In order to support using the compiler on versions of React prior to 19,
we need the ability to statically import `c` (aka useMemoCache) or
fallback to a polyfill supplied by `react-compiler-runtime` (note: this
is a separate npm package, not to be confused with
`react/compiler-runtime`, which is currently a part of react).
To do this we first need to re-export `useMemoCache` under the top level
React namespace again, which is additive and thus non-breaking. Doing so
allows `react-compiler-runtime` to statically either re-export
`React.__COMPILER_RUNTIME.c` or supply a polyfill, without the need for
a dynamic import which is finicky to support due to returning a promise.
In later PRs I will remove `react/compiler-runtime` and update the
compiler to emit imports to `react-compiler-runtime` instead.
A slight behavior change here too is that I now mark the start of the
commit phase before the BeforeMutationEffect phase. This affects
`<Profiler>` too.
The named sequences are as follows:
Render -> Suspended or Throttled -> Commit -> Waiting for Paint ->
Remaining Effects
The Suspended phase is only logged if we delay the Commit due to CSS /
images.
The Throttled phase is only logged if we delay the commit due to the
Suspense throttling timer.
<img width="1246" alt="Screenshot 2024-09-20 at 9 14 23 PM"
src="https://github.com/user-attachments/assets/8d01f444-bb85-472b-9b42-6157d92c81b4">
I don't yet log render phases that don't complete. I think I also need
to special case renders that or don't commit after being suspended.
This tracks the current window.event.timeStamp the first time we
setState or call startTransition. For either the blocking track or
transition track. We can use this to show how long we were blocked by
other events or overhead from when the user interacted until we got
called into React.
Then we track the time we start awaiting a Promise returned from
startTransition. We can use this track how long we waited on an Action
to complete before setState was called.
Then finally we track when setState was called so we can track how long
we were blocked by other word before we could actually start rendering.
For a Transition this might be blocked by Blocking React render work.
We only log these once a subsequent render actually happened. If no
render was actually scheduled, then we don't log these. E.g. if an
isomorphic Action doesn't call startTransition there's no render so we
don't log it.
We only log the first event/update/transition even if multiple are
batched into it later. If multiple Actions are entangled they're all
treated as one until an update happens. If no update happens and all
entangled actions finish, we clear the transition so that the next time
a new sequence starts we can log it.
We also clamp these (start the track later) if they were scheduled
within a render/commit. Since we share a single track we don't want to
create overlapping tracks.
The purpose of this is not to show every event/action that happens but
to show a prelude to how long we were blocked before a render started.
So you can follow the first event to commit.
<img width="674" alt="Screenshot 2024-09-20 at 1 59 58 AM"
src="https://github.com/user-attachments/assets/151ba9e8-6b3c-4fa1-9f8d-e3602745eeb7">
I still need to add the rendering/suspended phases to the timeline which
why this screenshot has a gap.
<img width="993" alt="Screenshot 2024-09-20 at 12 50 27 AM"
src="https://github.com/user-attachments/assets/155b6675-b78a-4a22-a32b-212c15051074">
In this case it's a Form Action which started a render into the form
which then suspended on the action. The action then caused a refresh,
which interrupts with its own update that's blocked before rendering.
Suspended roots like this is interesting because we could in theory
start working on a different root in the meantime which makes this
timeline less linear.
This code is weird. It reads back the transition that it just set from
the shared internals. It's almost like it expects it to be a getter or
something.
This avoids that and makes it consistent with what ReactFiberHooks
already does.
Stacked on #30979.
The problem with the previous approach is that it recursively walked the
tree up to propagate the resulting time from recording a layout effect.
Instead, we keep a running count of the effect duration on the module
scope. Then we reset it when entering a nested Profiler and then we add
its elapsed count when we exit the Profiler.
This also fixes a bug where we weren't previously including unmount
times for some detached trees since they couldn't bubble up to find the
profiler.
Stacked on #30960 and #30966. Behind the enableComponentPerformanceTrack
flag.
This is the first step of performance logging. This logs the start and
end time of a component render in the passive effect phase. We use the
data we're already tracking on components when the Profiler component or
DevTools is active in the Profiling or Dev builds. By backdating this
after committing we avoid adding more overhead in the hot path. By only
logging things that actually committed, we avoid the costly unwinding of
an interrupted render which was hard to maintain in earlier versions.
