Custom block tags in a post liquid 4.0 world

I’m in the middle of upgrading my site to Jekyll 3.5 (and liquid 4)

I’ve got a number of custom block based tags (as in Foo < Liquid::Block) that no longer seem to match how things are done now.

I’m doing the work in the render function, because I need the context, and as such per the old code, I’m was also calling render_all (from Convertable iirc) as the base render function used to.

This seems to have changed. I’m not sure if this was a Jekyll cause or a Liquid cause, but I cannot find what I should change these to, or any updated examples of how to make a block tag. The docs area on the jekyll site only has a Liquid::Tag example.

Any help or updated examples are appreciated.

Much much much digging lead to the (a?) solution, just swapping the render_all() with super to punt the rendering work back to the original code (which now does some fancy BlockBody stuff), and did indeed return the parsed token array I was expecting. Everything built as expected!