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Cheng Shao pushed to branch wip/wasm-fix-serviceworker at Glasgow Haskell Compiler / GHC

Commits:

1f50c9cd

by Cheng Shao at 2026-05-24T16:38:15+00:00

wasm: ensure post-linker output is synchronous ESM

This patch fixes wasm backend's post-linker output script to ensure
it's synchronous ESM and doesn't use top-level await, which doesn't
work in ServiceWorkers. Fixes #27257.

2 changed files:

+ changelog.d/wasm-fix-serviceworker
utils/jsffi/prelude.mjs

Changes:

changelog.d/wasm-fix-serviceworker

 +section: wasm-backend
 +synopsis: Ensure post-linker output is synchronous ESM and fix loading in ServiceWorker
 +issues: #27257
 +mrs: !16093

utils/jsffi/prelude.mjs

@@ -39,19 +39,13 @@ export class JSValManager {
  // To benchmark different setImmediate() implementations in the
  // browser, use https://github.com/jphpsf/setImmediate-shim-demo as a
  // starting point.
 -export const setImmediate = await (async () => {
 -  // node, bun, or other scripts might have set this up in the browser
 +export const setImmediate = (() => {
 +  // node, deno, bun, or other scripts might have set this up in the
 +  // browser
    if (globalThis.setImmediate) {
      return globalThis.setImmediate;
+   }
 -  // deno
 -  if (globalThis.Deno) {
 -    try {
 -      return (await import("node:timers")).setImmediate;
 -    } catch {}
 -  }
+-
    // https://developer.mozilla.org/en-US/docs/Web/API/Scheduler/postTask
    if (globalThis.scheduler) {
      return (cb, ...args) => scheduler.postTask(() => cb(...args));