 --> [ local path prefix ]/constant/undef_3.fpp:2:16
  |
2 | constant b = M.a
  |                ^ cannot find constant `a` in scope

 --> [ local path prefix ]/constant/undef_3.fpp:2:14
  |
2 | constant b = M.a
  |              ^ not a constant symbol
  |
 ::: [ local path prefix ]/constant/undef_3.fpp:1:8
  |
1 | module M { }
  |        - M defined here

