Adding a HighLevelContext to touch_data and _length_0_1_if_typetracer causes to_layout to be called on the array, which falls back to to_iter, which fails because it's a typetracer array. These functions only make sense if the argument is already a typetracer array, so this effectively breaks them. It's responsible for #3077 (comment) (which is an issue about a regression, and the last version they checked is, indeed, before this PR).

The reason you added HighLevelContext here was to propagate attrs. Is there a way to propagate attrs without something that eventually goes to to_layout? I could do it the pedestrian way of just checking for the things that need to be propagated, attrs and behaviors, and propagating them. I would be in favor of that for these exceptional functions—low-level functions that need to propagate high-level state—but if there's a utility function for it already, I ought to use that.

Is there a utility function for what I'm trying to do? If not, I'll happily do it the pedestrian way.

This conversation is continuing at #3077 (comment).