add flatten

[realbigsean]

Resolves #30

[michaelsproul]

awesome! will review tomorrow

[realbigsean]

fixed a little bug here, but now this is working in lighthouse sigp/lighthouse#5158

Also a limitation right now is we don't have a way to nest inner types that have a subset of variants of the outer type. I think vice-versa should work though (haven't tested it). So nesting an execution payload in a block in lighthouse wouldn't benefit from this for example.

[realbigsean]

Also a limitation right now is we don't have a way to nest inner types that have a subset of variants of the outer type. I think vice-versa should work though (haven't tested it). So nesting an execution payload in a block in lighthouse wouldn't benefit from this for example.

This actually wasn't so bad to get working, I added it here: 76b67a1

[michaelsproul]

I pushed a bugfix for an issue I noticed with using the field_index to modify the variant_fields. If there are earlier fields that aren't on a variant (due to only), then the field index from the whole struct will not be the location of the field in the variant_fields. I added a test that fails without my change, and passes with it, but I could do with a second pair of eyes on it

52eba9f

[michaelsproul]

I also think we want to use the last part of the path, e.g. types::ExecutionPayload we want ExecutionPayload not types: 30f768f

[michaelsproul]

I can't spot any other issues, so I think this is good to merge!