We already have the start time but we don't have the end time. That's
because `actualStartTime + actualDuration` isn't enough since
`actualDuration` counts the actual CPU time excluding yields and
suspending in the render.
Instead, we infer the end time to be the start time of the next sibling
or the complete time of the whole root if there are no more siblings. We
need to pass this down the passive effect tree. This will mean that any
overhead and yields are attributed to this component's span. In a follow
up, we'll need to start logging these yields to make it clear that this
is not part of the component's self-time.
In follow ups, I'll do the same for commit phases. We'll also need to
log more information about the phases in the top track. We'll also need
to filter out more components from the trees that we don't need to
highlight like the internal Offscreen components. It also needs polish
on colors etc.
Currently, I place the components into separate tracks depending on
which lane currently committed. That way you can see what was blocking
Transitions or Suspense etc. One problem that I've hit with the new
performance.measure extensions is that these tracks show up in the order
they're used which is not the order of priority that we use. Even when
you add fake markers they have to actually be within the performance run
since otherwise the calls are noops so it's not enough to do that once.
However, I think this visualization is actually not good because these
trees end up so large that you can't see any other lanes once you expand
one. Therefore, I think in a follow up I'll actually instead switch to a
model where Components is a single track regardless of lane since we
don't currently have overlap anyway. Then the description about what is
actually rendering can be separate lanes.
<img width="1512" alt="Screenshot 2024-09-15 at 10 55 55 PM"
src="https://github.com/user-attachments/assets/5ca3fa74-97ce-40c7-97f7-80c1dd7d6470">
<img width="1512" alt="Screenshot 2024-09-15 at 10 56 27 PM"
src="https://github.com/user-attachments/assets/557ad65b-4190-465f-843c-0bc6cbb9326d">
## Summary
Flow will eventually remove the specific `React.Element` type. For most
of the code, it can be replaced with `React.MixedElement` or
`React.Node`.
When specific react elements are required, it needs to be replaced with
either `React$Element` which will trigger a `internal-type` lint error
that can be disabled project-wide, or use
`ExactReactElement_DEPRECATED`.
Fortunately in this case, this one can be replaced with just
`React.MixedElement`.
## How did you test this change?
`flow`
**This API is not intended to ship. This is a temporary unstable hook
for internal performance profiling.**
This PR exposes `unstable_useContextWithBailout`, which takes a compare
function in addition to Context. The comparison function is run to
determine if Context propagation and render should bail out earlier.
`unstable_useContextWithBailout` returns the full Context value, same as
`useContext`.
We can profile this API against `useContext` to better measure the cost
of Context value updates and gather more data around propagation and
render performance.
The bailout logic and test cases are based on
https://github.com/facebook/react/pull/20646
Additionally, this implementation allows multiple values to be compared
in one hook by returning a tuple to avoid requiring additional Context
consumer hooks.
Concurrent by default has been unshipped! Let's clean it up.
Here we remove `forceConcurrentByDefaultForTesting`, which allows us to
run tests against both concurrent strategies. In the next PR, we'll
remove the actual concurrent by default code path.
React transpiles some of its own `console.error` calls into a helper
that appends component stacks to those calls. However, this doesn't
cover user space `console.error` calls - which includes React helpers
that React has moved into third parties like createClass and prop-types.
The idea is that any user space component can add a warning just like
React can which is why React DevTools adds them too if they don't
already exist. Having them appended in both places is tricky because now
you have to know whether to remove them from React's logs.
Similarly it's often common for server-side frameworks to forget to
cover the `console.error` logs from other sources since React DevTools
isn't active there. However, it's also annoying to get component stacks
clogging the terminal - depending on where the log came from.
In the future `console.createTask()` will cover this use case natively
and when available we don't append them at all.
The new strategy relies on either:
- React DevTools existing to add them to React logs as well as third
parties.
- `console.createTask` being supported and surfaced.
- A third party framework showing the component stack either in an Error
Dialog or appended to terminal output.
