Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 4f2a21f7 by Andreas Klebinger at 2026-08-02T22:46:46-04:00 Apply oneShot Monad trick to STG LintM - - - - - 21e4b89d by Andreas Klebinger at 2026-08-02T22:46:46-04:00 stgLint: Use a single reader env for read only arguments. - - - - - d415f38a by Alan Zimmerman at 2026-08-02T22:47:27-04:00 EPA: Remove LocatedP from CType The next step of removing use of LocatedP by moving the AnnPragma for CType into its TTG extension point instead. - - - - - f663faf7 by Ben Gamari at 2026-08-03T14:03:56-04:00 base: Don't drop exception context in SomeException(toException) For reasons that are lost to time, the implementation of [CLC #200] that was merged inappropriately dropped `ExceptionContext` in the `toException` implementation given to `SomeException`. Fix this infelicity. [CLC #200]: https://github.com/haskell/core-libraries-committee/issues/200 - - - - - 19732024 by Simon Jakobi at 2026-08-03T14:03:58-04:00 testsuite: Expect length001 failure in nonmoving_thr_sanity length001 relies on an optimization rule to avoid excessive stack use. The nonmoving_thr_sanity way does not enable optimization, so classify its stack overflow as an expected failure, as is already done for the other unoptimized nonmoving ways. Assisted-by: gpt-5.6-sol via Codex CLI - - - - - 8eec1aa9 by Simon Jakobi at 2026-08-03T14:03:58-04:00 testsuite: Omit T22859 in nonmoving threaded ways T22859 checks allocation-limit handlers with output that depends on precise allocation behaviour. The nonmoving threaded ways change where these limits are reached, just as the already-omitted LLVM ways do. Omit these ways instead of treating their incidental output differences as test failures. Assisted-by: gpt-5.6-sol via Codex CLI - - - - - 2c6d8d0e by Simon Jakobi at 2026-08-03T14:03:58-04:00 testsuite: Make listThreads1 insensitive to the RTS's own threads listThreads1 expected `listThreads` to return exactly [ThreadId 1]. That holds only under a non-threaded RTS. Under a threaded RTS however there are more threads present, so we change the test to simply check that `myThreadId` is present in the list. Assisted-by: Claude Opus 5 - - - - - 15 changed files: - + changelog.d/T27455 - compiler/GHC/Hs/Decls.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Stg/Lint.hs - compiler/GHC/Types/ForeignCall.hs - libraries/base/changelog.md - libraries/base/tests/all.T - libraries/base/tests/listThreads1.hs - libraries/base/tests/listThreads1.stdout - libraries/ghc-internal/src/GHC/Internal/Exception/Type.hs - testsuite/tests/ghc-e/should_run/ghc-e005.stderr - testsuite/tests/rts/all.T - utils/check-exact/ExactPrint.hs - utils/haddock/haddock-api/src/Haddock/Types.hs Changes: ===================================== changelog.d/T27455 ===================================== @@ -0,0 +1,8 @@ +section: base +issues: #27455 +mrs: !16274 +synopsis: + Don't drop `ExceptionContext` in `SomeException(toException)` +description: + Previously the implementation of ``Exception(toException)`` given to `SomeException` would inappropriately drop the carried `ExceptionContext`. Now ``toException = id``, faithfully implementing the semantics proposed in :ref:`CLC Proposal #200 <https://github.com/haskell/core-libraries-committee/issues/200>`. + ===================================== compiler/GHC/Hs/Decls.hs ===================================== @@ -1583,7 +1583,7 @@ type instance Anno (FunDep (GhcPass p)) = SrcSpanAnnA type instance Anno (FamilyResultSig (GhcPass p)) = EpAnnCO type instance Anno (FamilyDecl (GhcPass p)) = SrcSpanAnnA type instance Anno (InjectivityAnn (GhcPass p)) = EpAnnCO -type instance Anno (CType (GhcPass p)) = SrcSpanAnnP +type instance Anno (CType (GhcPass p)) = SrcSpanAnnA type instance Anno (HsDerivingClause (GhcPass p)) = EpAnnCO type instance Anno (DerivClauseTys (GhcPass _)) = SrcSpanAnnA type instance Anno (StandaloneKindSig (GhcPass p)) = SrcSpanAnnA ===================================== compiler/GHC/Parser.y ===================================== @@ -1707,15 +1707,17 @@ datafam_inst_hdr :: { Located (Maybe (LHsContext GhcPs), HsOuterFamEqnTyVarBndrs | type { sL1 $1 (Nothing, mkHsOuterImplicit, $1) } -capi_ctype :: { Maybe (LocatedP (CType GhcPs)) } +capi_ctype :: { Maybe (LocatedA (CType GhcPs)) } capi_ctype : '{-# CTYPE' STRING STRING '#-}' - {% fmap Just $ amsr (sLL $1 $> (mkCType (getCTYPEs $1) (getSTRINGs $3) (Just (Header (getSTRINGs $2) (getSTRING $2))) - (getSTRING $3))) - (AnnPragma (glR $1) (epTok $4) noAnn (glR $2) (glR $3) noAnn noAnn) } + {% fmap Just $ amsA' (sLL $1 $> (mkCType (getCTYPEs $1) (getSTRINGs $3) + (AnnPragma (glR $1) (epTok $4) noAnn (glR $2) (glR $3) noAnn noAnn) + (Just (Header (getSTRINGs $2) (getSTRING $2))) + (getSTRING $3)))} | '{-# CTYPE' STRING '#-}' - {% fmap Just $ amsr (sLL $1 $> (mkCType (getCTYPEs $1) (getSTRINGs $2) Nothing (getSTRING $2))) - (AnnPragma (glR $1) (epTok $3) noAnn noAnn (glR $2) noAnn noAnn) } + {% fmap Just $ amsA' (sLL $1 $> (mkCType (getCTYPEs $1) (getSTRINGs $2) + (AnnPragma (glR $1) (epTok $3) noAnn noAnn (glR $2) noAnn noAnn) + Nothing (getSTRING $2)))} | { Nothing } ===================================== compiler/GHC/Parser/PostProcess.hs ===================================== @@ -229,7 +229,7 @@ mkClassDecl loc' (L _ (mcxt, tycl_hdr)) fds where_cls layout annsIn mkTyData :: SrcSpan -> Bool -> NewOrData - -> Maybe (LocatedP (CType GhcPs)) + -> Maybe (LocatedA (CType GhcPs)) -> Located (Maybe (LHsContext GhcPs), LHsType GhcPs) -> Maybe (LHsKind GhcPs) -> [LConDecl GhcPs] @@ -251,7 +251,7 @@ mkTyData loc' is_type_data new_or_data cType (L _ (mcxt, tycl_hdr)) tcdDataDefn = defn, tcdModifiers = [] })) } -mkDataDefn :: Maybe (LocatedP (CType GhcPs)) +mkDataDefn :: Maybe (LocatedA (CType GhcPs)) -> Maybe (LHsContext GhcPs) -> Maybe (LHsKind GhcPs) -> DataDefnCons (LConDecl GhcPs) @@ -326,7 +326,7 @@ mkTyFamInstEqn loc bndrs lhs rhs annEq mkDataFamInst :: SrcSpan -> NewOrData - -> Maybe (LocatedP (CType GhcPs)) + -> Maybe (LocatedA (CType GhcPs)) -> (Maybe ( LHsContext GhcPs), HsOuterFamEqnTyVarBndrs GhcPs , LHsType GhcPs) -> Maybe (LHsKind GhcPs) ===================================== compiler/GHC/Stg/Lint.hs ===================================== @@ -92,6 +92,7 @@ be ill-typed in Core. But it must still be well-kinded! -} {-# LANGUAGE TypeFamilies #-} +{-# LANGUAGE PatternSynonyms #-} module GHC.Stg.Lint ( lintStgTopBindings ) where @@ -123,6 +124,7 @@ import GHC.Unit.Module ( Module ) import GHC.Data.Bag ( Bag, emptyBag, isEmptyBag, snocBag, bagToList ) import Control.Monad +import GHC.Exts ( oneShot ) import GHC.Core.Multiplicity (scaledThing) import GHC.Settings (Platform) import GHC.Core.TyCon (primRepCompatible, primRepsCompatible) @@ -432,17 +434,40 @@ The Lint monad ************************************************************************ -} -newtype LintM a = LintM - { unLintM :: Module - -> LintFlags - -> DiagOpts -- Diagnostic options - -> StgPprOpts -- Pretty-printing options +data LintReaderEnv = LintReaderEnv + { le_mod :: !Module + , le_flags :: !LintFlags + , le_diag_opts :: !DiagOpts -- Diagnostic options + , le_ppr_opts :: !StgPprOpts -- Pretty-printing options + } + +newtype LintM a = LintM' + { unLintM :: LintReaderEnv -> [LintLocInfo] -- Locations -> IdSet -- Local vars in scope -> Bag SDoc -- Error messages so far -> (a, Bag SDoc) -- Result and error messages (if any) } - deriving (Functor) +instance Functor LintM where + fmap f (LintM m) = + LintM $ \env loc scope errs -> + case m env loc scope errs of + (a, errs') -> (f a, errs') + +-- See Note [The one-shot state monad trick] in GHC.Utils.Monad +{-# COMPLETE LintM #-} +pattern LintM :: (LintReaderEnv + -> [LintLocInfo] + -> IdSet + -> Bag SDoc + -> (a, Bag SDoc)) + -> LintM a +pattern LintM m <- LintM' m + where + LintM m = LintM' $ oneShot (\env -> oneShot + (\loc -> oneShot + (\scope -> oneShot + (\errs -> m env loc scope errs)))) data LintFlags = LintFlags { lf_unarised :: !Bool , lf_platform :: !Platform @@ -473,14 +498,16 @@ pp_binders bs initL :: Platform -> DiagOpts -> Module -> Bool -> StgPprOpts -> IdSet -> LintM a -> Maybe SDoc initL platform diag_opts this_mod unarised opts locals (LintM m) = do - let (_, errs) = m this_mod (LintFlags unarised platform) diag_opts opts [] locals emptyBag + let !flags = LintFlags unarised platform + !env = LintReaderEnv this_mod flags diag_opts opts + (_, errs) = m env [] locals emptyBag if isEmptyBag errs then Nothing else Just (vcat (punctuate blankLine (bagToList errs))) instance Applicative LintM where - pure a = LintM $ \_mod _lf _df _opts _loc _scope errs -> (a, errs) + pure a = LintM $ \_env _loc _scope errs -> (a, errs) (<*>) = ap (*>) = thenL_ @@ -489,14 +516,14 @@ instance Monad LintM where (>>) = (*>) thenL :: LintM a -> (a -> LintM b) -> LintM b -thenL m k = LintM $ \mod lf diag_opts opts loc scope errs - -> case unLintM m mod lf diag_opts opts loc scope errs of - (r, errs') -> unLintM (k r) mod lf diag_opts opts loc scope errs' +thenL m k = LintM $ \env loc scope errs + -> case unLintM m env loc scope errs of + (r, errs') -> unLintM (k r) env loc scope errs' thenL_ :: LintM a -> LintM b -> LintM b -thenL_ m k = LintM $ \mod lf diag_opts opts loc scope errs - -> case unLintM m mod lf diag_opts opts loc scope errs of - (_, errs') -> unLintM k mod lf diag_opts opts loc scope errs' +thenL_ m k = LintM $ \env loc scope errs + -> case unLintM m env loc scope errs of + (_, errs') -> unLintM k env loc scope errs' checkL :: Bool -> SDoc -> LintM () checkL True _ = return () @@ -525,7 +552,8 @@ checkPostUnariseId id id_ty = idType id addErrL :: SDoc -> LintM () -addErrL msg = LintM $ \_mod _lf df _opts loc _scope errs -> ((), addErr df errs msg loc) +addErrL msg = LintM $ \LintReaderEnv{le_diag_opts = df} loc _scope errs + -> ((), addErr df errs msg loc) addErr :: DiagOpts -> Bag SDoc -> SDoc -> [LintLocInfo] -> Bag SDoc addErr diag_opts errs_so_far msg locs @@ -537,23 +565,23 @@ addErr diag_opts errs_so_far msg locs mk_msg [] = msg addLoc :: LintLocInfo -> LintM a -> LintM a -addLoc extra_loc m = LintM $ \mod lf diag_opts opts loc scope errs - -> unLintM m mod lf