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[Git][ghc/ghc][wip/T27828] Wibbles
by Simon Peyton Jones (＠simonpj) 25 Sep '26

25 Sep '26

Simon Peyton Jones pushed to branch wip/T27828 at Glasgow Haskell Compiler / GHC Commits: 75745004 by Simon Peyton Jones at 2026-09-24T23:43:34+01:00 Wibbles - - - - - 4 changed files: - compiler/GHC/Core/FamInstEnv.hs - compiler/GHC/Iface/Decl.hs - compiler/GHC/Iface/Syntax.hs - compiler/GHC/IfaceToCore.hs Changes: ===================================== compiler/GHC/Core/FamInstEnv.hs ===================================== @@ -610,12 +610,14 @@ compareBranches b1@(CoAxBranch { cab_lhs = lhs1, cab_rhs = rhs1 }) -- Here we need the cab_tvs of the two branches to be disinct. -- See Note [CoAxBranch type variables] in GHC.Core.Coercion.Axiom. SurelyApart -> BC_Apart - MaybeApart {} -> pprPanic "compareBranches" (ppr b1 $$ ppr b2) Unifiable subst | Type.substTyAddInScope subst rhs1 `eqType` Type.substTyAddInScope subst rhs2 -> BC_Compat | otherwise -> BC_Incompat + MaybeApart {} -> BC_Incompat + -- An occurs check yields MaybeApart; + -- see Note [Infinitary substitutions] in GHC.Core.Unify where (commonlhs1, commonlhs2) = zipAndUnzip lhs1 lhs2 -- See Note [Compatibility of eta-reduced axioms] ===================================== compiler/GHC/Iface/Decl.hs ===================================== @@ -112,7 +112,7 @@ coAxBranchToIfaceBranch tc lhs_s , ifaxbRoles = roles , ifaxbRHS = toIfaceType rhs , ifaxbIncomps = iface_incomps } - where + where iface_incomps = map (expectJust . flip findIndex lhs_s . eqTypes ===================================== compiler/GHC/Iface/Syntax.hs ===================================== @@ -338,7 +338,12 @@ data IfaceAxBranch = IfaceAxBranch { ifaxbTyVars :: [IfaceTvBndr] , ifaxbRoles :: [Role] , ifaxbRHS :: IfaceType , ifaxbIncomps :: [BranchIndex] } - -- See Note [Storing compatibility] in GHC.Core.Coercion.Axiom + -- We store the incompatibilities in IfaceAxBranch + -- just for (perhaps unnecessary) display purposes: + -- see Note [Displaying axiom incompatibilities] + -- When we construct a real CoAxBranch we compute cab_incomps directly + -- from the equations, ignoring the ifaxbIncomps. + -- We could consider getting rid of ifaxbIncomps altogether. data IfaceConDecls = IfAbstractTyCon -- c.f TyCon.AbstractTyCon ===================================== compiler/GHC/IfaceToCore.hs ===================================== @@ -1111,15 +1111,14 @@ tc_fd (tvs1, tvs2) = do { tvs1' <- mapM tcIfaceTyVar tvs1 ; return (tvs1', tvs2') } tc_ax_branches :: [IfaceAxBranch] -> IfL [CoAxBranch] -tc_ax_branches if_branches = foldlM tc_ax_branch [] if_branches +tc_ax_branches if_branches = mapM tc_ax_branch if_branches -tc_ax_branch :: [CoAxBranch] -> IfaceAxBranch -> IfL [CoAxBranch] -tc_ax_branch prev_branches - (IfaceAxBranch { ifaxbTyVars = tv_bndrs +tc_ax_branch :: IfaceAxBranch -> IfL CoAxBranch +tc_ax_branch (IfaceAxBranch { ifaxbTyVars = tv_bndrs , ifaxbEtaTyVars = eta_tv_bndrs , ifaxbCoVars = cv_bndrs , ifaxbLHS = lhs, ifaxbRHS = rhs - , ifaxbRoles = roles, ifaxbIncomps = _incomps }) + , ifaxbRoles = roles }) = bindIfaceTyConBinders_AT (map (\b -> Bndr (IfaceTvBndr b) (NamedTCB Inferred)) tv_bndrs) $ \ tvs -> -- The _AT variant is needed here; see Note [CoAxBranch type variables] in GHC.Core.Coercion.Axiom @@ -1130,16 +1129,15 @@ tc_ax_branch prev_branches ; this_mod <- getIfModule ; let loc = mkGeneralSrcSpan (fsLit "module " `appendFS` moduleNameFS (moduleName this_mod)) - br = CoAxBranch { cab_loc = loc - , cab_tvs = binderVars tvs - , cab_eta_tvs = eta_tvs - , cab_cvs = cvs - , cab_lhs = tc_lhs - , cab_roles = roles - , cab_rhs = tc_rhs - , cab_overlaps = placeHolderOverlaps - , cab_incomps = placeHolderIncomps } - ; return (prev_branches ++ [br]) } + ; return (CoAxBranch { cab_loc = loc + , cab_tvs = binderVars tvs + , cab_eta_tvs = eta_tvs + , cab_cvs = cvs + , cab_lhs = tc_lhs + , cab_roles = roles + , cab_rhs = tc_rhs + , cab_overlaps = placeHolderOverlaps + , cab_incomps = placeHolderIncomps }) } tcIfaceDataCons :: Name -> TyCon -> IfaceConDecls -> IfL AlgTyConRhs tcIfaceDataCons tycon_name tycon if_cons View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/75745004ef3f28f18a532b015cfe729… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/75745004ef3f28f18a532b015cfe729… You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc] Pushed new branch wip/apk/fix-timeout
by Andreas Klebinger (＠AndreasK) 25 Sep '26

25 Sep '26

Andreas Klebinger pushed new branch wip/apk/fix-timeout at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/apk/fix-timeout You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc] Pushed new branch wip/sjakobi/T27847-ghci-rethrow-backtrace
by Simon Jakobi (＠sjakobi) 24 Sep '26

24 Sep '26

Simon Jakobi pushed new branch wip/sjakobi/T27847-ghci-rethrow-backtrace at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/sjakobi/T27847-ghci-rethrow-b… You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 2 commits: Correct the documentation of `explicitUnits`
by Marge Bot (＠marge-bot) 24 Sep '26