For a third party to be able to implement this they need to be able to
get the component stack. To get the component stack from within a
`console.error` call you need to use the `React.captureOwnerStack()`
helper which is only available in `enableOwnerStacks` flag. However,
it's possible to polyfill with parent stacks using internals as a stop
gap. There's a question of whether React 19 should just go out with
`enableOwnerStacks` to expose this but regardless I think it's best it
doesn't include component stacks from the runtime for consistency.
In practice it's not really a regression though because typically either
of the other options exists and error dialogs don't implement
`console.error` overrides anyway yet. SSR terminals might miss them but
they'd only have them in DEV warnings to begin with an a subset of React
warnings. Typically those are either going to happen on the client
anyway or replayed.
Our tests are written to assert that component stacks work in various
scenarios all over the place. To ensure that this keeps working I
implement a "polyfill" that is similar to that expected a server
framework might do - in `assertConsoleErrorDev` and `toErrorDev`.
This PR doesn't yet change www or RN since they have their own forks of
consoleWithStackDev for now.
I noticed that the www-modern builds pick up the `.experimental.js`
entry points but these flags that are associated with these exports are
not enabled in www, so it gets the wrong builds.
This file is just a clone over the stable `ReactServer.js` one. We
should probably do the reexport pattern instead.
The full stack is the current execution stack (`new Error().stack`) +
the current owner stack (`React.captureOwnerStack()`).
The idea with the top frame was that when we append it to console.error
we'd include both since otherwise the true reason would be obscured
behind the little `>` to expand. So we'd just put both stack front and
center. By adding this into getCurrentStack it was easy to use the same
filtering. I never implemented in Fizz or Flight though.
However, with the public API `React.captureOwnerStack()` it's not
necessary to include the current stack since you already have it and
you'd have filtering capabilities in user space too.
Since I'm removing the component stacks from React itself we no longer
need this. It's expected that maybe RDT or framework polyfill would
include this same technique though.
For environments that still have legacy contexts available, this adds a
warning to make the remaining call sites easier to locate and encourage
upgrades.
This is all behind the `enableOwnerStacks` flag.
This is a follow up to #29088. In that I moved type validation into the
renderer since that's the one that knows what types are allowed.
However, I only removed it from `React.createElement` and not the JSX
which was an oversight.
However, I also noticed that for invalid types we don't have the right
stack trace for throws because we're not yet inside the JSX element that
itself is invalid. We should use its stack for the stack trace. That's
the reason it's enough to just use the throw now because we can get a
good stack trace from the owner stack. This is fixed by creating a fake
Throw Fiber that gets assigned the right stack.
Additionally, I noticed that for certain invalid types like the most
common one `undefined` we error in Flight so a missing import in RSC
leads to a generic error. Instead of erroring on the Flight side we
should just let anything that's not a Server Component through to the
client and then let the Client renderer determine whether it's a valid
type or not. Since we now have owner stacks through the server too, this
will still be able to provide a good stack trace on the client that
points to the server in that case.
<img width="571" alt="Screenshot 2024-06-25 at 6 46 35 PM"
src="https://github.com/facebook/react/assets/63648/6812c24f-e274-4e09-b4de-21deda9ea1d4">
To get the best stack you have to expand the little icon and the regular
stack is noisy [due to this Chrome
bug](https://issues.chromium.org/issues/345248263) which makes it a
little harder to find but once that's fixed it might be easier.
Only with the enableOwnerStacks flag (which is not on in www).
This is a new DEV-only API to be able to implement what we do for
console.error in user space.
This API does not actually include the current stack that you'd get from
`new Error().stack`. That you'd have to add yourself.
This adds the ability to have conditional development exports because we
plan on eventually having separate ESM builds that use the "development"
or "production" export conditions.
NOTE: This removes the export of `act` from `react` in prod (as opposed
to a function that throws) - inline with what we do with other
conditional exports.
Basically make `console.error` and `console.warn` behave like normal -
when a component stack isn't appended. I need this because I need to be
able to print rich logs with the component stack option and to be able
to disable instrumentation completely in `console.createTask`
environments that don't need it.
