June 2026 - ghc-commits

[Git][ghc/ghc][wip/fendor/no-code-output-constr] Improve by-design documentation of backendCodeOutput
by Rodrigo Mesquita (＠alt-romes) 24 Jun '26

24 Jun '26

Rodrigo Mesquita pushed to branch wip/fendor/no-code-output-constr at Glasgow Haskell Compiler / GHC Commits: 2b3ffb19 by Rodrigo Mesquita at 2026-06-24T16:05:48+01:00 Improve by-design documentation of backendCodeOutput `Backend` is **abstract by design**. Make this clearer in `backendCodeOutput` which is incorrectly being used as a proxy for `Backend`. Instead, define the desired property predicates in GHC.Driver.Backend In the process, make `backendCodeOutput` total. - - - - - 5 changed files: - compiler/GHC/Driver/Backend.hs - compiler/GHC/Driver/CodeOutput.hs - compiler/GHC/Driver/Main/Compile.hs - compiler/GHC/Driver/Pipeline.hs - compiler/GHC/Driver/Session.hs Changes: ===================================== compiler/GHC/Driver/Backend.hs ===================================== @@ -118,7 +118,6 @@ import GHC.Driver.Phases import GHC.Utils.Error -import GHC.Utils.Panic import GHC.Driver.Pipeline.Monad import GHC.Platform @@ -369,7 +368,8 @@ data PrimitiveImplementation -- We expect one function per back end—or more precisely, one function -- for each back end that writes code to a file. (The interpreter -- does not write to files; its output lives only in memory.) - +-- +-- See Note [Backend Defunctionalization] data DefunctionalizedCodeOutput = NcgCodeOutput | ViaCCodeOutput @@ -779,20 +779,33 @@ backendCDefs (Named NoBackend) = NoCDefs -- > -> Set UnitId -- ^ dependencies -- > -> Stream IO RawCmmGroup a -- results from `StgToCmm` -- > -> IO a -backendCodeOutput :: Backend -> DefunctionalizedCodeOutput -backendCodeOutput (Named NCG) = NcgCodeOutput -backendCodeOutput (Named LLVM) = LlvmCodeOutput -backendCodeOutput (Named ViaC) = ViaCCodeOutput -backendCodeOutput (Named JavaScript) = JSCodeOutput -backendCodeOutput (Named Bytecode) = panic "backendCodeOutput: bytecodeBackend" -backendCodeOutput (Named NoBackend) = panic "backendCodeOutput: noBackend" +-- +-- See Note [Backend Defunctionalization] +-- +-- === __WARNING__ +-- +-- Do NOT use 'backendCodeOutput' (or other functions in this module) as a +-- proxy for the 'Backend', which is __abstract by design__. +-- +-- If you need to determine some property of the backend, do NOT match on +-- 'DefunctionalizedCodeOutput'; Instead, write a new property predicate in +-- this module. This makes it easier to add new backends because essentially +-- all backend properties depended upon throughout the compiler are all found +-- here. +backendCodeOutput :: Backend -> Maybe DefunctionalizedCodeOutput +backendCodeOutput (Named NCG) = Just NcgCodeOutput +backendCodeOutput (Named LLVM) = Just LlvmCodeOutput +backendCodeOutput (Named ViaC) = Just ViaCCodeOutput +backendCodeOutput (Named JavaScript) = Just JSCodeOutput +backendCodeOutput (Named Bytecode) = Nothing +backendCodeOutput (Named NoBackend) = Nothing backendUseJSLinker :: Backend -> Bool backendUseJSLinker (Named NCG) = False backendUseJSLinker (Named LLVM) = False backendUseJSLinker (Named ViaC) = False backendUseJSLinker (Named JavaScript) = True -backendUseJSLinker (Named Bytecode) = False +backendUseJSLinker (Named Bytecode) = False backendUseJSLinker (Named NoBackend) = False -- | This (defunctionalized) function tells the compiler ===================================== compiler/GHC/Driver/CodeOutput.hs ===================================== @@ -4,7 +4,6 @@ \section{Code output phase} -} - module GHC.Driver.CodeOutput ( codeOutput , outputForeignStubs @@ -50,7 +49,7 @@ import GHC.Utils.Outputable import GHC.Utils.Logger import GHC.Utils.Exception ( bracket ) import GHC.Utils.Ppr (Mode(..)) -import GHC.Utils.Panic.Plain ( pgmError ) +import GHC.Utils.Panic.Plain ( panic, pgmError ) import GHC.Unit import GHC.Unit.Finder ( mkStubPaths ) @@ -63,7 +62,6 @@ import GHC.Types.Unique.Supply ( UniqueTag(..) ) import System.IO import Data.Set (Set) import qualified Data.Set as Set -import GHC.Plugins (panic) {- ************************************************************************ @@ -125,11 +123,12 @@ codeOutput logger tmpfs llvm_config dflags unit_state this_mod filenm location g ; let dus1 = newTagDUniqSupply CodeGenTag dus0 ; (stubs, a) <- case backendCodeOutput (backend dflags) of - NcgCodeOutput -> outputAsm logger dflags this_mod location filenm dus1 - final_stream - ViaCCodeOutput -> outputC logger dflags filenm dus1 final_stream pkg_deps - LlvmCodeOutput -> outputLlvm logger llvm_config dflags filenm dus1 final_stream - JSCodeOutput -> outputJS logger llvm_config dflags filenm final_stream + Just NcgCodeOutput -> outputAsm logger dflags this_mod location filenm dus1 + final_stream + Just ViaCCodeOutput -> outputC logger dflags filenm dus1 final_stream pkg_deps + Just LlvmCodeOutput -> outputLlvm logger llvm_config dflags filenm dus1 final_stream + Just JSCodeOutput -> outputJS logger llvm_config dflags filenm final_stream + Nothing -> panic $ "backendCodeOutput: " ++ show (backend dflags) ++ " doesn't support code output" ; stubs_exist <- outputForeignStubs logger tmpfs dflags unit_state this_mod location stubs ; return (filenm, stubs_exist, foreign_fps, a) } ===================================== compiler/GHC/Driver/Main/Compile.hs ===================================== @@ -2,6 +2,7 @@ {-# LANGUAGE MultiWayIf #-} {-# OPTIONS_GHC -fprof-auto-top #-} +{-# OPTIONS_GHC -Wno-x-backend #-} -- we do use backendCodeOutput for defunctionalization ------------------------------------------------------------------------------- -- @@ -670,7 +671,7 @@ hscGenHardCode hsc_env cgguts mod_loc output_filename = do -- next withTiming after this will be "Assembler" (hard code only). withTiming logger (text "CodeGen"<+>brackets (ppr this_mod)) (const ()) $ case backendCodeOutput (backend dflags) of - JSCodeOutput -> + Just JSCodeOutput -> do let js_config = initStgToJSConfig dflags @@ -696,7 +697,7 @@ hscGenHardCode hsc_env cgguts mod_loc output_filename = do stgToJS logger js_config stg_binds this_mod spt_entries foreign_stubs0 cost_centre_info output_filename return (output_filename, stub_c_exists, foreign_fps, Just stg_cg_infos, Just cmm_cg_infos) - _ -> + Just _ -> do cmms <- {-# SCC "StgToCmm" #-} doCodeGen hsc_env this_mod denv tycons @@ -724,6 +725,7 @@ hscGenHardCode hsc_env cgguts mod_loc output_filename = do foreign_stubs foreign_files dependencies (initDUniqSupply 'n' 0) rawcmms1 return ( output_filename, stub_c_exists, foreign_fps , Just stg_cg_infos, Just cmm_cg_infos) + Nothing -> panic $ "backendCodeOutput: " ++ show (backend dflags) ++ " doesn't support code output" -- The part of CgGuts that we need for HscInteractive ===================================== compiler/GHC/Driver/Pipeline.hs ===================================== @@ -743,7 +743,7 @@ compileEmptyStub dflags hsc_env basename location mod_name = do let home_unit = hsc_home_unit hsc_env case backendCodeOutput (backend dflags) of - JSCodeOutput -> do + Just JSCodeOutput -> do empty_stub <- newTempName logger tmpfs (tmpDir dflags) TFL_CurrentModule "js" let src = ppr (mkHomeModule home_unit mod_name) <+> text "= 0;" writeFile empty_stub (showSDoc dflags (pprCode src)) @@ -752,7 +752,7 @@ compileEmptyStub dflags hsc_env basename location mod_name = do _ <- runPipeline (hsc_hooks hsc_env) pipeline pure () - _ -> do + Just _ -> do empty_stub <- newTempName logger tmpfs (tmpDir dflags) TFL_CurrentModule "c" let src = text "int" <+> ppr (mkHomeModule home_unit mod_name) <+> text "= 0;" writeFile empty_stub (showSDoc dflags (pprCode src)) @@ -760,6 +760,7 @@ compileEmptyStub dflags hsc_env basename location mod_name = do pipeline = viaCPipeline HCc pipe_env hsc_env (Just location) empty_stub _ <- runPipeline (hsc_hooks hsc_env) pipeline pure () + Nothing -> panic $ "backendCodeOutput: " ++ show (backend dflags) ++ " doesn't support code output" ===================================== compiler/GHC/Driver/Session.hs ===================================== @@ -3856,8 +3856,8 @@ makeDynFlagsConsistent dflags && os == OSMinGW32 && arch == ArchAArch64 = case backendCodeOutput (backend dflags) of - LlvmCodeOutput -> pgmError "-fllvm is incompatible with enabled TablesNextToCode at Windows Aarch64" - NcgCodeOutput -> pgmError "-fasm is incompatible with enabled TablesNextToCode at Windows Aarch64" + Just LlvmCodeOutput -> pgmError "-fllvm is incompatible with enabled TablesNextToCode at Windows Aarch64" + Just NcgCodeOutput -> pgmError "-fasm is incompatible with enabled TablesNextToCode at Windows Aarch64" _ -> (dflags, mempty, mempty) -- When we do ghci, force using dyn ways if the target RTS linker View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/2b3ffb19c154d5b2a72e57698296e64… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/2b3ffb19c154d5b2a72e57698296e64… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc] Pushed new branch wip/mangoiv/9.12.5-rc3-fixes
by Magnus (＠MangoIV) 24 Jun '26

