fix: using tokens from parser to handle asi#11577
Merged
Conversation
✅ Deploy Preview for rspack canceled.
|
24aa288 to
bedc58d
Compare
Contributor
📦 Binary Size-limit
❌ Size increased by 206.50KB from 47.23MB to 47.43MB (⬆️0.43%) |
CodSpeed Performance ReportMerging #11577 will not alter performanceComparing 🎉 Hooray!
|
7e8715e to
ef318d8
Compare
Contributor
|
📝 Benchmark detail: Open
|
853f714 to
12187ce
Compare
d1d9cb8 to
7a90a92
Compare
Contributor
There was a problem hiding this comment.
Pull Request Overview
This PR fixes automatic semicolon insertion (ASI) handling by switching from using a separate lexer to collect tokens to obtaining tokens directly from the parser during the parsing phase. This addresses compatibility issues that arose when migrating from an old context-aware lexer to a newer, faster lexer that has less context but struggles with ambiguous syntax outside of the parser.
- Removes the separate lexer instantiation and token collection approach
- Updates the parser to return both AST and tokens when requested
- Switches token imports from
swc_ecma_lexertoswc_core::ecma::parser::unstable
Reviewed Changes
Copilot reviewed 5 out of 6 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| crates/rspack_plugin_javascript/src/visitors/semicolon.rs | Updates token imports to use parser's unstable module |
| crates/rspack_plugin_javascript/src/parser_and_generator/mod.rs | Removes separate lexer, updates parser call to collect tokens |
| crates/rspack_plugin_javascript/Cargo.toml | Removes swc_ecma_lexer dependency |
| crates/rspack_javascript_compiler/src/compiler/parse.rs | Adds token collection capability to parser methods |
| crates/rspack_javascript_compiler/Cargo.toml | Adds ecma_parser_unstable feature and swc_ecma_lexer dependency |
Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.
CPunisher
approved these changes
Sep 11, 2025
quininer
approved these changes
Sep 11, 2025
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
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
There's a subtle difference between old lexer and new lexer,
That's why we met #11555 when migrate from old lexer to new lexer.
The key problem is that the new lexer can not be used out of parser now(but it's good for performance), so we need to collect tokens during parse phase other than use the old lexer(which not only slow but also increase code size).
we can easily tell the difference between lexer + collect and lexer +paser in following example:
/a/gLet's see some real world case to show the different behaviors of different lexers.
code:
[ TokenAndSpan { token: `, had_line_break: true, span: 1..2, }, TokenAndSpan { token: template token (), had_line_break: false, span: 2..2, }, TokenAndSpan { token: ${, had_line_break: false, span: 2..4, }, TokenAndSpan { token: a, had_line_break: false, span: 4..5, }, TokenAndSpan { token: }, had_line_break: false, span: 5..6, }, TokenAndSpan { token: template token (b), had_line_break: false, span: 6..7, }, TokenAndSpan { token: `, had_line_break: false, span: 7..8, }, TokenAndSpan { token: ;, had_line_break: false, span: 8..9, }, ][ TokenAndSpan { token: `, had_line_break: true, span: 1..2, }, TokenAndSpan { token: ${, had_line_break: false, span: 2..4, }, TokenAndSpan { token: a, had_line_break: false, span: 4..5, }, TokenAndSpan { token: }, had_line_break: false, span: 5..6, }, TokenAndSpan { token: template token (b), had_line_break: false, span: 6..7, }, TokenAndSpan { token: `, had_line_break: false, span: 7..8, }, TokenAndSpan { token: ;, had_line_break: false, span: 8..9, }, ][ TokenAndSpan { token: None, had_line_break: true, span: 1..4, }, TokenAndSpan { token: <identifier>, had_line_break: false, span: 4..5, }, TokenAndSpan { token: }, had_line_break: false, span: 5..6, }, TokenAndSpan { token: <identifier>, had_line_break: false, span: 6..7, }, TokenAndSpan { token: token:error, had_line_break: false, span: 7..9, }, ][ TokenAndSpan { token: <template head>, had_line_break: true, span: 1..4, }, TokenAndSpan { token: <identifier>, had_line_break: false, span: 4..5, }, TokenAndSpan { token: }, had_line_break: false, span: 5..6, }, TokenAndSpan { token: ;, had_line_break: false, span: 8..9, }, ]Follow up
Related links
related to #11555 microsoft/typescript-go#1554
Checklist