DynFlags.hs

{-# LANGUAGE CPP #-}
{-# LANGUAGE FlexibleInstances #-}

-------------------------------------------------------------------------------
--
-- | Dynamic flags
--
-- Most flags are dynamic flags, which means they can change from compilation
-- to compilation using @OPTIONS_GHC@ pragmas, and in a multi-session GHC each
-- session can be using different dynamic flags. Dynamic flags can also be set
-- at the prompt in GHCi.
--
-- (c) The University of Glasgow 2005
--
-------------------------------------------------------------------------------

{-# OPTIONS_GHC -fno-cse #-}
-- -fno-cse is needed for GLOBAL_VAR's to behave properly

module DynFlags (
        -- * Dynamic flags and associated configuration types
        DumpFlag(..),
        GeneralFlag(..),
        WarningFlag(..),
        Language(..),
        PlatformConstants(..),
        FatalMessager, LogAction, FlushOut(..), FlushErr(..),
        ProfAuto(..),
        glasgowExtsFlags,
        dopt, dopt_set, dopt_unset,
        gopt, gopt_set, gopt_unset, setGeneralFlag', unSetGeneralFlag',
        wopt, wopt_set, wopt_unset,
        xopt, xopt_set, xopt_unset,
        lang_set,
        useUnicodeSyntax,
        whenGeneratingDynamicToo, ifGeneratingDynamicToo,
        whenCannotGenerateDynamicToo,
        dynamicTooMkDynamicDynFlags,
        DynFlags(..),
        FlagSpec(..),
        HasDynFlags(..), ContainsDynFlags(..),
        RtsOptsEnabled(..),
        HscTarget(..), isObjectTarget, defaultObjectTarget,
        targetRetainsAllBindings,
        GhcMode(..), isOneShot,
        GhcLink(..), isNoLink,
        PackageFlag(..), PackageArg(..), ModRenaming(..),
        IgnorePackageFlag(..), TrustFlag(..),
        PkgConfRef(..),
        Option(..), showOpt,
        DynLibLoader(..),
        fFlags, fLangFlags, xFlags,
        wWarningFlags,
        dynFlagDependencies,
        tablesNextToCode, mkTablesNextToCode,
        SigOf, getSigOf,
        makeDynFlagsConsistent,

        Way(..), mkBuildTag, wayRTSOnly, addWay', updateWays,
        wayGeneralFlags, wayUnsetGeneralFlags,

        -- ** Safe Haskell
        SafeHaskellMode(..),
        safeHaskellOn, safeImportsOn, safeLanguageOn, safeInferOn,
        packageTrustOn,
        safeDirectImpsReq, safeImplicitImpsReq,
        unsafeFlags, unsafeFlagsForInfer,

        -- ** System tool settings and locations
        Settings(..),
        targetPlatform, programName, projectVersion,
        ghcUsagePath, ghciUsagePath, topDir, tmpDir, rawSettings,
        versionedAppDir,
        extraGccViaCFlags, systemPackageConfig,
        pgm_L, pgm_P, pgm_F, pgm_c, pgm_s, pgm_a, pgm_l, pgm_dll, pgm_T,
        pgm_windres, pgm_libtool, pgm_lo, pgm_lc, pgm_i,
        opt_L, opt_P, opt_F, opt_c, opt_a, opt_l, opt_i,
        opt_windres, opt_lo, opt_lc,


        -- ** Manipulating DynFlags
        defaultDynFlags,                -- Settings -> DynFlags
        defaultWays,
        interpWays,
        interpreterProfiled, interpreterDynamic,
        initDynFlags,                   -- DynFlags -> IO DynFlags
        defaultFatalMessager,
        defaultLogAction,
        defaultLogActionHPrintDoc,
        defaultLogActionHPutStrDoc,
        defaultFlushOut,
        defaultFlushErr,

        getOpts,                        -- DynFlags -> (DynFlags -> [a]) -> [a]
        getVerbFlags,
        updOptLevel,
        setTmpDir,
        setUnitId,
        interpretPackageEnv,

        -- ** Parsing DynFlags
        parseDynamicFlagsCmdLine,
        parseDynamicFilePragma,
        parseDynamicFlagsFull,

        -- ** Available DynFlags
        allNonDeprecatedFlags,
        flagsAll,
        flagsDynamic,
        flagsPackage,
        flagsForCompletion,

        supportedLanguagesAndExtensions,
        languageExtensions,

        -- ** DynFlags C compiler options
        picCCOpts, picPOpts,

        -- * Compiler configuration suitable for display to the user
        compilerInfo,