24 Jun '26

Magnus pushed new branch wip/mangoiv/9.12.5-rc3-fixes at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/wip/mangoiv/9.12.5-rc3-fixes You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/fendor/no-code-output-constr] 2 commits: Add 'backendSupportsInfoTableMap' backend predicate
by Hannes Siebenhandl (＠fendor) 24 Jun '26

24 Jun '26

Hannes Siebenhandl pushed to branch wip/fendor/no-code-output-constr at Glasgow Haskell Compiler / GHC Commits: 046418ca by fendor at 2026-06-24T16:16:50+02:00 Add 'backendSupportsInfoTableMap' backend predicate Check whether the backend supports the `-finfo-table-map` flag and ignore it otherwise. - - - - - 61d935d3 by Matthew Pickering at 2026-06-24T16:16:50+02:00 Add failing test for `-finfo-table-map` and bytecode backend If you compile a module using the bytecode backend, with -finfo-table-map, then the info table map doesn't get populated for the module. This is because the -finfo-table-map code path is implemented mostly in the StgToCmm phase which isn't run when creating bytecode. Ticket #27039 - - - - - 7 changed files: - compiler/GHC/Driver/Backend.hs - compiler/GHC/Driver/CodeOutput.hs - compiler/GHC/Driver/Session.hs - testsuite/tests/ghci/scripts/all.T - + testsuite/tests/ghci/scripts/bytecodeIPE.hs - + testsuite/tests/ghci/scripts/bytecodeIPE.script - + testsuite/tests/ghci/scripts/bytecodeIPE.stdout Changes: ===================================== compiler/GHC/Driver/Backend.hs ===================================== @@ -99,6 +99,7 @@ module GHC.Driver.Backend , backendPostHscPipeline , backendNormalSuccessorPhase , backendName + , backendSupportsInfoTableMap , backendValidityOfCImport , backendValidityOfCExport @@ -680,6 +681,16 @@ backendSupportsBreakpoints = \case Named Bytecode -> True Named NoBackend -> False +-- | If this flag is unset, then the driver ignores the flag @-finfo-table-map@, +-- since the backend doesn't support generating the info table map. +backendSupportsInfoTableMap :: Backend -> Bool +backendSupportsInfoTableMap (Named NCG) = True +backendSupportsInfoTableMap (Named LLVM) = False +backendSupportsInfoTableMap (Named ViaC) = True +backendSupportsInfoTableMap (Named JavaScript) = False +backendSupportsInfoTableMap (Named Bytecode) = False +backendSupportsInfoTableMap (Named NoBackend) = True -- We are not generating code, so we ignore it any way + -- | If this flag is set, then the driver forces the -- optimization level to 0, issuing a warning message if -- the command line requested a higher optimization level. ===================================== compiler/GHC/Driver/CodeOutput.hs ===================================== @@ -63,6 +63,7 @@ import GHC.Types.Unique.Supply ( UniqueTag(..) ) import System.IO import Data.Set (Set) import qualified Data.Set as Set +import GHC.Plugins (panic) {- ************************************************************************ ===================================== compiler/GHC/Driver/Session.hs ===================================== @@ -3903,9 +3903,9 @@ makeDynFlagsConsistent dflags in dflags_c | gopt Opt_InfoTableMap dflags - , LlvmCodeOutput <- backendCodeOutput (backend dflags) + , backendSupportsInfoTableMap (backend dflags) = loop (gopt_unset dflags Opt_InfoTableMap) - "-finfo-table-map is incompatible with -fllvm and is disabled (See #26435)" + $ "-finfo-table-map is incompatible with " ++ show (backend dflags) ++ " and is disabled (See #26435)" | otherwise = (dflags, mempty, mempty) where loc = mkGeneralSrcSpan (fsLit "when making flags consistent") ===================================== testsuite/tests/ghci/scripts/all.T ===================================== @@ -385,6 +385,14 @@ test('ListTuplePunsPpr', normal, ghci_script, ['ListTuplePunsPpr.script']) test('ListTuplePunsPprNoAbbrevTuple', [limit_stdout_lines(14)], ghci_script, ['ListTuplePunsPprNoAbbrevTuple.script']) test('T24459', normal, ghci_script, ['T24459.script']) test('T24632', normal, ghci_script, ['T24632.script']) +# bytecode backend doesn't support '-finfo-table-map' (#27039) +test('bytecodeIPE', + [ extra_hc_opts('-finfo-table-map') + , extra_files(['bytecodeIPE.hs']) + , req_rts_linker + , when(arch('wasm32') or arch('javascript'), skip) + ], + ghci_script, ['bytecodeIPE.script']) # Test package renaming in GHCi session test('GhciPackageRename', ===================================== testsuite/tests/ghci/scripts/bytecodeIPE.hs ===================================== @@ -0,0 +1,12 @@ +module BytecodeIPE where + +import Data.Maybe (isJust) +import GHC.InfoProv (whereFrom) + +marker :: String +marker = id "bytecode-stub-init" +{-# NOINLINE marker #-} + +-- `whereFrom` only succeeds if the module's IPE initializer ran. +probe :: IO Bool +probe = isJust <$> whereFrom marker ===================================== testsuite/tests/ghci/scripts/bytecodeIPE.script ===================================== @@ -0,0 +1,2 @@ +:load bytecodeIPE.hs +probe ===================================== testsuite/tests/ghci/scripts/bytecodeIPE.stdout ===================================== @@ -0,0 +1 @@ +False View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/fe056b958602665057dc101c57627b… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/fe056b958602665057dc101c57627b… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/fendor/no-code-output-constr] 2 commits: Add 'backendSupportsInfoTableMap' backend predicate
by Hannes Siebenhandl (＠fendor) 24 Jun '26

