fix(typescript): Bad handling of semicolons in commutative merging of class bodies #585

One could perhaps come up with other solutions on Mergiraf's side

You probably mean creating a ChildrenGroup for (public)_field_definitions which has ; as its separator? That honestly sounds like the most logical solution to the problem at hand, even if it would require relaxing the separator restriction, because the latter is imo also pretty sensible, even on its own. Should I try to implement that?

I think the only problematic place is commutatively_merge_lists, where we first call keep_content_only on each side, which removes the separators and the delimiters, in order to be able to call child_separator to find what the actual separator is. I think the way we would adjust that is to not use keep_content_only at all, and instead make child_separator smarter:

1. make it take nodes directly, not their kinds
2. for each ChildrenGroup it considers:
   1. filter out all the nodes which match the group's separator/delimiter (we should also somehow include the CommutativeParent's default separator in this calculation)
   2. check whether all the remaining nodes' kinds are accepted by the group

This would be somewhat more computationally expensive, but I don't really see a way around it?...

One question -- currently, we first map each node to a leader (in keep_contents), then map those back to all representatives, and for each of those, check whether they're extra. But isn't the "extraness" of a leader the same as of all its representatives, similarly to the grammar kind?

So, here's what I came up with. Interestingly enough, it deviated wildly from the original code during development, but ended up returning to more or less the same thing in the end

Really cool, thank you so much for the fix! I think it makes a lot of sense like this.

Thank you, I am quite proud of this one:)

The effect on merge output seems unambiguously positive too (the timing difference shouldn't be meaningful though, the load on the machine was variable):

How nice!