Currently we can't print logs with richer objects because they're
toString:ed first. In practice, pretty much all arguments we log are
already toString:ed so it's not necessary anyway. Some might be like a
number. So it would only be a problem if some environment can't handle
proper consoles but then it's up to that environment to toString it
before logging.
The `Warning: ` prefix is historic and is both noisy and confusing. It's
mostly unnecessary since the UI surrounding `console.error` and
`console.warn` tend to have visual treatment around it anyway. However,
it's actively misleading when `console.error` gets prefixed with a
Warning that we consider an error level. There's an argument to be made
that some of our `console.error` don't make the bar for an error but
then the argument is to downgrade each of those to `console.warn` - not
to brand all our actual error logging with `Warning: `.
Apparently something needs to change in React Native before landing this
because it depends on the prefix somehow which probably doesn't make
sense already.
## Overview
Updates `eslint-plugin-jest` and enables the recommended rules with some
turned off that are unhelpful.
The main motivations is:
a) we have a few duplicated tests, which this found an I deleted
b) making sure we don't accidentally commit skipped tests
This refactors key warning to happen inline after we've matched a Fiber.
I didn't want to do that originally because it was riskier. But it turns
out to be straightforward enough.
This lets us use that Fiber as the source of the warning which matters
to DevTools because then DevTools can associate it with the right
component after it mounts.
We can also associate the duplicate key warning with this Fiber. That
way we'll get the callsite with the duplicate key on the stack and can
associate this warning with the child that had the duplicate.
I kept the forked DevTools tests because the warning now is counted on
the Child instead of the Parent (18 behavior).
However, this won't be released in 19.0.0 so I only test this in
whatever the next version is.
Doesn't seem worth it to have a test for just the 19.0.0 behavior.
While most builds of Flight and Fizz schedule work in new tasks some do
execute work synchronously. While this is necessary for legacy APIs like
renderToString for modern APIs there really isn't a great reason to do
this synchronously.
We could schedule works as microtasks but we actually want to yield so
the runtime can run events and other things that will unblock additional
work before starting the next work loop.
This change updates all non-legacy uses to be async using the best
availalble macrotask scheduler.
Browser now uses postMessage
Bun uses setTimeout because while it also supports setImmediate the
scheduling is not as eager as the same API in node
the FB build also uses setTimeout
This change required a number of changes to tests which were utilizing
the sync nature of work in the Browser builds to avoid having to manage
timers and tasks. I added a patch to install MessageChannel which is
required by the browser builds and made this patched version integrate
with the Scheduler mock. This way we can effectively use `act` to flush
flight and fizz work similar to how we do this on the client.
## Overview
We didn't have any tests that ran in persistent mode with the xplat
feature flags (for either variant).
As a result, invalid test gating like in
https://github.com/facebook/react/pull/29664 were not caught.
This PR adds test flavors for `ReactFeatureFlag-native-fb.js` in both
variants.
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## Summary
Remove `startTransition` and `useActionState` from `react-server`
condition of react, as they should only stay in client bundle.
This will reduce the server bundle of react itself.
Found this while tracing where the `process.emit` was called.
<!--
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## How did you test this change?
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This information is available in the regular stack but since that's
hidden behind an expando and our appended stack to logs is not hidden,
it hides the most important frames like the name of the current
component.
This is closer to what happens to the native stack.
We only include stacks if they're within a ReactFiberCallUserSpace call
frame. This should be most that have a current fiber but this is
critical to filtering out most React frames if the regular node_modules
filter doesn't work.
Most React warnings fire during the rendering phase and not inside a
user space function but some do like hooks warnings and setState in
render. This feature is more important if we port this to React DevTools
appending stacks to all logs where it's likely to originate from inside
a component and you want the line within that component to immediately
part of the visible stack.
One thing that kind sucks is that we don't have a reliable way to
exclude React internal stack frames. We filter node_modules but it might
not match. For other cases I try hard to only track the stack frame at
the root of React (e.g. immediately inside createElement) until the
ReactFiberCallUserSpace so we don't need the filtering to work. In this
case it's hard to achieve the same thing though. This is easier in RDT
because we have the start/end line and parsing of stack traces so we can
use that to exclude internals but that's a lot of code/complexity for
shipping within the library.