24 Jun '26

Hannes Siebenhandl pushed to branch wip/fendor/no-code-output-constr at Glasgow Haskell Compiler / GHC Commits: 7cd7dbf8 by fendor at 2026-06-24T16:10:06+02:00 Add 'backendSupportsInfoTableMap' backend predicate Check whether the backend supports the `-finfo-table-map` flag and ignore it otherwise. - - - - - fe056b95 by Matthew Pickering at 2026-06-24T16:11:29+02:00 Add failing test for `-finfo-table-map` and bytecode backend If you compile a module using the bytecode backend, with -finfo-table-map, then the info table map doesn't get populated for the module. This is because the -finfo-table-map code path is implemented mostly in the StgToCmm phase which isn't run when creating bytecode. Ticket #27039 - - - - - 7 changed files: - compiler/GHC/Driver/Backend.hs - compiler/GHC/Driver/CodeOutput.hs - compiler/GHC/Driver/Session.hs - testsuite/tests/ghci/scripts/all.T - + testsuite/tests/ghci/scripts/bytecodeIPE.hs - + testsuite/tests/ghci/scripts/bytecodeIPE.script - + testsuite/tests/ghci/scripts/bytecodeIPE.stdout Changes: ===================================== compiler/GHC/Driver/Backend.hs ===================================== @@ -99,6 +99,7 @@ module GHC.Driver.Backend , backendPostHscPipeline , backendNormalSuccessorPhase , backendName + , backendSupportsInfoTableMap , backendValidityOfCImport , backendValidityOfCExport @@ -680,6 +681,16 @@ backendSupportsBreakpoints = \case Named Bytecode -> True Named NoBackend -> False +-- | If this flag is unset, then the driver ignores the flag @-finfo-table-map@, +-- since the backend doesn't support generating the info table map. +backendSupportsInfoTableMap :: Backend -> Bool +backendSupportsInfoTableMap (Named NCG) = True +backendSupportsInfoTableMap (Named LLVM) = False +backendSupportsInfoTableMap (Named ViaC) = True +backendSupportsInfoTableMap (Named JavaScript) = False +backendSupportsInfoTableMap (Named Bytecode) = False +backendSupportsInfoTableMap (Named NoBackend) = True -- We are not generating code, so we ignore it any way + -- | If this flag is set, then the driver forces the -- optimization level to 0, issuing a warning message if -- the command line requested a higher optimization level. ===================================== compiler/GHC/Driver/CodeOutput.hs ===================================== @@ -63,6 +63,7 @@ import GHC.Types.Unique.Supply ( UniqueTag(..) ) import System.IO import Data.Set (Set) import qualified Data.Set as Set +import GHC.Plugins (panic) {- ************************************************************************ ===================================== compiler/GHC/Driver/Session.hs ===================================== @@ -3903,7 +3903,7 @@ makeDynFlagsConsistent dflags in dflags_c | gopt Opt_InfoTableMap dflags - , LlvmCodeOutput <- backendCodeOutput (backend dflags) + , backendSupportsInfoTableMap (backend dflags) = loop (gopt_unset dflags Opt_InfoTableMap) "-finfo-table-map is incompatible with -fllvm and is disabled (See #26435)" ===================================== testsuite/tests/ghci/scripts/all.T ===================================== @@ -385,6 +385,14 @@ test('ListTuplePunsPpr', normal, ghci_script, ['ListTuplePunsPpr.script']) test('ListTuplePunsPprNoAbbrevTuple', [limit_stdout_lines(14)], ghci_script, ['ListTuplePunsPprNoAbbrevTuple.script']) test('T24459', normal, ghci_script, ['T24459.script']) test('T24632', normal, ghci_script, ['T24632.script']) +# bytecode backend doesn't support '-finfo-table-map' (#27039) +test('bytecodeIPE', + [ extra_hc_opts('-finfo-table-map') + , extra_files(['bytecodeIPE.hs']) + , req_rts_linker + , when(arch('wasm32') or arch('javascript'), skip) + ], + ghci_script, ['bytecodeIPE.script']) # Test package renaming in GHCi session test('GhciPackageRename', ===================================== testsuite/tests/ghci/scripts/bytecodeIPE.hs ===================================== @@ -0,0 +1,12 @@ +module BytecodeIPE where + +import Data.Maybe (isJust) +import GHC.InfoProv (whereFrom) + +marker :: String +marker = id "bytecode-stub-init" +{-# NOINLINE marker #-} + +-- `whereFrom` only succeeds if the module's IPE initializer ran. +probe :: IO Bool +probe = isJust <$> whereFrom marker ===================================== testsuite/tests/ghci/scripts/bytecodeIPE.script ===================================== @@ -0,0 +1,2 @@ +:load bytecodeIPE.hs +probe ===================================== testsuite/tests/ghci/scripts/bytecodeIPE.stdout ===================================== @@ -0,0 +1 @@ +False View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/04d9678420774db5ce14ff67fa40dc… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/04d9678420774db5ce14ff67fa40dc… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/marge_bot_batch_merge_job] 4 commits: compiler: refactor error reporting code for ExplicitLevelImports
by Marge Bot (＠marge-bot) 24 Jun '26

24 Jun '26

Marge Bot pushed to branch wip/marge_bot_batch_merge_job at Glasgow Haskell Compiler / GHC Commits: 89526177 by mangoiv at 2026-06-24T09:59:20-04:00 compiler: refactor error reporting code for ExplicitLevelImports Refactors error reporting code for ExplicitLevelImports to pass in a RdrName and a GlobalReaderElt to be able to report errors that are faithful to the source and to more precisely distinguish between names that are in scope from different qualifications. Fixes #27385 and #26616 - - - - - 8a195215 by Simon Hengel at 2026-06-24T09:59:22-04:00 Set GHC_VERSION when calling custom pre-processors (see #25952) (so that pre-processors can emit backwards compatible code) - - - - - 72727259 by Simon Hengel at 2026-06-24T09:59:23-04:00 Add a flag to control GHCi specific error hints (close #27409) - - - - - a0f24c8e by Simon Hengel at 2026-06-24T09:59:24-04:00 Reference correct package in error messages for reexported modules (fixes #27417) - - - - - 89 changed files: - + changelog.d/26616 - + changelog.d/interactive-error-hints - + changelog.d/pp-set-ghc-version - + changelog.d/reexported-module-errors - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/Driver/Flags.hs - compiler/GHC/Driver/Session.hs - compiler/GHC/Hs/Expr.hs - compiler/GHC/Iface/Errors.hs - compiler/GHC/Iface/Errors/Ppr.hs - compiler/GHC/Iface/Errors/Types.hs - compiler/GHC/Rename/Env.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/HsType.hs - compiler/GHC/Rename/Module.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/Rename/Splice.hs - compiler/GHC/Rename/Splice.hs-boot - compiler/GHC/Rename/Unbound.hs - compiler/GHC/SysTools/Tasks.hs - compiler/GHC/Tc/Errors.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/Export.hs - compiler/GHC/Tc/Utils/Env.hs - compiler/GHC/Tc/Utils/Monad.hs - compiler/GHC/Types/Hint/Ppr.hs - compiler/GHC/Types/Name/Reader.hs - compiler/GHC/Unit/Finder.hs - compiler/GHC/Unit/Finder/Types.hs - compiler/GHC/Unit/State.hs - compiler/GHC/Utils/Outputable.hs - docs/users_guide/ghci.rst - docs/users_guide/phases.rst - ghc/GHCi/UI/Exception.hs - ghc/Main.hs - testsuite/tests/annotations/should_fail/annfail03.stderr - testsuite/tests/annotations/should_fail/annfail04.stderr - testsuite/tests/annotations/should_fail/annfail06.stderr - testsuite/tests/annotations/should_fail/annfail09.stderr - testsuite/tests/ghci/prog-mhu002/prog-mhu002c.stdout - testsuite/tests/ghci/scripts/ghci024.stdout - testsuite/tests/ghci/scripts/ghci024.stdout-mingw32 - + testsuite/tests/package/ImportReexport.hs - + testsuite/tests/package/ImportReexport.stderr - testsuite/tests/package/all.T - testsuite/tests/quasiquotation/qq001/qq001.stderr - testsuite/tests/quasiquotation/qq002/qq002.stderr - testsuite/tests/quasiquotation/qq003/qq003.stderr - testsuite/tests/quasiquotation/qq004/qq004.stderr - testsuite/tests/quotes/LiftErrMsg.stderr - testsuite/tests/quotes/LiftErrMsgDefer.stderr - testsuite/tests/quotes/LiftErrMsgTyped.stderr - testsuite/tests/quotes/T10384.stderr - testsuite/tests/quotes/T5721.stderr - testsuite/tests/quotes/TH_localname.stderr - testsuite/tests/splice-imports/SI03.stderr - testsuite/tests/splice-imports/SI05.stderr - testsuite/tests/splice-imports/SI08.stderr - testsuite/tests/splice-imports/SI08_oneshot.stderr - testsuite/tests/splice-imports/SI16.stderr - testsuite/tests/splice-imports/SI18.stderr - testsuite/tests/splice-imports/SI20.stderr - testsuite/tests/splice-imports/SI25.stderr - testsuite/tests/splice-imports/SI28.stderr - testsuite/tests/splice-imports/SI29.stderr - testsuite/tests/splice-imports/SI31.stderr - testsuite/tests/splice-imports/SI36.stderr - testsuite/tests/splice-imports/T26088.stderr - testsuite/tests/splice-imports/T26090.stderr - + testsuite/tests/splice-imports/T26616.hs - + testsuite/tests/splice-imports/T26616.stderr - testsuite/tests/splice-imports/all.T - testsuite/tests/th/T16976z.stderr - testsuite/tests/th/T17820a.stderr - testsuite/tests/th/T17820b.stderr - testsuite/tests/th/T17820c.stderr - testsuite/tests/th/T17820d.stderr - testsuite/tests/th/T17820e.stderr - testsuite/tests/th/T21547.stderr - testsuite/tests/th/T23829_hasty.stderr - testsuite/tests/th/T23829_hasty_b.stderr - testsuite/tests/th/T23829_tardy.ghc.stderr - testsuite/tests/th/T26098_local.stderr - testsuite/tests/th/T26098_quote.stderr - testsuite/tests/th/T26098_splice.stderr - testsuite/tests/th/T26099.stderr - testsuite/tests/th/T26568.stderr - testsuite/tests/th/T5795.stderr The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/6d436d9c7bbd288f70db91db1b8be5… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/6d436d9c7bbd288f70db91db1b8be5… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc] Deleted branch wip/sol/warning-flags
by Simon Hengel (＠sol) 24 Jun '26

