Remove Reconciler fork (1/2) (#25774)

We've heard from multiple contributors that the Reconciler forking
mechanism was confusing and/or annoying to deal with. Since it's
currently unused and there's no immediate plans to start using it again,
this removes the forking.

Fully removing the fork is split into 2 steps to preserve file history:

**This PR**
- remove `enableNewReconciler` feature flag.
- remove `unstable_isNewReconciler` export
- remove eslint rules for cross fork imports
- remove `*.new.js` files and update imports
- merge non-suffixed files into `*.old` files where both exist
(sometimes types were defined there)

**#25775**
- rename `*.old` files

Author: kassens

.circleci/config.yml

@@ -462,35 +462,6 @@ jobs:
             cp ./scripts/release/ci-npmrc ~/.npmrc
             scripts/release/publish.js --ci --tags << parameters.dist_tag >>
 
-  # We don't always keep the reconciler forks in sync (otherwise it we wouldn't
-  # have forked it) but during periods when they are meant to be in sync, we
-  # use this job to confirm there are no differences.
-  sync_reconciler_forks:
-    docker: *docker
-    environment: *environment
-    steps:
-      - checkout
-      - *restore_node_modules
-      - run:
-          name: Fetch revisions that contain an intentional fork
-          # This will fetch each revision listed in the `forked-revisions` file,
-          # which may be necessary if it's not part of main. For example, it
-          # may have been part of a PR branch that was squashed on merge.
-          command: |
-            cut -d " " -f 1 scripts/merge-fork/forked-revisions | xargs -r git fetch origin
-      - run:
-          name: Revert forked revisions
-          # This will revert the changes without committing. At the end, it's
-          # expected that both forks will be identical.
-          command: |
-            cut -d " " -f 1 scripts/merge-fork/forked-revisions | xargs -r git revert --no-commit
-      - run:
-          name: Confirm reconciler forks are the same
-          command: |
-            yarn replace-fork
-            git diff --quiet || (echo "Reconciler forks are not the same! Run yarn replace-fork. Or, if this was intentional, add the commit SHA to scripts/merge-fork/forked-revisions." && false)
-
-
 workflows:
   version: 2
 
@@ -506,11 +477,6 @@ workflows:
       - yarn_flow:
           requires:
             - setup
-      # NOTE: This job is only enabled when we want the forks to be in sync.
-      # When the forks intentionally diverge, comment out the job to disable it.
-      - sync_reconciler_forks:
-          requires:
-            - setup
       - check_generated_fizz_runtime:
           requires:
             - setup

.eslintrc.js

@@ -112,14 +112,6 @@ module.exports = {
     'react-internal/no-to-warn-dev-within-to-throw': ERROR,
     'react-internal/warning-args': ERROR,
     'react-internal/no-production-logging': ERROR,
-    'react-internal/no-cross-fork-imports': ERROR,
-    'react-internal/no-cross-fork-types': [
-      ERROR,
-      {
-        old: [],
-        new: [],
-      },
-    ],
   },
 
   overrides: [

package.json

@@ -140,8 +140,6 @@
     "prettier": "node ./scripts/prettier/index.js write-changed",
     "prettier-all": "node ./scripts/prettier/index.js write",
     "version-check": "node ./scripts/tasks/version-check.js",
-    "merge-fork": "node ./scripts/merge-fork/merge-fork.js",
-    "replace-fork": "node ./scripts/merge-fork/replace-fork.js",
     "publish-prereleases": "node ./scripts/release/publish-using-ci-workflow.js",
     "download-build": "node ./scripts/release/download-experimental-build.js",
     "download-build-for-head": "node ./scripts/release/download-experimental-build.js --commit=$(git rev-parse HEAD)",

packages/react-art/src/ReactART.js

@@ -12,7 +12,7 @@ import {
   createContainer,
   updateContainer,
   injectIntoDevTools,
-} from 'react-reconciler/src/ReactFiberReconciler';
+} from 'react-reconciler/src/ReactFiberReconciler.old';
 import Transform from 'art/core/transform';
 import Mode from 'art/modes/current';
 import FastNoSideEffects from 'art/modes/fast-noSideEffects';

packages/react-art/src/ReactARTHostConfig.js

@@ -10,7 +10,7 @@ import Mode from 'art/modes/current';
 
 import {TYPES, EVENT_TYPES, childrenAsString} from './ReactARTInternals';
 
