Simon Peyton Jones pushed to branch wip/T26709 at Glasgow Haskell Compiler / GHC Commits: 8a317b6f by Aaron Allen at 2026-01-01T03:05:15-05:00 [#26183] Associated Type Iface Fix When determining "extras" for class decl interface entries, axioms for the associated types need to included so that dependent modules will be recompiled if those axioms change. resolves #26183 - - - - - ae1aeaab by Cheng Shao at 2026-01-01T03:06:32-05:00 testsuite: run numeric tests with optasm when available This patch adds the `optasm` extra way to nueric tests when NCG is available. Some numeric bugs only surface with optimization, omitting this can hide these bugs and even make them slip into release! (e.g. #26711) - - - - - 6213bb57 by maralorn at 2026-01-02T16:30:32+01:00 GHC.Internal.Exception.Context: Fix comment on addExceptionAnnotation - - - - - b820ff50 by Janis Voigtlaender at 2026-01-05T02:43:18-05:00 GHC.Internal.Control.Monad.replicateM: Fix comment - - - - - a8a94aad by Cheng Shao at 2026-01-05T16:24:04-05:00 hadrian: drops unused PE linker script for windows This patch drops unused PE linker script for windows in the `MergeObjects` builder of hadrian. The linker script is used for merging object files into a single `HS*.o` object file and undoing the effect of split sections, when building the "ghci library" object file. However, we don't build the ghci library on windows, and this code path is actually unreachable. - - - - - 53038ea9 by Cheng Shao at 2026-01-05T16:24:04-05:00 hadrian: drop unused logic for building ghci libraries This patch drops the unused logic for building ghci libraries in hadrian: - The term "ghci library" refers to an optional object file per library `HS*.o`, which is merged from multiple object files in that library using the `MergeObjects` builder in hadrian. - The original rationale of having a ghci library object, in addition to normal archives, was to speedup ghci loading, since the combined object is linked with a linker script to undo the effects of `-fsplit-sections` to reduce section count and make it easier for the RTS linker to handle. - However, most GHC builds enable `dynamicGhcPrograms` by default, in such cases the ghci library would already not be built. - `dynamicGhcPrograms` is disabled on Windows, but still we don't build the ghci library due to lack of functioning merge objects command. - The only case that we actually build ghci library objects, are alpine fully static bindists. However, for other reasons, split sections is already disabled for fully static builds anyway! - There will not be any regression if the ghci library objects are absent from a GHC global libdir when `dynamicGhcPrograms` is disabled. The RTS linker can already load the archives without any issue. Hence the removal. We now forcibly disable ghci libraries for all Cabal components, and rip out all logic related to `MergeObjects` and ghci libraries in hadrian. This also nicely cleans up some old todos and fixmes that are no longer relevant. Note that MergeObjects in hadrian is not the same thing as merge objects in the GHC driver. The latter is not affected by this patch. ------------------------- Metric Decrease: libdir ------------------------- Co-authored-by: Codex - - - - - 8f209336 by Simon Jakobi at 2026-01-05T16:24:48-05:00 User's guide: Fix link to language extensions Instead of linking to haddocks, it seemed more useful to link to the extension overview in the user's guide. Closes #26614. - - - - - 0b7df6db by Simon Peyton Jones at 2026-01-06T09:32:23-05:00 Improved fundeps for closed type families The big payload of this commit is to execute the plan suggested in #23162, by improving the way that we generate functional dependencies for closed type families. It is all described in Note [Exploiting closed type families] Most of the changes are in GHC.Tc.Solver.FunDeps Other small changes * GHC.Tc.Solver.bumpReductionDepth. This function brings together the code that * Bumps the depth * Checks for overflow Previously the two were separated, sometimes quite widely. * GHC.Core.Unify.niFixSubst: minor improvement, removing an unnecessary itraetion in the base case. * GHC.Core.Unify: no need to pass an InScopeSet to tcUnifyTysForInjectivity. It can calculate one for itself; and it is never inspected anyway so it's free to do so. * GHC.Tc.Errors.Ppr: slight impovement to the error message for reduction-stack overflow, when a constraint (rather than a type) is involved. * GHC.Tc.Solver.Monad.wrapUnifier: small change to the API - - - - - fde8bd88 by Simon Peyton Jones at 2026-01-06T09:32:23-05:00 Add missing (KK4) to kick-out criteria There was a missing case in kick-out that meant we could fail to solve an eminently-solvable constraint. See the new notes about (KK4) - - - - - 00082844 by Simon Peyton Jones at 2026-01-06T09:32:23-05:00 Some small refactorings of error reporting in the typechecker This is just a tidy-up commit. * Add ei_insoluble to ErrorItem, to cache insolubility. Small tidy-up. * Remove `is_ip` and `mkIPErr` from GHC.Tc.Errors; instead enhance mkDictErr to handle implicit parameters. Small refactor. - - - - - fe4cb252 by Simon Peyton Jones at 2026-01-06T09:32:24-05:00 Improve recording of insolubility for fundeps This commit addresses #22652, by recording when the fundeps for a constraint are definitely insoluble. That in turn improves the perspicacity of the pattern-match overlap checker. See Note [Insoluble fundeps] - - - - - df0ffaa5 by Simon Peyton Jones at 2026-01-06T09:32:24-05:00 Fix a buglet in niFixSubst The MR of which this is part failed an assertion check extendTvSubst because we extended the TvSubst with a CoVar. Boo. This tiny patch fixes it, and adds the regression test from #13882 that showed it up. - - - - - 3d6aba77 by konsumlamm at 2026-01-06T09:33:16-05:00 Fix changelog formatting - - - - - 5358fe3f by Simon Peyton Jones at 2026-01-06T15:38:11+00:00 Refactor srutOkForBinderSwap This MR does a small refactor: * Moves `scrutOkForBinderSwap` and `BinderSwapDecision` to GHC.Core.Utils * Inverts the sense of the coercion it returns, which makes more sense No effect on behaviour - - - - - a6ca9f04 by Simon Peyton Jones at 2026-01-06T15:38:11+00:00 Improve case merging This small MR makes case merging happen a bit more often than it otherwise could, by getting join points out of the way. See #26709 and GHC.Core.Utils Note [Floating join points out of DEFAULT alternatives] - - - - - 107 changed files: - compiler/GHC/Core/FamInstEnv.hs - compiler/GHC/Core/Opt/OccurAnal.hs - compiler/GHC/Core/Opt/Simplify/Iteration.hs - compiler/GHC/Core/Opt/Simplify/Utils.hs - compiler/GHC/Core/Opt/SpecConstr.hs - compiler/GHC/Core/TyCo/Subst.hs - compiler/GHC/Core/TyCon.hs - compiler/GHC/Core/Unify.hs - compiler/GHC/Core/Utils.hs - compiler/GHC/HsToCore/Monad.hs - compiler/GHC/Iface/Recomp.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/Splice.hs - compiler/GHC/Tc/Solver.hs - compiler/GHC/Tc/Solver/Default.hs - compiler/GHC/Tc/Solver/Dict.hs - compiler/GHC/Tc/Solver/Equality.hs - compiler/GHC/Tc/Solver/FunDeps.hs - compiler/GHC/Tc/Solver/InertSet.hs - compiler/GHC/Tc/Solver/Monad.hs - compiler/GHC/Tc/Solver/Rewrite.hs - compiler/GHC/Tc/Types/Constraint.hs - compiler/GHC/Tc/Types/CtLoc.