24 Jun '26

Simon Hengel deleted branch wip/sol/warning-flags at Glasgow Haskell Compiler / GHC -- You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc] Pushed new tag ghc-9.12.5-rc2
by Magnus (＠MangoIV) 24 Jun '26

24 Jun '26

Magnus pushed new tag ghc-9.12.5-rc2 at Glasgow Haskell Compiler / GHC -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/tree/ghc-9.12.5-rc2 You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/sjakobi/lazy-field-anns] Add -XLazyFieldAnnotations
by Simon Jakobi (＠sjakobi2) 24 Jun '26

24 Jun '26

Simon Jakobi pushed to branch wip/sjakobi/lazy-field-anns at Glasgow Haskell Compiler / GHC Commits: 19e0f321 by Simon Jakobi at 2026-06-24T13:57:54+02:00 Add -XLazyFieldAnnotations Unbundle the prefix `~` lazy field annotation syntax from StrictData. The new LazyFieldAnnotations extension controls only whether `~` is accepted on data and GADT constructor fields; StrictData (and hence Strict) implies it but continues to own the default strictness of unannotated fields. This lets hand-written and generated code write an explicit lazy annotation without flipping the module-wide default. The validity check in checkValidDataCon now keys off LazyFieldAnnotations instead of StrictData. Implements GHC proposal 752 (https://github.com/ghc-proposals/ghc-proposals/pull/752) Closes #24455. Co-Authored-By: Claude Opus 4.8 <noreply(a)anthropic.com> - - - - - 16 changed files: - + changelog.d/lazy-field-annotations - compiler/GHC/Driver/Flags.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/TyCl.hs - docs/users_guide/exts/strict.rst - libraries/ghc-internal/src/GHC/Internal/LanguageExtensions.hs - + testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.hs - + testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.stdout - testsuite/tests/deSugar/should_run/all.T - + testsuite/tests/typecheck/should_compile/LazyFieldAnnotations.hs - testsuite/tests/typecheck/should_compile/all.T - testsuite/tests/typecheck/should_fail/LazyFieldsDisabled.stderr - + testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.hs - + testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.stderr - testsuite/tests/typecheck/should_fail/all.T Changes: ===================================== changelog.d/lazy-field-annotations ===================================== @@ -0,0 +1,12 @@ +section: language +synopsis: Add the `LazyFieldAnnotations` extension +issues: #24455 +mrs: !16246 + +description: { + The new :extension:`LazyFieldAnnotations` extension permits the prefix + ``~`` lazy field annotation on data and GADT constructor fields without + enabling :extension:`StrictData`. :extension:`StrictData` (and therefore + :extension:`Strict`) now implies :extension:`LazyFieldAnnotations` and + continues to control the default strictness of unannotated fields. +} ===================================== compiler/GHC/Driver/Flags.hs ===================================== @@ -261,6 +261,7 @@ extensionName = \case LangExt.ExplicitLevelImports -> "ExplicitLevelImports" LangExt.ImplicitStagePersistence -> "ImplicitStagePersistence" LangExt.QualifiedStrings -> "QualifiedStrings" + LangExt.LazyFieldAnnotations -> "LazyFieldAnnotations" -- | Is this extension known by any other names? For example -- -XGeneralizedNewtypeDeriving is accepted @@ -343,6 +344,7 @@ impliedXFlags , (LangExt.TemplateHaskell, On LangExt.TemplateHaskellQuotes) , (LangExt.Strict, On LangExt.StrictData) + , (LangExt.StrictData, On LangExt.LazyFieldAnnotations) -- Historically only UnboxedTuples was required for unboxed sums to work. -- To avoid breaking code, we make UnboxedTuples imply UnboxedSums. ===================================== compiler/GHC/Tc/Errors/Ppr.hs ===================================== @@ -3231,7 +3231,7 @@ instance Diagnostic TcRnMessage where TcRnHasFieldResolvedIncomplete{} -> noHints TcRnBadFieldAnnotation _ _ LazyFieldsDisabled - -> [suggestExtension LangExt.StrictData] + -> [suggestExtension LangExt.LazyFieldAnnotations] TcRnBadFieldAnnotation{} -> noHints TcRnSuperclassCycle{} ===================================== compiler/GHC/Tc/Errors/Types.hs ===================================== @@ -6355,7 +6355,7 @@ data PatSynInvalidRhsReason data BadFieldAnnotationReason where {-| A lazy data type field annotation (~) was used without enabling the - extension StrictData. + extension LazyFieldAnnotations. Test cases: LazyFieldsDisabled ===================================== compiler/GHC/Tc/TyCl.hs ===================================== @@ -5186,7 +5186,7 @@ checkValidDataCon dflags existential_ok tc con ; let check_bang :: Type -> HsSrcBang -> HsImplBang -> Int -> TcM () check_bang orig_arg_ty bang rep_bang n | HsSrcBang _ _ SrcLazy <- bang - , not (bang_opt_strict_data bang_opts) + , not (xopt LangExt.LazyFieldAnnotations dflags) = addErrTc (bad_bang n LazyFieldsDisabled) -- Warn about UNPACK without "!" ===================================== docs/users_guide/exts/strict.rst ===================================== @@ -155,6 +155,44 @@ Note the following points: for more discussion and examples. +.. _lazy-field-annotations: + +Lazy field annotations +---------------------- + +.. extension:: LazyFieldAnnotations + :shortdesc: Allow the prefix ``~`` lazy field annotation on constructor fields. + + :since: 10.2.1 + + Allow the prefix ``~`` lazy field annotation on data and GADT constructor + fields. + +``LazyFieldAnnotations`` allows a prefix ``~`` lazy annotation in every +constructor-field position where a prefix ``!