Indentation hangs in `typescript--backward-to-parameter-list` when previous function has unbalanced parens

[tkil]

I haven't had a chance to isolate it, but I ran across a case where indentation would hang when trying to indent parameters in a function. It turns out that the function before that one had unbalanced parentheses (one too many close parens). The behavior was that typescript--backward-to-parameter-list got stuck in one place and never made progress.

A quick fix would be at least to verify that we're making progress in that loop.

The actual case looked something like this:

function1(): void {
  blah = baz(foo));  // <--- note extra closing paren
}

function2(
  param1: thing,  // <--- go to start of line, hit TAB, emacs hangs.
): void {
   whatever;
}

I did some quick-and-dirty instrumenting (see the now-commented-out message invocation at the top of the cl-loop):

(defun typescript--backward-to-parameter-list ()
  "..."
  (let ((location
         (or
          ;; This handles the case of a function with return type annotation.
          (save-excursion
            (cl-loop named search-loop
                  do
                  ;; (message "top of loop, point=%d" (point))
                  (typescript--backward-syntactic-ws)
                  ;; Check whether we are at "):".
                  (when (and (eq (char-before) ?\:)

That yielded the following messages, which I've annotated with comments:

;;; compile my modified function, get...
typescript--backward-to-parameter-list  

;;; hit TAB; emacs hangs after a few times through the loop
;;; (Note the "5435 times"...)
top of loop, point=6894
top of loop, point=6882
top of loop, point=6873
top of loop, point=6867
top of loop, point=6637 [5435 times]

;;; I hit C-g and see what I can figure out.
Entering debugger...

Hopefully this is enough to give someone a hint on where to start looking. If this is drawing a blank with everyone else, I'll see if I can't put together a repro.

Thanks for the great mode!

I'm using typescript-mode from ELPA:

typescript-mode    0.3           installed             Major mode for editing typescript