perf(@angular/build): cache transformed configuration in TypeScript compilation - #34192
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This pull request introduces a caching mechanism for the TypeScript configuration in the Angular build process to improve performance during watch mode rebuilds. The reviewer suggests enhancing this cache by tracking the 'rootFiles' to ensure the cache is properly invalidated when the set of root files changes, preventing potential compilation errors or stale configurations. All review comments are actionable and provide necessary improvements to the implementation.
alan-agius4
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…ompilation When `rootFiles` are explicitly provided (such as in library builds), avoid re-reading and re-parsing `tsconfig.json` and traversing the project directory structure on every watch rebuild. Cache the `TransformedConfiguration` and invalidate it only when a `.json` configuration file changes.
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When
rootFilesare explicitly provided (e.g. in library builds), re-parsingtsconfig.jsonand traversing the project directory structure viareadConfigurationon every incremental watch rebuild is redundant and adds measurable overhead (~200-350ms on large libraries).This change caches the
TransformedConfigurationinTypeScriptCompilationwhen explicitrootFilesare provided and invalidates the cache only when a.jsonconfiguration file changes.See: angular/angular#71034