`` strict annotation is accepted: +Haskell-98 prefix and record fields, and GADT argument types and record +fields. :: + + {-# LANGUAGE LazyFieldAnnotations #-} + + data A = A ~Int Bool + data B = B { b1 :: ~Int, b2 :: !Bool } + + data C where + C1 :: ~Int -> C + C2 :: { c1 :: ~Int, c2 :: !Bool } -> C + +A field annotated with ``~`` is lazy: it is not forced when the constructor is +built, but held as a thunk — the same behaviour as an unannotated field. + +The ``~`` annotation must be written in prefix form:: + + data T = MkT ~Int -- valid + data T = MkT ~ Int -- invalid + +See `GHC Proposal #229 <https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0229-w…>`__ +for the precise rules. + .. _strict-data: Strict-by-default data types @@ -163,6 +201,8 @@ Strict-by-default data types .. extension:: StrictData :shortdesc: Treat datatype fields as strict by default. + :implies: :extension:`LazyFieldAnnotations` + :since: 8.0.1 Make fields of data types defined in the current module strict by default. @@ -183,13 +223,8 @@ we interpret it as if they had written :: The extension only affects definitions in this module. -The ``~`` annotation must be written in prefix form:: - - data T = MkT ~Int -- valid - data T = MkT ~ Int -- invalid - -See `GHC Proposal #229 <https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0229-w…>`__ -for the precise rules. +The ``~`` lazy field annotation is provided by :extension:`LazyFieldAnnotations` +(which ``StrictData`` implies); see :ref:`lazy-field-annotations`. .. _strict: ===================================== libraries/ghc-internal/src/GHC/Internal/LanguageExtensions.hs ===================================== @@ -169,6 +169,7 @@ data Extension | ExplicitLevelImports | ImplicitStagePersistence | QualifiedStrings + | LazyFieldAnnotations deriving (Eq, Enum, Show, Generic, Bounded) -- 'Ord' and 'Bounded' are provided for GHC API users (see discussions -- in https://gitlab.haskell.org/ghc/ghc/merge_requests/2707 and ===================================== testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.hs ===================================== @@ -0,0 +1,24 @@ +{-# LANGUAGE LazyFieldAnnotations #-} + +-- | LazyFieldAnnotations does not change the default strictness of fields. +-- Without StrictData an unannotated field stays lazy and a ~ field is lazy +-- too; a ! field is still strict. +module Main where + +import Control.Exception (try, evaluate, SomeException) + +data T = Plain Int -- unannotated: lazy + | Lazy ~Int -- explicit ~: lazy + | Strict !Int -- explicit !: strict + +-- | Does building the constructor force the field? +forcesField :: T -> IO Bool +forcesField x = do + r <- try (evaluate x) :: IO (Either SomeException T) + pure (either (const True) (const False) r) + +main :: IO () +main = do + print =<< forcesField (Plain undefined) -- False: lazy + print =<< forcesField (Lazy undefined) -- False: lazy + print =<< forcesField (Strict undefined) -- True: strict ===================================== testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.stdout ===================================== @@ -0,0 +1,3 @@ +False +False +True ===================================== testsuite/tests/deSugar/should_run/all.T ===================================== @@ -76,3 +76,5 @@ test('T19680A', normal, compile_and_run, ['']) test('T20024', exit_code(1), compile_and_run, ['']) test('Or5', exit_code(1), compile_and_run, ['']) + +test('LazyFieldAnnotationsSemantics', normal, compile_and_run, ['']) ===================================== testsuite/tests/typecheck/should_compile/LazyFieldAnnotations.hs ===================================== @@ -0,0 +1,15 @@ +{-# LANGUAGE LazyFieldAnnotations #-} +{-# LANGUAGE GADTs #-} + +-- | LazyFieldAnnotations alone accepts the prefix ~ annotation in every +-- constructor-field position, without enabling StrictData. +module LazyFieldAnnotations where + +-- Haskell-98 prefix and record fields +data A = A ~Int Bool +data B = B { b1 :: ~Int, b2 :: !Bool } + +-- GADT argument types and record fields +data C where + C1 :: ~Int -> C + C2 :: { c1 :: ~Int, c2 :: !Bool } -> C ===================================== testsuite/tests/typecheck/should_compile/all.T ===================================== @@ -967,4 +967,5 @@ test('T26805a', normal, compile, ['']) test('T24464', normal, compile, ['']) test('ExpansionQLIm', normal, compile, ['']) test('T23135', normal, compile, ['']) +test('LazyFieldAnnotations', normal, compile, ['']) ===================================== testsuite/tests/typecheck/should_fail/LazyFieldsDisabled.stderr ===================================== @@ -1,8 +1,8 @@ - LazyFieldsDisabled.hs:3:10: error: [GHC-81601] • Lazy field annotations (~) are disabled on the first argument of ‘A’ • In the definition of data constructor ‘A’ In the data type declaration for ‘A’ Suggested fix: - Perhaps you intended to use the ‘StrictData’ extension (implied by ‘Strict’) + Perhaps you intended to use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + ===================================== testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.hs ===================================== @@ -0,0 +1,8 @@ +{-# LANGUAGE StrictData #-} +{-# LANGUAGE NoLazyFieldAnnotations #-} + +-- | A later NoLazyFieldAnnotations overrides the implication from StrictData, +-- so ~ is rejected even though unannotated fields remain strict. +module LazyFieldsDisabledStrictData where + +data A = A ~Int ===================================== testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.stderr ===================================== @@ -0,0 +1,8 @@ +LazyFieldsDisabledStrictData.hs:8:10: error: [GHC-81601] + • Lazy field annotations (~) are disabled + on the first argument of ‘A’ + • In the definition of data constructor ‘A’ + In the data type declaration for ‘A’ + Suggested fix: + Perhaps you intended to use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + ===================================== testsuite/tests/typecheck/should_fail/all.T ===================================== @@ -690,6 +690,7 @@ test('T21444', normal, compile_fail, ['']) test('T23308', normal, compile_fail, ['']) test('MultiAssocDefaults', normal, compile_fail, ['']) test('LazyFieldsDisabled', normal, compile_fail, ['']) +test('LazyFieldsDisabledStrictData', normal, compile_fail, ['']) test('TyfamsDisabled', normal, compile_fail, ['']) test('CommonFieldResultTypeMismatch', normal, compile_fail, ['']) test('CommonFieldTypeMismatch', normal, compile_fail, ['']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/19e0f321bfe845c409d3b95dadcf583… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/19e0f321bfe845c409d3b95dadcf583… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/sjakobi/lazy-field-anns] Add -XLazyFieldAnnotations
by Simon Jakobi (＠sjakobi2) 24 Jun '26