#ifdef GHCI
        rtsIsProfiled,
#endif
        dynamicGhc,

#include "../includes/dist-derivedconstants/header/GHCConstantsHaskellExports.hs"
        bLOCK_SIZE_W,
        wORD_SIZE_IN_BITS,
        tAG_MASK,
        mAX_PTR_TAG,
        tARGET_MIN_INT, tARGET_MAX_INT, tARGET_MAX_WORD,

        unsafeGlobalDynFlags, setUnsafeGlobalDynFlags,

        -- * SSE and AVX
        isSseEnabled,
        isSse2Enabled,
        isSse4_2Enabled,
        isAvxEnabled,
        isAvx2Enabled,
        isAvx512cdEnabled,
        isAvx512erEnabled,
        isAvx512fEnabled,
        isAvx512pfEnabled,

        -- * Linker/compiler information
        LinkerInfo(..),
        CompilerInfo(..),
  ) where

#include "HsVersions.h"

import Platform
import PlatformConstants
import Module
import PackageConfig
import {-# SOURCE #-} Hooks
import {-# SOURCE #-} PrelNames ( mAIN )
import {-# SOURCE #-} Packages (PackageState, emptyPackageState)
import DriverPhases     ( Phase(..), phaseInputExt )
import Config
import CmdLineParser
import Constants
import Panic
import Util
import Maybes
import MonadUtils
import qualified Pretty
import SrcLoc
import BasicTypes       ( IntWithInf, treatZeroAsInf )
import FastString
import Outputable
import Foreign.C        ( CInt(..) )
import System.IO.Unsafe ( unsafeDupablePerformIO )
import {-# SOURCE #-} ErrUtils ( Severity(..), MsgDoc, mkLocMessage )

import System.IO.Unsafe ( unsafePerformIO )
import Data.IORef
import Control.Arrow ((&&&))
import Control.Monad
import Control.Monad.Trans.Class
import Control.Monad.Trans.Writer
import Control.Monad.Trans.Reader
import Control.Monad.Trans.Except
import Control.Exception (throwIO)

import Data.Bits
import Data.Char
import Data.Int
import Data.List
import Data.Map (Map)
import qualified Data.Map as Map
import Data.Set (Set)
import qualified Data.Set as Set
import Data.Word
import System.FilePath
import System.Directory
import System.Environment (getEnv)
import System.IO
import System.IO.Error
import Text.ParserCombinators.ReadP hiding (char)
import Text.ParserCombinators.ReadP as R

import Data.IntSet (IntSet)
import qualified Data.IntSet as IntSet

import GHC.Foreign (withCString, peekCString)
import qualified GHC.LanguageExtensions as LangExt

-- Note [Updating flag description in the User's Guide]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
-- If you modify anything in this file please make sure that your changes are
-- described in the User's Guide. Usually at least two sections need to be
-- updated:
--
--  * Flag Reference section generated from the modules in
--    utils/mkUserGuidePart/Options
--
--  * Flag description in docs/users_guide/using.rst provides a detailed
--    explanation of flags' usage.

-- Note [Supporting CLI completion]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
-- The command line interface completion (in for example bash) is an easy way
-- for the developer to learn what flags are available from GHC.
-- GHC helps by separating which flags are available when compiling with GHC,
-- and which flags are available when using GHCi.
-- A flag is assumed to either work in both these modes, or only in one of them.
-- When adding or changing a flag, please consider for which mode the flag will
-- have effect, and annotate it accordingly. For Flags use defFlag, defGhcFlag,
-- defGhciFlag, and for FlagSpec use flagSpec or flagGhciSpec.