diag_opts opts (extra_loc:loc) scope errs +addLoc extra_loc m = LintM $ \env loc scope errs + -> unLintM m env (extra_loc:loc) scope errs addInScopeVars :: [Id] -> LintM a -> LintM a -addInScopeVars ids m = LintM $ \mod lf diag_opts opts loc scope errs +addInScopeVars ids m = LintM $ \env loc scope errs -> let new_set = mkVarSet ids - in unLintM m mod lf diag_opts opts loc (scope `unionVarSet` new_set) errs + in unLintM m env loc (scope `unionVarSet` new_set) errs getLintFlags :: LintM LintFlags -getLintFlags = LintM $ \_mod lf _df _opts _loc _scope errs -> (lf, errs) +getLintFlags = LintM $ \LintReaderEnv{le_flags = lf} _loc _scope errs -> (lf, errs) getStgPprOpts :: LintM StgPprOpts -getStgPprOpts = LintM $ \_mod _lf _df opts _loc _scope errs -> (opts, errs) +getStgPprOpts = LintM $ \LintReaderEnv{le_ppr_opts = opts} _loc _scope errs -> (opts, errs) checkInScope :: Id -> LintM () -checkInScope id = LintM $ \mod _lf diag_opts _opts loc scope errs +checkInScope id = LintM $ \LintReaderEnv{le_mod = mod, le_diag_opts = diag_opts} loc scope errs -> if nameIsLocalOrFrom mod (idName id) && not (id `elemVarSet` scope) then ((), addErr diag_opts errs (hsep [ppr id, dcolon, ppr (idType id), text "is out of scope"]) loc) ===================================== compiler/GHC/Types/ForeignCall.hs ===================================== @@ -109,6 +109,7 @@ import Data.Data (Data) import Data.Functor ((<&>)) import Control.DeepSeq (NFData(..)) +import GHC.Parser.Annotation (AnnPragma, noAnn) {- ************************************************************************ @@ -213,11 +214,11 @@ instance Outputable CCallSpec where defaultCType :: String -> CType (GhcPass p) defaultCType = - CType (CTypeGhc NoSourceText NoSourceText) Nothing . packHText + CType (CTypeGhc NoSourceText NoSourceText noAnn) Nothing . packHText -mkCType :: SourceText -> SourceText -> Maybe (Header (GhcPass p)) -> HText -> CType (GhcPass p) -mkCType x y m = - CType (CTypeGhc x y) m +mkCType :: SourceText -> SourceText -> AnnPragma -> Maybe (Header (GhcPass p)) -> HText -> CType (GhcPass p) +mkCType x y ann m = + CType (CTypeGhc x y ann) m typeCheckCType :: CType GhcRn -> CType GhcTc typeCheckCType (CType x y z) = CType x (typeCheckHeader <$> y) z @@ -302,6 +303,7 @@ data StaticTargetGhc = StaticTargetGhc data CTypeGhc = CTypeGhc { cTypeSourceText :: SourceText , cTypeOtherText :: SourceText + , cTypeAnn :: AnnPragma } deriving (Data, Eq) @@ -349,6 +351,7 @@ instance Binary CTypeGhc where return $ CTypeGhc { cTypeSourceText = str1 , cTypeOtherText = str2 + , cTypeAnn = noAnn } instance NFData StaticTargetGhc where ===================================== libraries/base/changelog.md ===================================== @@ -38,6 +38,7 @@ * Show `ExceptionContext` in `displayExceptionAnnotation` implementation of `WhileHandling` ([GHC #27456](https://gitlab.haskell.org/ghc/ghc/-/issues/27456)) * Hide implementation details when throwing exceptions in throw and throwSTM. ([CLC proposal #387](https://github.com/haskell/core-libraries-committee/issues/387)) * Change `hIsReadable` and `hIsWritable` such that they always throw a respective exception when encountering a closed or semi-closed handle, not just in the case of a file handle. ([CLC proposal #371](github.com/haskell/core-libraries-committee/issues/371)) + * The implementation of `toException` in `SomeException`'s `Exception` instance no longer drops exception context, in keeping with the behavior originally proposed in [CLC Proposal #200](https://github.com/haskell/core-libraries-committee/issues/200). * Annotate `onException` continuation with `WhileHandling`. ([CLC Proposal #397](https://github.com/haskell/core-libraries-committee/issues/397)) * Improve error message for `Data.Char.chr`. ([CLC Proposal #384](https://github.com/haskell/core-libraries-committee/issues/384)) ===================================== libraries/base/tests/all.T ===================================== @@ -80,7 +80,7 @@ test('length001', # excessive amounts of stack space. So we specifically set a low # stack limit and mark it as failing under a few conditions. [extra_run_opts('+RTS -K8m -RTS'), - expect_fail_for(['normal', 'threaded1', 'llvm', 'nonmoving', 'nonmoving_thr', 'nonmoving_thr_ghc', 'ext-interp']), + expect_fail_for(['normal', 'threaded1', 'llvm', 'nonmoving', 'nonmoving_thr', 'nonmoving_thr_sanity', 'nonmoving_thr_ghc', 'ext-interp']), # JS doesn't support stack limit so the test sometimes passes just fine. Therefore the test is # marked as fragile. when(js_arch(), fragile(22921))], ===================================== libraries/base/tests/listThreads1.hs ===================================== @@ -2,5 +2,10 @@ module Main where import GHC.Conc.Sync +-- Regression test for the JS backend's ListThreadsOp, which used to omit the +-- running thread. Whatever other threads the RTS has is irrelevant here. main :: IO () -main = listThreads >>= print +main = do + tid <- myThreadId + ts <- listThreads + print (tid `elem` ts) ===================================== libraries/base/tests/listThreads1.stdout ===================================== @@ -1 +1 @@ -[ThreadId 1] +True ===================================== libraries/ghc-internal/src/GHC/Internal/Exception/Type.hs ===================================== @@ -55,7 +55,7 @@ import GHC.Internal.Data.Maybe import GHC.Internal.Data.Typeable (Typeable, TypeRep, cast) import qualified GHC.Internal.Data.Typeable as Typeable -- loop: GHC.Internal.Data.Typeable -> GHC.Internal.Err -> GHC.Internal.Exception -import GHC.Internal.Base (String, Void, fmap, return, ($), (.), (++)) +import GHC.Internal.Base (String, Void, fmap, return, ($), (.), (++), id) import GHC.Internal.Show import GHC.Internal.Types (Bool(..)) import GHC.Internal.Exception.Context @@ -208,7 +208,16 @@ Caught MismatchedParentheses -} class (Typeable e, Show e) => Exception e where - -- | @toException@ should produce a 'SomeException' with no attached 'ExceptionContext'. + -- | 'toException' converts an exception into the existential 'SomeException' + -- wrapper type. + -- + -- In doing so, 'toException' should not /add/ an 'ExceptionContext'. + -- + -- - In most cases, the exception does not store its own 'ExceptionContext'. + -- The default implementation of 'toException' (which does not store any + -- 'ExceptionContext') is suitable for these cases. + -- - In the rare case that the exception itself stores an 'ExceptionContext', + -- this context should be preserved by 'toException'. toException :: e -> SomeException fromException :: SomeException -> Maybe e @@ -231,13 +240,11 @@ class (Typeable e, Show e) => Exception e where -- | @since base-4.8.0.0 instance Exception Void --- | This drops any attached 'ExceptionContext'. +-- | NB: this instance