24 Sep '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: db9c95ac by Wolfgang Jeltsch at 2026-09-24T15:51:34-04:00 Correct the documentation of `explicitUnits` Resolves #27787. - - - - - a6b642b6 by Simon Jakobi at 2026-09-24T15:51:35-04:00 Remove stale specHeader bullet from Note [Don't make fillers for constraint types] The Note said that Specialise.specHeader also calls mkAbsentFiller. abfc224a27c removed that call: the specialiser no longer drops dead arguments at all, see Note [Do not drop dead args from specialisations] in GHC.Core.Opt.Specialise. Assisted-by: Claude Fable 5.1 - - - - - 2 changed files: - compiler/GHC/Core/Opt/WorkWrap/Utils.hs - compiler/GHC/Unit/State.hs Changes: ===================================== compiler/GHC/Core/Opt/WorkWrap/Utils.hs ===================================== @@ -1367,13 +1367,8 @@ It's surprisingly subtle. application; see test `T27627f`. TL;DR: we play safe: we never make an absent filler for any /constraint-kinded/ type, -using `isPredTy` to decide. - - * `mkAbsentFiller` returns `Nothing` for any constraint type, so worker/wrapper - keeps the real argument. - - * `Specialise.specHeader` calls `mkAbsentFiller` too, so it likewise keeps the - dead dictionary argument rather than dropping it for a filler. +using `isPredTy` to decide: `mkAbsentFiller` returns `Nothing` for any constraint +type, so worker/wrapper keeps the real argument. Prior failed approaches ===================================== compiler/GHC/Unit/State.hs ===================================== @@ -369,10 +369,15 @@ data UnitState = UnitState { -- is always mentioned before the units it depends on. preloadUnits :: [UnitId], - -- | Units which we explicitly depend on (from a command line flag). - -- We'll use this to generate version macros and the unused packages warning. The - -- original flag which was used to bring the unit into scope is recorded for the - -- -Wunused-packages warning. + -- | The units that can be used by the respective home unit. Despite the + -- identifier, this does not just cover units that are enabled explicitly + -- using flags but also units from the package database that are enabled + -- implicitly in case @-hide-all-packages@ is absent. The former are paired + -- with 'Just' applied to the respective flags, the latter are paired with + -- 'Nothing'. + -- + -- This field is used for generating version macros and “unused packages” + -- warnings. explicitUnits :: [(Unit, Maybe PackageArg)], homeUnitDepends :: Set UnitId, @@ -907,7 +912,7 @@ mkUnitState logger unit_index cfg = do let pkgname_map = listToUFM [ (unitPackageName p, unitInstanceOf p) | p <- pkgs2 ] - -- The explicitUnits accurately reflects the set of units we have turned + -- The explicitUnits accurately reflects the set of units that are turned -- on; as such, it also is the only way one can come up with requirements. -- The requirement context is directly based off of this: we simply -- look for nested unit IDs that are directly fed holes: the requirements View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f08bae90b4359fde91eb2493f9bd49… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/f08bae90b4359fde91eb2493f9bd49… You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc][wip/az/exactprint-annotation-rationalisation] 33 commits: MOVE: Exactprint layout scope plan. Do not commit
by Alan Zimmerman (＠alanz) 24 Sep '26