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Tc/Utils/Unify.hs - compiler/GHC/Types/TyThing.hs - docs/users_guide/9.16.1-notes.rst - docs/users_guide/exts/pragmas.rst - docs/users_guide/exts/table.rst - − driver/utils/merge_sections.ld - − driver/utils/merge_sections_pe.ld - hadrian/hadrian.cabal - hadrian/src/Builder.hs - hadrian/src/Context.hs - hadrian/src/Hadrian/Haskell/Cabal/Parse.hs - hadrian/src/Hadrian/Haskell/Cabal/Type.hs - hadrian/src/Hadrian/Haskell/Hash.hs - hadrian/src/Oracles/Flag.hs - hadrian/src/Rules.hs - hadrian/src/Rules/Library.hs - hadrian/src/Rules/Register.hs - hadrian/src/Settings/Builders/Cabal.hs - − hadrian/src/Settings/Builders/MergeObjects.hs - hadrian/src/Settings/Builders/SplitSections.hs - hadrian/src/Settings/Default.hs - hadrian/src/Settings/Packages.hs - libraries/base/changelog.md - libraries/ghc-internal/src/GHC/Internal/Control/Monad.hs - libraries/ghc-internal/src/GHC/Internal/Exception/Context.hs - linters/lint-codes/LintCodes/Static.hs - + testsuite/tests/driver/recomp26183/M.hs - + testsuite/tests/driver/recomp26183/M2A.hs - + testsuite/tests/driver/recomp26183/M2B.hs - + testsuite/tests/driver/recomp26183/Makefile - + testsuite/tests/driver/recomp26183/all.T - + testsuite/tests/driver/recomp26183/recomp26183.stderr - testsuite/tests/indexed-types/should_compile/CEqCanOccursCheck.hs - testsuite/tests/indexed-types/should_fail/T12522a.hs - testsuite/tests/indexed-types/should_fail/T26176.stderr - testsuite/tests/numeric/should_run/all.T - testsuite/tests/parser/should_fail/RecordDotSyntaxFail10.stderr - testsuite/tests/parser/should_fail/RecordDotSyntaxFail13.stderr - testsuite/tests/parser/should_fail/T20654a.stderr - testsuite/tests/pmcheck/should_compile/T15753c.hs - + testsuite/tests/pmcheck/should_compile/T15753c.stderr - testsuite/tests/pmcheck/should_compile/T15753d.hs - + testsuite/tests/pmcheck/should_compile/T15753d.stderr - + testsuite/tests/pmcheck/should_compile/T22652.hs - + testsuite/tests/pmcheck/should_compile/T22652a.hs - testsuite/tests/pmcheck/should_compile/all.T - + testsuite/tests/polykinds/T13882.hs - testsuite/tests/polykinds/all.T - testsuite/tests/quantified-constraints/T15316A.stderr - testsuite/tests/quantified-constraints/T17267.stderr - testsuite/tests/quantified-constraints/T17267a.stderr - testsuite/tests/quantified-constraints/T17267b.stderr - testsuite/tests/quantified-constraints/T17267c.stderr - testsuite/tests/quantified-constraints/T17267e.stderr - testsuite/tests/quantified-constraints/T17458.stderr - + testsuite/tests/simplCore/should_compile/T26709.hs - + testsuite/tests/simplCore/should_compile/T26709.stderr - testsuite/tests/simplCore/should_compile/all.T - testsuite/tests/typecheck/should_compile/T16188.hs - testsuite/tests/typecheck/should_fail/ContextStack1.stderr - testsuite/tests/typecheck/should_fail/FD3.stderr - testsuite/tests/typecheck/should_fail/FDsFromGivens2.stderr - testsuite/tests/typecheck/should_fail/FunDepOrigin1b.stderr - testsuite/tests/typecheck/should_fail/T13506.stderr - testsuite/tests/typecheck/should_fail/T15767.stderr - testsuite/tests/typecheck/should_fail/T19415.stderr - testsuite/tests/typecheck/should_fail/T19415b.stderr - testsuite/tests/typecheck/should_fail/T22924b.stderr - + testsuite/tests/typecheck/should_fail/T23162b.hs - + testsuite/tests/typecheck/should_fail/T23162b.stderr - + testsuite/tests/typecheck/should_fail/T23162c.hs - + testsuite/tests/typecheck/should_fail/T23162d.hs - testsuite/tests/typecheck/should_fail/T25325.stderr - testsuite/tests/typecheck/should_fail/T5236.stderr - testsuite/tests/typecheck/should_fail/T5246.stderr - testsuite/tests/typecheck/should_fail/T5978.stderr - testsuite/tests/typecheck/should_fail/T9612.stderr - testsuite/tests/typecheck/should_fail/TcCoercibleFail.stderr - testsuite/tests/typecheck/should_fail/all.T - testsuite/tests/typecheck/should_fail/tcfail143.stderr - utils/haddock/haddock-api/src/Haddock/Convert.hs The diff was not included because it is too large. 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