jflex has error-prone fall-through

[regisd]

jflex/jflex-unicode-maven-plugin/target/generated-sources/jflex/jflex/ArchaicLineBreakScanner.java:702: error: [FallThrough] Execution may fall through from the previous case; add a // fall through comment before this line if it was deliberate

          case 11: break;
          ^

see http://errorprone.info/bugpattern/FallThrough

[lsf37]

The fall-through violations seem to be in generated code -- we could automatically add the // fall through comment in the generator to indicate that this is on purpose.

[regisd]

Unfortunately, that's not enough.

At the end of emitActions, I have added a fall-through comment

  println("            { " + action.content);
  println("            } ");
  println("            // fall through ");

The problem is that action.content can contain a return or a throw statement ; in which case the fall-through comment is not legitimate anymore.

[lsf37]

Right, that's actually what that specific fall through is for: to guard for the cases where there is no return or throw and the scan just continues. Do we get warnings for fall through comments that are spurious? If not, we could add another line with something like
// allowed to fall through if action does not return or throw