Simon Jakobi pushed to branch wip/sjakobi/multi-caret at Glasgow Haskell Compiler / GHC Commits: 72c8de5c by Simon Jakobi at 2026-05-23T18:41:42-04:00 Implement List.elem via foldr ...in order to allow specialization to Eq instances. The implementation of notElem is updated for consistency.` Corresponding CLC proposal: https://github.com/haskell/core-libraries-committee/issues/412 Addresses #27096. - - - - - 3268c610 by Alan Zimmerman at 2026-05-23T18:42:30-04:00 EPA: Fix span for qualified multiline string Fix the span for a qualified multiline string like Text.""" I'm a multiline Text value ! """ to extend to the end of the entire string, not just the first line. Closes #27274 - - - - - 1f096790 by Alan Zimmerman at 2026-05-23T18:43:20-04:00 EPA: Fix exact printing namespace-specified wildcards Ensures correct printing of imports of the form import Data.Bool (data True(data ..)) import Data.Bool (data True(type ..)) Closes #27291 - - - - - 56ada7c0 by Mrjtjmn at 2026-05-23T18:44:19-04:00 Fix ambiguous syntax of BangPatterns in users guide Update documentation for the BangPatterns extension to specify how surrounding whitespace affects interpretation of `!`. * Only when there is whitespace before `!` and no whitespace after, it is recognized as a BangPattern. * Other cases `⟨varid⟩!⟨varid⟩`, `⟨varid⟩ ! ⟨varid⟩`, `⟨varid⟩! ⟨varid⟩` are treated as infix operators. - - - - - 579aa0b7 by Simon Jakobi at 2026-05-25T16:31:26-04:00 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. - - - - - cccf45da by Cheng Shao at 2026-05-25T16:32:13-04:00 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. - - - - - 8db331a3 by Zubin Duggal at 2026-05-26T04:54:03-04:00 Update to semaphore-compat 2.0.0 using v2 of the protocol On Linux and other POSIX platforms, GHC's -jsem jobserver client now speaks v2 of the semaphore-compat protocol, which uses Unix domain sockets in place of POSIX named semaphores. This avoids the libc-ABI issues that affected the old implementation. Windows is unaffected and continues to use the v1 protocol (Win32 named semaphores); its reported protocol version remains v1. When GHC receives a -jsem name whose protocol version it does not support, it emits a -Wsemaphore-version-mismatch warning and falls back to -j<N> rather than crashing. ghc --info exposes the supported version in a new "Semaphore version" entry so cabal-install can detect a mismatch before invoking GHC. Users on a cabal-install that predates the v2 update will continue to build successfully on Linux/POSIX, but will lose the cross-process -jsem coordination and fall back to -j<N> per GHC invocation. Users must upgrade to a cabal-install that supports protocol v2 to recover full parallelism. Also fix a leak in cleanupSem (#27253): cleanupSem used to snapshot heldTokens and release them before killing the loop, while the loop's in-flight acquire/release children could still be mutating it. Cleanup now runs inside the loop's own exit handler, after draining the active child via a new activeChild TVar, so the snapshot has no concurrent mutator. See also: - GHC proposal amendment: https://github.com/ghc-proposals/ghc-proposals/pull/673 - cabal-install patch: https://github.com/haskell/cabal/pull/11628 - semaphore-compat MR: https://gitlab.haskell.org/ghc/semaphore-compat/-/merge_requests/8 Bump semaphore-compat submodule to 2.0.0 Fixes #25087 and #27253 - - - - - 17be4f1f by Alan Zimmerman at 2026-05-26T04:54:52-04:00 EPA: Record semicolons in HsModifier Ensure the semi colons are captured in the ParsedSource for code like %True;; %False; instance C D It makes HsModifier (and hence HsModifierOf) LocatedA, so the semi colons can be recorded as [TrailingAnn] Also rename pprHsModifiers to pprLHsModifiers to match. Closes #27294 - - - - - 8f991755 by fendor at 2026-05-26T11:02:52-04:00 Revert prog003 acceptance We thought the commit 286f1adff3e78d775ff325caff71d0cee25d710b fixed the test, but due to changes to ghci, modules loaded