Function shared_prop 

pub fn shared_prop(name: &str, spelling: Spelling) -> bool

Is name a row every element reads — a schema row, a composite, an alias — as opposed to a misspelling? What known_prop answers for an element that admits only some rows still depends on this: a row the element does not read is dropped like a misspelling, but the warning can say so instead of hunting for a nearer spelling.