24 Jun '26

Simon Jakobi pushed to branch wip/sjakobi/lazy-field-anns at Glasgow Haskell Compiler / GHC Commits: 46d5c55a by Simon Jakobi at 2026-06-24T13:50:17+02:00 Add -XLazyFieldAnnotations Unbundle the prefix `~` lazy field annotation syntax from StrictData. The new LazyFieldAnnotations extension controls only whether `~` is accepted on data and GADT constructor fields; StrictData (and hence Strict) implies it but continues to own the default strictness of unannotated fields. This lets hand-written and generated code write an explicit lazy annotation without flipping the module-wide default. The validity check in checkValidDataCon now keys off LazyFieldAnnotations instead of StrictData. Implements GHC proposal 752 (https://github.com/ghc-proposals/ghc-proposals/pull/752) Closes #24455. Co-Authored-By: Claude Opus 4.8 <noreply(a)anthropic.com> - - - - - 16 changed files: - compiler/GHC/Driver/Flags.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/TyCl.hs - + docs/users_guide/changelog.d/lazy-field-annotations - docs/users_guide/exts/strict.rst - libraries/ghc-internal/src/GHC/Internal/LanguageExtensions.hs - + testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.hs - + testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.stdout - testsuite/tests/deSugar/should_run/all.T - + testsuite/tests/typecheck/should_compile/LazyFieldAnnotations.hs - testsuite/tests/typecheck/should_compile/all.T - testsuite/tests/typecheck/should_fail/LazyFieldsDisabled.stderr - + testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.hs - + testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.stderr - testsuite/tests/typecheck/should_fail/all.T Changes: ===================================== compiler/GHC/Driver/Flags.hs ===================================== @@ -261,6 +261,7 @@ extensionName = \case LangExt.ExplicitLevelImports -> "ExplicitLevelImports" LangExt.ImplicitStagePersistence -> "ImplicitStagePersistence" LangExt.QualifiedStrings -> "QualifiedStrings" + LangExt.LazyFieldAnnotations -> "LazyFieldAnnotations" -- | Is this extension known by any other names? For example -- -XGeneralizedNewtypeDeriving is accepted @@ -343,6 +344,7 @@ impliedXFlags , (LangExt.TemplateHaskell, On LangExt.TemplateHaskellQuotes) , (LangExt.Strict, On LangExt.StrictData) + , (LangExt.StrictData, On LangExt.LazyFieldAnnotations) -- Historically only UnboxedTuples was required for unboxed sums to work. -- To avoid breaking code, we make UnboxedTuples imply UnboxedSums. ===================================== compiler/GHC/Tc/Errors/Ppr.hs ===================================== @@ -3231,7 +3231,7 @@ instance Diagnostic TcRnMessage where TcRnHasFieldResolvedIncomplete{} -> noHints TcRnBadFieldAnnotation _ _ LazyFieldsDisabled - -> [suggestExtension LangExt.StrictData] + -> [suggestExtension LangExt.LazyFieldAnnotations] TcRnBadFieldAnnotation{} -> noHints TcRnSuperclassCycle{} ===================================== compiler/GHC/Tc/Errors/Types.hs ===================================== @@ -6355,7 +6355,7 @@ data PatSynInvalidRhsReason data BadFieldAnnotationReason where {-| A lazy data type field annotation (~) was used without enabling the - extension StrictData. + extension LazyFieldAnnotations. Test cases: LazyFieldsDisabled ===================================== compiler/GHC/Tc/TyCl.hs ===================================== @@ -5186,7 +5186,7 @@ checkValidDataCon dflags existential_ok tc con ; let check_bang :: Type -> HsSrcBang -> HsImplBang -> Int -> TcM () check_bang orig_arg_ty bang rep_bang n | HsSrcBang _ _ SrcLazy <- bang - , not (bang_opt_strict_data bang_opts) + , not (xopt LangExt.LazyFieldAnnotations dflags) = addErrTc (bad_bang n LazyFieldsDisabled) -- Warn about UNPACK without "!" ===================================== docs/users_guide/changelog.d/lazy-field-annotations ===================================== @@ -0,0 +1,12 @@ +section: language +synopsis: Add the `LazyFieldAnnotations` extension +issues: #24455 +mrs: !16246 + +description: { + The new :extension:`LazyFieldAnnotations` extension permits the prefix + ``~`` lazy field annotation on data and GADT constructor fields without + enabling :extension:`StrictData`. :extension:`StrictData` (and therefore + :extension:`Strict`) now implies :extension:`LazyFieldAnnotations` and + continues to control the default strictness of unannotated fields. +} ===================================== docs/users_guide/exts/strict.rst ===================================== @@ -155,6 +155,44 @@ Note the following points: for more discussion and examples. +.. _lazy-field-annotations: + +Lazy field annotations +---------------------- + +.. extension:: LazyFieldAnnotations + :shortdesc: Allow the prefix ``~`` lazy field annotation on constructor fields. + + :since: 10.2.1 + + Allow the prefix ``~`` lazy field annotation on data and GADT constructor + fields. + +``LazyFieldAnnotations`` allows a prefix ``~`` lazy annotation in every +constructor-field position where a prefix ``!`` strict annotation is accepted: +Haskell-98 prefix and record fields, and GADT argument types and record +fields. :: + + {-# LANGUAGE LazyFieldAnnotations #-} + + data A = A ~Int Bool + data B = B { b1 :: ~Int, b2 :: !Bool } + + data C where + C1 :: ~Int -> C + C2 :: { c1 :: ~Int, c2 :: !Bool } -> C + +A field annotated with ``~`` is lazy: it is not forced when the constructor is +built, but held as a thunk — the same behaviour as an unannotated field. + +The ``~`` annotation must be written in prefix form:: + + data T = MkT ~Int -- valid + data T = MkT ~ Int -- invalid + +See `GHC Proposal #229 <https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0229-w…>`__ +for the precise rules. + .. _strict-data: Strict-by-default data types @@ -163,6 +201,8 @@ Strict-by-default data types .. extension:: StrictData :shortdesc: Treat datatype fields as strict by default. + :implies: :extension:`LazyFieldAnnotations` + :since: 8.0.1 Make fields of data types defined in the current module strict by default. @@ -183,13 +223,8 @@ we interpret it as if they had written :: The extension only affects definitions in this module. -The ``~`` annotation must be written in prefix form:: - - data T = MkT ~Int -- valid - data T = MkT ~ Int -- invalid - -See `GHC Proposal #229 <https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0229-w…>`__ -for the precise rules. +The ``~`` lazy field annotation is provided by :extension:`LazyFieldAnnotations` +(which ``StrictData`` implies); see :ref:`lazy-field-annotations`. .. _strict: ===================================== libraries/ghc-internal/src/GHC/Internal/LanguageExtensions.hs ===================================== @@ -169,6 +169,7 @@ data Extension | ExplicitLevelImports | ImplicitStagePersistence | QualifiedStrings + | LazyFieldAnnotations deriving (Eq, Enum, Show, Generic, Bounded) -- 'Ord' and 'Bounded' are provided for GHC API users (see discussions -- in https://gitlab.haskell.org/ghc/ghc/merge_requests/2707 and ===================================== testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.hs ===================================== @@ -0,0 +1,24 @@ +{-# LANGUAGE LazyFieldAnnotations #-} + +-- | LazyFieldAnnotations does not change the default strictness of fields. +-- Without StrictData an unannotated field stays lazy and a ~ field is lazy +-- too; a ! field is still strict. +module Main where + +import Control.Exception (try, evaluate, SomeException) + +data T = Plain Int -- unannotated: lazy + | Lazy ~Int -- explicit ~: lazy + | Strict !Int -- explicit !: strict + +-- | Does building the constructor force the field? +forcesField :: T -> IO Bool +forcesField x = do + r <- try (evaluate x) :: IO (Either SomeException T) + pure (either (const True) (const False) r) + +main :: IO () +main = do + print =<< forcesField (Plain undefined) -- False: lazy + print =<< forcesField (Lazy undefined) -- False: lazy + print =<< forcesField (Strict undefined) -- True: strict ===================================== testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.stdout ===================================== @@ -0,0 +1,3 @@ +False +False +True ===================================== testsuite/tests/deSugar/should_run/all.T ===================================== @@ -76,3 +76,5 @@ test('T19680A', normal, compile_and_run, ['']) test('T20024', exit_code(1), compile_and_run, ['']) test('Or5', exit_code(1), compile_and_run, ['']) + +test('LazyFieldAnnotationsSemantics', normal, compile_and_run, ['']) ===================================== testsuite/tests/typecheck/should_compile/LazyFieldAnnotations.hs ===================================== @@ -0,0 +1,15 @@ +{-# LANGUAGE LazyFieldAnnotations #-} +{-# LANGUAGE GADTs #-} + +-- | LazyFieldAnnotations alone accepts the prefix ~ annotation in every +-- constructor-field position, without enabling StrictData. +module LazyFieldAnnotations where + +-- Haskell-98 prefix and record fields +data A = A ~Int Bool +data B = B { b1 :: ~Int, b2 :: !Bool } + +-- GADT argument types and record fields +data C where + C1 :: ~Int -> C + C2 :: { c1 :: ~Int, c2 :: !Bool } -> C ===================================== testsuite/tests/typecheck/should_compile/all.T ===================================== @@ -967,4 +967,5 @@ test('T26805a', normal, compile, ['']) test('T24464', normal, compile, ['']) test('ExpansionQLIm', normal, compile, ['']) test('T23135', normal, compile, ['']) +test('LazyFieldAnnotations', normal, compile, ['']) ===================================== testsuite/tests/typecheck/should_fail/LazyFieldsDisabled.stderr ===================================== @@ -1,8 +1,8 @@ - LazyFieldsDisabled.hs:3:10: error: [GHC-81601] • Lazy field annotations (~) are disabled on the first argument of ‘A’ • In the definition of data constructor ‘A’ In the data type declaration for ‘A’ Suggested fix: - Perhaps you intended to use the ‘StrictData’ extension (implied by ‘Strict’) + Perhaps you intended to use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + ===================================== testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.hs ===================================== @@ -0,0 +1,8 @@ +{-# LANGUAGE StrictData #-} +{-# LANGUAGE NoLazyFieldAnnotations #-} + +-- | A later NoLazyFieldAnnotations overrides the implication from StrictData, +-- so ~ is rejected even though unannotated fields remain strict. +module LazyFieldsDisabledStrictData where + +data A = A ~Int ===================================== testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.stderr ===================================== @@ -0,0 +1,8 @@ +LazyFieldsDisabledStrictData.hs:8:10: error: [GHC-81601] + • Lazy field annotations (~) are disabled + on the first argument of ‘A’ + • In the definition of data constructor ‘A’ + In the data type declaration for ‘A’ + Suggested fix: + Perhaps you intended to use the ‘LazyFieldAnnotations’ extension (implied by ‘StrictData’) + ===================================== testsuite/tests/typecheck/should_fail/all.T ===================================== @@ -690,6 +690,7 @@ test('T21444', normal, compile_fail, ['']) test('T23308', normal, compile_fail, ['']) test('MultiAssocDefaults', normal, compile_fail, ['']) test('LazyFieldsDisabled', normal, compile_fail, ['']) +test('LazyFieldsDisabledStrictData', normal, compile_fail, ['']) test('TyfamsDisabled', normal, compile_fail, ['']) test('CommonFieldResultTypeMismatch', normal, compile_fail, ['']) test('CommonFieldTypeMismatch', normal, compile_fail, ['']) View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/46d5c55a017907ad9e62c5e9dc90e4e… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/46d5c55a017907ad9e62c5e9dc90e4e… You're receiving this email because of your account on gitlab.haskell.org.

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[Git][ghc/ghc][wip/sjakobi/lazy-field-anns] 20 commits: Desugar a `case` scrutinee only once (#27383, #20251)
by Simon Jakobi (＠sjakobi2) 24 Jun '26

