docs: rolldown and oxc

This commit is contained in:
Julien Calixte
2026-03-22 01:23:13 +01:00
parent d1bb9fa182
commit d457fd4064

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@@ -9,13 +9,13 @@ Rolldown's minifier drops the `while(`/`for(;` keyword when a `while (x in globa
## Target repositories
- https://github.com/rolldown/rolldown/issues
- https://github.com/oxc-project/oxc/issues (underlying minifier)
- <https://github.com/rolldown/rolldown/issues>
- <https://github.com/oxc-project/oxc/issues> (underlying minifier)
## Environment
| Package | Version |
|---|---|
| -------------------- | --------------------------------------- |
| `vite` | 8.0.1 |
| `rolldown` | 1.0.0-rc.10 |
| `@oxc-project/types` | 0.120.0 |
@@ -52,10 +52,16 @@ var dn=`$ark`,fn=2;for(;dn in globalThis;)dn=`$ark${fn++}`;var pn=dn;
Safari throws: `SyntaxError: Unexpected keyword 'in'. Expected a ';' following a return statement.`
Chrome and Firefox appear to tolerate the malformed output.
## Reproduction attempts
Direct Rolldown calls (even with the full `arktype` + `@better-fetch/fetch` bundle) do **not** reproduce the bug. It only manifests through Vite's full production build pipeline. This strongly suggests the issue is in the interaction between **Vite's module preprocessing** (dependency pre-bundling, plugin transforms, scope-flattening of ESM modules) and Rolldown's minifier `sequences` optimization pass.
Hypothesis: Vite's pipeline produces a flattened scope where multiple `var` declarations from different original modules are consecutive. When the `sequences` optimizer then tries to fold those `var` declarations into the `for` loop init, it incorrectly drops the `for(var` prefix when the loop condition contains the `in` operator.
## Notes
- The bug does **not** reproduce with a minimal isolated input — it is triggered by Rolldown merging multiple module-level `var` declarations across bundled modules before applying the loop optimization.
- Related closed issue: [rolldown/rolldown#8146](https://github.com/rolldown/rolldown/issues/8146) — "Minifier incorrectly merges statements into for-in expression via comma operator"
- To reproduce: run `pnpm build` in this project **without** `build.minify: "esbuild"` — the broken chunk is `getAuthor-*.js`
## Workaround