>But even in HarfBuzz and CoreText, there are hard limits on the recursion depth. HarfBuzz sets its limit to 6. Therefore, the above example will only work on s

>But even in HarfBuzz and CoreText, there are hard limits on the recursion depth. HarfBuzz sets its limit to 6. Therefore, the above example will only work on strings of length 7 or fewer. HarfBuzz is open source, though, so I simply used a custom build of HarfBuzz which bumps up this limit to 4 billion. This let me recurse to my heart’s content. A limit of 6 is probably a good thing; I don’t think users generally expect their text engines to be running arbitrary computation during layout. Truly, Zalgo waits just beyond the wall.