during the GHCi session, the test was actually no longer testing what it set out to do, "fixing" the broken test. As modules are added to the `interactive-session` home unit, the object code needs to be compiled with `-this-unit-id interactive-session`, otherwise the object code won't be used. Once this has been fixed in the test, the test fails as expected again. - - - - - 277a3687 by mangoiv at 2026-05-26T11:03:40-04:00 libraries/process: bump submodule to v1.6.29.0 This submodule bump resolves a segfault on macos 15. Fixes #27144 - - - - - 6779bb0c by mangoiv at 2026-05-26T11:03:40-04:00 libraries/unix: in submodule, don't pick branch 2.7 The 2.7 branch is outdated and the module has been advanced far beyond it anyway, so remove that line. - - - - - 4a645683 by Simon Peyton Jones at 2026-05-27T21:41:59-04:00 Trim the continuation in mkDupableContWithDmds When there are no remaining argument demands, it means the application is bottoming. In this case, we can trim the continuation to avoid the panic that was observed in #27261. See Note [Trimming the continuation for bottoming functions] in GHC.Core.Opt.Simplify.Iteration. - - - - - 8ab506ff by Cheng Shao at 2026-05-27T21:42:47-04:00 ghci: fix module name string lifetime in hs_hpc_module invocation This patch makes hpcAddModule pass a properly malloced module name string to hs_hpc_module, instead of using useAsCString which causes use-after-free of module name string. Fixes #27297. Co-authored-by: Codex - - - - - b0233814 by sheaf at 2026-05-27T21:43:31-04:00 Relax acceptance threshold for T10421 As seen in #27289, the 1% acceptance threshold for this text was overly narrow, resulting in spurious test failures. This commit widens the acceptance threshold to 2%. Fixes #27289. - - - - - 63ce5770 by Luite Stegeman at 2026-05-28T12:23:35-04:00 Fixes for black holes - suspend duplicate work for eager black holes - detect eager black holes in checkBlockingQueues - don't overwrite existing black holes even if they're not in an eager blackhole frame - don't deadlock on self when thunk is already blackholed Fixes #26936 - - - - - 037a80dc by Tom McLaughlin at 2026-05-28T12:24:36-04:00 Event/Windows.hsc: rethrow exceptions in overlapped IO This prevents the WinIO manager from swallowing exceptions in overlapped IO. It was added to make WinIO support possible in the `network` library. See https://gitlab.haskell.org/ghc/ghc/-/issues/27283. We also bump __IO_MANAGER_WINIO__ to 2 so libraries can gate on this using CPP. - - - - - 2d53bcdb by Wolfgang Jeltsch at 2026-05-28T12:25:21-04:00 Allow `downsweep` to use nodes of an existing module graph To this end, `downsweep` has not been able to use the nodes of a module graph obtained from a previous downsweeping round. In some GHC API applications, downsweeping is performed somewhat incrementally and therefore could profit from reusing such existing results. This contribution makes this possible. Resolves #27054. Co-authored-by: Matthew Pickering - - - - - f4fbb583 by Simon Jakobi at 2026-05-28T12:26:04-04:00 Add regression test for T11226 Closes #11226. - - - - - ed29a5e6 by Sven Tennie at 2026-05-28T17:30:36-04:00 Add optional config setting for LibDir (#19174) Previously, the `libDir` was derived from `topDir`. This won't work for inplace stage2 cross-compilers where binaries and libraries are in different stage dirs (`_build/stage1/` for executables and `_build/stage2` for libraries). `LibDir` is set in the inplace `settings` files. For bindists, we generate a new `settings` file with no `LibDir` entry. GHC then defaults to use `topDir` as `libDir` again. This keeps the bindist relocatable. If `LibDir` is a relative path, it is interpreted relatively to `topDir`. The global package db is part of the `lib/` folder. If we want to point for inplace cross-compilers to the succeeding stage's folder, this is done by setting `LibDir`. Thus, the global package db must be found relative to `libDir`` (which may default to `topDir` or be set by `LibDir`). The complexity of settings becomes scary. So, add a test to ensure `LibDir` works as expected. - - - - - 8339cf8f by Sven Tennie at 2026-05-28T17:30:36-04:00 Add Haddock to FileSettings Helping to understand the fields' meanings without deeper analyses. - - - - - 4ce251e4 by Sylvain Henry at 2026-05-28T17:31:39-04:00 foundation test: skip signed minBound `quot` (-1) (#27222) `minBound `quot` (-1)` for fixed-width signed integers is platform dependent: the mathematical result -minBound is not representable in the type. On x86, IDIV traps; LLVM's sdiv is undefined behaviour in this case; on AArch64/RISC-V, SDIV wraps to minBound. Co-Authored-By: Claude Opus 4.7 (1M context) - - - - - b8ba7e61 by Simon Jakobi at 2026-05-28T17:32:23-04:00 Prevent dictionary-passing in checkTyEqRhs ...by pre-specializing it to TcM. Previously, wherever checkTyEqRhs was used in other modules, the Core showed dictionary passing ($fMonadIOEnv). The added SPECIALIZE pragma prevents this. - - - - - d603477f by David Eichmann at 2026-05-29T13:17:12-04:00 Hadrian: create a ghc-internal .def file per ghc-internal dll The .def file generated from rts/win32/libHSghc-internal.def.in contains the name of the ghc-internal dll. The correct dll name differs based on if the dll is inplace/final and if using the Dynamic way. Previously, this was not accounted for and inconsistent dlls names where used. That led to failure when loading dlls at runtime in experiments with windows dynamic linking. - - - - - 1fc21753 by Sylvain Henry at 2026-05-29T13:18:14-04:00 ghc-bignum: copy backend interface haddocks to Native backend (#27305) The haddock comments documenting the BigNat backend interface (function contracts, expected MutableWordArray# sizes, return-value semantics, etc.) were attached to the FFI backend module. Copy them to the Native backend so they remain in tree once the FFI backend is removed. Co-Authored-By: Claude Opus 4.7 (1M context) - - - - - 717059df by Sylvain Henry at 2026-05-29T13:18:14-04:00 ghc-bignum: remove FFI backend (#27305) The FFI backend of ghc-bignum (now part of ghc-internal) had no known users and is easy to recreate by relinking ghc-internal with a custom backend. Remove the backend module, the bignum-ffi cabal flag, and the ffi option from Hadrian's --bignum selector. The backend interface documentation now lives in the Native backend module. Co-Authored-By: Claude Opus 4.7 (1M context) - - - - - 4bb3b1d8 by Sylvain Henry at 2026-05-29T13:18:14-04:00 ghc-bignum: remove Check backend (#27305) The Check backend of ghc-bignum (now part of ghc-internal) compared the selected backend's output against the Native backend for validation. It had no known users. Remove the backend module, the bignum-check cabal flag, the bignumCheck Hadrian flavour field, and the check- prefix in Hadrian's --bignum selector. Co-Authored-By: Claude Opus 4.7 (1M context) - - - - - 6b3044a0 by David Eichmann at 2026-05-30T11:58:48-04:00 Add code comments to allocator code - - - - - f4e04210 by Matthew Pickering at 2026-05-30T11:59:34-04:00 hadrian: Refactor system-cxx-std-lib rules I noticed a few things wrong with the hadrian rules for `system-cxx-std-lib` rules. * For `text` there is an ad-hoc check to depend on `system-cxx-std-lib` outside of `configurePackage`. * The `system-cxx-std-lib` dependency is not read from cabal files. * Recache is not called on the packge database after the `.conf` file is generated, a more natural place for this rule is `registerRules`. Treating this uniformly like other packages is complicated by it not having any source code or a cabal file. However we can do a bit better by reporting the dependency firstly in `PackageData` and then needing the `.conf` file in the same place as every other package in `configurePackage`. This commit increases the `shakeVersion`, to provide backwards compatibility to previous builds with different PackageData. Fixes #25303 Co-authored-by: Sven