For example in Safari:
<img width="590" alt="Screenshot 2024-05-31 at 6 15 27 PM"
src="https://github.com/facebook/react/assets/63648/2820c8c0-8a03-42e9-8678-8348f66b051a">
Ideally warnOnUseFormStateInDev and useFormState wouldn't be included
since they're React internals. Before this change, the Counter.js line
also wasn't included though which points to exactly where the error is
within the user code.
(Note Server Components have V8 formatted lines and Client Components
have JSC formatted lines.)
When defining a displayName on forwardRef/memo we forward that name to
the inner function.
We used to use displayName for this but in #29206 I switched this to use
`"name"`. That's because V8 doesn't use displayName, it only uses the
overridden name in stack traces. This is the only thing covered by our
tests for component stacks.
However, I realized that Safari only uses displayName and not the name.
So this sets both.
## Summary
In https://github.com/facebook/react/pull/29088, the validation logic
for `React.Children` inspected whether `mappedChild` — the return value
of the map callback — has a valid `key`. However, this deviates from
existing behavior which only warns if the original `child` is missing a
required `key`.
This fixes false positive `key` validation warnings when using
`React.Children`, by validating the original `child` instead of
`mappedChild`.
This is a more general fix that expands upon my previous fix in
https://github.com/facebook/react/pull/29662.
## How did you test this change?
```
$ yarn test ReactChildren-test.js
```
## Summary
https://github.com/facebook/react/pull/29088 introduced a regression
triggering this warning when rendering flattened positional children:
> Each child in a list should have a unique "key" prop.
The specific scenario that triggers this is when rendering multiple
positional children (which do not require unique `key` props) after
flattening them with one of the `React.Children` utilities (e.g.
`React.Children.toArray`).
The refactored logic in `React.Children` incorrectly drops the
`element._store.validated` property in `__DEV__`. This diff fixes the
bug and introduces a unit test to prevent future regressions.
## How did you test this change?
```
$ yarn test ReactChildren-test.js
```
Throw an error during module initialization if the version of the
"react-dom" package does not match the version of "react".
We used to be more relaxed about this, because the "react" package
changed so infrequently. However, we now have many more features that
rely on an internal protocol between the two packages, including Hooks,
Float, and the compiler runtime. So it's important that both packages
are versioned in lockstep.
Before this change, a version mismatch would often result in a cryptic
internal error with no indication of the root cause.
Instead, we will now compare the versions during module initialization
and immediately throw an error to catch mistakes as early as possible
and provide a clear error message.
This one should be fully behind the `enableOwnerStacks` flag.
Instead of printing the parent Component stack all the way to the root,
this now prints the owner stack of every JSX callsite. It also includes
intermediate callsites between the Component and the JSX call so it has
potentially more frames. Mainly it provides the line number of the JSX
callsite. In terms of the number of components is a subset of the parent
component stack so it's less information in that regard. This is usually
better since it's more focused on components that might affect the
output but if it's contextual based on rendering it's still good to have
parent stack. Therefore, I still use the parent stack when printing DOM
nesting warnings but I plan on switching that format to a diff view
format instead (Next.js already reformats the parent stack like this).
__Follow ups__
- Server Components show up in the owner stack for client logs but logs
done by Server Components don't yet get their owner stack printed as
they're replayed. They're also not yet printed in the server logs of the
RSC server.
- Server Component stack frames are formatted as the server and added to
the end but this might be a different format than the browser. E.g. if
server is running V8 and browser is running JSC or vice versa. Ideally
we can reformat them in terms of the client formatting.
- This doesn't yet update Fizz or DevTools. Those will be follow ups.
Fizz still prints parent stacks in the server side logs. The stacks
added to user space `console.error` calls by DevTools still get the
parent stacks instead.
- It also doesn't yet expose these to user space so there's no way to
get them inside `onCaughtError` for example or inside a custom
`console.error` override.
- In another follow up I'll use `console.createTask` instead and
completely remove these stacks if it's available.
Note: Despite the similar-sounding description, this fix is unrelated to
the issue where updates that occur after an `await` in an async action
must also be wrapped in their own `startTransition`, due to the absence
of an AsyncContext mechanism in browsers today.
