error: Cannot find name `hydro_lab`; name was never assigned.
 --> tests/compile-fail/surface_varname_undefined.rs:5:9
  |
5 |         hydro_lab -> for_each(std::mem::drop);
  |         ^^^^^^^^^

error: `for_each` must have exactly 1 input(s), actually has 0.
 --> tests/compile-fail/surface_varname_undefined.rs:5:22
  |
5 |         hydro_lab -> for_each(std::mem::drop);
  |                      ^^^^^^^^^^^^^^^^^^^^^^^^