24 Sep '26

Alan Zimmerman pushed to branch wip/az/exactprint-annotation-rationalisation at Glasgow Haskell Compiler / GHC Commits: 0ff41c0e by Alan Zimmerman at 2026-09-24T11:02:40+01:00 MOVE: Exactprint layout scope plan. Do not commit - - - - - 97be233b by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: tidy up a bit. Combine somewhere else - - - - - ab12bb37 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Introduce LayoutFrame stacks in ExactPrint state - - - - - 751058a9 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 Align with ghc-exactprint - - - - - e917fb51 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Fix AnnList leading semis when layout When there is layout, anything printed triggers it, including leading semis. Add some test case examples too - - - - - 70714290 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 Exactprint: tidy up layout capturing - - - - - 290d1948 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: add makeDelta test for Test20297 The original #20297 related to comment placement for exact printing after running ExactPrint.makeDelta on ParsedSource. Add an additional test that explicitly tests this. - - - - - 69a5f176 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Make ValBinds LocatedA in HsLocalBindsLR If we have items with an AnnList Annotation, as part of another, which has different content, it must be LocatedA. This is a technical requirement due to the way comment allocation happens during the makeDelta processing. Comments are queued for printing, and as soon as any non-comment is to be printed, the pending comments before that position are printed, and in makeDelta processing these attached as preceding comments to the thing just printed. The means they end up captured inside the layout region of the AnnList item. So for foo = x where -- comment x = 3 the comment ends up as a preceding comment of `x = 3`, inside the layout, and prints as foo = x where -- comment x = 3 - - - - - dc1510c9 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Make IPBinds LocatedA - - - - - 0e1d283d by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Make ClsInstDecl decls LocatedA - - - - - 4d0574c8 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Make ClassDecls decls LocatedA - - - - - acb08ef2 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Make ClosedTypeFamily equations Located For FamilyDecl/ClosedTypeFamily - - - - - b77f1c3e by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Make dd_cons located - - - - - 1a6c9c54 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Make HsMultiIf options located - - - - - 4b960994 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Make DecBrl contents LocatedA - - - - - 90532ca0 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Located do statements - - - - - 40f055d7 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Print RecStmt located - - - - - 7d93f2ee by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: HsCmdDo Located - - - - - 8341dcd4 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 Extend Test20297 for additional occurrences - - - - - fce8043f by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Tweak PatSynBind location for comments - - - - - 7d05fed9 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: WIP, add test for where ;; ValBinds - - - - - 2495cef1 by Alan Zimmerman at 2026-09-24T11:02:49+01:00 EPA: Make EpVirtualBraces noSpanAnchor if no contents Otherwise the vocurly is emitted at the start of the next item parsed Check: is this needed, or just a check for empty contents? - - - - - 9cb8b9b9 by Alan Zimmerman at 2026-09-24T17:51:46+01:00 EPA: Use EpNoLayout in AnnList with empty contents and no explicit braces - - - - - 602cd545 by Alan Zimmerman at 2026-09-24T18:49:55+01:00 TODO: XClassDecl: remove additional EpLayout - - - - - 6170ccb1 by Alan Zimmerman at 2026-09-24T18:49:55+01:00 WIP: turn off exactprint debug printing - - - - - caa62748 by Alan Zimmerman at 2026-09-24T18:49:55+01:00 EPA: Remove CanUpdateAnchorOnly - - - - - 534c3e18 by Alan Zimmerman at 2026-09-24T18:49:55+01:00 Plan update DO NOT COMMIT - - - - - fb713865 by Alan Zimmerman at 2026-09-24T20:33:12+01:00 EPA: First pass implementation of HsList, for ClassDecls Just as a straight list replacement to start with, no payload. This shows the scope and invasiveness of the initial change - - - - - 0036bee3 by Alan Zimmerman at 2026-09-24T20:33:12+01:00 EPA: HsList attempt WIP - - - - - 823d41ac by Alan Zimmerman at 2026-09-24T20:33:12+01:00 Enable ppr test for Haddock1. It currently fails - - - - - 73458c58 by Alan Zimmerman at 2026-09-24T20:33:12+01:00 WIP on removing NoEpAnn. Likely abandon - - - - - f6c262d0 by Alan Zimmerman at 2026-09-24T20:33:12+01:00 EPA: Add an overview doc for exact printing - - - - - 88562119 by Simon Peyton Jones at 2026-09-24T20:33:12+01:00 Added an intro section - - - - - 80 changed files: - ANNLIST-LAYOUT-PLAN.md - + ExactPrint.md - + LAYOUT-SCOPE-PLAN.md - compiler/GHC/Driver/Backpack.hs - compiler/GHC/Driver/Main/Interactive.hs - compiler/GHC/Hs.hs - compiler/GHC/Hs/Binds.hs - compiler/GHC/Hs/Decls.hs - compiler/GHC/Hs/DocString.hs - compiler/GHC/Hs/Expr.hs - compiler/GHC/Hs/ImpExp.hs - compiler/GHC/Hs/Instances.hs - compiler/GHC/Hs/Stats.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/HsToCore/Docs.hs - compiler/GHC/HsToCore/Expr.hs - compiler/GHC/HsToCore/Pmc/Desugar.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/HsToCore/Ticks.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Parser/PostProcess/Haddock.hs - compiler/GHC/Rename/Bind.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/Module.hs - compiler/GHC/Rename/Names.hs - compiler/GHC/Rename/Splice.hs - compiler/GHC/Runtime/Eval.hs - compiler/GHC/Tc/Deriv.hs - compiler/GHC/Tc/Gen/Bind.hs - compiler/GHC/Tc/Gen/Expr.hs - compiler/GHC/Tc/Module.hs - compiler/GHC/Tc/TyCl.hs - compiler/GHC/Tc/TyCl/Instance.hs - compiler/GHC/Tc/Types/Origin.hs - compiler/GHC/Tc/Utils/Env.hs - compiler/GHC/Tc/Zonk/Type.hs - compiler/GHC/ThToHs.hs - compiler/Language/Haskell/Syntax.hs - compiler/Language/Haskell/Syntax/Basic.hs - compiler/Language/Haskell/Syntax/Binds.hs - compiler/Language/Haskell/Syntax/Decls.hs - compiler/Language/Haskell/Syntax/Expr.hs - ghc/GHCi/UI.hs - testsuite/tests/ghc-api/exactprint/Test20239.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T17544.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T17544_kw.stderr - testsuite/tests/haddock/should_compile_flag_haddock/T24221.stderr - testsuite/tests/parser/should_compile/DumpParsedAst.stderr - testsuite/tests/parser/should_compile/DumpRenamedAst.stderr - testsuite/tests/parser/should_compile/DumpSemis.hs - testsuite/tests/parser/should_compile/DumpSemis.stderr - testsuite/tests/parser/should_compile/KindSigs.stderr - testsuite/tests/parser/should_compile/T14189.stderr - testsuite/tests/parser/should_compile/T15323.stderr - testsuite/tests/parser/should_compile/T20452.stderr - testsuite/tests/perf/compiler/hard_hole_fits.stderr - testsuite/tests/printer/Makefile - testsuite/tests/printer/Ppr003.hs - testsuite/tests/printer/T18791.stderr - + testsuite/tests/printer/Test20297.expected.hs - testsuite/tests/printer/Test20297.hs - testsuite/tests/printer/Test20297.stdout - + testsuite/tests/printer/Test20297MD.stdout - testsuite/tests/printer/Test24533.stdout - testsuite/tests/printer/all.T - utils/check-exact/ExactPrint.hs - utils/check-exact/Main.hs - utils/check-exact/Parsers.hs - utils/check-exact/Transform.hs - utils/check-exact/Utils.hs - utils/haddock/haddock-api/src/Haddock/Backends/Hoogle.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/GhcUtils.hs - utils/haddock/haddock-api/src/Haddock/Interface/Create.hs - utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs - utils/haddock/haddock-api/src/Haddock/Types.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8ebd722dffe09368c05d69ad201f9f… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/8ebd722dffe09368c05d69ad201f9f… You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 4 commits: Change the C types of hs_{bitrev,bswap}{16,32} to match the Haskell types
by Marge Bot (＠marge-bot) 24 Sep '26

