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Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC

Commits:

156f09b8

by Simon Jakobi at 2026-05-25T08:30:50-04:00

Ensure that SetOps.{minusList,unionListsOrd} can be specialized

...by marking them INLINABLE. Haddock allocates 0.1–0.3% less as a
result.

This also removes some redundant constraints on unionListsOrd.

6a76e7aa

by Cheng Shao at 2026-05-25T08:30:50-04:00

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.

3 changed files:

+ changelog.d/wasm-fix-serviceworker
compiler/GHC/Data/List/SetOps.hs
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

compiler/GHC/Data/List/SetOps.hs

@@ -60,12 +60,13 @@ getNth xs n = assertPpr (xs `lengthExceeds` n) (ppr n $$ ppr xs) $
  --
  -- Uses a set internally to record duplicates. This makes it slightly slower for
  -- very small lists but avoids quadratic behaviour for large lists.
 -unionListsOrd :: (HasDebugCallStack, Outputable a, Ord a) => [a] -> [a] -> [a]
 +unionListsOrd :: Ord a => [a] -> [a] -> [a]
  unionListsOrd xs ys
 -  -- Since both arguments don't have internal duplicates we can just take all of xs
 -  -- and every element of ys that's not already in xs.
 +  -- Since both arguments don't have internal duplicates we can just take all of ys
 +  -- and every element of xs that's not already in ys.
    = let set_ys = S.fromList ys
      in (filter (\e -> not $ S.member e set_ys) xs) ++ ys
 +{-# INLINABLE unionListsOrd #-} -- Ensure the function can be specialized.
  -- | Assumes that the arguments contain no duplicates
  unionLists :: (HasDebugCallStack, Outputable a, Eq a) => [a] -> [a] -> [a]
@@ -108,6 +109,7 @@ minusList xs [y] = filter (/= y) xs
  minusList xs ys = filter (`S.notMember` yss) xs
    where
      yss = S.fromList ys
 +{-# INLINABLE minusList #-} -- Ensure the function can be specialized.
  {-
  ************************************************************************

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));