Script for syncing changes between forked modules.

yarn merge-fork --base-dir=packages/react-reconciler/src ReactFiberWorkLoop

This will take all the changes in ReactFiberWorkLoop.new.js and apply them to ReactFiberWorkLoop.old.js.

You can merge multiple modules at a time:

yarn merge-fork \
  --base-dir=packages/react-reconciler/src \
  ReactFiberWorkLoop \
  ReactFiberBeginWork \
  ReactFiberCompleteWork \
  ReactFiberCommitWork

You can provide explicit "old" and "new" file names. This only works for one module at a time:

yarn merge-fork \
  --base-dir=packages/react-reconciler/src \
  --old=ReactFiberExpirationTime.js \
  --new=ReactFiberLane.js

The default is to merge changes from the new module to the old one. To merge changes in the opposite direction, use --reverse.

yarn merge-fork \
  --reverse \
  --base-dir=packages/react-reconciler/src \
  ReactFiberWorkLoop

By default, the changes are compared to HEAD. You can use --base-ref to compare to any rev. For example, while working on a PR, you might make multiple commits to the new fork before you're ready to backport them to the old one. In that case, you want to compare to the merge base of your PR branch:

yarn merge-fork \
  --base-ref=$(git merge-base HEAD origin/main)
  --base-dir=packages/react-reconciler/src \
  ReactFiberWorkLoop