fix(minifier): keep classes with static properties + side effect initializer #12848
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CodSpeed Instrumentation Performance ReportMerging #12848 will not alter performanceComparing Summary
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…ializer (#12848) For the record, here's the whole process: [TypeScript ES2022 + useDefineForClassFields = false](https://www.typescriptlang.org/play/?useDefineForClassFields=true&noUnusedLocals=true&noUnusedParameters=true&experimentalDecorators=true&emitDecoratorMetadata=true&target=9&jsx=0&module=0&stripInternal=false&isolatedModules=false&verbatimModuleSyntax=false&allowSyntheticDefaultImports=true&isolatedDeclarations=false&noCheck=false&lib=true&ts=5.9.2&filetype=ts#code/MYGwhgzhAEDC0G8BQ1oQC5nQS2NAZtALyIC+A3EqUA) transforms (Note Oxc has the exact same transform) ```js class C { static f = side_effect(); } ``` into ```js class C { static { this.f = side_effect(); } } ``` then babel [@babel/plugin-transform-class-static-block](https://babel.dev/repl#?corejs=3.21&spec=true&code_lz=MYGwhgzhAEDC0G8BQ1XQgFzBglsR0GAFjhAHQBm0AvIgL4Dc0dSdQA&forceAllTransforms=true&modules=commonjs&timeTravel=true&sourceType=module&lineWrap=true&presets=react%2Ctypescript&version=7.26.1&externalPlugins=%40babel%2Fplugin-transform-class-static-block%407.27.1) transforms to (Note Oxc has the exact same transform) ```js class C { static #_ = this.f = side_effect(); } ``` and the minifier remove unused code trims it down to ```js this.f = side_effect(); ``` --- To eliminate this bug, we will temporary keep all classes that have static properties + side effect initializer. i.e. ```js class C { static #_ = this.f = side_effect(); } ``` does not get trimmed down to `this.f = side_effect()`. --- Also note, this came from a project with a tsconfig ```js "useDefineForClassFields": false ``` + browserslist target `ios 16` where ES2022 `@babel/plugin-transform-class-properties` is off and ES2022 `@babel/plugin-transform-class-static-block` on.
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changes: * oxc-project/oxc#12848 * oxc-project/oxc#12829 closes #5591
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changes: * oxc-project/oxc#12848 * oxc-project/oxc#12829 closes #5591
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changes: * oxc-project/oxc#12848 * oxc-project/oxc#12829 closes #5591
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changes: * oxc-project/oxc#12848 * oxc-project/oxc#12829 closes #5591
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changes: * oxc-project/oxc#12848 * oxc-project/oxc#12829 closes #5591
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…ializer (oxc-project#12848) For the record, here's the whole process: [TypeScript ES2022 + useDefineForClassFields = false](https://www.typescriptlang.org/play/?useDefineForClassFields=true&noUnusedLocals=true&noUnusedParameters=true&experimentalDecorators=true&emitDecoratorMetadata=true&target=9&jsx=0&module=0&stripInternal=false&isolatedModules=false&verbatimModuleSyntax=false&allowSyntheticDefaultImports=true&isolatedDeclarations=false&noCheck=false&lib=true&ts=5.9.2&filetype=ts#code/MYGwhgzhAEDC0G8BQ1oQC5nQS2NAZtALyIC+A3EqUA) transforms (Note Oxc has the exact same transform) ```js class C { static f = side_effect(); } ``` into ```js class C { static { this.f = side_effect(); } } ``` then babel [@babel/plugin-transform-class-static-block](https://babel.dev/repl#?corejs=3.21&spec=true&code_lz=MYGwhgzhAEDC0G8BQ1XQgFzBglsR0GAFjhAHQBm0AvIgL4Dc0dSdQA&forceAllTransforms=true&modules=commonjs&timeTravel=true&sourceType=module&lineWrap=true&presets=react%2Ctypescript&version=7.26.1&externalPlugins=%40babel%2Fplugin-transform-class-static-block%407.27.1) transforms to (Note Oxc has the exact same transform) ```js class C { static #_ = this.f = side_effect(); } ``` and the minifier remove unused code trims it down to ```js this.f = side_effect(); ``` --- To eliminate this bug, we will temporary keep all classes that have static properties + side effect initializer. i.e. ```js class C { static #_ = this.f = side_effect(); } ``` does not get trimmed down to `this.f = side_effect()`. --- Also note, this came from a project with a tsconfig ```js "useDefineForClassFields": false ``` + browserslist target `ios 16` where ES2022 `@babel/plugin-transform-class-properties` is off and ES2022 `@babel/plugin-transform-class-static-block` on.
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For the record, here's the whole process:
TypeScript ES2022 + useDefineForClassFields = false transforms
(Note Oxc has the exact same transform)
into
then babel @babel/plugin-transform-class-static-block transforms to
(Note Oxc has the exact same transform)
and the minifier remove unused code trims it down to
To eliminate this bug, we will temporary keep all classes that have static properties + side effect initializer.
i.e.
does not get trimmed down to
this.f = side_effect().Also note, this came from a project with a tsconfig
ios 16where ES2022@babel/plugin-transform-class-propertiesis off and ES2022@babel/plugin-transform-class-static-blockon.