-- Note [Adding a language extension]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
-- There are a few steps to adding (or removing) a language extension,
--
--  * Adding the extension to GHC.LanguageExtensions
--
--    The Extension type in libraries/ghc-boot/GHC/LanguageExtensions.hs is
--    the canonical list of language extensions known by GHC.
--
--  * Adding a flag to DynFlags.xFlags
--
--    This is fairly self-explanatory. The name should be concise, memorable,
--    and consistent with any previous implementations of the similar idea in
--    other Haskell compilers.
--
--  * Adding the flag to the documentation
--
--    This is the same as any other flag. See
--    Note [Updating flag description in the User's Guide]
--
--  * Adding the flag to Cabal
--
--    The Cabal library has its own list of all language extensions supported
--    by all major compilers. This is the list that user code being uploaded
--    to Hackage is checked against to ensure language extension validity.
--    Consequently, it is very important that this list remains up-to-date.
--
--    To this end, there is a testsuite test (testsuite/tests/driver/T4437.hs)
--    whose job it is to ensure these GHC's extensions are consistent with
--    Cabal.
--
--    The recommended workflow is,
--
--     1. Temporarily add your new language extension to the
--        expectedGhcOnlyExtensions list in T4437 to ensure the test doesn't
--        break while Cabal is updated.
--
--     2. After your GHC change is accepted, submit a Cabal pull request adding
--        your new extension to Cabal's list (found in
--        Cabal/Language/Haskell/Extension.hs).
--
--     3. After your Cabal change is accepted, let the GHC developers know so
--        they can update the Cabal submodule and remove the extensions from
--        expectedGhcOnlyExtensions.
--
--  * Adding the flag to the GHC Wiki
--
--    There is a change log tracking language extension additions and removals
--    on the GHC wiki:  https://ghc.haskell.org/trac/ghc/wiki/LanguagePragmaHistory
--
--  See Trac #4437 and #8176.

-- -----------------------------------------------------------------------------
-- DynFlags

data DumpFlag
-- See Note [Updating flag description in the User's Guide]

   -- debugging flags
   = Opt_D_dump_cmm
   | Opt_D_dump_cmm_raw
   -- All of the cmm subflags (there are a lot!)  Automatically
   -- enabled if you run -ddump-cmm
   | Opt_D_dump_cmm_cfg
   | Opt_D_dump_cmm_cbe
   | Opt_D_dump_cmm_switch
   | Opt_D_dump_cmm_proc
   | Opt_D_dump_cmm_sink
   | Opt_D_dump_cmm_sp
   | Opt_D_dump_cmm_procmap
   | Opt_D_dump_cmm_split
   | Opt_D_dump_cmm_info
   | Opt_D_dump_cmm_cps
   -- end cmm subflags
   | Opt_D_dump_asm
   | Opt_D_dump_asm_native
   | Opt_D_dump_asm_liveness
   | Opt_D_dump_asm_regalloc
   | Opt_D_dump_asm_regalloc_stages
   | Opt_D_dump_asm_conflicts
   | Opt_D_dump_asm_stats
   | Opt_D_dump_asm_expanded
   | Opt_D_dump_llvm
   | Opt_D_dump_core_stats
   | Opt_D_dump_deriv
   | Opt_D_dump_ds
   | Opt_D_dump_foreign
   | Opt_D_dump_inlinings
   | Opt_D_dump_rule_firings
   | Opt_D_dump_rule_rewrites
   | Opt_D_dump_simpl_trace
   | Opt_D_dump_occur_anal
   | Opt_D_dump_parsed
   | Opt_D_dump_rn
   | Opt_D_dump_simpl
   | Opt_D_dump_simpl_iterations
   | Opt_D_dump_spec
   | Opt_D_dump_prep
   | Opt_D_dump_stg
   | Opt_D_dump_call_arity
   | Opt_D_dump_stranal
   | Opt_D_dump_strsigs
   | Opt_D_dump_tc
   | Opt_D_dump_types
   | Opt_D_dump_rules
   | Opt_D_dump_cse
   | Opt_D_dump_worker_wrapper
   | Opt_D_dump_rn_trace
   | Opt_D_dump_rn_stats
   | Opt_D_dump_opt_cmm
   | Opt_D_dump_simpl_stats
   | Opt_D_dump_cs_trace -- Constraint solver in type checker
   | Opt_D_dump_tc_trace
   | Opt_D_dump_if_trace
   | Opt_D_dump_vt_trace
   | Opt_D_dump_splices
   | Opt_D_th_dec_file
   | Opt_D_dump_BCOs
   | Opt_D_dump_vect
   | Opt_D_dump_ticked
   | Opt_D_dump_rtti
   | Opt_D_source_stats
   | Opt_D_verbose_stg2stg
   | Opt_D_dump_hi
   | Opt_D_dump_hi_diffs
   | Opt_D_dump_mod_cycles
   | Opt_D_dump_mod_map
   | Opt_D_dump_view_pattern_commoning
   | Opt_D_verbose_core2core
   | Opt_D_dump_debug

   deriving (Eq, Show, Enum)

