let
inherit (builtins.trace "used" { a = 1; b = 2; }) a b;
x.c = 3;
y.d = 4;
merged = {
inner = {
inherit (y) d;
};
inherit (x) c;
in
[ a b rec { x.c = []; inherit (x) c; inherit (y) d; __overrides.y.d = []; } merged ]