https://nixos.org/manual/nix/stable/language/constructs.html#inheriting-attributes

let
  x = 123;
in { 
  inherit x;
  y = 456;
}

is equivalent to

let
  x = 123;
in {
  x = x;
  y = 456;
}


...
inherit x y z;
inherit (src-set) a b c;
...
is equivalent to
...
x = x; y = y; z = z;
a = src-set.a; b = src-set.b; c = src-set.c;