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fix(parser): scope strict-mode block function declarations to their block - #22800
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…lock Only sloppy-mode Annex B hoists a plain function declaration out of its block; strict, async and generator ones stay block-scoped. Fixes #22797
🦋 Changeset detectedLatest commit: 0dd4cff 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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📝 Walkthrough
Priority: ➖ Normal Change: Bug fix · Severity of issue fixed: Medium Merge Risk: ⚪ Minimal · up to
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| Check name | Status | Explanation | Resolution |
|---|---|---|---|
| Title check |  |
The title uses valid Conventional Commit syntax, uses the allowed type fix, and accurately describes the parser change. The branch prefix is not provided, so the required type-to-branch-prefix match… |
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Check name Status Explanation Description Check Check skipped - CodeRabbit’s high-level summary is enabled. Linked Issues check Issue #22797requires strict-mode block function declarations to remain block-scoped so an outer CommonJSrequire("./lib.js")remains detectable.JavascriptParserskips strict, async, and generato…Out of Scope Changes check The changes stay within JavaScript parser scope handling, syntax declaration handling, release notes, and focused regression tests. The custom-parser and preStatementcoverage support the parser com…Full details: Linked Issues check
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Explanation
Issue
#22797requires strict-mode block function declarations to remain block-scoped so an outer CommonJSrequire("./lib.js")remains detectable.JavascriptParserskips strict, async, and generator block functions during scope hoisting, andblockPreWalkFunctionDeclarationbinds them in the block. The regression fixtures verify strict outer and inner behavior, module behavior, sloppy async and generator behavior, and Annex B behavior. The custom-parser fixture covers ASTs without a parser record.
Full details: Out of Scope Changes check
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Explanation
The changes stay within JavaScript parser scope handling, syntax declaration handling, release notes, and focused regression tests. The custom-parser and
preStatementcoverage support the parser compatibility paths described by the change. No unrelated product behavior or unrelated files are identified. The excludedtypes.d.tsfile is not required for this assessment.
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Full details: Title check
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The title uses valid Conventional Commit syntax, uses the allowed type
fix, and accurately describes the parser change. The branch prefix is not provided, so the required type-to-branch-prefix match cannot be verified.Resolution
Provide the branch name or branch prefix so the
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Actionable comments posted: 1
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Inline comments:
Review comments at @lib/javascript/JavascriptParser.js:
- Around line 2759-2765: Apply the block-aware hoist filter in the legacy
pre-walk used by _preWalkHoistedDeclarations before preWalkFunctionDeclaration
binds functions: only bind direct-statement function declarations that pass the
strict, async, and generator checks. Preserve the full legacy walk and its
callbacks, and keep blockPreWalkFunctionDeclaration responsible for block-scoped
bindings.
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ℹ️ Review info
⚙️ Run configuration
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⛔ Files ignored due to path filters: 1
types.d.tsis excluded by!types.d.ts
📒 Files selected for processing: 11
.changeset/060-strict-block-function-scope.mdlib/javascript/JavascriptParser.jslib/javascript/syntax-parser.jstest/configCases/parsing/custom-parser-hoisting/block-functions.jstest/configCases/parsing/custom-parser-hoisting/index.jstest/configCases/parsing/custom-parser-hoisting/lib.jstest/configCases/parsing/strict-block-function/block-functions.jstest/configCases/parsing/strict-block-function/index.jstest/configCases/parsing/strict-block-function/lib.jstest/configCases/parsing/strict-block-function/module.jstest/configCases/parsing/strict-block-function/webpack.config.js
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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@22800
yarn add -D webpack@https://pkg.pr.new/webpack@22800
pnpm add -D webpack@https://pkg.pr.new/webpack@22800 |
Types CoverageCoverage after merging fix/strict-block-function-scope into main will be
Coverage Report |
A tap on the deprecated preStatement hook walks nested blocks, where the typed hooks declared a strict block function in the enclosing scope.
Generated code sizeComparing base (
Read 1 asset(s) changed size, test untouched
1 asset(s) changed size, test edited
2 asset(s) this pull request adds
No runtime that both runs build changed which runtime modules it carries. 2 runtime(s) this pull request adds or no longer builds
Built |
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #22800 +/- ##
=======================================
Coverage 96.50% 96.51%
=======================================
Files 778 778
Lines 137909 137952 +43
Branches 46882 46902 +20
=======================================
+ Hits 133091 133139 +48
+ Misses 4818 4813 -5
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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A function body is walked as its own block scope, so binding every function there hid the tags plugins put on scope-level ones, such as the nested __webpack_require__ rename. Also count an exported declaration as the scope's own.
