Turbopack: Tree-shake auto-detected barrel files #88878
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When following re-export chains, Turbopack would stop and include the entire module if it isn't marked `sideEffects: false` in package.json. This causes barrel files to pull in all their dependencies even when only one export is used. As the existing comment notes, it is unfortunate that we have to use the whole module here, but we can fix that by allowing modules marked ModuleEvaluationIsSideEffectFree to be followed through in re-export chains. This fixes tree-shaking for packages like zod/mini where intermediate barrel files don't explicitly set `sideEffects: false`. Fixes: vercel#88643
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When following re-export chains, Turbopack would stop and include the entire module if it isn't marked
sideEffects: falsein package.json. This causes barrel files to pull in all their dependencies even when only one export is used.As the existing comment notes, it is unfortunate that we have to use the whole module here, but we can fix that by allowing modules marked ModuleEvaluationIsSideEffectFree to be followed through in re-export chains. This fixes tree-shaking for packages like zod/mini where intermediate barrel files don't explicitly set
sideEffects: false.Fixes: #88643