pub trait AttrRefObserver {
// Required methods
fn attr_ref_replaced(&self, attr_name: &str, loc: SourceLocation);
fn attr_ref_missing(&self, attr_name: &str, loc: SourceLocation);
}pub trait AttrRefObserver {
// Required methods
fn attr_ref_replaced(&self, attr_name: &str, loc: SourceLocation);
fn attr_ref_missing(&self, attr_name: &str, loc: SourceLocation);
}