feat(minify): write strings as templates where every one can be, split the gzip-noise gaps by cause - #22923

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• Source mode: Auto
• Repository: webpack/webpack
• Branch: feat/minify-gzip-gaps
• File: .coderabbit.yaml
• Commit: 03cd53b
• Layers: Repository YAML
• Review profile: CHILL
• Plan: Advanced
• Run ID: d13d1e99-8d52-4577-b627-e1ecc2ca8af6

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Reviewing files that changed from the base of the PR and between 4b2d644 and 03cd53b.

Files ignored due to path filters: 4

• test/configCases/optimization/minify-object-enumeration/__snapshots__/ConfigCacheTest.snap is excluded by !**/*.snap, !test/**/__snapshots__/**
• test/configCases/optimization/minify-object-enumeration/__snapshots__/ConfigTest.snap is excluded by !**/*.snap, !test/**/__snapshots__/**
• test/unitCases/javascript/__snapshots__/printer.unittest.js.snap is excluded by !**/*.snap, !test/**/__snapshots__/**
• types.d.ts is excluded by !types.d.ts

Files selected for processing: 8

• .changeset/068-minify-gzip-gaps.md
• cspell.json
• docs/syntax.md
• lib/javascript/syntax-printer.js
• test/helpers/oxcSmaller.js
• test/helpers/swcSmaller.js
• test/specCases/minify-corpora.spectest.js
• test/unitCases/javascript/printer.unittest.js

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The printer adds conditional conversion of eligible strings to template literals and adjusts tail-return and for-of simplification. Tests and corpus comparisons are updated to cover these changes and categorize output-size differences.

Changes: JavaScript minifier changes

Layer / File(s)	Summary
Backtick rewriting lib/javascript/syntax-printer.js, test/unitCases/javascript/printer.unittest.js, .changeset/068-minify-gzip-gaps.md	The printer records eligible string literals and rewrites them as template literals when the improvement is enabled and its conditions are met. Tests cover output equivalence, source maps, and contexts or settings that retain quotes.
Tail-return and loop simplification lib/javascript/syntax-printer.js, test/unitCases/javascript/printer.unittest.js	Tail-return shortening preserves conditional effects and can convert a final if statement to a logical expression. The for-of improvement keeps a preceding expression outside the iterable unless it assigns the value read there. Tests cover both changes.
Corpus size comparisons test/helpers/oxcSmaller.js, test/helpers/swcSmaller.js, test/specCases/minify-corpora.spectest.js, docs/syntax.md, cspell.json	The size-comparison helpers split broad gzip-difference categories into reason-specific groups. Corpus exceptions and documentation change, and the spell-check dictionary adds dangi.

Possibly related PRs

• webpack/webpack#22919: Adds function inlining and value substitution in the improve phase, which the syntax documentation also describes.
• webpack/webpack#22887: Changes execution of the minify-corpora tests; this PR also updates their corpus exception table.
• webpack/webpack#22909: Implements improve-phase transformations that the syntax documentation describes alongside other minifier changes.

Suggested labels: area: parser, area: types

Suggested reviewers: aryanraj45, bjohansebas

Merge Risk: Minimal · up to 03cd5

No actionable merge blocker is established by the supplied evidence; normal validation remains appropriate.

Pre-merge checks: 3 · 1

Failed checks: 1 inconclusive

Check name	Status	Explanation	Resolution
Title check		The title uses valid Conventional Commit syntax with the allowed type feat and the scope minify. It accurately describes the main changes. The branch prefix is not provided, so the required type-p…	Provide the branch name or branch prefix. Confirm that it uses the feat prefix, or update the title type to match the branch prefix.

Passed checks: 3 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Title check

Explanation

The title uses valid Conventional Commit syntax with the allowed type feat and the scope minify. It accurately describes the main changes. The branch prefix is not provided, so the required type-prefix match cannot be verified.

Resolution

Provide the branch name or branch prefix. Confirm that it uses the feat prefix, or update the title type to match the branch prefix.

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⚠️ 117 benchmarks are dominated by system calls

System calls cannot be simulated consistently and are left out of the measure. The reported value understates the real cost. Switch to the Walltime instrument to measure them.

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⚠️ Base and head ran on different runner types

Some benchmarks with significant performance changes were compared across different runner types, so the changes might not come from the code. Run base and head on the same runner type, or use CodSpeed Macro Runners for more stable results.

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ℹ️ 45 benchmarks have no flamegraph

The flamegraph wasn't generated: most of the time was spent in runtime internals, which would leave nothing useful to analyze.

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