ExprLet was previously inheriting from ExprAttrs for the data, while
ignoring all
set-specific operations on it. The set specific code has now been split
off so that
let doesn't inherit it anymore:
- ExprAttrs (not an Expr), containing the attributes and the related
logic
- ExprLet : Expr, ExprAttrs
- ExprSet : Expr, ExprAttrs
Co-authored-by: eldritch horrors <pennae@lix.systems>
Change-Id: I63f2fbcd1e790b3cffb56eec1e7565ee3cdbf964