-- | Enumerates the simple on-or-off dynamic flags
data GeneralFlag
-- See Note [Updating flag description in the User's Guide]

   = Opt_DumpToFile                     -- ^ Append dump output to files instead of stdout.
   | Opt_D_faststring_stats
   | Opt_D_dump_minimal_imports
   | Opt_DoCoreLinting
   | Opt_DoStgLinting
   | Opt_DoCmmLinting
   | Opt_DoAsmLinting
   | Opt_DoAnnotationLinting
   | Opt_NoLlvmMangler                 -- hidden flag

   | Opt_WarnIsError                    -- -Werror; makes warnings fatal

   | Opt_PrintExplicitForalls
   | Opt_PrintExplicitKinds
   | Opt_PrintExplicitCoercions
   | Opt_PrintEqualityRelations
   | Opt_PrintUnicodeSyntax
   | Opt_PrintExpandedSynonyms
   | Opt_PrintPotentialInstances
   | Opt_PrintTypecheckerElaboration

   -- optimisation opts
   | Opt_CallArity
   | Opt_Strictness
   | Opt_LateDmdAnal
   | Opt_KillAbsence
   | Opt_KillOneShot
   | Opt_FullLaziness
   | Opt_FloatIn
   | Opt_Specialise
   | Opt_SpecialiseAggressively
   | Opt_CrossModuleSpecialise
   | Opt_StaticArgumentTransformation
   | Opt_CSE
   | Opt_LiberateCase
   | Opt_SpecConstr
   | Opt_DoLambdaEtaExpansion
   | Opt_IgnoreAsserts
   | Opt_DoEtaReduction
   | Opt_CaseMerge
   | Opt_UnboxStrictFields
   | Opt_UnboxSmallStrictFields
   | Opt_DictsCheap
   | Opt_EnableRewriteRules             -- Apply rewrite rules during simplification
   | Opt_Vectorise
   | Opt_VectorisationAvoidance
   | Opt_RegsGraph                      -- do graph coloring register allocation
   | Opt_RegsIterative                  -- do iterative coalescing graph coloring register allocation
   | Opt_PedanticBottoms                -- Be picky about how we treat bottom
   | Opt_LlvmTBAA                       -- Use LLVM TBAA infastructure for improving AA (hidden flag)
   | Opt_LlvmPassVectorsInRegisters     -- Pass SIMD vectors in registers (requires a patched LLVM) (hidden flag)
   | Opt_LlvmFillUndefWithGarbage       -- Testing for undef bugs (hidden flag)
   | Opt_IrrefutableTuples
   | Opt_CmmSink
   | Opt_CmmElimCommonBlocks
   | Opt_OmitYields
   | Opt_SimpleListLiterals
   | Opt_FunToThunk               -- allow WwLib.mkWorkerArgs to remove all value lambdas
   | Opt_DictsStrict                     -- be strict in argument dictionaries
   | Opt_DmdTxDictSel              -- use a special demand transformer for dictionary selectors
   | Opt_Loopification                  -- See Note [Self-recursive tail calls]
   | Opt_CprAnal
   | Opt_WorkerWrapper

   -- Interface files
   | Opt_IgnoreInterfacePragmas
   | Opt_OmitInterfacePragmas
   | Opt_ExposeAllUnfoldings
   | Opt_WriteInterface -- forces .hi files to be written even with -fno-code

   -- profiling opts
   | Opt_AutoSccsOnIndividualCafs
   | Opt_ProfCountEntries

   -- misc opts
   | Opt_Pp
   | Opt_ForceRecomp
   | Opt_ExcessPrecision
   | Opt_EagerBlackHoling
   | Opt_NoHsMain
   | Opt_SplitObjs
   | Opt_SplitSections
   | Opt_StgStats
   | Opt_HideAllPackages
   | Opt_HideAllPluginPackages
   | Opt_PrintBindResult
   | Opt_Haddock
   | Opt_HaddockOptions
   | Opt_BreakOnException
   | Opt_BreakOnError
   | Opt_PrintEvldWithShow
   | Opt_PrintBindContents
   | Opt_GenManifest
   | Opt_EmbedManifest
   | Opt_SharedImplib
   | Opt_BuildingCabalPackage
   | Opt_IgnoreDotGhci
   | Opt_GhciSandbox
   | Opt_GhciHistory
   | Opt_HelpfulErrors
   | Opt_DeferTypeErrors
   | Opt_DeferTypedHoles
   | Opt_PIC
   | Opt_SccProfilingOn
   | Opt_Ticky
   | Opt_Ticky_Allocd
   | Opt_Ticky_LNE
   | Opt_Ticky_Dyn_Thunk
   | Opt_RPath
   | Opt_RelativeDynlibPaths
   | Opt_Hpc
   | Opt_FlatCache
   | Opt_ExternalInterpreter