Merging this PR will regress 3 benchmarks
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| Mode | Benchmark | BASE |
HEAD |
Efficiency | |
|---|---|---|---|---|---|
| ❌ | Memory | benchmark "no-exports-analysis", scenario '{"name":"mode-production","mode":"production"}' |
786.8 KB | 1,296.4 KB | -39.31% |
| ❌ | Memory | benchmark "hmr", scenario '{"name":"mode-production","mode":"production"}' |
914.1 KB | 1,506.1 KB | -39.3% |
| ❌ | WallTime | benchmark "react", scenario '{"name":"mode-development","mode":"development"}' |
84 ms | 106.2 ms | -20.9% |
| ⚡ | Memory | unit benchmark "html-parser-document-unit", parseHtml (skip text) |
425.7 KB | 55.8 KB | ×7.6 |
| ⚡ | Memory | unit benchmark "html-printer-document-unit", minify (document) |
326.8 KB | 194.9 KB | +67.69% |
Tip
Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.
Comparing fix/strict-block-function-scope (0dd4cff) with main (b90cb59)
Footnotes
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212 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩
This PR contains the following updates: | Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) | |---|---|---|---| | [webpack](https://github.com/webpack/webpack) | [`5.112.0` → `5.112.2`](https://renovatebot.com/diffs/npm/webpack/5.112.0/5.112.2) |  |  | --- >⚠️ **Warning** > > Some dependencies could not be looked up. Check the [Dependency Dashboard](issues/99) for more information. --- ### Release Notes <details> <summary>webpack/webpack (webpack)</summary> ### [`v5.112.2`](https://github.com/webpack/webpack/blob/HEAD/CHANGELOG.md#51122) [Compare Source](webpack/webpack@v5.112.1...v5.112.2) ##### Patch Changes - Reduce repeated scans when concatenating imported modules. (by [@​xiaoxiaojx](https://github.com/xiaoxiaojx) in [#​22865](webpack/webpack#22865)) - Avoid allocating CSS module sets for single-group chunks. (by [@​xiaoxiaojx](https://github.com/xiaoxiaojx) in [#​22866](webpack/webpack#22866)) - Return the value of every module type loaded with `importModule()`. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22869](webpack/webpack#22869)) ### [`v5.112.1`](https://github.com/webpack/webpack/blob/HEAD/CHANGELOG.md#51121) [Compare Source](webpack/webpack@v5.112.0...v5.112.1) ##### Patch Changes - Rebuild a lazy barrel in watch when what it defers changes, and keep the imports and re-exports it still runs. (by [@​aryanraj45](https://github.com/aryanraj45) in [#​22699](webpack/webpack#22699)) - Rebuild under `cacheUnaffected` a module whose re-export target goes or returns. (by [@​aryanraj45](https://github.com/aryanraj45) in [#​22749](webpack/webpack#22749)) - Fix "Self-reference dependency has unused export name" for CommonJS namespace re-exports. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22791](webpack/webpack#22791)) - Fix `exportType: "style"` CSS modules throwing outside the runtime chunk. (by [@​lazerg](https://github.com/lazerg) in [#​22833](webpack/webpack#22833)) - Fix crash when a CSS module with `exportType: "style"` imports an ignored stylesheet. (by [@​codeXsidd](https://github.com/codeXsidd) in [#​22846](webpack/webpack#22846)) - Keep empty process environment variables that `.env` files don't define in `DotenvPlugin`. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22794](webpack/webpack#22794)) - Rehash an ESM entry chunk when a chunk it imports by file name changes. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22804](webpack/webpack#22804)) - Handle a NUL inside an HTML CDATA section the way the parsing spec does. (by [@​dependabot](https://github.com/apps/dependabot) in [#​22811](webpack/webpack#22811)) - Keep module exports live across chunks, runtimes, HMR and eval, sparing globals. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22733](webpack/webpack#22733)) - Await asynchronous modules that `ProvidePlugin` injects into ES modules. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22728](webpack/webpack#22728)) - Keep a resolve that ends after the compiler closed from throwing. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22795](webpack/webpack#22795)) - Preserve string names passed to SharedWorker constructors. (by [@​bjohansebas](https://github.com/bjohansebas) in [#​22770](webpack/webpack#22770)) - Preserve string contents when extracting source map comments. (by [@​bjohansebas](https://github.com/bjohansebas) in [#​22768](webpack/webpack#22768)) - Scope strict-mode, async and generator block function declarations to their block. