swift234

Part of logging an NSView is redrawing it if it's dirty
However, a view can ask to be redrawn by setting its needsDisplay flag to true
When this happens in a playground, the
self.needsDisplay = true line
forces the view to be logged - logging the view forces it to be redrawn, and unless there's a way out that does not force-redraw, this ends up being an endless loop & of course at some point we run out of stack, and "random" crashes ensue

Add a set of views currently being logged and add/remove views as needed to ensure we don't try to actively log the same view twice

Since UI drawing can only happen on the main thread, if you try to concurrently log views from different threads, you already have a problem, so this can be treated as a single-threaded problem

Fixes <rdar://problem/17027976>


Swift SVN r19730