24 Sep '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 545fd4fb by ARATA Mizuki at 2026-09-22T15:03:24-04:00 Change the C types of hs_{bitrev,bswap}{16,32} to match the Haskell types bitReverse{16,32}# and byteSwap{16,32}# have the type Word# -> Word#, but their C correspondents took and returned StgWord{16,32}. The mismatch on bitReverse16# led to the problem reported in #27299. Although no similar issue is reported for bitReverse32# and byteSwap{16,32}#, it seemed wise to change them proactively. This commit fixes the mismatch by changing the C type. Fixes #27299 - - - - - bf17f289 by fendor at 2026-09-22T15:04:05-04:00 Don't lose instances from shadowed imported modules with the same name When we look for instances below the current module, we need to check the unit id as well when we check for whether the module is the current module, otherwise we ignore modules we import that have the same name as the import module. Adds regression test. - - - - - 9169b4fa by Wolfgang Jeltsch at 2026-09-24T15:02:15-04:00 Correct the documentation of `explicitUnits` Resolves #27787. - - - - - f08bae90 by Simon Jakobi at 2026-09-24T15:02:16-04:00 Remove stale specHeader bullet from Note [Don't make fillers for constraint types] The Note said that Specialise.specHeader also calls mkAbsentFiller. abfc224a27c removed that call: the specialiser no longer drops dead arguments at all, see Note [Do not drop dead args from specialisations] in GHC.Core.Opt.Specialise. Assisted-by: Claude Fable 5.1 - - - - - 18 changed files: - + changelog.d/26610 - compiler/GHC/Core/Opt/WorkWrap/Utils.hs - compiler/GHC/Driver/Env.hs - compiler/GHC/Unit/State.hs - rts/include/stg/Prim.h - rts/prim/bitrev.c - rts/prim/bswap.c - + testsuite/tests/ghci/prog-mhu008/Makefile - + testsuite/tests/ghci/prog-mhu008/a/M.hs - + testsuite/tests/ghci/prog-mhu008/all.T - + testsuite/tests/ghci/prog-mhu008/b/M.hs - + testsuite/tests/ghci/prog-mhu008/prog-mhu008.script - + testsuite/tests/ghci/prog-mhu008/prog-mhu008.stdout - + testsuite/tests/ghci/prog-mhu008/unitA - + testsuite/tests/ghci/prog-mhu008/unitB - + testsuite/tests/primops/should_run/T27299.hs - + testsuite/tests/primops/should_run/T27299.stdout - testsuite/tests/primops/should_run/all.T Changes: ===================================== changelog.d/26610 ===================================== @@ -0,0 +1,7 @@ +section: compiler +synopsis: Fix instance resolution for shadowed modules +description: + Instances imported from modules with the same module name as the importing module + were dropped accidentally since we didn't account for the unit id of the imported module. +mrs: !16648 +issues: #26610 ===================================== compiler/GHC/Core/Opt/WorkWrap/Utils.hs ===================================== @@ -1367,13 +1367,8 @@ It's surprisingly subtle. application; see test `T27627f`. TL;DR: we play safe: we never make an absent filler for any /constraint-kinded/ type, -using `isPredTy` to decide. - - * `mkAbsentFiller` returns `Nothing` for any constraint type, so worker/wrapper - keeps the real argument. - - * `Specialise.specHeader` calls `mkAbsentFiller` too, so it likewise keeps the - dead dictionary argument rather than dropping it for a filler. +using `isPredTy` to decide: `mkAbsentFiller` returns `Nothing` for any constraint +type, so worker/wrapper keeps the real argument. Prior failed approaches ===================================== compiler/GHC/Driver/Env.hs ===================================== @@ -263,13 +263,13 @@ hugCompleteSigsBelow hsc uid mn = foldr (++) [] <$> -- | Find instances visible from the given set of imports hugInstancesBelow :: HscEnv -> UnitId -> ModuleNameWithIsBoot -> IO (InstEnv, [FamInst]) hugInstancesBelow hsc_env uid mnwib = do - let mn = gwib_mod mnwib + let mn = mkModule uid (gwib_mod mnwib) (insts, famInsts) <- unzip . concat <$> hugSomeThingsBelowUs (\mod_info -> let details = hm_details mod_info -- Don't include instances for the current module - in if moduleName (mi_module (hm_iface mod_info)) == mn + in if fmap toUnitId (mi_module (hm_iface mod_info)) == mn then [] else [(md_insts details, md_fam_insts details)]) True -- Include -hi-boot ===================================== compiler/GHC/Unit/State.hs ===================================== @@ -369,10 +369,15 @@ data UnitState = UnitState { -- is always mentioned before the units it depends on. preloadUnits :: [UnitId], - -- | Units which we explicitly depend on (from a command line flag). - -- We'll use this to generate version macros and the unused packages warning. The - -- original flag which was used to bring the unit into scope is recorded for the - -- -Wunused-packages warning. + -- | The units that can be used by the respective home unit. Despite the + -- identifier, this does not just cover units that are enabled explicitly + -- using flags but also units from the package database that are enabled + -- implicitly in case @-hide-all-packages@ is absent. The former are paired + -- with 'Just' applied to the respective flags, the latter are paired with + -- 'Nothing'. + -- + -- This field is used for generating version macros and “unused packages” + -- warnings. explicitUnits :: [(Unit, Maybe PackageArg)], homeUnitDepends :: Set UnitId, @@ -907,7 +912,7 @@ mkUnitState logger unit_index cfg = do let pkgname_map = listToUFM [ (unitPackageName p, unitInstanceOf p) | p <- pkgs2 ] - -- The explicitUnits accurately reflects the set of units we have turned + -- The explicitUnits accurately reflects the set of units that are turned -- on; as such, it also is the only way one can come up with requirements. -- The requirement context is directly based off of this: we simply -- look for nested unit IDs that are directly fed holes: the requirements ===================================== rts/include/stg/Prim.h ===================================== @@ -59,16 +59,16 @@ StgWord hs_xchg32(StgWord x, StgWord val); StgWord64 hs_xchg64(StgWord x, StgWord64 val); /* rts/prim/bswap.c */ -StgWord16 hs_bswap16(StgWord16 x); -StgWord32 hs_bswap32(StgWord32 x); +StgWord hs_bswap16(StgWord x); +StgWord hs_bswap32(StgWord x); StgWord64 hs_bswap64(StgWord64 x); /* rts/prim/bitrev.c This was done as part of issue #16164. See Note [Bit reversal primop] for more details about the implementation.