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.
With this change, a simple object type `{ }` means an exact object `{| |}` which most people assume.
Opting for inexact requires the extra `{ a: number, ... }` syntax at the end.
A followup, someone could replace all the `{| |}` with `{ }`.
* Fix error handling when the Flight client itself errors
* Serialize references to errors in the error priority queue
It doesn't make sense to emit references to future values at higher pri
than the value that they're referencing.
This ensures that we don't emit hard forward references to values that
don't yet exist.
* Internal `act`: Unwrapping resolved promises
This update our internal implementation of `act` to support React's new
behavior for unwrapping promises. Like we did with Scheduler, when
something suspends, it will yield to the main thread so the microtasks
can run, then continue in a new task.
I need to implement the same behavior in the public version of `act`,
but there are some additional considerations so I'll do that in a
separate commit.
* Move throwException to after work loop resumes
throwException is the function that finds the nearest boundary and
schedules it for a second render pass. We should only call it right
before we unwind the stack — not if we receive an immediate ping and
render the fiber again.
This was an oversight in 8ef3a7c that I didn't notice because it happens
to mostly work, anyway. What made me notice the mistake is that
throwException also marks the entire render phase as suspended
(RootDidSuspend or RootDidSuspendWithDelay), which is only supposed to
be happen if we show a fallback. One consequence was that, in the
RootDidSuspendWithDelay case, the entire commit phase was blocked,
because that's the exit status we use to block a bad fallback
from appearing.
* Use expando to check whether promise has resolved
Add a `status` expando to a thrown thenable to track when its value has
resolved.
In a later step, we'll also use `value` and `reason` expandos to track
the resolved value.
This is not part of the official JavaScript spec — think of
it as an extension of the Promise API, or a custom interface that is a
superset of Thenable. However, it's inspired by the terminology used
by `Promise.allSettled`.
The intent is that this will be a public API — Suspense implementations
can set these expandos to allow React to unwrap the value synchronously
without waiting a microtask.
* Scaffolding for `experimental_use` hook
Sets up a new experimental hook behind a feature flag, but does not
implement it yet.
* use(promise)
Adds experimental support to Fiber for unwrapping the value of a promise
inside a component. It is not yet implemented for Server Components,
but that is planned.
If promise has already resolved, the value can be unwrapped
"immediately" without showing a fallback. The trick we use to implement
this is to yield to the main thread (literally suspending the work
loop), wait for the microtask queue to drain, then check if the promise
resolved in the meantime. If so, we can resume the last attempted fiber
without unwinding the stack. This functionality was implemented in
previous commits.
Another feature is that the promises do not need to be cached between
attempts. Because we assume idempotent execution of components, React
will track the promises that were used during the previous attempt and
reuse the result. You shouldn't rely on this property, but during
initial render it mostly just works. Updates are trickier, though,
because if you used an uncached promise, we have no way of knowing
whether the underlying data has changed, so we have to unwrap the
promise every time. It will still work, but it's inefficient and can
lead to unnecessary fallbacks if it happens during a discrete update.
When we implement this for Server Components, this will be less of an
issue because there are no updates in that environment. However, it's
still better for performance to cache data requests, so the same
principles largely apply.
The intention is that this will eventually be the only supported way to
suspend on arbitrary promises. Throwing a promise directly will
be deprecated.
Implement basic support for "Resources". In the context of this commit, the only thing that is currently a Resource are
<link rel="stylesheet" precedence="some-value" ...>
Resources can be rendered anywhere in the react tree, even outside of normal parenting rules, for instance you can render a resource before you have rendered the <html><head> tags for your application. In the stream we reorder this so the browser always receives valid HTML and resources are emitted either in place (normal circumstances) or at the top of the <head> (when you render them above or before the <head> in your react tree)
On the client, resources opt into an entirely different hydration path. Instead of matching the location within the Document these resources are queried for in the entire document. It is an error to have more than one resource with the same href attribute.
The use of precedence here as an opt-in signal for resourcifying the link is in preparation for a more complete Resource implementation which will dedupe resource references (multiple will be valid), hoist to the appropriate container (body, head, or elsewhere), order (according to precedence) and Suspend boundaries that depend on them. More details will come in the coming weeks on this plan.
This feature is gated by an experimental flag and will only be made available in experimental builds until some future time.
This applies forked changes from the "new" reconciler to the "old" one.
