Disable JS class transforms for Hermes V1 (use SH-native class support) #55039
+12
−13
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
meta-cla
bot
added
the
CLA Signed
facebook-github-bot
pushed a commit
that referenced
this pull request
Jan 6, 2026
…t) (#55039) Summary: When `unstable_transformProfile` (either the preset option or via `caller` from Metro) is set to `'hermes-stable'` or `'hermes-canary'`, infer that the target engine is Hermes V1. For Hermes V1, we don't need to transform `class` syntax any more - this has been proven in production experiments. This should improve the performance of class-intensive APIs, like `Animated`, reduce bundle size, and improve bundling times. Changelog: [Internal] Disable JS class transform behind unstable_transformProfile=hermes-stable Reviewed By: huntie Differential Revision: D89724839
facebook-github-bot
force-pushed
the
export-D89724839
branch
from
1ffcb15 to
ff75be9
Compare
facebook-github-bot
pushed a commit
that referenced
this pull request
Jan 6, 2026
…t) (#55039) Summary: When `unstable_transformProfile` (either the preset option or via `caller` from Metro) is set to `'hermes-stable'` or `'hermes-canary'`, infer that the target engine is Hermes V1. For Hermes V1, we don't need to transform `class` syntax any more - this has been proven in production experiments. This should improve the performance of class-intensive APIs, like `Animated`, reduce bundle size, and improve bundling times. Changelog: [Internal] Disable JS class transform behind unstable_transformProfile=hermes-stable Reviewed By: huntie Differential Revision: D89724839
facebook-github-bot
force-pushed
the
export-D89724839
branch
from
ff75be9 to
d4cab74
Compare
…t) (#55039) Summary: When `unstable_transformProfile` (either the preset option or via `caller` from Metro) is set to `'hermes-stable'` or `'hermes-canary'`, infer that the target engine is Hermes V1. For Hermes V1, we don't need to transform `class` syntax any more - this has been proven in production experiments. This should improve the performance of class-intensive APIs, like `Animated`, reduce bundle size, and improve bundling times. Changelog: [Internal] Disable JS class transform behind unstable_transformProfile=hermes-stable Reviewed By: huntie Differential Revision: D89724839
facebook-github-bot
force-pushed
the
export-D89724839
branch
from
d4cab74 to
4378975
Compare
Collaborator
|
This pull request was successfully merged by @robhogan in f654168 When will my fix make it into a release? | How to file a pick request? |
|
This pull request has been merged in f654168. |
Contributor
|
This pull request has been reverted by 1236b6b. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Summary:
When
unstable_transformProfile(either the preset option or viacallerfrom Metro) is set to'hermes-stable'or'hermes-canary', infer that the target engine is Hermes V1.For Hermes V1, we don't need to transform
classsyntax any more - this has been proven in production experiments.This should improve the performance of class-intensive APIs, like
Animated, reduce bundle size, and improve bundling times.Differential Revision: D89724839