*/ StgWord hs_bitrev8(StgWord x); -StgWord16 hs_bitrev16(StgWord16 x); -StgWord32 hs_bitrev32(StgWord32 x); +StgWord hs_bitrev16(StgWord x); +StgWord hs_bitrev32(StgWord x); StgWord64 hs_bitrev64(StgWord64 x); /* rts/prim/longlong.c */ ===================================== rts/prim/bitrev.c ===================================== @@ -36,8 +36,8 @@ hs_bitrev8(StgWord x) return x; } -StgWord16 -hs_bitrev16(StgWord16 x) +StgWord +hs_bitrev16(StgWord x) { x = ((x >> 1) & 0x5555) | ((x & 0x5555) << 1 ); x = ((x >> 2) & 0x3333) | ((x & 0x3333) << 2 ); @@ -46,14 +46,14 @@ hs_bitrev16(StgWord16 x) return x; } -StgWord32 -hs_bitrev32(StgWord32 x) +StgWord +hs_bitrev32(StgWord x) { - x = ((x >> 1) & 0x55555555) | ((x & 0x55555555) << 1 ); - x = ((x >> 2) & 0x33333333) | ((x & 0x33333333) << 2 ); - x = ((x >> 4) & 0x0F0F0F0F) | ((x & 0x0F0F0F0F) << 4 ); - x = ((x >> 8) & 0x00FF00FF) | ((x & 0x00FF00FF) << 8 ); - x = ( x >> 16 ) | ( x << 16 ); + x = ((x >> 1) & 0x55555555) | ((x & 0x55555555) << 1 ); + x = ((x >> 2) & 0x33333333) | ((x & 0x33333333) << 2 ); + x = ((x >> 4) & 0x0F0F0F0F) | ((x & 0x0F0F0F0F) << 4 ); + x = ((x >> 8) & 0x00FF00FF) | ((x & 0x00FF00FF) << 8 ); + x = ((x >> 16) & 0x0000FFFF) | ((x & 0x0000FFFF) << 16); return x; } ===================================== rts/prim/bswap.c ===================================== @@ -1,16 +1,18 @@ #include "Rts.h" -StgWord16 -hs_bswap16(StgWord16 x) +StgWord +hs_bswap16(StgWord x) { - return ((x >> 8) | (x << 8)); + x = (StgWord16)x; + return (StgWord16)((x >> 8) | (x << 8)); } -StgWord32 -hs_bswap32(StgWord32 x) +StgWord +hs_bswap32(StgWord x) { - return ((x >> 24) | ((x >> 8) & 0xff00) | - (x << 24) | ((x & 0xff00) << 8)); + x = (StgWord32)x; + return (StgWord32)((x >> 24) | ((x >> 8) & 0xff00) | + (x << 24) | ((x & 0xff00) << 8)); } StgWord64 ===================================== testsuite/tests/ghci/prog-mhu008/Makefile ===================================== @@ -0,0 +1,3 @@ +TOP=../../.. +include $(TOP)/mk/boilerplate.mk +include $(TOP)/mk/test.mk ===================================== testsuite/tests/ghci/prog-mhu008/a/M.hs ===================================== @@ -0,0 +1,4 @@ +module M (T (..)) where + +newtype T = MkT Int + deriving (Eq, Ord) ===================================== testsuite/tests/ghci/prog-mhu008/all.T ===================================== @@ -0,0 +1,5 @@ +test('prog-mhu008', + [extra_files(['a/', 'b/', 'unitA', 'unitB']), + cmd_prefix('ghciWayFlags=' + config.ghci_way_flags), + req_interp], + ghci_multiunit_script, [['unitA', 'unitB'], 'prog-mhu008.script']) ===================================== testsuite/tests/ghci/prog-mhu008/b/M.hs ===================================== @@ -0,0 +1,11 @@ +{-# LANGUAGE PackageImports #-} + +module M + ( module Export + , cmp + ) where + +import "a" M as Export + +cmp :: T -> T -> Bool +cmp x y = x <= y ===================================== testsuite/tests/ghci/prog-mhu008/prog-mhu008.script ===================================== @@ -0,0 +1,5 @@ +:set -XPackageImports +import "a" M qualified as MA +import "b" M qualified as MB + +MB.cmp (MA.MkT 1) (MA.MkT 2) ===================================== testsuite/tests/ghci/prog-mhu008/prog-mhu008.stdout ===================================== @@ -0,0 +1 @@ +True ===================================== testsuite/tests/ghci/prog-mhu008/unitA ===================================== @@ -0,0 +1,5 @@ +-this-unit-id a-0-inplace +-this-package-name a +-i +-ia +M ===================================== testsuite/tests/ghci/prog-mhu008/unitB ===================================== @@ -0,0 +1,6 @@ +-this-unit-id b-0-inplace +-this-package-name b +-package-id a-0-inplace +-i +-ib +M ===================================== testsuite/tests/primops/should_run/T27299.hs ===================================== @@ -0,0 +1,23 @@ +{-# LANGUAGE MagicHash #-} +import GHC.Exts +import GHC.Word +import Numeric + +main :: IO () +main = do + putStrLn $ showHex (W# (bitReverse8# 0x55##)) "" + putStrLn $ showHex (W# (bitReverse8# 0xAA##)) "" + putStrLn $ showHex (W# (bitReverse16# 0x5555##)) "" + putStrLn $ showHex (W# (bitReverse16# 0xAAAA##)) "" + putStrLn $ showHex (W# (bitReverse32# 0x5555_5555##)) "" + putStrLn $ showHex (W# (bitReverse32# 0xAAAA_AAAA##)) "" + putStrLn $ showHex (W# (byteSwap16# 0xABCD##)) "" + putStrLn $ showHex (W# (byteSwap32# 0xABCD_EF12##)) "" + putStrLn $ showHex (W# (noinline bitReverse8# 0x55##)) "" + putStrLn $ showHex (W# (noinline bitReverse8# 0xAA##)) "" + putStrLn $ showHex (W# (noinline bitReverse16# 0x5555##)) "" + putStrLn $ showHex (W# (noinline bitReverse16# 0xAAAA##)) "" + putStrLn $ showHex (W# (noinline bitReverse32# 0x5555_5555##)) "" + putStrLn $ showHex (W# (noinline bitReverse32# 0xAAAA_AAAA##)) "" + putStrLn $ showHex (W# (noinline byteSwap16# 0xABCD##)) "" + putStrLn $ showHex (W# (noinline byteSwap32# 0xABCD_EF12##)) "" ===================================== testsuite/tests/primops/should_run/T27299.stdout ===================================== @@ -0,0 +1,16 @@ +aa +55 +aaaa +5555 +aaaaaaaa +55555555 +cdab +12efcdab +aa +55 +aaaa +5555 +aaaaaaaa +55555555 +cdab +12efcdab ===================================== testsuite/tests/primops/should_run/all.T ===================================== @@ -91,3 +91,4 @@ test('T24496' ] , compile_and_run, ['-O']) test('T6026', normal, compile_and_run, ['']) +test('T27299', normal, compile_and_run, ['']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/43ddbbbafab824cd34325d6c1fab27… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/43ddbbbafab824cd34325d6c1fab27… You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc] Pushed new branch wip/T27844
by Simon Peyton Jones (＠simonpj) 24 Sep '26

