Rolldown minifier drops `while(` keyword — invalid syntax in Safari

Status: To be filed Workaround applied: build: { minify: "esbuild" } in vite.config.mts

Summary

Rolldown's minifier drops the while(/for(; keyword when a while (x in globalThis) loop is bundled alongside other module-level variable declarations. The resulting output is a syntax error that crashes Safari.

Target repositories

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
Triggered by	`@ark/schema` 0.56.0 / `arktype` 2.1.29

Source

File: node_modules/@ark/schema/out/shared/registry.js

let _registryName = "$ark";
let suffix = 2;
while (_registryName in globalThis)
    _registryName = `$ark${suffix++}`;
export const registryName = _registryName;

Actual minified output

un=Pe(`implementedTraits`),dn=`$ark`,fn=2;dn in globalThis;)dn=`$ark${fn++}`;var pn=dn;

The while( keyword is missing. The orphaned ) is a syntax error.

Expected output

var dn=`$ark`,fn=2;for(;dn in globalThis;)dn=`$ark${fn++}`;var pn=dn;

Impact

Safari throws: SyntaxError: Unexpected keyword 'in'. Expected a ';' following a return statement. Chrome and Firefox appear to tolerate the malformed output.

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 — "Minifier incorrectly merges statements into for-in expression via comma operator"

Workaround

Add to vite.config.mts:

build: {
  minify: "esbuild",
},

esbuild correctly outputs for(;Dt in globalThis;)Dt=\$ark${za++}``.

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Rolldown minifier drops while( keyword — invalid syntax in Safari