preserves the attached 'ExceptionContext'. -- -- @since base-3.0 instance Exception SomeException where - toException (SomeException e) = - let ?exceptionContext = emptyExceptionContext - in SomeException e + toException = id fromException = Just backtraceDesired (SomeException e) = backtraceDesired e displayException (SomeException e) = displayException e ===================================== testsuite/tests/ghc-e/should_run/ghc-e005.stderr ===================================== @@ -4,3 +4,8 @@ foo HasCallStack backtrace: error, called at ghc-e005.hs:12:10 in main:Main + + +HasCallStack backtrace: + throwIO, called at ghc\GHCi\UI.hs:1655:31 in ghc-bin-10.1.20260629-inplace:GHCi.UI + ===================================== testsuite/tests/rts/all.T ===================================== @@ -679,7 +679,7 @@ test('T22859', [js_skip, # This test is vulnerable to changes in allocation behaviour, so we disable it in some ways when(arch('wasm32'), skip), - omit_ways(llvm_ways)], + omit_ways(llvm_ways + ['nonmoving_thr', 'nonmoving_thr_sanity'])], compile_and_run, ['-with-rtsopts -A8K']) # These tests need access to the internal RTS headers. ===================================== utils/check-exact/ExactPrint.hs ===================================== @@ -4401,13 +4401,14 @@ instance ExactPrint t => ExactPrint (HsModifierOf t GhcPs) where -- --------------------------------------------------------------------- -instance Typeable p => ExactPrint (LocatedP (CType (GhcPass p))) where - getAnnotationEntry = entryFromLocatedA - setAnnotationAnchor = setAnchorAn +instance Typeable p => ExactPrint (CType (GhcPass p)) where + getAnnotationEntry _ = NoEntryVal + setAnnotationAnchor a _ _ _ = a - exact (L (EpAnn l (AnnPragma o c s l1 l2 t m) cs) (CType ext mh ct)) = do + exact (CType ext mh ct) = do let stp = cTypeSourceText ext stct = cTypeOtherText ext + AnnPragma o c s l1 l2 t m = cTypeAnn ext o' <- markAnnOpen'' o stp "{-# CTYPE" l1' <- case mh of Nothing -> return l1 @@ -4415,7 +4416,7 @@ instance Typeable p => ExactPrint (LocatedP (CType (GhcPass p))) where printStringAtAA l1 (toSourceTextWithSuffix srcH "" "") l2' <- printStringAtAA l2 (toSourceTextWithSuffix stct (unpackHText ct) "") c' <- markEpToken c - return (L (EpAnn l (AnnPragma o' c' s l1' l2' t m) cs) (CType ext mh ct)) + return (CType (ext { cTypeAnn = AnnPragma o' c' s l1' l2' t m }) mh ct) -- --------------------------------------------------------------------- ===================================== utils/haddock/haddock-api/src/Haddock/Types.hs ===================================== @@ -837,7 +837,7 @@ type instance Anno (HsOuterTyVarBndrs Specificity DocNameI) = SrcSpanAnnA type instance Anno (HsSigType DocNameI) = SrcSpanAnnA type instance Anno (BooleanFormula DocNameI) = SrcSpanAnnBF type instance Anno (OverlapMode DocNameI) = SrcSpanAnnA -type instance Anno (CType DocNameI) = EpAnn AnnPragma +type instance Anno (CType DocNameI) = SrcSpanAnnA type instance Anno (Header DocNameI) = EpAnn AnnPragma type instance Anno (HsModifierOf (LocatedA (HsType DocNameI)) DocNameI) = SrcSpanAnnA type instance Anno (HsContextDetails DocNameI a) = SrcSpanAnnA View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/66c5544e50fd7657e1cf22b0a55d781... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/66c5544e50fd7657e1cf22b0a55d781... 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