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fix: cover the CSS, HTML and JavaScript parsers from their own tests - #22889
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🦋 Changeset detectedLatest commit: 8453c2d The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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| Layer / File(s) | Summary |
|---|---|
CSS parsing and skip-mode behavior .changeset/060-parser-fixes.md, lib/css/syntax-parser.js, test/unitCases/css/parser.unittest.js |
CSS parsing now accounts for skipped values during brace validation, recognizes escaped custom-property prefixes, and updates raw-node creation and declaration recovery. Tests cover parser edge cases, paths, skip sets, traversal, and minification. |
HTML foster parenting and foreign-content dispatch lib/html/syntax-parser.js, test/unitCases/html/parser.unittest.js |
Foster insertion and foreign-content dispatch changed. Tests cover fostered-node placement, text handling, foreign-content doctypes, and frameset eligibility. |
HTML token modes, fragments, and srcset lib/html/syntax-parser.js, test/unitCases/html/parser.unittest.js |
HTML parsing changed for column-group whitespace, raw-text fragments, plaintext handling, and srcset descriptors. Tests also cover accessors, source ranges, traversal, URL parsing, and buffer reuse. |
JavaScript parsing and callbacks lib/javascript/syntax-parser.js, test/unitCases/javascript/parser.unittest.js |
JavaScript parser behavior changed for async-arrow recognition, literal handling, lazy callbacks, string reading, and function-body metadata. Tests compare parser paths and callback behavior with Acorn and add regression cases. |
JavaScript tree-backed parser modes lib/javascript/syntax-parser.js, test/unitCases/javascript/parser.unittest.js |
Syntax-tree helpers changed child-slot handling, and tree-backed checks use child accessors. Tests cover syntax-tree copying, node lists, import and export loop bodies, and invalid node types. |
HTML name handling and parser state lib/html/syntax-parser.js, test/unitCases/html/parser.unittest.js |
HTML name hashing and end-tag source scanning changed. Tests also cover processing-instruction names, task entries, and parser state reuse. |
Performance configuration warning filter test/configCases/performance/hotspots-clean/webpack.config.js |
The configuration ignores HotspotsWarning messages that do not include BurnPlugin. The burn(0) plugin remains configured. |
Priority:
Change: Bug fix
Merge Risk: 
8453c
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The reviewed warning-filter configuration is consistent with its stated behavior and is mergeable.
Pre-merge checks: 
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Check name Status Explanation Resolution Title check The title uses the conventional-commit form with type "fix" and no scope. The changeset adds tests for the CSS, HTML and JavaScript parsers and fixes bugs that those tests found, so the type and summa… Confirm that the branch name uses the fix prefix. The title form and type otherwise meet the requirement, so no title change is needed if the branch prefix is fix. -
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The title uses the conventional-commit form with type "fix" and no scope. The changeset adds tests for the CSS, HTML and JavaScript parsers and fixes bugs that those tests found, so the type and summary match the main change. The title does not name the branch prefix, which the requirement also checks, so the title check cannot fully confirm compliance.
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Confirm that the branch name uses the fix prefix. The title form and type otherwise meet the requirement, so no title change is needed if the branch prefix is fix.
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This PR is packaged and the instant preview of its latest commit is available. Install it locally:
npm i -D webpack@https://pkg.pr.new/webpack@22889
yarn add -D webpack@https://pkg.pr.new/webpack@22889
pnpm add -D webpack@https://pkg.pr.new/webpack@22889 |
Types CoverageCoverage after merging test/parser-coverage into main will be
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Read No asset changed size. No runtime gained or lost a runtime module. Built |
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Merging this PR will improve performance by 57.16%1 warning, 1 note
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Inline comments:
Review comments at @lib/javascript/syntax-parser.js:
- Line 10447: Update _treeNode’s handling of slot3 to convert non-null object
values with _treeId while preserving numeric and undefined values, so import or
export nodes remain intact as for-statement bodies when imports and exports are
allowed everywhere. Update the slot3 JSDoc and nearby WHY comment to describe
this case.
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📒 Files selected for processing: 7
.changeset/060-parser-fixes.mdlib/css/syntax-parser.jslib/html/syntax-parser.jslib/javascript/syntax-parser.jstest/unitCases/css/parser.unittest.jstest/unitCases/html/parser.unittest.jstest/unitCases/javascript/parser.unittest.js
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- An escaped `--` name (`\2d-x:{…}`) is a custom property: dropped at
the top level (§5.4.3) and read as a declaration when nested (§5.4.6
step 8). The checks read the source text instead of the ident's value;
`_identStartsWithDashes` now decides, as the printer already did.
- A skip set no longer changes the tree: a leaf the list dropped still
stands beside a `{}` block, so `a{div:hover{color:red}}` stays a
nested rule with idents skipped.
- Input a nested block rejects is kept trimmed but for an escaped end:
`a{foo\ ;color:red}` no longer minifies to `a{foo\;color:red}`.
The parser tests now reach every statement and branch of the parser;
checks no input could fail (callers that already skip whitespace, a
nested `--x:` arm, a bad-declaration recovery only reached at the top
level) are folded away.
Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
…t found - In column group without a colgroup open (a template's `<col>`, or the colgroup fragment context), the whitespace among the characters the mode ignores is inserted, as each character is its own token. - A raw-text tag the column group ignores no longer switches the tokenizer to RCDATA/RAWTEXT, so the markup after it stays markup. - Text in a `<plaintext>` opened in a table, cell or caption mode keeps its character references literal. - A raw-text fragment context (title, textarea, style, script, …) reads the whole input as text: there is no appropriate end tag to leave it. Found against parse5 on ~600k random documents and the WPT tree-construction corpus. The parser tests now reach every statement and branch of the tree builder and microsyntax parsers; fallbacks the tree builder's invariants rule out (foster parenting with no table parent, `insertAtPlace` text merges, …) are folded away, loop guards kept. Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
…t found - `for (using a = b in c)` written into a SyntaxTree reported "Using declaration is not allowed in for-in loops": the check read `.init` off a declarator that is a tree id. It now reads the child, and reports acorn's "for-in loop variable declaration may not have an initializer", as eager and lazy parses do. - Lazy parses passed `null` as `onInsertedSemicolon`'s location, where acorn passes `undefined`. The parser tests now run the acorn corpus through the build parser eager, lazy, into a SyntaxTree and with every fast path turned off, record recoverable errors as acorn-loose would, and reach every statement and branch of SyntaxParser, WebpackParser and SyntaxTree; checks no input could fail (`potentialArrowInForAwait`, a bigint that cannot be null, eof after a template element, …) are folded away. Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
Acorn and the port both throw a TypeError on `class A { set a() {} }`
once the setter's missing parameter is only noted; JavaScriptCore words
it after the expression that failed, so the messages differ on Bun.
Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
With allowImportExportEverywhere, a for or while body can be an import or export declaration, which stays a node object: _treeNode wrote it into the tree's fourth slot unconverted, and the body was lost. Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #22889 +/- ##
==========================================
+ Coverage 96.61% 96.67% +0.06%
==========================================
Files 778 778
Lines 143349 143308 -41
Branches 49238 49196 -42
==========================================
+ Hits 138497 138550 +53
+ Misses 4852 4758 -94
Flags with carried forward coverage won't be shown. Click here to find out more. ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
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On a loaded runner webpack's own DefaultStatsPresetPlugin held the main thread for 228 ms, past the hint's 100 ms floor, and the case that a plugin costing nothing stays unnamed failed on a warning about another plugin. It now ignores hotspot warnings that do not name BurnPlugin. Claude-Session: https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP
Follow-up to #22872 (tokenizers): each language's
parser.unittest.jsnow covers its parser on its own, and the bugs that turned up are fixed. Code no input can reach is removed or folded, not markedistanbul ignore.Parser code = every top-level function, object-literal method and class method statically reachable from the parse entry points (and the
Atree accessor), minus the tokenizer, not following into the_stream*printer hooks the parser hands its output to. Measured with only the parser test file and--collectCoverageFromthe syntax parser.What CSS and HTML leave uncovered is printer-only code the static reach pulls in by name:
TakenPiece#charCodeAt/#_uncutand the_hoistedRunsreset in_clearRuleEntries(CSS, only reached when nesting is lowered);decodeEntities' map mode (onlyHtmlParser.jsasks for it) and the print-only tail of the walk (HTML). Every unit the parser runs is at 100%. Tokenizer coverage stays at 100%.Fixes
CSS (checked against §5 and
@csstools/css-parser-algorithms, ~300k differential inputs)--name (\2d-x:{…}) is a custom property: dropped at the top level (§5.4.3), a declaration when nested (§5.4.6 step 8). Three checks read the source text instead of the ident's value.a{div:hover{color:red}}stayed a declaration instead of a nested rule.a{foo\ ;color:red}minified toa{foo\;color:red}, losingcolor:red.HTML (checked against parse5 on ~600k random documents and the WPT tree-construction corpus: 1973 cases, one known exception)
<plaintext>opened in a table, cell or caption mode keeps its character references literal.title,textarea,style,script, …) reads the whole input as text:</title><b>kept losing the<b>.JavaScript (acorn corpus run eager, lazy, into a
SyntaxTreeand with every fast path off; recoverable errors recorded as acorn-loose would)for (using a = b in c)written into aSyntaxTreereported the wrong error: the check read.initoff a tree id.nullasonInsertedSemicolon's location where acorn passesundefined.Left as is (documented)
parseACommaSeparatedListOfComponentValues(",")gives one group (current §5.3.11 text);parseAComponentValuegivesundefinedfor whitespace only.selectfollows the current spec (parse5 still has "in select");searchis special.import … assert {…}clause; lazy mode's offsets-only contract (noonTokentokens, no commentrange, nosourceFile).Unreachable code removed
Each with the invariant that rules it out, e.g. CSS checks after callers that already skip whitespace and a nested
--x:arm declarations always take; HTML foster-parenting fallbacks for a table with no parent andinsertAtPlacetext merges (loop guards kept); JavaScriptpotentialArrowInForAwait(never set), a bigint that cannot be null, an eof check after a template element that already raised.Each fix has a test that fails without it.
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Summary by CodeRabbit
srcsetdescriptors.for awaitheads, BigInt literals, and string line separators in older language modes.