error:
       … while evaluating the attribute 'body'
         at /pwd/lang/eval-fail-scope-5.nix:13:3:
           12|
           13|   body = f { };
             |   ^
           14|

       … from call site
         at /pwd/lang/eval-fail-scope-5.nix:13:10:
           12|
           13|   body = f { };
             |          ^
           14|

       … while calling 'f'
         at /pwd/lang/eval-fail-scope-5.nix:7:5:
            6|   f =
            7|     {
             |     ^
            8|       x ? y,

       error: infinite recursion encountered
       at /pwd/lang/eval-fail-scope-5.nix:8:11:
            7|     {
            8|       x ? y,
             |           ^
            9|       y ? x,