This update range includes:
- `types_first` ([blog](https://flow.org/en/docs/lang/types-first/), all exports need annotated types) is default. I disabled this for now to make that change incremental.
- Generics that escape the scope they are defined in are an error. I fixed some with explicit type annotations and some are suppressed that I didn't easily figure out.
* Move createRoot/hydrateRoot to /client
We want these APIs ideally to be imported separately from things you
might use in arbitrary components (like flushSync). Those other methods
are "isomorphic" to how the ReactDOM tree is rendered. Similar to hooks.
E.g. importing flushSync into a component that only uses it on the client
should ideally not also pull in the entry client implementation on the
server.
This also creates a nicer parity with /server where the roots are in a
separate entry point.
Unfortunately, I can't quite do this yet because we have some legacy APIs
that we plan on removing (like findDOMNode) and we also haven't implemented
flushSync using a flag like startTransition does yet.
Another problem is that we currently encourage these APIs to be aliased by
/profiling (or unstable_testing). In the future you don't have to alias
them because you can just change your roots to just import those APIs and
they'll still work with the isomorphic forms. Although we might also just
use export conditions for them.
For that all to work, I went with a different strategy for now where the
real API is in / but it comes with a warning if you use it. If you instead
import /client it disables the warning in a wrapper. That means that if you
alias / then import /client that will inturn import the alias and it'll
just work.
In a future breaking changes (likely when we switch to ESM) we can just
remove createRoot/hydrateRoot from / and move away from the aliasing
strategy.
* Update tests to import from react-dom/client
* Fix fixtures
* Update warnings
* Add test for the warning
* Update devtools
* Change order of react-dom, react-dom/client alias
I think the order matters here. The first one takes precedence.
* Require react-dom through client so it can be aliased
Co-authored-by: Andrew Clark <git@andrewclark.io>
* Add .browser and .node explicit entry points
This can be useful when the automatic selection doesn't work properly.
* Remove react/index
I'm not sure why I added this in the first place. Perhaps due to how our
builds work somehow.
* Remove build-info.json from files field
* Move internal version of act to shared module
No reason to have three different copies of this anymore.
I've left the the renderer-specific `act` entry points because legacy
mode tests need to also be wrapped in `batchedUpdates`. Next, I'll update
the tests to use `batchedUpdates` manually when needed.
* Migrates tests to use internal module directly
Instead of the `unstable_concurrentAct` exports. Now we can drop those
from the public builds.
I put it in the jest-react package since that's where we put our other
testing utilities (like `toFlushAndYield`). Not so much so it can be
consumed publicly (nobody uses that package except us), but so it works
with our build tests.
* Remove unused internal fields
These were used by the old act implementation. No longer needed.
The following APIs have been added to the `react` stable entry point:
* `SuspenseList`
* `startTransition`
* `unstable_createMutableSource`
* `unstable_useMutableSource`
* `useDeferredValue`
* `useTransition`
The following APIs have been added or removed from the `react-dom` stable entry point:
* `createRoot`
* `unstable_createPortal` (removed)
The following APIs have been added to the `react-is` stable entry point:
* `SuspenseList`
* `isSuspenseList`
The following feature flags have been changed from experimental to true:
* `enableLazyElements`
* `enableSelectiveHydration`
* `enableSuspenseServerRenderer`
* [Fast Refresh] Support callthrough HOCs
* Add a newly failing testing to demonstrate the flaw
This shows why my initial approach doesn't make sense.
* Attach signatures at every nesting level
* Sign nested memo/forwardRef too
* Add an IIFE test
This is not a case that is important for Fast Refresh, but we shouldn't change the code semantics. This case shows the transform isn't quite correct. It's wrapping the call at the wrong place.
* Find HOCs above more precisely
This fixes a false positive that was causing an IIFE to be wrapped in the wrong place, which made the wrapping unsafe.
* Be defensive against non-components being passed to setSignature
* Fix lint
In some scenarios (either timing dependent, or pre-FR compatible React versions) FR blocked calling the React DevTools commit hook. This PR adds a test and a fix for that.
In the next major release, we intend to drop support for using the `act`
testing helper in production. (It already fires a warning.) The
rationale is that, in order for `act` to work, you must either mock the
testing environment or add extra logic at runtime. Mocking the testing
environment isn't ideal because it requires extra set up for the user.
Extra logic at runtime is fine only in development mode — we don't want
to slow down the production builds.
Since most people only run their tests in development mode, dropping
support for production should be fine; if there's demand, we can add it
back later using a special testing build that is identical to the
production build except for the additional testing logic.
One blocker for removing production support is that we currently use
`act` to test React itself. We must test React in both development and
production modes.
So, the solution is to fork `act` into separate public and
internal implementations:
- *public implementation of `act`* – exposed to users, only works in
development mode, uses special runtime logic, does not support partial
rendering
- *internal implementation of `act`* – private, works in both
development and productionm modes, only used by the React Core test
suite, uses no special runtime logic, supports partial rendering (i.e.
`toFlushAndYieldThrough`)
The internal implementation should mostly match the public
implementation's behavior, but since it's a private API, it doesn't have
to match exactly. It works by mocking the test environment: it uses a
mock build of Scheduler to flush rendering tasks, and Jest's mock timers
to flush Suspense placeholders.
---
In this first commit, I've added the internal forks of `act` and
migrated our tests to use them. The public `act` implementation is
unaffected for now; I will leave refactoring/clean-up for a later step.
