[jwatzman]

Post author here.

One of the nice advantages we had in using our static analysis tool for this, with real code intelligence, instead of a simpler linter, was that we could do a much more clever check. The actual rule was "every case must be terminal", and we had a rich analysis for "terminal", so stuff like this would be considered legal:

    case blah:
      if (cond) {
        throw blah;
      }
      if (cond2) {
        some_noreturn_function();
      } else {
        return 42;
      }

etc etc. My example is a bit contrived, and the wisdom of doing such complicated things in switch/case is questionable, but it was useful when dealing with an existing codebase.

Another advantage was that our tool was designed for extremely fast analysis over the entire codebase, so errors were given to programmers as they were writing code, immediately. (200ms response time to any change. At that level you can run it on every keystroke, which we did.) Traditional linters can in principle do this, but in practise are often not written with this sort of performance requirements in mind.

(And yes, PHP allowing arbitrary expressions in case labels was... probably not a good idea.)

[muglug]

FYI, phpcs now has something similar (since roughly 2016), but I imagine your implementation predates that by a significant margin (and yours obviously supports noreturn too).

> PHP allowing arbitrary expressions in case labels was... probably not a good idea.

Yeah, possibly the worst offender is the (somewhat common) "switch (true)" pattern: https://psalm.dev/r/4c168a9c5d

Sadly I don't have the latitude you all do to govern how code gets written by users of my own static analysis tool – fall-through has to work there, too: https://psalm.dev/r/1d4ee59bd6