---
Discovered a flaw in the current implementation of the isomorphic
startTransition implementation (React.startTransition), related to async
actions. It only creates an async scope if something calls setState
within the synchronous part of the action (i.e. before the first
`await`). I had thought this was fine because if there's no update
during this part, then there's nothing that needs to be entangled. I
didn't think this through, though — if there are multiple async updates
interleaved throughout the rest of the action, we need the async scope
to have already been created so that _those_ are batched together.
An even easier way to observe this is to schedule an optimistic update
after an `await` — the optimistic update should not be reverted until
the async action is complete.
To implement, during the reconciler's module initialization, we compose
its startTransition implementation with any previous reconciler's
startTransition that was already initialized. Then, the isomorphic
startTransition is the composition of every
reconciler's startTransition.
```js
function startTransition(fn) {
return startTransitionDOM(() => {
return startTransitionART(() => {
return startTransitionThreeFiber(() => {
// and so on...
return fn();
});
});
});
}
```
This is basically how flushSync is implemented, too.
This is necessary to simplify the component stack handling to make way
for owner stacks. It also solves some hacks that we used to have but
don't quite make sense. It also solves the problem where things like key
warnings get silenced in RSC because they get deduped. It also surfaces
areas where we were missing key warnings to begin with.
Almost every type of warning is issued from the renderer. React Elements
are really not anything special themselves. They're just lazily invoked
functions and its really the renderer that determines there semantics.
We have three types of warnings that previously fired in
JSX/createElement:
- Fragment props validation.
- Type validation.
- Key warning.
It's nice to be able to do some validation in the JSX/createElement
because it has a more specific stack frame at the callsite. However,
that's the case for every type of component and validation. That's the
whole point of enableOwnerStacks. It's also not sufficient to do it in
JSX/createElement so we also have validation in the renderers too. So
this validation is really just an eager validation but also happens
again later.
The problem with these is that we don't really know what types are valid
until we get to the renderer. Additionally, by placing it in the
isomorphic code it becomes harder to do deduping of warnings in a way
that makes sense for that renderer. It also means we can't reuse logic
for managing stacks etc.
Fragment props validation really should just be part of the renderer
like any other component type. This also matters once we add Fragment
refs and other fragment features. So I moved this into Fiber. However,
since some Fragments don't have Fibers, I do the validation in
ChildFiber instead of beginWork where it would normally happen.
For `type` validation we already do validation when rendering. By
leaving it to the renderer we don't have to hard code an extra list.
This list also varies by context. E.g. class components aren't allowed
in RSC but client references are but we don't have an isomorphic way to
identify client references because they're defined by the host config so
the current logic is flawed anyway. I kept the early validation for now
without the `enableOwnerStacks` since it does provide a nicer stack
frame but with that flag on it'll be handled with nice stacks anyway. I
normalized some of the errors to ensure tests pass.
For `key` validation it's the same principle. The mechanism for the
heuristic is still the same - if it passes statically through a parent
JSX/createElement call then it's considered validated. We already did
print the error later from the renderer so this also disables the early
log in the `enableOwnerStacks` flag.
I also added logging to Fizz so that key warnings can print in SSR logs.
Flight is a bit more complex. For elements that end up on the client we
just pass the `validated` flag along to the client and let the client
renderer print the error once rendered. For server components we log the
error from Flight with the server component as the owner on the stack
which will allow us to print the right stack for context. The factoring
of this is a little tricky because we only want to warn if it's in an
array parent but we want to log the error later to get the right debug
info.
Fiber/Fizz has a similar factoring problem that causes us to create a
fake Fiber for the owner which means the logs won't be associated with
the right place in DevTools.
This is the first step to experimenting with a new type of stack traces
behind the `enableOwnerStacks` flag - in DEV only.
The idea is to generate stacks that are more like if the JSX was a
direct call even though it's actually a lazy call. Not only can you see
which exact JSX call line number generated the erroring component but if
that's inside an abstraction function, which function called that
function and if it's a component, which component generated that
component. For this to make sense it really need to be the "owner" stack
rather than the parent stack like we do for other component stacks. On
one hand it has more precise information but on the other hand it also
loses context. For most types of problems the owner stack is the most
useful though since it tells you which component rendered this
component.