Includes:
- 67de5e3 [FORKED] Hidden trees should capture Suspense
- 6ab05ee [FORKED] Track nearest Suspense handler on stack
- 051ac55 [FORKED] Add HiddenContext to track if subtree is hidden
* [FORKED] Hidden trees should capture Suspense
If something suspends inside a hidden tree, it should not affect
anything in the visible part of the UI. This means that Offscreen acts
like a Suspense boundary whenever it's in its hidden state.
* Add previous commit to forked revisions
* [FORKED] Add HiddenContext to track if subtree is hidden
This adds a new stack cursor for tracking whether we're rendering inside
a subtree that's currently hidden.
This corresponds to the same place where we're already tracking the
"base lanes" needed to reveal a hidden subtree — that is, when going
from hidden -> visible, the base lanes are the ones that we skipped
over when we deferred the subtree. We must includes all the base lanes
and their updates in order to avoid an inconsistency with the
surrounding content that already committed.
I consolidated the base lanes logic and the hidden logic into the same
set of push/pop calls.
This is intended to replace the InvisibleParentContext that is currently
part of SuspenseContext, but I haven't done that part yet.
* Add previous commit to forked revisions
* [FORKED] Track nearest Suspense handler on stack
Instead of traversing the return path whenever something suspends to
find the nearest Suspense boundary, we can push the Suspense boundary
onto the stack before entering its subtree. This doesn't affect the
overall algorithm that much, but because we already do all the same
logic in the begin phase, we can save some redundant work by tracking
that information on the stack instead of recomputing it every time.
* Add previous commit to forked revisions
Offscreen is only enabled in the www and experimental channels. Instead
of listing these on every Offscreen test, I added a test gate alias
called `enableOffscreen`. Makes it easier to grep for these, and edit or
remove the channels later.
This applies forked changes from the "new" reconciler to the "old" one.
Includes:
- d410f0a [FORKED] Bugfix: Offscreen instance is null during setState
- 58bb117 [FORKED] Check for infinite update loops even if unmounted
- 31882b5 [FORKED] Bugfix: Revealing a hidden update
- 17691ac [FORKED] Don't update childLanes until after current render
* [FORKED] Bugfix: Offscreen instance is null during setState
During a setState, we traverse up the return path and check if any
parent Offscreen components are currently hidden. To do that, we must
access the Offscreen fiber's `stateNode` field.
On a mounted Offscreen fiber, the `stateNode` is never null, so usually
we don't need to refine the type. When a fiber is unmounted, though,
we null out its `stateNode` field to prevent memory cycles. However,
we also null out its `return` field, so I had assumed that an unmounted
Offscreen fiber would never be reachable.
What I didn't consider is that it's possible to call `setState` on a
fiber that never finished mounting. Because it never mounted, it was
never deleted. Because it was never deleted, its `return` field was
never disconnected.
This pattern is always accompanied by a warning but we still need to
account for it. There may also be other patterns where an unmounted
Offscreen instance is reachable, too.
The discovery also suggests it may be better for memory
usage if we don't attach the `return` pointer until the commit phase,
though in order to do that we'd need some other way to track the return
pointer during initial render, like on the stack.
The fix is to add a null check before reading the instance
during setState.
* Add previous commit to list of forked revisions
* [FORKED] Check for infinite update loops even if unmounted
The infinite update loop check doesn't need to run if the component
already unmounted, because an update to an unmounted component can't
cause a re-render. But because we used to run the check in this case,
anyway, I found one test in www that happens to "rely on" this behavior
(accidentally). The test is a pretty messy snapshot thing that I have no
interest fixing so to unblock the sync I'm just going to switch this
back to how it was.
* Add previous commit to forked revisions
* [Fizz] Support abort reasons
Fizz supports aborting the render but does not currently accept a reason. The various render functions that use Fizz have some automatic and some user-controlled abort semantics that can be useful to communicate with the running program and users about why an Abort happened.
This change implements abort reasons for renderToReadableStream and renderToPipeable stream as well as legacy renderers such as renderToString and related implementations.
For AbortController implementations the reason passed to the abort method is forwarded to Fizz and sent to the onError handler. If no reason is provided the AbortController should construct an AbortError DOMException and as a fallback Fizz will generate a similar error in the absence of a reason
For pipeable streams, an abort function is returned alongside pipe which already accepted a reason. That reason is now forwarded to Fizz and the implementation described above.
