fix(@angular/build): prevent IIFE wrapper interleaving for adjacent classes in minified files - #33700
Merged
alan-agius4 merged 1 commit intoJul 30, 2026
Conversation
…lasses in minified files In 22.1.0, the Babel-based advancedOptimizations pass was replaced with oxc-parser + magic-string. When wrapping a class declaration in a pure IIFE, appendLeft was used for the opener and appendRight for the closer. In minified bundles where sibling top-level class declarations are adjacent without whitespace (classA.end === classB.start), magic-string emits appendLeft content before appendRight content at a shared index. This caused class B's IIFE opener to be emitted ahead of class A's IIFE closer, interleaving the wrappers and resulting in duplicate symbol declarations in subsequent build phases. This change swaps the insertion methods to use appendRight for the opening fragment and appendLeft for the closing fragment (and when splitting default exports), ensuring correct ordering at shared boundaries. closes angular#33699
alan-agius4
added
action: review
alan-agius4
force-pushed
the
fix/oxc-adjacent-class-iife-33699
branch
from
July 30, 2026 12:14
015fdbe to
2101c73
Compare
![gemini-code-assist[bot]](https://avatars.githubusercontent.com/in/956858?s=60&v=4){kind=small}
There was a problem hiding this comment.
Code Review
This pull request modifies the oxc-transform Babel plugin to prevent interleaving issues when wrapping adjacent class declarations. It swaps the usage of s.appendLeft and s.appendRight on the MagicString instance when wrapping classes in IIFEs or splitting default exports, ensuring correct output ordering. Additionally, comprehensive unit tests have been added to verify that adjacent class declarations, exported classes, and default exports are wrapped correctly without interleaving. I have no feedback to provide on these changes.
dgp1130
approved these changes
Jul 30, 2026
alan-agius4
added
action: merge
Collaborator
Author
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
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.
In 22.1.0, the Babel-based advancedOptimizations pass was replaced with oxc-parser + magic-string. When wrapping a class declaration in a pure IIFE, appendLeft was used for the opener and appendRight for the closer.
In minified bundles where sibling top-level class declarations are adjacent without whitespace (classA.end === classB.start), magic-string emits appendLeft content before appendRight content at a shared index. This caused class B's IIFE opener to be emitted ahead of class A's IIFE closer, interleaving the wrappers and resulting in duplicate symbol declarations in subsequent build phases.
This change swaps the insertion methods to use appendRight for the opening fragment and appendLeft for the closing fragment (and when splitting default exports), ensuring correct ordering at shared boundaries.
closes #33699