24 Sep '26

Simon Peyton Jones pushed new branch wip/T27844 at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/T27844 You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc] Pushed new branch wip/sjakobi/T27477-changelog
by Simon Jakobi (＠sjakobi) 24 Sep '26

24 Sep '26

Simon Jakobi pushed new branch wip/sjakobi/T27477-changelog at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/sjakobi/T27477-changelog You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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[Git][ghc/ghc][wip/T27828] Add cab_overlaps
by Simon Peyton Jones (＠simonpj) 24 Sep '26

24 Sep '26

Simon Peyton Jones pushed to branch wip/T27828 at Glasgow Haskell Compiler / GHC Commits: b9431ef2 by Simon Peyton Jones at 2026-09-24T15:42:33+01:00 Add cab_overlaps Needs some documentation; fixes bug discovered by Fable - - - - - 8 changed files: - changelog.d/T27828 - compiler/GHC/Builtin/WiredIn/Types/Box.hs - compiler/GHC/Core/Coercion/Axiom.hs - compiler/GHC/Core/FamInstEnv.hs - compiler/GHC/IfaceToCore.hs - compiler/GHC/Tc/Solver/FunDeps.hs - compiler/GHC/Tc/TyCl.hs - testsuite/tests/indexed-types/should_compile/all.T Changes: ===================================== changelog.d/T27828 ===================================== @@ -4,5 +4,5 @@ issues: #27828 mrs: !16714 description: { - There was a bug in the implemenation of functional dependencies for type families. + There was a bug in the implementation of functional dependencies for type families. } ===================================== compiler/GHC/Builtin/WiredIn/Types/Box.hs ===================================== @@ -329,7 +329,8 @@ mkWiredInNewTyCon tc_name dc_name nt_co_uniq bndrs roles nt_fld_ty = , cab_roles = roles , cab_lhs = mkTyVarTys tvs , cab_rhs = nt_fld_ty - , cab_incomps = [] } + , cab_overlaps = [] + , cab_incomps = [] } -- | The wired-in @Box@ newtype: -- ===================================== compiler/GHC/Core/Coercion/Axiom.hs ===================================== @@ -18,7 +18,7 @@ module GHC.Core.Coercion.Axiom ( coAxiomSingleBranch, coAxBranchTyVars, coAxBranchCoVars, coAxBranchRoles, coAxBranchLHS, coAxBranchRHS, coAxBranchSpan, coAxBranchIncomps, - placeHolderIncomps, + placeHolderIncomps, placeHolderOverlaps, Role(..), @@ -275,8 +275,15 @@ data CoAxBranch , cab_rhs :: Type -- ^ Right-hand side of the equality -- See Note [CoAxioms are homogeneous] + + , cab_overlaps :: [CoAxBranch] + -- ^ The preceding branches whose LHSs are /unify with/ this one + -- Order is unimportant + -- See Note [Storing compatibility] + , cab_incomps :: [CoAxBranch] - -- ^ The previous incompatible branches + -- ^ The preceding branches that are /incompatible/ with this one + -- Order is unimportant -- See Note [Storing compatibility] } deriving Data.Data @@ -349,8 +356,9 @@ coAxBranchIncomps :: CoAxBranch -> [CoAxBranch] coAxBranchIncomps = cab_incomps -- See Note [Compatibility] in GHC.Core.FamInstEnv -placeHolderIncomps :: [CoAxBranch] -placeHolderIncomps = panic "placeHolderIncomps" +placeHolderIncomps, placeHolderOverlaps :: [CoAxBranch] +placeHolderIncomps = panic "placeHolderIncomps" +placeHolderOverlaps = panic "placeHolderOverlaps" {- Note [CoAxBranch type variables] ===================================== compiler/GHC/Core/FamInstEnv.hs ===================================== @@ -487,22 +487,45 @@ in GHC.Core.Unify.) Note [Compatibility] ~~~~~~~~~~~~~~~~~~~~ -Two patterns are /compatible/ if either of the following conditions hold: +Consider a closed type family with two equations (X1) and (X2) + type family F a where + F lhs1 = rhs1 -- (X1) + ... + F lhs2 = rhs2 -- (X2) + ... +Then equations (X1) and (X2) are /compatible/ if any target (F ty) that +matches both equations yields the very same right hand side. Example: + And True True = True + And a True = a +The target (And True True) matches both equations but they then both +produce the same reduct True. + +More precisely (X1) and (X2) are /compatible/ iff + If LHSs unify with a substitution S, then S(rhs1) = S(rhs2) + +Conversely, (X1) and (X2) are /incompatible/ if + Their LHSs unify with S, and S(rhs1) /= S(rhs2) - 1) The patterns are apart. +For open type families, only compatible instances are allowed. For closed +families, we use the Closed Family Matching Rule (see function `findBranch`): - 2) The patterns unify with a substitution S, and their right hand sides - are equal under that substitution. + When looking up a target (F ty) in a closed type family F, + find an equation (branch) such that: + * the LHS matches the target + * the target is apart from every previous /incompatible/ equation for F -For open type families, only compatible instances are allowed. For closed -type families, the story is slightly more complicated. Consider the following: +We don't need to check the earlier equations that are compatible with the +matching equation, because they are either irrelevant (clause 1 of compatible) +or benign (clause 2 of compatible). + +Some examples: -type family F a where - F Int = Bool - F a = Int + type family F a where + F Int = Bool + F a = Int -g :: Show a => a -> F a -g x = length (show x) + g :: Show a => a -> F a + g x = length (show x) Should that type-check? No. We need to allow for the possibility that 'a' might be Int and therefore 'F a' should be Bool. We can simplify 'F a' to Int @@ -518,12 +541,12 @@ potentially-overlapping group is closed. As another example, consider this: -type family G x where - G Int = Bool - G a = Double + type family G x where + G Int = Bool + G a = Double -type family H y --- no instances + type family H y + -- no instances Now, we want to simplify (G (H Char)). We can't, because (H Char) might later simplify to be Int. So, (G (H Char)) is stuck, for now. @@ -531,18 +554,13 @@ simplify to be Int. So, (G (H Char)) is stuck, for now. While everything above is quite sound, it isn't as expressive as we'd like. Consider this: -type family J a where - J Int = Int - J a = a + type family J a where + J Int = Int + J a = a Can we simplify (J b) to b? Sure we can. Yes, the first equation matches if b is instantiated with Int, but the RHSs coincide there, so it's all OK. - -So, the rule is this: when looking up a branch in a closed type family, we -find a branch that matches the target, but then we make sure that the target -is apart from every previous *incompatible* branch. We don't check the -branches that are