Add a feature to allow any json in a variant

[EmileTrotignon]

Syntax is as follow :

type t =
| Other of Yojson.Basic.t [@allow_any]
| Foo
[@@deriving json]

Then, if the json j is invalid for type t, Other j is returned instead.

There is support for both runtime and js (although their Json type is different: is that an issue ? We could introduce a [%json] extension that translates to Js.Json.t in Js and Yojson.Basic.t in runtime if its an issue.)

As a bonus, I improved an error message that slipped through in my error message PR. Because its only on JS I did not find it with my cram tests.

[EmileTrotignon]

I also moved the common folder inside the native one. The reason for that is that then I can use it with include subdirs, which enables merlin inside it, which is very useful for developing.

using copy_files means that merlin does not work inside these files.

[EmileTrotignon]

Something similar exists in atdgen, it only allows extra tags instead of any json. I think allowing any json is a good idea, especially because we have structured types for json so we can easily check afterward if its tag-shapped.

[anmonteiro]

I think this makes sense, no strong opinions

[EmileTrotignon]

Hey @anmonteiro I have added the label you asked, and remove the stray comment. Any other change required ?

[anmonteiro]

looks good

[EmileTrotignon]

Could this be merged ? I don't have right to do so @anmonteiro

[anmonteiro]

We should still snapshot the tests that are failing before merging

[EmileTrotignon]

Yeah. The failures are not reproduced on my machine, so I am not sure how to do it.

[andreypopp]

This seems to be the difference in ocamlformat versions installed on CI vs local.

[EmileTrotignon]

There should be a .ocamlformat file with a fixed version to avoid that.

[EmileTrotignon]

There is a test that is failing or succeeding depending on the version. I think this one is impossible to promote.

Should I try and fix or is this good enough ?

[anmonteiro]

hey @EmileTrotignon, I just pushed a commit fixing this test so that we can promote it for all ocaml versions.

[EmileTrotignon]

This is ready for merging