p:pat_param )|+ => $msg:expr ),+ $(,)?
    ) => { ... };
}

If $e throws an error matching the pattern, throw a validation failure. Other errors are passed back to the caller, unchanged – and if they reach the root of the visitor, we make sure only validation errors and InvalidProgram errors are left. This lets you use the patterns as a kind of validation list, asserting which errors can possibly happen:

let v = try_validation!(some_fn(x), some_path, {
    Foo | Bar | Baz => format!("some failure involving {x}"),
});

The patterns must be of type UndefinedBehaviorInfo.