compatible with the matching branch, because they are either -irrelevant (clause 1 of compatible) or benign (clause 2 of compatible). +Hence the Closed Family Matching Rule. Note [Compatibility of eta-reduced axioms] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -574,15 +592,30 @@ fails anyway. -- See Note [Compatibility] compatibleBranches :: CoAxBranch -> CoAxBranch -> Bool -compatibleBranches (CoAxBranch { cab_lhs = lhs1, cab_rhs = rhs1 }) - (CoAxBranch { cab_lhs = lhs2, cab_rhs = rhs2 }) +compatibleBranches b1 b2 + = case compareBranches b1 b2 of + BC_Apart -> True + BC_Compat -> True + BC_Incompat -> False + +data BranchCompatibility + = BC_Apart -- LHSs are apart + | BC_Compat -- LHSs unify with S, and S(rhs1)=S(rhs2) + | BC_Incompat -- LHSs unify with S, and S(rhs1)/=S(rhs2) + +compareBranches :: CoAxBranch -> CoAxBranch -> BranchCompatibility +compareBranches b1@(CoAxBranch { cab_lhs = lhs1, cab_rhs = rhs1 }) + b2@(CoAxBranch { cab_lhs = lhs2, cab_rhs = rhs2 }) = case tcUnifyTysFG alwaysBindFam alwaysBindTv commonlhs1 commonlhs2 of -- Here we need the cab_tvs of the two branches to be disinct. -- See Note [CoAxBranch type variables] in GHC.Core.Coercion.Axiom. - SurelyApart -> True - MaybeApart {} -> False - Unifiable subst -> Type.substTyAddInScope subst rhs1 `eqType` + SurelyApart -> BC_Apart + MaybeApart {} -> pprPanic "compareBranches" (ppr b1 $$ ppr b2) + Unifiable subst | Type.substTyAddInScope subst rhs1 `eqType` Type.substTyAddInScope subst rhs2 + -> BC_Compat + | otherwise + -> BC_Incompat where (commonlhs1, commonlhs2) = zipAndUnzip lhs1 lhs2 -- See Note [Compatibility of eta-reduced axioms] @@ -630,10 +663,10 @@ injectiveBranches injectivity lhs1Subst = Type.substTys subst (getInjArgs lhs1) lhs2Subst = Type.substTys subst (getInjArgs lhs2) --- takes a CoAxiom with unknown branch incompatibilities and computes --- the compatibilities --- See Note [Storing compatibility] in GHC.Core.Coercion.Axiom computeAxiomIncomps :: [CoAxBranch] -> [CoAxBranch] +-- Takes a CoAxiom for a closed type family with place-holder +-- `cab_incomps` and `cab_overlaps` fields, and computes those fields +-- See Note [Storing compatibility] in GHC.Core.Coercion.Axiom computeAxiomIncomps branches = snd (mapAccumL go [] branches) where @@ -641,11 +674,23 @@ computeAxiomIncomps branches go prev_brs cur_br = (new_br : prev_brs, new_br) where - new_br = cur_br { cab_incomps = mk_incomps prev_brs cur_br } - - mk_incomps :: [CoAxBranch] -> CoAxBranch -> [CoAxBranch] - mk_incomps prev_brs cur_br - = filter (not . compatibleBranches cur_br) prev_brs + (overlaps,incomps) = get_cab [] [] prev_brs + new_br = cur_br { cab_overlaps = overlaps, cab_incomps = incomps } + + get_cab :: [CoAxBranch] -> [CoAxBranch] -- Accumulators + -> [CoAxBranch] + -> ([CoAxBranch], [CoAxBranch]) + get_cab overlaps incomps [] = (overlaps,incomps) + get_cab overlaps incomps (br:brs) + = case compareBranches cur_br br of + BC_Apart -> get_cab overlaps incomps brs + BC_Compat -> get_cab (br:overlaps) incomps brs + BC_Incompat -> get_cab (br:overlaps) (br:incomps) brs + +noAxiomIncomps :: CoAxBranch -> CoAxBranch +-- Overwrite the placeholders for `cab_incomps` and `cab_overlaps` +-- with [], because unbranched axioms have no "preceding" equations +noAxiomIncomps branch = branch { cab_incomps = [], cab_overlaps = [] } {- ************************************************************************ @@ -716,14 +761,15 @@ mkCoAxBranch :: [TyVar] -- original, possibly stale, tyvars -> SrcSpan -> CoAxBranch mkCoAxBranch tvs eta_tvs cvs lhs rhs roles loc - = CoAxBranch { cab_tvs = tvs' - , cab_eta_tvs = eta_tvs' - , cab_cvs = cvs' - , cab_lhs = tidyTypes env lhs - , cab_roles = roles - , cab_rhs = tidyType env rhs - , cab_loc = loc - , cab_incomps = placeHolderIncomps } + = CoAxBranch { cab_tvs = tvs' + , cab_eta_tvs = eta_tvs' + , cab_cvs = cvs' + , cab_lhs = tidyTypes env lhs + , cab_roles = roles + , cab_rhs = tidyType env rhs + , cab_loc = loc + , cab_overlaps = placeHolderOverlaps + , cab_incomps = placeHolderIncomps } where (env1, tvs') = tidyVarBndrs init_tidy_env tvs (env2, eta_tvs') = tidyVarBndrs env1 eta_tvs @@ -737,12 +783,12 @@ mkCoAxBranch tvs eta_tvs cvs lhs rhs roles loc -- all of the following code is here to avoid mutual dependencies with -- Coercion -mkBranchedCoAxiom :: Name -> TyCon -> [CoAxBranch] -> CoAxiom Branched -mkBranchedCoAxiom ax_name fam_tc branches +mkBranchedCoAxiom :: Role -> Name -> TyCon -> [CoAxBranch] -> CoAxiom Branched +mkBranchedCoAxiom role ax_name fam_tc branches = CoAxiom { co_ax_unique = nameUnique ax_name , co_ax_name = ax_name , co_ax_tc = fam_tc - , co_ax_role = Nominal + , co_ax_role = role , co_ax_implicit = False , co_ax_branches = manyBranches (computeAxiomIncomps branches) } @@ -753,7 +799,7 @@ mkUnbranchedCoAxiom ax_name fam_tc branch , co_ax_tc = fam_tc , co_ax_role = Nominal , co_ax_implicit = False - , co_ax_branches = unbranched (branch { cab_incomps = [] }) } + , co_ax_branches = unbranched (noAxiomIncomps branch) } mkSingleCoAxiom :: Role -> Name -> [TyVar] -> [TyVar] -> [CoVar] @@ -768,7 +814,7 @@ mkSingleCoAxiom role ax_name tvs eta_tvs cvs fam_tc lhs_tys rhs_ty , co_ax_tc = fam_tc , co_ax_role = role , co_ax_implicit = False - , co_ax_branches = unbranched (branch { cab_incomps = [] }) } + , co_ax_branches = unbranched (noAxiomIncomps branch) } where branch = mkCoAxBranch tvs eta_tvs cvs lhs_tys rhs_ty (map (const Nominal) tvs) @@ -786,7 +832,7 @@ mkNewTypeCoAxiom name tycon tvs roles rhs_ty , co_ax_implicit = True -- See Note [Implicit axioms] in GHC.Core.TyCon , co_ax_role = Representational , co_ax_tc = tycon - , co_ax_branches = unbranched (branch { cab_incomps = [] }) } + , co_ax_branches = unbranched (noAxiomIncomps branch) } where branch = mkCoAxBranch tvs [] [] (mkTyVarTys tvs) rhs_ty roles (getSrcSpan name) @@ -1224,7 +1270,9 @@ findBranch :: Array BranchIndex CoAxBranch -> Maybe (BranchIndex, [Type], [Coercion]) -- coercions relate requested types to returned axiom LHS at role N findBranch branches target_tys - = foldr go Nothing (assocs branches) + = -- Implements the Closed Family Matching Rule + -- in Note [Compatibility] + foldr go Nothing (assocs branches) where go :: (BranchIndex, CoAxBranch) -> Maybe (BranchIndex, [Type], [Coercion]) @@ -1264,8 +1312,8 @@ noEarlierMatchCheck :: [Type] -> CoAxBranch -- ^ The candidate equation we wish to use -> Bool -- ^ True <=> equation can fire -noEarlierMatchCheck target (CoAxBranch { cab_incomps = incomps }) - = not (any matches incomps) +noEarlierMatchCheck target (CoAxBranch { cab_overlaps = overlaps }) + = not (any matches overlaps) where matches earlier_branch = isJust (tcMatchTys (coAxBranchLHS earlier_branch) target) ===================================== compiler/GHC/IfaceToCore.hs ===================================== @@ -903,12 +903,7 @@ tc_iface_decl _ _ (IfaceAxiom { ifName = tc_name, ifTyCon = tc -- See #13803 ; tc_branches <- forkM (text "Axiom branches" <+> ppr tc_name) $ tc_ax_branches branches - ; let axiom = CoAxiom { co_ax_unique = nameUnique tc_name - , co_ax_name = tc_name - , co_ax_tc = tc_tycon - , co_ax_role = role - , co_ax_branches = manyBranches tc_branches - , co_ax_implicit = False } + ; let axiom = mkBranchedCoAxiom role tc_name tc_tycon tc_branches ; return (ACoAxiom axiom) } tc_iface_decl _ _ (IfacePatSyn{ ifName = name @@ -1124,7 +1119,7 @@ tc_ax_branch prev_branches , ifaxbEtaTyVars = eta_tv_bndrs , ifaxbCoVars = cv_bndrs , ifaxbLHS = lhs, ifaxbRHS = rhs - , ifaxbRoles = roles, ifaxbIncomps = incomps }) + , ifaxbRoles = roles, ifaxbIncomps = _incomps }) = bindIfaceTyConBinders_AT (map (\b -> Bndr (IfaceTvBndr b) (NamedTCB Inferred)) tv_bndrs) $ \ tvs -> -- The _AT variant is needed here; see Note [CoAxBranch type variables] in GHC.Core.Coercion.Axiom @@ -1135,14 +1130,15 @@ tc_ax_branch prev_branches ; this_mod <- getIfModule ; let loc = mkGeneralSrcSpan (fsLit "module " `appendFS` moduleNameFS (moduleName this_mod)) - br = CoAxBranch { cab_loc = loc - , cab_tvs = binderVars tvs - , cab_eta_tvs = eta_tvs - , cab_cvs = cvs - , cab_lhs = tc_lhs - , cab_roles = roles - , cab_rhs = tc_rhs - , cab_incomps = map (prev_branches `getNth`) incomps } + br = CoAxBranch { cab_loc = loc + , cab_tvs = binderVars tvs + , cab_eta_tvs = eta_tvs + , cab_cvs = cvs + , cab_lhs = tc_lhs + , cab_roles = roles + , cab_rhs = tc_rhs + , cab_overlaps = placeHolderOverlaps + , cab_incomps = placeHolderIncomps } ; return (prev_branches ++ [br]) } tcIfaceDataCons :: Name -> TyCon -> IfaceConDecls -> IfL AlgTyConRhs ===================================== compiler/GHC/Tc/Solver/FunDeps.hs ===================================== @@ -1047,7 +1047,7 @@ Note [Exploiting closed type families]. You might think that (B3) could be instantiated to Bak Char ~ Char; but actually that instantiation will never fire because (B2) Bak Char ~ Int would fire first. So the only way to return a Char is via (B1); so we - can emit [W] alpha ~ Int. Hence (B3) is not relevant; only (B2) is relevant. + can emit [W] alpha ~ Int. Hence (B3) is not relevant; only (B1) is relevant. That is the reason for condition (R2) in the definition of Relevance above. A watertight proof that this is the Right Thing is not very easy. See more @@ -1072,6 +1072,23 @@ Note [Exploiting closed type families]. TMessage @SC @Req alpha and equation (T1) does not match that. (It does unify, but we don't care.) +(RW5) `noEarlierMatchCheck`: in (RW4) We really do need to check that /no/ + earlier equation matches, not just no earlier /incompatible/ equation + matches. Consider T27282a: + type family F a where + F Int = Int -- B1 + F Char = Bool -- B2 + F a = a -- B3 + + [W] F alpha ~ Int + + (B1) is relevant, and (B2) is not. What about (B3)? It pre-unifies with + the Wanted via [alpha :-> Int, a :-> Int]. But under that substitution + (B1) would fire, so (B3) is not relevant. + + And yet, (B1) is /compatible/ with (B3), so it's no good just looking at + the `cab_incomps` of (B3). Instead we look at `cab_overlaps`. + Note [Exploiting open type families] see `mkTopOpenFamEqFDs` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Generating fundeps from a top-level type instance is covered in Section 5.2 in @@ -1451,6 +1468,8 @@ solveFunDeps work_ev fd_eqns ; uPairsTcM uenv eqs } instantiateFunDepEqns :: FunDepEqns -> TcM [TypeEqn] +-- See GHC.Tc.Instance.Fundeps Note [Improving against instances] +-- Wrinkle (IMP1) instantiateFunDepEqns (FDEqns { fd_qtvs = qtvs, fd_eqs = eqs }) | null qtvs = return rev_eqs @@ -1463,11 +1482,9 @@ instantiateFunDepEqns (FDEqns { fd_qtvs = qtvs, fd_eqs = eqs }) -- (reverse eqs): See Note [Reverse order of fundep equations] subst_pair subst (Pair ty1 ty2) - = Pair (substTy subst' ty1) (substTy subst' ty2) --- ToDo not correct! + = Pair (substTy subst' ty1) ty2 -- ty2 does not mention fd_qtvs, so no need to subst it. - -- See GHC.Tc.Instance.Fundeps Note [Improving against instances] - -- Wrinkle (IMP1) + -- See invariant on `fv_eqs` in `data FunDepEqns`. where subst' = extendSubstInScopeSet subst (tyCoVarsOfTypes [ty1,ty2]) -- The free vars of ty1 aren't just fd_qtvs: ty1 is the result ===================================== compiler/GHC/Tc/TyCl.hs ===================================== @@ -3462,7 +3462,7 @@ tcFamDecl1 parent (FamilyDecl { fdInfo = fam_info ; let mb_co_ax | null eqns = Nothing -- mkBranchedCoAxiom fails on empty list - | otherwise = Just (mkBranchedCoAxiom co_ax_name fam_tc branches) + | otherwise = Just (mkBranchedCoAxiom Nominal co_ax_name fam_tc branches) fam_tc = mkFamilyTyCon tc_name kind tc_bndrs 0 res_kind (resultVariableName sig) (ClosedTypeFamilyTyCon $ CTF mb_co_ax) parent inj' ===================================== testsuite/tests/indexed-types/should_compile/all.T ===================================== @@ -317,3 +317,4 @@ test('T25611c', normal, compile, ['']) test('T25611d', normal, compile, ['']) test('T25657', normal, compile, ['']) test('T27828', normal, compile, ['']) +test('T27828a', normal, compile, ['']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b9431ef21af13163fdfde045cd1f500… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b9431ef21af13163fdfde045cd1f500… You're receiving this email because of your account on gitlab.haskell.org. 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[Git][ghc/ghc] Pushed new branch wip/sjakobi/absent-filler-note
by Simon Jakobi (＠sjakobi) 24 Sep '26

24 Sep '26

Simon Jakobi pushed new branch wip/sjakobi/absent-filler-note at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/sjakobi/absent-filler-note You're receiving this email because of your account on gitlab.haskell.org. Manage all notifications: https://gitlab.haskell.org/-/profile/notifications | Help: https://gitlab.haskell.org/help

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