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22800](webpack/webpack#22800)) - Preserve raw dotenv values when reusing cached environment files. (by [@​Eshiv-Pandey](https://github.com/Eshiv-Pandey) in [#​22787](webpack/webpack#22787)) - Preserve assigned or patched built-ins, conversions and pattern targets. (by [@​aryanraj45](https://github.com/aryanraj45) in [#​22761](webpack/webpack#22761)) - Keep globals a `globalThis` write replaces, and `slice` on a patched array. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22862](webpack/webpack#22862)) - Skip HTML script tags for shared chunks that emit no JavaScript. (by [@​bjohansebas](https://github.com/bjohansebas) in [#​22779](webpack/webpack#22779)) - Keep the digits Firefox lays out a minified CSS percentage with. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22718](webpack/webpack#22718)) - Reject a second `srcset` descriptor after a `0x` density descriptor. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22741](webpack/webpack#22741)) - Minify JavaScript faster, folding string methods on constants and `x -= 1`. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22823](webpack/webpack#22823)) - Shorten minified JavaScript, and keep it running like its source. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22717](webpack/webpack#22717)) - Drop more unused functions, arguments, calls, global reads and variable copies when minifying JavaScript. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22789](webpack/webpack#22789)) - Minify JavaScript smaller where swc does, and fold a function's `length` right. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22826](webpack/webpack#22826)) - Reduce JavaScript output size where oxc or swc produce smaller output. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22829](webpack/webpack#22829)) - Update watchpack to 2.6.3 and rebuild on a `node_modules` created mid-build. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22743](webpack/webpack#22743)) - Support `concatenateModules` with `cacheUnaffected`. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22746](webpack/webpack#22746)) - Update schema-utils to 4.8.1. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22774](webpack/webpack#22774)) - Keep CSS fallbacks, vendor overrides, `oklch()` hues and HTML elements. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22753](webpack/webpack#22753)) - Validate `CleanPlugin` and `DotenvPlugin` options with a precompiled check, so valid options no longer compile their schema at startup. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22758](webpack/webpack#22758)) - Speed up startup and CSS minification, sharing the compile cache with workers. (by [@​xiaoxiaojx](https://github.com/xiaoxiaojx) in [#​22706](webpack/webpack#22706)) - Use precise, generic types for modules, parsers, generators, stats and loaders. (by [@​alexander-akait](https://github.com/alexander-akait) in [#​22731](webpack/webpack#22731)) </details> --- ### Configuration 📅 **Schedule**: (UTC) - Branch creation - "before 9am on tuesday" - Automerge - At any time (no schedule defined) 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box --- This PR has been generated by [Mend Renovate CLI](https://github.com/renovatebot/renovate). <!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0NC4xNzUuMSIsInVwZGF0ZWRJblZlciI6IjQ0LjE3NS4xIiwidGFyZ2V0QnJhbmNoIjoiZGV2ZWxvcCIsImxhYmVscyI6WyJkZXBlbmRlbmNpZXMiLCJyZW5vdmF0ZSJdfQ==--> Reviewed-on: https://code.futo.org/harbor/harbor/pulls/2035
Summary
Fixes #22797.
The parser hoisted every function declaration in a nested block to the enclosing function scope. Only sloppy-mode Annex B does that for a plain function; strict,
asyncand generator ones stay in their block. So a block-levelfunction require() {}in strict code hid the outerrequire, and the dependency was dropped.The walker now skips such declarations when hoisting (deciding by its own
scope.isStrict, sincejavascript/autoparses scripts as strict modules first), and the block pass binds every function declaration in its block.The deprecated full pre-walk (only used when a plugin taps
hooks.preStatement) is unchanged.What kind of change does this PR introduce?
fix
Did you add tests for your changes?
Yes:
test/configCases/parsing/strict-block-function/(strict, async, generator, sloppy Annex B, ES module) and the same fixture intest/configCases/parsing/custom-parser-hoisting/for ASTs without a parser record.Does this PR introduce a breaking change?
No.
If relevant, what needs to be documented once your changes are merged or what have you already documented?
n/a
Use of AI
Claude Code investigated the issue, wrote the fix and tests, and ran the targeted tests and lint; the change was reviewed by the author.
Generated by Claude Code
Summary by CodeRabbit
requirereferences around block-scoped functions, including cases where a localrequireappears inside a block.require.