vlib/v/checker/tests/assign_immutable_reference_var_err.vv:8:11: notice: `x` is immutable, cannot have a mutable reference to an immutable object
    6 | 
    7 | fn y(x &Foo) {
    8 |     mut m := x
      |              ^
    9 |     m.value = 42
   10 | }
vlib/v/checker/tests/assign_immutable_reference_var_err.vv:9:4: error: `m.value` aliases mutable data from an immutable value
    7 | fn y(x &Foo) {
    8 |     mut m := x
    9 |     m.value = 42
      |       ~~~~~
   10 | }
   11 |