Metadata v14 content

With the new scale-info features, many need to migrate and in general we should discuss and inform builders of it.

• What versions of Substrate include this?
• What changes in your nodes need to be made?
• What changes in clients/apps need to be made?

Migration guide: https://gist.github.com/ascjones/0d81a4c44e84cacd9f714cd34a6de823

[JoshOrndorff]

The scale-info crate docs are helpful too https://docs.rs/crate/scale-info/1.0.0

And great tip from @wischli in https://gist.github.com/ascjones/0d81a4c44e84cacd9f714cd34a6de823#gistcomment-3931135

I would like to add that you should add #[scale_info(skip_type_params(T))] for structs which lazily use the pallet’s Config as generic such as pub struct Example<T: Config> - if this statement is correct. This would have saved me quite some time when debugging our upgrade to 0.9.11 sweat_smile

[ascjones]

I had promised to write some docs on this which I have failed to do so far. I will do a session on this at the retreat so need to do some prep this week and can send over my unedited notes for this as a start.