error:
… in the right operand of the update(//) operator
at /pwd/lang/eval-fail-recursion.nix:1:12:1| let a = {} // a; in a.foo
| ^
2|
error: infinite recursion encountered
at /pwd/lang/eval-fail-recursion.nix:1:15:1| let a = {} // a; in a.foo
| ^
2|