For legacy renderers there is no exposed abort functionality but it is used internally and the reasons provided give useful context to, for instance to the fact that Suspense is not supported in renderToString-like renderers
* Add `isHidden` to OffscreenInstance
We need to be able to read whether an offscreen tree is hidden from
an imperative event. We can store this on its OffscreenInstance.
We were already scheduling a commit effect whenever the visibility
changes, in order to toggle the inner effects. So we can reuse that.
* [FORKED] Bugfix: Revealing a hidden update
This fixes a bug I discovered related to revealing a hidden Offscreen
tree. When this happens, we include in that render all the updates that
had previously been deferred — that is, all the updates that would have
already committed if the tree weren't hidden. This is necessary to avoid
tearing with the surrounding contents. (This was the "flickering"
Suspense bug we found a few years ago: #18411.)
The way we do this is by tracking the lanes of the updates that were
deferred by a hidden tree. These are the "base" lanes. Then, in order
to reveal the hidden tree, we process any update that matches one of
those base lanes.
The bug I discovered is that some of these base lanes may include
updates that were not present at the time the tree was hidden. We cannot
flush those updates earlier that the surrounding contents — that, too,
could cause tearing.
The crux of the problem is that we sometimes reuse the same lane for
base updates and for non-base updates. So the lane alone isn't
sufficient to distinguish between these cases. We must track this in
some other way.
The solution I landed upon was to add an extra OffscreenLane bit to any
update that is made to a hidden tree. Then later when we reveal the
tree, we'll know not to treat them as base updates.
The extra OffscreenLane bit is removed as soon as that lane is committed
by the root (markRootFinished) — at that point, it gets
"upgraded" to a base update.
The trickiest part of this algorithm is reliably detecting when an
update is made to a hidden tree. What makes this challenging is when the
update is received during a concurrent event, while a render is already
in progress — it's possible the work-in-progress render is about to
flip the visibility of the tree that's being updated, leading to a race
condition.
To avoid a race condition, we will wait to read the visibility of the
tree until the current render has finished. In other words, this makes
it an atomic operation. Most of this logic was already implemented
in #24663.
Because this bugfix depends on a moderately risky refactor to the update
queue (#24663), it only works in the "new" reconciler fork. We will roll
it out gradually to www before landing in the main fork.
* Add previous commit to list of forked revisions
* [Fizz] Disallow complex children in <title> elements
<title> Elements in the DOM can only have Text content. In Fizz if more than one text node is emitted an HTML comment node is used as a text separator. Unfortunately because of the content restriction of the DOM representation of the title element this separator is displayed as escaped text which is not what the component author intended.
This commit special cases title handling, primarily to issue warnings if you pass complex children to <title>. At the moment title expects to receive a single child or an array of length 1. In both cases the type of that child must be string or number. If anything more complex is provided a warning will be logged to the console explaining why this is problematic.
There is no runtime behavior change so broken things are still broken (e.g. returning two text nodes which will cause a separator or using Suspense inside title children) but they should at least be accompanied by warnings that are useful.
One edge case that will now warn but won't technically break an application is if you use a Component that returns a single string as a child of title. This is a form of indirection that works but becasue we cannot discriminate between a Component that will follow the rules and one that violates them the warning is issued regardless.
* fixup dev warning conditional logic
* lints
* fix bugs
* extend onRecoverableError API to support errorInfo
errorInfo has been used in Error Boundaries wiht componentDidCatch for a while now. To date this metadata only contained a componentStack. onRecoverableError only receives an error (type mixed) argument and thus providing additional error metadata was not possible without mutating user created mixed objects.
This change modifies rootConcurrentErrors rootRecoverableErrors, and hydrationErrors so all expect CapturedValue types. additionally a new factory function allows the creation of CapturedValues from a value plus a hash and stack.
In general, client derived CapturedValues will be created using the original function which derives a componentStack from a fiber and server originated CapturedValues will be created using with a passed in hash and optional componentStack.
We have a currently unreproducible flaky e2e test. This PR captures snapshots on e2e test failures so we can better debug flaky e2e tests that don't fail locally.
* Always push updates to interleaved queue first
Interleaves updates (updates that are scheduled while another render
is already is progress) go into a special queue that isn't applied until
the end of the current render. They are transferred to the "real" queue
at the beginning of the next render.
Currently we check during `setState` whether an update should go
directly onto the real queue or onto the special interleaved queue. The
logic is subtle and it can lead to bugs if you mess it up, as in #24400.
