### Summary
Migrate `next/dynamic` to implementation based on `React.lazy` and
`Suspense`. Then it becomes easier to migrate the existing code in pages
to layouts. Then we can support both `ssr` and `loading` option for
`next/dynamic`.
For `loading` option, it will work like `Suspense`'s `fallback` property
```js
<Suspense fallback={loading}>
<DynamicComponent />
</Suspense>
```
For `ssr` option, by default `React.lazy` supports SSR, but we'll
disable the `ssr: false` case for dynamic import in server components
since there's no client side involved.
Then we don't need `suspense` option anymore as react >= 18 is always
required. Mark it as deprecated.
It also supports to load client component dynamically in server
components now.
#### Code code changes
* switch loadable component to `lazy` + `Suspense`
* will make sure it's retuning a module from `loader()` to
`loader().then(mod => ({ default: mod.default || mod }))` since `lazy()`
only accepts loader returning a module
* Inside suspense boundary, throwing an error for ssr: false, catch the
error on server and client side and ignore it.
* Ignore options like ssr: false for server components since they're on
server, doesn't make sense
* Remove legacy dynamic related transform
#### Feature changes
* `next/dynamic` will work in the same way across the board (appDir and
pages)
* For the throwing error, will make it become a API that throws error
later in the future, so users can customize more with `Suspense`
* You can load client components now in server components with dynamic.
Resolves#43147
#### Tests
* existing dynamic tests all work
* add case: import client component and load through next/dynamic in
server components
### Issues
The PR fixes#40388.
Currently, `next/dynamic` will try to provide a default `loading` to the
`loadableOptions` even when `suspense` is enabled, thus triggering the
incorrect warning. The PR fixes that. The corresponding integration test
case is also updated.
cc @huozhi
## Bug
- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
Co-authored-by: huozhi <inbox@huozhi.im>
This updates our `yarn next` command to leverage react v18 by default and removes the need for the test require hook/config modifying when testing react 18. There are some fixtures we need to investigate react 18 support in follow-ups:
- `test/integration/client-navigation-a11y`
- `test/integration/critical-css`
- `test/integration/custom-error-page-exception`
- `test/integration/font-optimization`
- AMP specific tests