   -- PreInlining is on by default. The option is there just to see how
   -- bad things get if you turn it off!
   | Opt_SimplPreInlining

   -- output style opts
   | Opt_ErrorSpans -- Include full span info in error messages,
                    -- instead of just the start position.
   | Opt_PprCaseAsLet
   | Opt_PprShowTicks

   -- Suppress all coercions, them replacing with '...'
   | Opt_SuppressCoercions
   | Opt_SuppressVarKinds
   -- Suppress module id prefixes on variables.
   | Opt_SuppressModulePrefixes
   -- Suppress type applications.
   | Opt_SuppressTypeApplications
   -- Suppress info such as arity and unfoldings on identifiers.
   | Opt_SuppressIdInfo
   -- Suppress separate type signatures in core, but leave types on
   -- lambda bound vars
   | Opt_SuppressUnfoldings
   -- Suppress the details of even stable unfoldings
   | Opt_SuppressTypeSignatures
   -- Suppress unique ids on variables.
   -- Except for uniques, as some simplifier phases introduce new
   -- variables that have otherwise identical names.
   | Opt_SuppressUniques

   -- temporary flags
   | Opt_AutoLinkPackages
   | Opt_ImplicitImportQualified

   -- keeping stuff
   | Opt_KeepHiDiffs
   | Opt_KeepHcFiles
   | Opt_KeepSFiles
   | Opt_KeepTmpFiles
   | Opt_KeepRawTokenStream
   | Opt_KeepLlvmFiles

   | Opt_BuildDynamicToo

   -- safe haskell flags
   | Opt_DistrustAllPackages
   | Opt_PackageTrust
   deriving (Eq, Show, Enum)

data WarningFlag =
-- See Note [Updating flag description in the User's Guide]
     Opt_WarnDuplicateExports
   | Opt_WarnDuplicateConstraints
   | Opt_WarnRedundantConstraints
   | Opt_WarnHiShadows
   | Opt_WarnImplicitPrelude
   | Opt_WarnIncompletePatterns
   | Opt_WarnIncompleteUniPatterns
   | Opt_WarnIncompletePatternsRecUpd
   | Opt_WarnOverflowedLiterals
   | Opt_WarnEmptyEnumerations
   | Opt_WarnMissingFields
   | Opt_WarnMissingImportList
   | Opt_WarnMissingMethods
   | Opt_WarnMissingSigs
   | Opt_WarnMissingLocalSigs
   | Opt_WarnNameShadowing
   | Opt_WarnOverlappingPatterns
   | Opt_WarnTypeDefaults
   | Opt_WarnMonomorphism
   | Opt_WarnUnusedTopBinds
   | Opt_WarnUnusedLocalBinds
   | Opt_WarnUnusedPatternBinds
   | Opt_WarnUnusedImports
   | Opt_WarnUnusedMatches
   | Opt_WarnUnusedTypePatterns
   | Opt_WarnUnusedForalls
   | Opt_WarnContextQuantification -- remove in 8.2
   | Opt_WarnWarningsDeprecations
   | Opt_WarnDeprecatedFlags
   | Opt_WarnAMP -- Introduced in GHC 7.8, obsolete since 7.10
   | Opt_WarnMissingMonadFailInstances -- since 8.0
   | Opt_WarnSemigroup -- since 8.0
   | Opt_WarnDodgyExports
   | Opt_WarnDodgyImports
   | Opt_WarnOrphans
   | Opt_WarnAutoOrphans
   | Opt_WarnIdentities
   | Opt_WarnTabs
   | Opt_WarnUnrecognisedPragmas
   | Opt_WarnDodgyForeignImports
   | Opt_WarnUnusedDoBind
   | Opt_WarnWrongDoBind
   | Opt_WarnAlternativeLayoutRuleTransitional
   | Opt_WarnUnsafe
   | Opt_WarnSafe
   | Opt_WarnTrustworthySafe
   | Opt_WarnMissedSpecs
   | Opt_WarnAllMissedSpecs
   | Opt_WarnUnsupportedCallingConventions
   | Opt_WarnUnsupportedLlvmVersion
   | Opt_WarnInlineRuleShadowing
   | Opt_WarnTypedHoles
   | Opt_WarnPartialTypeSignatures
   | Opt_WarnMissingExportedSigs
   | Opt_WarnUntickedPromotedConstructors
   | Opt_WarnDerivingTypeable
   | Opt_WarnDeferredTypeErrors
   | Opt_WarnNonCanonicalMonadInstances   -- since 8.0
   | Opt_WarnNonCanonicalMonadFailInstances -- since 8.0
   | Opt_WarnNonCanonicalMonoidInstances  -- since 8.0
   | Opt_WarnMissingPatSynSigs            -- since 8.0
   | Opt_WarnUnrecognisedWarningFlags     -- since 8.0
   deriving (Eq, Show, Enum)