Instead, this changes it to always go onto the interleaved queue. The
behavior is the same but the logic is simpler.
As a further step, we can also wait to update the `childLanes` until
the end of the current render. I'll do this in the next step.
* Move setState return path traversal to own call
A lot of the logic around scheduling an update needs access to the
fiber root. To obtain this reference, we must walk up the fiber return
path. We also do this to update `childLanes` on all the parent
nodes, so we can use the same traversal for both purposes.
The traversal currently happens inside `scheduleUpdateOnFiber`, but
sometimes we need to access it beyond that function, too.
So I've hoisted the traversal out of `scheduleUpdateOnFiber` into its
own function call that happens at the beginning of the
`setState` algorithm.
* Rename ReactInterleavedUpdates -> ReactFiberConcurrentUpdates
The scope of this module is expanding so I've renamed accordingly. No
behavioral changes.
* Enqueue and update childLanes in same function
During a setState, the childLanes are updated immediately, even if a
render is already in progress. This can lead to subtle concurrency bugs,
so the plan is to wait until the in-progress render has finished before
updating the childLanes, to prevent subtle concurrency bugs.
As a step toward that change, when scheduling an update, we should not
update the childLanes directly, but instead defer to the
ReactConcurrentUpdates module to do it at the appropriate time.
This makes markUpdateLaneFromFiberToRoot a private function that is
only called from the ReactConcurrentUpdates module.
* [FORKED] Don't update childLanes until after current render
(This is the riskiest commit in the stack. Only affects the "new"
reconciler fork.)
Updates that occur in a concurrent event while a render is already in
progress can't be processed during that render. This is tricky to get
right. Previously we solved this by adding concurrent updates to a
special `interleaved` queue, then transferring the `interleaved` queue
to the `pending` queue after the render phase had completed.
However, we would still mutate the `childLanes` along the parent path
immediately, which can lead to its own subtle data races.
Instead, we can queue the entire operation until after the render phase
has completed. This replaces the need for an `interleaved` field on
every fiber/hook queue.
The main motivation for this change, aside from simplifying the logic a
bit, is so we can read information about the current fiber while we're
walking up its return path, like whether it's inside a hidden tree.
(I haven't done anything like that in this commit, though.)
* Add 17691ac to forked revisions
* Track revs that intentionaly fork the reconciler
When we fork the the "old" and "new" reconciler implementations, it can
be difficult to keep track of which commits introduced the delta
in behavior. This makes bisecting difficult if one of the changes
introduces a bug.
I've added a new file called `forked-revisions` that contains the list
of commits that intentionally forked the reconcilers.
In CI, we'll confirm that the reconcilers are identical except for the
changes in the listed revisions. This also ensures that the revisions
can be cleanly reverted.
* [TEST] Add trivial divergence between forks
This should fail CI. We'll see if the next commit fixes it.
* [TEST] Update list of forked revisions
This should fix CI
* Revert temporary fork
This reverts the temporary fork added in the previous commits that was
used to test CI.
* Update error message when CI fails
* Allow aritfacts download even if CI is broken
Adds an option to the download script to disable the CI check and
continue downloading the artifacts even if CI is broken.
I often rely on this to debug broken build artifacts. I was thinking
the sizebot should also use this when downloading the base artifacts
from main, since for the purposes of size tracking, it really doesn't
matter whether the base commit is broken.
* Sizebot should work even if base rev is broken
Sizebot works by downloading the build artifacts for the base revision
and comparing the fize sizes, but the download script will fail if
the base revision has a failing CI job. This happens more often than it
should because of flaky cron jobs, but even when it does, we shouldn't
let it affect the sizebot — for the purposes of tracking sizes, it
doesn't really matter whether the base revision is broken.
* Implements useId hook for Flight server.
The approach for ids for Flight is different from Fizz/Client where there is a need for determinancy. Flight rendered elements will not be rendered on the client and as such the ids generated in a request only need to be unique. However since FLight does support refetching subtrees it is possible a client will need to patch up a part of the tree rather than replacing the entire thing so it is not safe to use a simple incrementing counter. To solve for this we allow the caller to specify a prefix. On an initial fetch it is likely this will be empty but on refetches or subtrees we expect to have a client `useId` provide the prefix since it will guaranteed be unique for that subtree and thus for the entire tree. It is also possible that we will automatically provide prefixes based on a client/Fizz useId on refetches
in addition to the core change I also modified the structure of options for renderToReadableStream where `onError`, `context`, and the new `identifierPrefix` are properties of an Options object argument to avoid the clumsiness of a growing list of optional function arguments.