24 Jun '26

Simon Jakobi pushed to branch wip/sjakobi/lazy-field-anns at Glasgow Haskell Compiler / GHC Commits: 67d41299 by Sebastian Graf at 2026-06-18T05:18:24-04:00 Desugar a `case` scrutinee only once (#27383, #20251) In `dsExpr` for `HsCase` we desugared the scrutinee /twice/: once to build the Core `case` itself, and again inside `matchWrapper`, which re-desugared the source scrutinee (via `addHsScrutTmCs`) purely to record long-distance information for the pattern-match checker. For a single `case` that is merely wasteful. But for nested cases it is catastrophic. Consider case (case (case e of ... ) of ... ) of ... Desugaring the outer scrutinee desugars the middle `case` twice, each of which desugars the inner `case` twice, and so on. The work doubles at every level, so desugaring takes O(2^n) time in the nesting depth. That is the blowup reported in #27383; it is also what makes the machine-generated program in #20251 take an age to compile. The fix is simple. `matchWrapper` is handed the scrutinee anyway, so we give it the Core expression we have /already/ desugared, and record the long-distance term constraint with `addCoreScrutTmCs` instead of re-desugaring from source. This is just what `matchSinglePatVar` already does for single-pattern matches. So: * `matchWrapper` now takes `Maybe [CoreExpr]` rather than `Maybe [LHsExpr GhcTc]`. * The `HsCase` equation of `dsExpr` passes the already-desugared `core_discrim`; the arrow desugarer passes its match variables. * `addHsScrutTmCs` had no other use, so it is gone. Desugaring is now linear in the nesting depth. (The coverage checker still runs `simpleOptExpr` over each scrutinee, which leaves the total at O(n^2); that is ample.) The long-distance information itself is unchanged: the checker sees precisely the Core that backs the generated code. Test: deSugar/should_compile/T27383 - - - - - fa5defde by Rodrigo Mesquita at 2026-06-18T05:19:11-04:00 fix: Save FastStrings in the PMC There is no point in adding the unique to the occurrence FastString we create, since it is part of the Id anyway. Adding it to the FastString, meant each FastString was unique unnecessarily! In a separate branch, running the compiler on test `InstanceMatching` observed 30000 `FastString`s created by this code path. Plus, `fsLit "pm"` follows the existing pattern in `mkPmId`. - - - - - 4efb4a66 by Alan Zimmerman at 2026-06-18T14:41:14-04:00 TTG: Add extension points to HsConDetails Extend HsConDetails as data HsConDetails p arg rec = PrefixCon !(XPrefixCon p) [arg] -- C @t1 @t2 p1 p2 p3 | RecCon !(XRecCon p) rec -- C { x = p1, y = p2 } | InfixCon !(XInfixCon p) arg arg -- p1 `C` p2 | XHsConDetails !(XXHsConDetails p) type family XPrefixCon p type family XRecCon p type family XInfixCon p type family XXHsConDetails p - - - - - c8d27dd4 by Simon Jakobi at 2026-06-18T14:41:59-04:00 CI: quiet submodule clean output in after_script and setup The clean and cleanup_submodules functions ran 'git submodule foreach git clean -xdf', flooding the job log with 'Entering ...' and 'Removing ...' lines. Pass --quiet to 'git submodule' and -q to 'git clean' to drop the success output; errors are still reported. Co-Authored-By: Claude Opus 4.8 <noreply(a)anthropic.com> - - - - - 09326ca6 by Matthew Pickering at 2026-06-20T23:41:12+02:00 Add missing req_interp modifier to T18441fail3 and T18441fail19 These tests require the interpreter but they were failing in a different way with the javascript backend because the interpreter was disabled and stderr is ignored by the test. - - - - - 521e55bf by Matthew Pickering at 2026-06-20T23:41:13+02:00 hadrian: Fill in more of the default.host toolchain file When you are building a cross compiler this file will be used to build stage1 and it's libraries, so we need enough information here to work accurately. There is still more work to be done (see for example, word size is still fixed). - - - - - 23c9b6c3 by Matthew Pickering at 2026-06-20T23:42:52+02:00 hadrian: Build stage 2 cross compilers * Most of hadrian is abstracted over the stage in order to remove the assumption that the target of all stages is the same platform. This allows the RTS to be built for two different targets for example. * Abstracts the bindist creation logic to allow building either normal or cross bindists. Normal bindists use stage 1 libraries and a stage 2 compiler. Cross bindists use stage 2 libararies and a stage 2 compiler. * hadrian: Make binary-dist-dir the default build target. This allows us to have the logic in one place about which libraries/stages to build with cross compilers. Fixes #24192 New hadrian target: * `binary-dist-dir-cross`: Build a cross compiler bindist (compiler = stage 1, libraries = stage 2) This commit also contains various changes to make stage2 compilers feasible. ------------------------- Metric Decrease: LinkableUsage02 ManyAlternatives ManyConstructors MultiComponentModulesRecomp MultiLayerModulesRecomp RecordUpdPerf T10421 T12150 T12227 T12425 T12707 T13035 T13379 T13820 T15703 T16577 T18140 T18282 T18698a T18698b T18923 T1969 T20049 T21839c T3294 T4801 T5030 T5321FD T5321Fun T5631 T5642 T6048 T783 T9020 T9198 T9233 T9630 T9872d T9961 parsing001 T3064 Metric Increase: T26989 hard_hole_fits ------------------------- Co-authored-by: Sven Tennie <sven.tennie(a)gmail.com> - - - - - 26fed8ab by Matthew Pickering at 2026-06-20T23:42:52+02:00 ci: Test cross bindists We remove the special logic for testing in-tree cross compilers and instead test cross compiler bindists, like we do for all other platforms. - - - - - 80c8910e by Matthew Pickering at 2026-06-20T23:42:52+02:00 ci: Introduce CROSS_STAGE variable In preparation for building and testing stage3 bindists we introduce the CROSS_STAGE variable which is used by a CI job to determine what kind of bindist the CI job should produce. At the moment we are only using CROSS_STAGE=2 but in the future we will have some jobs which set CROSS_STAGE=3 to produce native bindists for a target, but produced by a cross compiler, which can be tested on by another CI job on the native platform. CROSS_STAGE=2: Build a normal cross compiler bindist CROSS_STAGE=3: Build a stage 3 bindist, one which is a native compiler and library for the target - - - - - 8215573d by Sven Tennie at 2026-06-20T23:42:52+02:00 ci: Increase timeout for emulators Test runs with emulators naturally take longer than on native machines. Generate jobs.yml - - - - - 5acb7dbc by Matthew Pickering at 2026-06-20T23:42:52+02:00 ci: Javascript don't set CROSS_EMULATOR There is no CROSS_EMULATOR needed to run javascript binaries, so we don't set the CROSS_EMULATOR to some dummy value. - - - - - 48345343 by Sven Tennie at 2026-06-20T23:42:52+02:00 Javascript skip T23697 See #22355 about how HSC2HS and the Javascript target don't play well together. - - - - - 5e44fd05 by Sven Tennie at 2026-06-20T23:42:52+02:00 Mark T24602 as fragile It was skipped before (due to CROSS_EMULATOR being set, which changed for JS), so we don't make things worse by marking it as fragile. - - - - - ab349ec2 by Sven Tennie at 2026-06-20T23:42:52+02:00 Fix T22744 for GHCJS In fact, this test needs Template Haskell, not necessarily an interpreter. - - - - - c73352d8 by Sven Tennie at 2026-06-20T23:42:52+02:00 haddock-test: fix GHCJS haddock test failures Add --ghc-pkg-path flag support so haddock test runner can find cross-prefixed ghc-pkg (e.g. javascript-unknown-ghcjs-ghc-pkg) which is not on $PATH in cross install directories. Skip haddockHtmlTest on GHCJS: Threaded.hs uses forkOS in a TH splice, which GHCJS RTS doesn't support. Mark with js_skip in all.T. - - - - - 5e814e76 by Andreas Klebinger at 2026-06-22T23:00:24-04:00 compiler: Deduplicate hscTidy This function was accidentally duplicated during a refactor. Fixes #27351 - - - - - 473b97eb by sheaf at 2026-06-22T23:01:22-04:00 Avoid mkTick in Core Prep breaking ANF (part II) Hotfix for 2f9579765f55b3920ceb2e04995ff41a9d0e2d4e fixing a small oversight in the call to tickTickedExpr from mkTick, in which we improperly recursively called mkTick without passing on the preserve_anf flag. Fixes #27386 - - - - - 9284a1f7 by Simon Hengel at 2026-06-23T05:55:33-04:00 Don't use global variables to address concurrency bugs! (fixes #27234) This was originally introduce