The problem with the platform in its current state is that there's two
ways to deal with stacks:
1) `new Error().stack`
2) `console.createTask()`
The nice thing about `new Error().stack` is that we can extract the
frames and piece them together in whatever way we want. That is great
for constructing custom UIs like error dialogs. Unfortunately, we can't
take custom stacks and set them in the native UIs like Chrome DevTools.
The nice thing about `console.createTask()` is that the resulting stacks
are natively integrated into the Chrome DevTools in the console and the
breakpoint debugger. They also automatically follow source mapping and
ignoreLists. The downside is that there's no way to extract the async
stack outside the native UI itself so this information cannot be used
for custom UIs like errors dialogs. It also means we can't collect this
on the server and then pass it to the client for server components.
The solution here is that we use both techniques and collect both an
`Error` object and a `Task` object for every JSX call.
The main concern about this approach is the performance so that's the
main thing to test. It's certainly too slow for production but it might
also be too slow even for DEV.
This first PR doesn't actually use the stacks yet. It just collects them
as the first step. The next step is to start utilizing this information
in error printing etc.
For RSC we pass the stack along across over the wire. This can be
concatenated on the client following the owner path to create an owner
stack leading back into the server. We'll later use this information to
restore fake frames on the client for native integration. Since this
information quickly gets pretty heavy if we include all frames, we strip
out the top frame. We also strip out everything below the functions that
call into user space in the Flight runtime. To do this we need to figure
out the frames that represents calling out into user space. The
resulting stack is typically just the one frame inside the owner
component's JSX callsite. I also eagerly strip out things we expect to
be ignoreList:ed anyway - such as `node_modules` and Node.js internals.
Facebook: merge react index.classic.fb and index.modern.fb
These export the same.
NOTE: The 2 builds are still different based on flags and other forked
files.
Following #28768, add a path to testing Fast JSX on www.
We want to measure the impact of Fast JSX and enable a path to testing
before string refs are completely removed in www (which is a work in
progress).
Without `disableStringRefs`, we need to copy any object with a `ref` key
so we can pass it through `coerceStringRef()` and copy it into the
object. This de-opt path is what is gated behind
`enableFastJSXWithStringRefs`.
The additional checks should have no perf impact in OSS as the flags
remain true there and the build output is not changed. For www, I've
benchmarked the addition of the boolean checks with values cached at
module scope. There is no significant change observed from our
benchmarks and any latency will apply to test and control branches
evenly. This added experiment complexity is temporary. We should be able
to clean it up, along with the flag checks for `enableRefAsProp` and
`disableStringRefs` shortly.
Rebasing and landing https://github.com/facebook/react/pull/28798
This PR was approved already but held back to give time for the sync.
Rebased and landing here without pushing to seb's remote to avoid
possibility of lost updates
---------
Co-authored-by: Sebastian Markbage <sebastian@calyptus.eu>
It turns out we already made refs writable in #25696, which has been in
canary for over a year. The approach in that PR also has the benefit of
being slightly more perf sensitive because it still uses a shared object
until the fiber is mounted. So let's just go back to that.
This removes the automatic patching of the global `fetch` function in
Server Components environments to dedupe requests using `React.cache`, a
behavior that some RSC framework maintainers have objected to.
We may revisit this decision in the future, but for now it's not worth
the controversy.
Frameworks that have already shipped this behavior, like Next.js, can
reimplement it in userspace.
I considered keeping the implementation in the codebase and disabling it
by setting `enableFetchInstrumentation` to `false` everywhere, but since
that also disables the tests, it doesn't seem worth it because without
test coverage the behavior is likely to drift regardless. We can just
revert this PR later if desired.
We have changed the shape (and the runtime) of React Elements. To help
avoid precompiled or inlined JSX having subtle breakages or deopting
hidden classes, I renamed the symbol so that we can early error if
private implementation details are used or mismatching versions are
used.
Why "transitional"? Well, because this is not the last time we'll change
the shape. This is just a stepping stone to removing the `ref` field on
the elements in the next version so we'll likely have to do it again.