* defend against useId call outside of rendering
* switch to S from F for Server Component ids
* default to empty string identifier prefix
* Add a test demonstrating that there is no warning when double rendering on the client a server component that used useId
* lints and gates
Modified the `run_devtools_e2e_tests` script so that you can pass in a React version. If you pass in a version, it will build the DevTools shell and run the e2e tests with that version.
This PR adds a `--replaceBuild` option to the script that downloads older React version builds. If this flag is true, we will replace the contents of the `build` folder with the contents of the `build-regression` folder and remove the `build-regression` folder after, which was the original behavior.
However, for e2e tests, we need both the original build (for DevTools) and the new build (for the React Apps), so we need both the `build` and the `build-regression` folders. Not adding the `--replaceBuild` option will do this.
This PR also modifies the circle CI config to reflect this change.
* use return from onError
* export getSuspenseInstanceFallbackError
* stringToChunk
* return string from onError in downstream type signatures
* 1 more type
* support encoding errors in html stream and escape user input
This commit adds another way to get errors to the suspense instance by encoding them as dataset properties of a template element at the head of the boundary. Previously if there was an error before the boundary flushed there was no way to stream the error to the client because there would never be a client render instruction.
Additionally the error is sent in 3 parts
1) error hash - this is always sent (dev or prod) if one is provided
2) error message - Dev only
3) error component stack - Dev only, this now captures the stack at the point of error
Another item addressed in this commit is the escaping of potentially unsafe data. all error components are escaped as test for browers when written into the html and as javascript strings when written into a client render instruction.
* nits
Co-authored-by: Marco Salazar <salazarm@fb.com>
We need the regression config moduleNameMapper to come before the current moduleNameMapper so when it tries to map "/^react-dom\/([^/]+)$/ it doesn't get confused. The reason is because order in which the mappings are defined matters. Patterns are checked one by one until one fits, and the most specific rule should be listed first.
This PR adds a script that downloads the specified react version from NPM (ie. react-dom, react, and react-test-renderer) and replaces the corresponding files in the build folder with the downloaded react files.
The scheduler package, unlike react-dom, react, and react-test-renderer, is versioned differently, so we also need to specifically account for that in the script.
Some older React versions have different module import names and are missing certain features. This PR mocks modules that don't exist and maps modules in older versions to the ones that are required in tests. Specifically:
* In React v16.5, scheduler is named schedule
* In pre concurrent React, there is no act
* Prior to React v18.0, react-dom/client doesn't exist
* In DevTools, we expect to use scheduler/tracing-profiling instead of scheduler/tracing
`string.replaceAll` doesn't exist in our CircleCI Docker environment. We also don't need it in this case because `semver.satisfies` allows for whitespace when specifying a range. This PR removes the unnecessary call.
I added a `--sourceMaps` option to our test command that enables inline
source maps. I've kept it disabled by default, since it makes the tests
run slower. But it's super useful when attaching to a debugger.
This reverts #24106.
There was a regression in CircleCI's artifacts API recently where you
could no longer access artifacts without an authorization token. This
broke our size reporting CI job because we can't use an authorization
token on external PRs without potentially leaking it. As a temporary
workaround, I changed the size reporting job to use a public mirror of
our build artifacts.
The CircleCI API has since been fixed to no longer require
authorization, so we can revert the workaround.
Add `--reactVersion` argument. This argument is only used in DevTools. When this is specified, run only the tests that have the `// @reactVersion` pragma that satisfies the semver version range. Otherwise, run tests as normal
In DevTools tests, if the REACT_VERSION specified, we know this is a regression test (testing older React Versions). Because a lot of tests test the DevTools front end and we don't want to run them in the regression test scenario, we decided to only run tests that have the // @reactVersion pragma defined.
Because if there are no tests specified, jest will fail, we also opt to use jest.skip to skip all the tests that we don't want to run for a specific React version istead.
This PR makes this change.
This PR:
Adds a transform-react-version-pragma that transforms // @reactVersion SEMVER_VERSION into _test_react_version(...) and _test_react_version_focus(...) that lets us only run a test if it satisfies the right react version.
Adds _test_react_version and _test_react_version_focus to the devtools setupEnv file
Add a devtools preprocessor file for devtools specific plugins