with 88f38b03025386f0f1e8f5861eed67d80495168a to address #17922. In this specific case a better fix would have been to synchronize on stderr: withHandle_ "stderrSupportsAnsiColors" stderr $ \ _ -> do ... But apparently the dependency on `terminfo` was removed in 32ab07bf3d6ce45e8ea5b55e8095174a6b42a7f0, preventing #17922 in the first place. - - - - - 44309cd3 by Alan Zimmerman at 2026-06-23T05:56:20-04:00 EPA: remove LocatedL / SrcSpanAnnL and LocatedLI / SrcSpanAnnLI This is part of a refactor towards only having LocatedA / SrcSpanAnnA It removes the stated items, but has to add back one for BooleanFormula, LocatedBF / SrcSpanAnnBF This commit also use the HsConDetails RecCon extension point to capture the braces in a record constructor - - - - - dc63db45 by Simon Jakobi at 2026-06-24T13:40:25+02:00 Add -XLazyFieldAnnotations Unbundle the prefix `~` lazy field annotation syntax from StrictData. The new LazyFieldAnnotations extension controls only whether `~` is accepted on data and GADT constructor fields; StrictData (and hence Strict) implies it but continues to own the default strictness of unannotated fields. This lets hand-written and generated code write an explicit lazy annotation without flipping the module-wide default. The validity check in checkValidDataCon now keys off LazyFieldAnnotations instead of StrictData. Implements ghc-proposals #752. Closes #24455. Co-Authored-By: Claude Opus 4.8 <noreply(a)anthropic.com> - - - - - 184 changed files: - .gitlab/ci.sh - .gitlab/generate-ci/gen_ci.hs - .gitlab/jobs.yaml - + changelog.d/T27386 - + changelog.d/fix-exponential-case-desugar-27383 - + changelog.d/stage2-cross-compilers - compiler/GHC/Core/Opt/Arity.hs - compiler/GHC/Core/Utils.hs - compiler/GHC/Data/BooleanFormula.hs - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/Driver/Flags.hs - compiler/GHC/Driver/Main/Interactive.hs - compiler/GHC/Driver/Main/Passes.hs - compiler/GHC/Driver/Main/Passes.hs-boot - compiler/GHC/Hs.hs - compiler/GHC/Hs/Binds.hs - compiler/GHC/Hs/Decls.hs - compiler/GHC/Hs/Dump.hs - compiler/GHC/Hs/Expr.hs - compiler/GHC/Hs/ImpExp.hs - compiler/GHC/Hs/Instances.hs - compiler/GHC/Hs/Pat.hs - compiler/GHC/Hs/Stats.hs - compiler/GHC/Hs/Type.hs - compiler/GHC/Hs/Utils.hs - compiler/GHC/HsToCore/Arrows.hs - compiler/GHC/HsToCore/Docs.hs - compiler/GHC/HsToCore/Expr.hs - compiler/GHC/HsToCore/Match.hs - compiler/GHC/HsToCore/Match.hs-boot - compiler/GHC/HsToCore/Match/Constructor.hs - compiler/GHC/HsToCore/Pmc.hs - compiler/GHC/HsToCore/Pmc/Desugar.hs - compiler/GHC/HsToCore/Pmc/Solver.hs - compiler/GHC/HsToCore/Quote.hs - compiler/GHC/HsToCore/Ticks.hs - compiler/GHC/Iface/Ext/Ast.hs - compiler/GHC/Parser.y - compiler/GHC/Parser/Annotation.hs - compiler/GHC/Parser/PostProcess.hs - compiler/GHC/Parser/PostProcess/Haddock.hs - compiler/GHC/Rename/Bind.hs - compiler/GHC/Rename/Expr.hs - compiler/GHC/Rename/HsType.hs - compiler/GHC/Rename/Module.hs - compiler/GHC/Rename/Names.hs - compiler/GHC/Rename/Pat.hs - compiler/GHC/Rename/Utils.hs - compiler/GHC/SysTools/Terminal.hs - compiler/GHC/Tc/Deriv/Generate.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Tc/Gen/Export.hs - compiler/GHC/Tc/Gen/Pat.hs - compiler/GHC/Tc/Module.hs - compiler/GHC/Tc/TyCl.hs - compiler/GHC/Tc/TyCl/PatSyn.hs - compiler/GHC/Tc/TyCl/Utils.hs - compiler/GHC/Tc/Utils/Backpack.hs - compiler/GHC/Tc/Zonk/Type.hs - compiler/GHC/ThToHs.hs - compiler/Language/Haskell/Syntax.hs - compiler/Language/Haskell/Syntax/Binds.hs - compiler/Language/Haskell/Syntax/Decls.hs - compiler/Language/Haskell/Syntax/ImpExp.hs - compiler/Language/Haskell/Syntax/Pat.hs - compiler/Language/Haskell/Syntax/Type.hs - configure.ac - distrib/configure.ac.in - + docs/users_guide/changelog.d/lazy-field-annotations - docs/users_guide/exts/strict.rst - ghc/GHCi/UI.hs - hadrian/README.md - hadrian/bindist/config.mk.in - hadrian/cfg/default.host.target.in - + hadrian/cfg/system.config.host.in - hadrian/cfg/system.config.in - + hadrian/cfg/system.config.target.in - hadrian/hadrian.cabal - hadrian/src/Base.hs - + hadrian/src/BindistConfig.hs - hadrian/src/Builder.hs - hadrian/src/Context.hs - hadrian/src/Expression.hs - hadrian/src/Flavour.hs - hadrian/src/Flavour/Type.hs - hadrian/src/Hadrian/Builder.hs - hadrian/src/Hadrian/Haskell/Hash.hs - hadrian/src/Hadrian/Oracles/TextFile.hs - hadrian/src/Main.hs - hadrian/src/Oracles/Flag.hs - hadrian/src/Oracles/Flavour.hs - hadrian/src/Oracles/Setting.hs - hadrian/src/Oracles/TestSettings.hs - hadrian/src/Packages.hs - hadrian/src/Rules.hs - hadrian/src/Rules/BinaryDist.hs - hadrian/src/Rules/CabalReinstall.hs - hadrian/src/Rules/Changelog.hs - hadrian/src/Rules/Compile.hs - hadrian/src/Rules/Documentation.hs - hadrian/src/Rules/Generate.hs - hadrian/src/Rules/Gmp.hs - hadrian/src/Rules/Library.hs - hadrian/src/Rules/Program.hs - hadrian/src/Rules/Register.hs - hadrian/src/Rules/Rts.hs - hadrian/src/Rules/Test.hs - hadrian/src/Settings.hs - hadrian/src/Settings/Builders/Cabal.hs - hadrian/src/Settings/Builders/Common.hs - hadrian/src/Settings/Builders/Configure.hs - hadrian/src/Settings/Builders/DeriveConstants.hs - hadrian/src/Settings/Builders/Ghc.hs - hadrian/src/Settings/Builders/Hsc2Hs.hs - hadrian/src/Settings/Builders/RunTest.hs - hadrian/src/Settings/Builders/SplitSections.hs - hadrian/src/Settings/Default.hs - hadrian/src/Settings/Flavours/GhcInGhci.hs - hadrian/src/Settings/Flavours/Performance.hs - hadrian/src/Settings/Flavours/QuickCross.hs - hadrian/src/Settings/Packages.hs - hadrian/src/Settings/Program.hs - hadrian/src/Settings/Warnings.hs - libraries/base/tests/all.T - libraries/ghc-internal/src/GHC/Internal/LanguageExtensions.hs - m4/fp_find_nm.m4 - m4/prep_target_file.m4 - testsuite/ghc-config/ghc-config.hs - + testsuite/tests/deSugar/should_compile/T27383.hs - testsuite/tests/deSugar/should_compile/all.T - + testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.hs - + testsuite/tests/deSugar/should_run/LazyFieldAnnotationsSemantics.stdout - testsuite/tests/deSugar/should_run/all.T - testsuite/tests/ghc-api/exactprint/T22919.stderr - testsuite/tests/ghc-api/exactprint/Test20239.stderr - testsuite/tests/ghc-api/exactprint/ZeroWidthSemi.stderr - testsuite/tests/ghc-e/should_fail/all.T - testsuite/tests/haddock/haddock_testsuite/Makefile - testsuite/tests/haddock/haddock_testsuite/all.T - 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/javascript/closure/all.T - testsuite/tests/module/mod185.stderr - testsuite/tests/parser/should_compile/DumpParsedAst.stderr - testsuite/tests/parser/should_compile/DumpParsedAstComments.stderr - testsuite/tests/parser/should_compile/DumpRenamedAst.stderr - 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/parser/should_compile/T20718.stderr - testsuite/tests/parser/should_compile/T20718b.stderr - testsuite/tests/parser/should_compile/T20846.stderr - testsuite/tests/parser/should_compile/T23315/T23315.stderr - testsuite/tests/perf/compiler/all.T - testsuite/tests/printer/AnnotationNoListTuplePuns.stdout - testsuite/tests/printer/T18791.stderr - testsuite/tests/printer/Test10309.hs - testsuite/tests/printer/Test20297.stdout - testsuite/tests/printer/Test24533.stdout - + testsuite/tests/profiling/should_compile/T27386.hs - testsuite/tests/profiling/should_compile/all.T - + testsuite/tests/typecheck/should_compile/LazyFieldAnnotations.hs - testsuite/tests/typecheck/should_compile/all.T - testsuite/tests/typecheck/should_fail/LazyFieldsDisabled.stderr - + testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.hs - + testsuite/tests/typecheck/should_fail/LazyFieldsDisabledStrictData.stderr - testsuite/tests/typecheck/should_fail/all.T - utils/check-exact/ExactPrint.hs - utils/check-exact/Main.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/LexParseRn.hs - utils/haddock/haddock-api/src/Haddock/Interface/Rename.hs - utils/haddock/haddock-api/src/Haddock/Types.hs - utils/haddock/haddock-test/src/Test/Haddock/Config.hs The diff was not included because it is too large. View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/5bf8e92af16f5cb675594a4cf26afa… -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/compare/5bf8e92af16f5cb675594a4cf26afa… You're receiving this email because of your account on gitlab.haskell.org.

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