* Add autofix to cross-fork lint rule
* replace-fork: Replaces old fork contents with new
For each file in the new fork, copies the contents into the
corresponding file of the old fork, replacing what was already there.
In contrast to merge-fork, which performs a three-way merge.
* Replace old fork contents with new fork
First I ran `yarn replace-fork`.
Then I ran `yarn lint` with autofix enabled. There's currently no way to
do that from the command line (we should fix that), so I had to edit the
lint script file.
* Manual fix-ups
Removes dead branches, removes prefixes from internal fields. Stuff
like that.
* Fix DevTools tests
DevTools tests only run against the old fork, which is why I didn't
catch these earlier.
There is one test that is still failing. I'm fairly certain it's related
to the layout of the Suspense fiber: we no longer conditionally wrap the
primary children. They are always wrapped in an extra fiber.
Since this has been running in www for weeks without major issues, I'll
defer fixing the remaining test to a follow up.
The motivation for doing this is to make it impossible for additional
uses of pre-rendering to sneak into www without going through the
LegacyHidden abstraction. Since this feature was already disabled in
the new fork, this brings the two closer to parity.
The LegacyHidden abstraction itself still needs to opt into
pre-rendering somehow, so rather than totally disabling the feature, I
updated the `hidden` prop check to be obnoxiously specific. Before, you
could set it to any truthy value; now, you must set it to the string
"unstable-do-not-use-legacy-hidden".
The node will still be hidden in the DOM, since any truthy value will
cause the browser to apply a style of `display: none`.
I will have to update the LegacyHidden component in www to use the
obnoxious string prop. This doesn't block merge, though, since the
behavior is gated by a dynamic flag. I will update the component before
I enable the flag.
* Expose LegacyHidden type
I will use this internally at Facebook to migrate away from
<div hidden />. The end goal is to migrate to the Offscreen type, but
that has different semantics. This is an incremental step.
* Disable <div hidden /> API in new fork
Migrates to the unstable_LegacyHidden type instead. The old fork does
not support the new component type, so I updated the tests to use an
indirection that picks the correct API. I will remove this once the
LegacyHidden (and/or Offscreen) type has landed in both implementations.
* Add gated warning for `<div hidden />` API
Only exists so we can detect callers in www and migrate them to the new
API. Should not visible to anyone outside React Core team.
We've been shipping unprefixed experimental APIs (like `createRoot` and
`useTransition`) to the Experimental release channel, with the rationale
that because these APIs do not appear in any stable release, we're free
to change or remove them later without breaking any downstream projects.
What we didn't consider is that downstream projects might be tempted to
use feature detection:
```js
const useTransition = React.useTransition || fallbackUseTransition;
```
This pattern assumes that the version of `useTransition` that exists in
the Experimental channel today has the same API contract as the final
`useTransition` API that we'll eventually ship to stable.
To discourage feature detection, I've added an `unstable_` prefix to
all of our unstable APIs.
The Facebook builds still have the unprefixed APIs, though. We will
continue to support those; if we make any breaking changes, we'll
migrate the internal callers like we usually do. To make testing easier,
I added the `unstable_`-prefixed APIs to the www builds, too. That way
our tests can always use the prefixed ones without gating on the
release channel.
Previously, we transformed
```
let Foo = styled.div``;
```
to
```
let Foo = _c1 = styled.div``;
```
and then babel-plugin-styled-components would infer `_c1` as the display name. Widen the existing case that applies to function expressions to apply to any type of variable declaration.
* Upgrade fbjs-scripts
This script takes into account the NODE_ENV as part of jest cache keys.
This avoids flaky tests since we depend on different transforms in prod
and dev.
* Upgrade Fresh test to Babel 7 transform
Some of our internal reconciler types have leaked into other packages.
Usually, these types are treated as opaque; we don't read and write
to its fields. This is good.
However, the type is often passed back to a reconciler method. For
example, React DOM creates a FiberRoot with `createContainer`, then
passes that root to `updateContainer`. It doesn't do anything with the
root except pass it through, but because `updateContainer` expects a
full FiberRoot, React DOM is still coupled to all its fields.
I don't know if there's an idiomatic way to handle this in Flow. Opaque
types are simlar, but those only work within a single file. AFAIK,
there's no way to use a package as the boundary for opaqueness.
The immediate problem this presents is that the reconciler refactor will
involve changes to our internal data structures. I don't want to have to
fork every single package that happens to pass through a Fiber or
FiberRoot, or access any one of its fields. So my current plan is to
share the same Flow type across both forks. The shared type will be a
superset of each implementation's type, e.g. Fiber will have both an
`expirationTime` field and a `lanes` field. The implementations will
diverge, but not the types.
To do this, I lifted the type definitions into a separate module.
* Enable prefer-const rule
Stylistically I don't like this but Closure Compiler takes advantage of
this information.
* Auto-fix lints
* Manually fix the remaining callsites
* Move remaining things to named exports
The interesting case here is the noop renderers. The wrappers around the
reconciler now changed to use a local export that gets mutated.
ReactNoop and ReactNoopPersistent now have to destructure the object to
list out the names it's going to export. We should probably refactor
ReactNoop away from createReactNoop. Especially since it's also not Flow
typed.
* Switch interactions to star exports
This will have esModule compatibility flag on them. They should ideally
export default instead.
