JSX V4: investigate leftovers after release.

[cristianoc]

This is done, leaving leftovers for a future release.

This task is to track the various activities related to JSX V4.

• PPX in the syntax repo JSX PPX V4 part2 syntax#586
• New configuration with bsconfig.json Wire to JSX PPX V4 and introduce Jsx* modules #5484
• Add support for jsx mode to rescript-react Update new jsx transform apis, bind to Jsx in compiler, for JSX V4. rescript-react#49
• Explore one more instance, such as rescript react native. https://github.com/rescript-react-native/rescript-react-native
• Spec for V4 (for writers of bindings to frameworks)
• Upgrade doc for V4
• Testing on real projects Checking the backward compatibility of V10 #5493 and https://github.com/green-labs/sinsunhi-frontend-mirror
• Editor support Make sure that editor support works with JSX V4 #5406
• GenType support Adapt genType to work with JSX V4 #5582
• Communication and community engagement https://forum.rescript-lang.org/t/jsx-v4-next-rescript-react-0-10-x/3431
• Look into dynamically loaded components Dynamic import ergonomics #5593

[cristianoc]

@mattdamon108 this topic has grown to be quite substantial. Adding a top-level issue to track the various activities taking place, to coordinate, and so that interested people can follow along.

[cristianoc]

@mattdamon108 I'm questioning the defaults.
Not sure the default should be "do nothing" as in V3. This is likely only confuse people.

How about making v4 react classic the default?

[mununki]

Is it what you want at the beginning? (backward compatibility) 😄 Switching the V4 as default is an effortless task like a finger snap.
One thing came to mind is the new jsx config in bsconfig. Switching the V4 as default without the hand-written configuration by the user, I'm afraid it becomes more confusing to our user. I think it looks mismatch between configuration and compilation. What do you think?

[cristianoc]

I think the vast majority of users will never need to change config. And beginners have 1 less thing to learn.
Plus there was a forum post right now about an issue due to not setting the configuration, which this would have prevented.

[cristianoc]

Also, there's no setting for "do nothing". So this is a weird initialization.

[mununki]

I think there is a setting for "do nothing", not adding "reason": { ... } nor "jsx": { ... }. If user doesn't add any of them, jsx ppx will not be triggered.

[mununki]

How about throwing more informative error message, in case user didn't add the jsx configuration, but has written JSX expressions or attribute @react.componet?

[mununki]

Before further discussion, let me clear your intention.

1. no configuration at all -> V4 + classic
2. configuration -> works as configuration

Is it correct?

[cristianoc]

More messages is OK. Except if it's an error it's a breaking change.

[cristianoc]

I think there is a setting for "do nothing", not adding "reason": { ... } nor "jsx": { ... }. If user doesn't add any of them, jsx ppx will not be triggered.

You can't do that per-file.
It's only a config that exists by omitting global config.

[mununki]

I got your point. Let me write down some user stories to make it clear.

First, "reason": 3 + V3 users -> JSX V4 + classic as default
If user has error or want to back to V3, then user changes the bsconfig "jsx": { "version": 3 }
If user wants to try V4 + automatic, go for it with bsconfig update, "jsx": {"version": 4, "mode": "automatic"}

In this regard, only concern is V4 + classic will be triggered even for users who doesn't have any configuration about jsx. I think it is not a big deal. That is how the ppx works normally, regardless of using an attribute or extension which trigger.
Does it make sense?

[mununki]

Yes, I think making V4 + classic as default brings the new feature with impact.

[mununki]

Oh, we can still make not triggering the jsx ppx if user doesn't have any configuration about jsx at all.

[mununki]

If we make V4 + classic as default, then submodules in dependencies will be affected by the same default, right? Is it your intention?