Tennie - - - - - b335fbdc by Simon Jakobi at 2026-06-02T01:01:21+02:00 Add support for related locations in Diagnostic * Convert TcRnBindingNameConflict to demonstrate this feature. * Enable -fdiagnostics-show-caret in some tests to show what error messages with multiple caret sections look like. * Carry diagnostic related spans through MessageClass. This prepares the ground for #22637. The diagnosticRelatedLocations name is inspired by #23414. - - - - - 335251cc by Simon Jakobi at 2026-06-02T01:08:39+02:00 Add related locations to duplicate-declaration and duplicate-export errors Attach diagnosticRelatedLocations (multi-caret) to: * TcRnDuplicateDecls * TcRnDuplicateExport * TcRnDuplicateNamedDefaultExport Enable -fdiagnostics-show-caret for the DuplicateExports and T25857 tests to exercise the new caret sections. check_occs now threads LIE GhcPs so these export items can carry their source spans. TcRnConflictingExports and TcRnDuplicateFieldExport were also tried but reverted to IE GhcPs: their export items already appear in the message text and name provenance is rendered too, so the carets only duplicated the primary span. Assisted-by: Claude Opus 4.8 - - - - - 172 changed files: - .gitmodules - + changelog.d/T27261 - + changelog.d/bump-process - + changelog.d/elem-via-foldr-27096 - + changelog.d/fix-blackhole-handling - + changelog.d/hadrian-system-cxx-std-lib-25303 - + changelog.d/jobserver-leak-fix - + changelog.d/libdir-setting - + changelog.d/module-graph-reuse-in-downsweep - + changelog.d/remove-bignum-check-backend - + changelog.d/remove-bignum-ffi-backend - + changelog.d/semaphore-v2 - + changelog.d/wasm-fix-serviceworker - + changelog.d/windows-rethrow-overlapped-exception - compiler/GHC/Core/Opt/Monad.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Data/List/SetOps.hs - compiler/GHC/Driver/Config/Interpreter.hs - compiler/GHC/Driver/Downsweep.hs - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/Driver/Errors.hs - compiler/GHC/Driver/Errors/Ppr.hs - compiler/GHC/Driver/Errors/Types.hs - compiler/GHC/Driver/Flags.hs - compiler/GHC/Driver/Make.hs - compiler/GHC/Driver/MakeAction.hs - compiler/GHC/Driver/MakeSem.hs - compiler/GHC/Driver/Session.hs - compiler/GHC/Hs/Binds.hs - compiler/GHC/Hs/Decls.hs - compiler/GHC/Hs/Pat.hs - compiler/GHC/Hs/Type.hs - compiler/GHC/HsToCore/Errors/Ppr.hs - compiler/GHC/HsToCore/Errors/Types.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Errors/Ppr.hs - compiler/GHC/Parser/Errors/Types.hs - compiler/GHC/Parser/Lexer.x - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Parser/Types.hs - compiler/GHC/Rename/HsType.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/Rename/Utils.hs - compiler/GHC/Settings.hs - compiler/GHC/Settings/IO.hs - compiler/GHC/SysTools/Cpp.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/App.hs - compiler/GHC/Tc/Gen/Bind.hs - compiler/GHC/Tc/Gen/Export.hs - compiler/GHC/Tc/Gen/HsType.hs - compiler/GHC/Tc/Gen/Sig.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/ThToHs.hs - compiler/GHC/Types/Error.hs - compiler/GHC/Types/Error.hs-boot - compiler/GHC/Types/Error/Codes.hs - compiler/GHC/Types/Hint.hs - compiler/GHC/Types/Hint/Ppr.hs - compiler/GHC/Utils/Error.hs - compiler/GHC/Utils/Logger.hs - compiler/Language/Haskell/Syntax/Binds.hs - compiler/Language/Haskell/Syntax/Decls.hs - compiler/Language/Haskell/Syntax/Decls/Foreign.hs - compiler/Language/Haskell/Syntax/Pat.hs - compiler/Language/Haskell/Syntax/Type.hs - docs/users_guide/exts/stolen_syntax.rst - docs/users_guide/using-warnings.rst - docs/users_guide/using.rst - ghc/GHCi/UI.hs - hadrian/README.md - hadrian/doc/user-settings.md - hadrian/src/CommandLine.hs - hadrian/src/Flavour.hs - hadrian/src/Flavour/Type.hs - hadrian/src/Hadrian/Haskell/Cabal/Parse.hs - hadrian/src/Hadrian/Haskell/Cabal/Type.hs - hadrian/src/Main.hs - hadrian/src/Rules/BinaryDist.hs - hadrian/src/Rules/Generate.hs - hadrian/src/Rules/Library.hs - hadrian/src/Rules/Register.hs - hadrian/src/Rules/Rts.hs - hadrian/src/Settings.hs - hadrian/src/Settings/Builders/RunTest.hs - hadrian/src/Settings/Default.hs - hadrian/src/Settings/Packages.hs - libraries/base/changelog.md - libraries/base/tests/perf/ElemNoFusion_O1.stderr - libraries/base/tests/perf/ElemNoFusion_O2.stderr - libraries/ghc-bignum/ghc-bignum.cabal - + libraries/ghc-boot/GHC/Data/ShortByteString.hs - libraries/ghc-boot/GHC/Settings/Utils.hs - libraries/ghc-boot/ghc-boot.cabal.in - libraries/ghc-internal/bignum-backend.rst - libraries/ghc-internal/ghc-internal.cabal.in - libraries/ghc-internal/src/GHC/Internal/Bignum/Backend.hs - − libraries/ghc-internal/src/GHC/Internal/Bignum/Backend/Check.hs - − libraries/ghc-internal/src/GHC/Internal/Bignum/Backend/FFI.hs - libraries/ghc-internal/src/GHC/Internal/Bignum/Backend/Native.hs - − libraries/ghc-internal/src/GHC/Internal/Bignum/Backend/Selected.hs - libraries/ghc-internal/src/GHC/Internal/Event/Windows.hsc - libraries/ghc-internal/src/GHC/Internal/List.hs - libraries/ghci/GHCi/Coverage.hs - libraries/ghci/GHCi/Run.hs - libraries/process - libraries/semaphore-compat - rts/Messages.c - rts/ThreadPaused.c - rts/Threads.c - rts/Updates.h - rts/include/rts/storage/ClosureMacros.h - rts/sm/BlockAlloc.c - rts/sm/MBlock.c - rts/win32/libHSghc-internal.def.in - testsuite/tests/MiniQuickCheck.hs - testsuite/tests/default/T25857.stderr - testsuite/tests/default/all.T - testsuite/tests/diagnostic-codes/codes.stdout - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/A.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/B.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/C.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/D.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/X.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/Y.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.modules/Z.hs - + testsuite/tests/ghc-api/downsweep/IncrementalDownsweep.stdout - testsuite/tests/ghc-api/downsweep/OldModLocation.hs - testsuite/tests/ghc-api/downsweep/PartialDownsweep.hs - testsuite/tests/ghc-api/downsweep/all.T - testsuite/tests/ghc-api/fixed-nodes/InterfaceModuleGraph.hs - + testsuite/tests/ghc-api/settings/LibDir.hs - + testsuite/tests/ghc-api/settings/LibDir.stdout - + testsuite/tests/ghc-api/settings/all.T - testsuite/tests/ghci/prog003/prog003.T - testsuite/tests/ghci/prog003/prog003.script - testsuite/tests/numeric/should_run/foundation.hs - testsuite/tests/overloadedrecflds/should_fail/DuplicateExports.stderr - testsuite/tests/overloadedrecflds/should_fail/all.T - testsuite/tests/patsyn/should_fail/T14114.stderr - testsuite/tests/patsyn/should_fail/all.T - testsuite/tests/perf/compiler/all.T - + testsuite/tests/perf/should_run/T11226.hs - + testsuite/tests/perf/should_run/T11226.stdout - testsuite/tests/perf/should_run/all.T - testsuite/tests/printer/Makefile - testsuite/tests/printer/PprModifiers.hs - + testsuite/tests/printer/PprQualifiedStrings.hs - + testsuite/tests/printer/Test27291.hs - testsuite/tests/printer/all.T - testsuite/tests/rename/should_fail/T7164.stderr - testsuite/tests/rename/should_fail/all.T - testsuite/tests/rename/should_fail/rnfail004.stderr - + testsuite/tests/simplCore/should_compile/T27261.hs - + testsuite/tests/simplCore/should_compile/T27261_aux.hs - testsuite/tests/simplCore/should_compile/all.T - testsuite/tests/typecheck/should_fail/all.T - testsuite/tests/typecheck/should_fail/tcfail038.stderr - utils/check-exact/ExactPrint.hs - utils/check-exact/Main.hs - utils/haddock/haddock-api/src/Haddock/Backends/LaTeX.hs - utils/haddock/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs - utils/haddock/haddock-api/src/Haddock/Convert.hs - utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs - utils/haddock/haddock-api/src/Haddock/Interface/RenameType.hs - utils/haddock/haddock-api/src/Haddock/Types.hs - utils/jsffi/prelude.mjs The diff was not included because it is too large. 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