-import {DefaultEventPriority} from 'react-reconciler/src/ReactEventPriorities';
+import {DefaultEventPriority} from 'react-reconciler/src/ReactEventPriorities.old';
 
 const pooledTransform = new Transform();
 

packages/react-dom-bindings/src/client/ReactDOMFloatClient.js

@@ -29,7 +29,7 @@ import {
   markNodeAsResource,
 } from './ReactDOMComponentTree';
 import {HTML_NAMESPACE, SVG_NAMESPACE} from '../shared/DOMNamespaces';
-import {getCurrentRootHostContainer} from 'react-reconciler/src/ReactFiberHostContext';
+import {getCurrentRootHostContainer} from 'react-reconciler/src/ReactFiberHostContext.old';
 
 // The resource types we support. currently they match the form for the as argument.
 // In the future this may need to change, especially when modules / scripts are supported

packages/react-dom-bindings/src/client/ReactDOMHostConfig.js

@@ -7,7 +7,7 @@
  * @flow
  */
 
-import type {EventPriority} from 'react-reconciler/src/ReactEventPriorities';
+import type {EventPriority} from 'react-reconciler/src/ReactEventPriorities.old';
 import type {DOMEventName} from '../events/DOMEventNames';
 import type {Fiber, FiberRoot} from 'react-reconciler/src/ReactInternalTypes';
 import type {
@@ -81,7 +81,7 @@ import {
 } from 'react-reconciler/src/ReactWorkTags';
 import {listenToAllSupportedEvents} from '../events/DOMPluginEventSystem';
 
-import {DefaultEventPriority} from 'react-reconciler/src/ReactEventPriorities';
+import {DefaultEventPriority} from 'react-reconciler/src/ReactEventPriorities.old';
 
 // TODO: Remove this deep import when we delete the legacy root API
 import {ConcurrentMode, NoMode} from 'react-reconciler/src/ReactTypeOfMode';

packages/react-dom-bindings/src/events/ReactDOMEventListener.js

@@ -7,7 +7,7 @@
  * @flow
  */
 
-import type {EventPriority} from 'react-reconciler/src/ReactEventPriorities';
+import type {EventPriority} from 'react-reconciler/src/ReactEventPriorities.old';
 import type {AnyNativeEvent} from '../events/PluginModuleType';
 import type {Fiber, FiberRoot} from 'react-reconciler/src/ReactInternalTypes';
 import type {Container, SuspenseInstance} from '../client/ReactDOMHostConfig';
@@ -52,7 +52,7 @@ import {
   IdleEventPriority,
   getCurrentUpdatePriority,
   setCurrentUpdatePriority,
-} from 'react-reconciler/src/ReactEventPriorities';
+} from 'react-reconciler/src/ReactEventPriorities.old';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import {isRootDehydrated} from 'react-reconciler/src/ReactFiberShellHydration';
 

packages/react-dom-bindings/src/events/ReactDOMEventReplaying.js

@@ -12,7 +12,7 @@ import type {Container, SuspenseInstance} from '../client/ReactDOMHostConfig';
 import type {DOMEventName} from '../events/DOMEventNames';
 import type {EventSystemFlags} from './EventSystemFlags';
 import type {FiberRoot} from 'react-reconciler/src/ReactInternalTypes';
-import type {EventPriority} from 'react-reconciler/src/ReactEventPriorities';
+import type {EventPriority} from 'react-reconciler/src/ReactEventPriorities.old';
 
 import {enableCapturePhaseSelectiveHydrationWithoutDiscreteEventReplay} from 'shared/ReactFeatureFlags';
 import {
@@ -35,7 +35,7 @@ import {
   getClosestInstanceFromNode,
 } from '../client/ReactDOMComponentTree';
 import {HostRoot, SuspenseComponent} from 'react-reconciler/src/ReactWorkTags';
-import {isHigherEventPriority} from 'react-reconciler/src/ReactEventPriorities';
+import {isHigherEventPriority} from 'react-reconciler/src/ReactEventPriorities.old';
 import {isRootDehydrated} from 'react-reconciler/src/ReactFiberShellHydration';
 
 let _attemptSynchronousHydration: (fiber: Object) => void;

packages/react-dom/index.classic.fb.js

@@ -30,7 +30,6 @@ export {
   unstable_batchedUpdates,
   unstable_createEventHandle,
   unstable_flushControlled,
-  unstable_isNewReconciler,
   unstable_renderSubtreeIntoContainer,
   unstable_runWithPriority, // DO NOT USE: Temporarily exposed to migrate off of Scheduler.runWithPriority.
   preinit,