data Language = Haskell98 | Haskell2010
   deriving (Eq, Enum, Show)

instance Outputable Language where
    ppr = text . show

-- | The various Safe Haskell modes
data SafeHaskellMode
   = Sf_None
   | Sf_Unsafe
   | Sf_Trustworthy
   | Sf_Safe
   deriving (Eq)

instance Show SafeHaskellMode where
    show Sf_None         = "None"
    show Sf_Unsafe       = "Unsafe"
    show Sf_Trustworthy  = "Trustworthy"
    show Sf_Safe         = "Safe"

instance Outputable SafeHaskellMode where
    ppr = text . show

type SigOf = Map ModuleName Module

getSigOf :: DynFlags -> ModuleName -> Maybe Module
getSigOf dflags n = Map.lookup n (sigOf dflags)

-- | Contains not only a collection of 'GeneralFlag's but also a plethora of
-- information relating to the compilation of a single file or GHC session
data DynFlags = DynFlags {
  ghcMode               :: GhcMode,
  ghcLink               :: GhcLink,
  hscTarget             :: HscTarget,
  settings              :: Settings,
  -- See Note [Signature parameters in TcGblEnv and DynFlags]
  sigOf                 :: SigOf,       -- ^ Compiling an hs-boot against impl.
  verbosity             :: Int,         -- ^ Verbosity level: see Note [Verbosity levels]
  optLevel              :: Int,         -- ^ Optimisation level
  debugLevel            :: Int,         -- ^ How much debug information to produce
  simplPhases           :: Int,         -- ^ Number of simplifier phases
  maxSimplIterations    :: Int,         -- ^ Max simplifier iterations
  maxPmCheckIterations  :: Int,         -- ^ Max no iterations for pm checking
  ruleCheck             :: Maybe String,
  strictnessBefore      :: [Int],       -- ^ Additional demand analysis

  parMakeCount          :: Maybe Int,   -- ^ The number of modules to compile in parallel
                                        --   in --make mode, where Nothing ==> compile as
                                        --   many in parallel as there are CPUs.

  enableTimeStats       :: Bool,        -- ^ Enable RTS timing statistics?
  ghcHeapSize           :: Maybe Int,   -- ^ The heap size to set.

  maxRelevantBinds      :: Maybe Int,   -- ^ Maximum number of bindings from the type envt
                                        --   to show in type error messages
  simplTickFactor       :: Int,         -- ^ Multiplier for simplifier ticks
  specConstrThreshold   :: Maybe Int,   -- ^ Threshold for SpecConstr
  specConstrCount       :: Maybe Int,   -- ^ Max number of specialisations for any one function
  specConstrRecursive   :: Int,         -- ^ Max number of specialisations for recursive types
                                        --   Not optional; otherwise ForceSpecConstr can diverge.
  liberateCaseThreshold :: Maybe Int,   -- ^ Threshold for LiberateCase
  floatLamArgs          :: Maybe Int,   -- ^ Arg count for lambda floating
                                        --   See CoreMonad.FloatOutSwitches

  historySize           :: Int,

  importPaths           :: [FilePath],
  mainModIs             :: Module,
  mainFunIs             :: Maybe String,
  reductionDepth        :: IntWithInf,   -- ^ Typechecker maximum stack depth
  solverIterations      :: IntWithInf,   -- ^ Number of iterations in the constraints solver
                                         --   Typically only 1 is needed

  thisPackage           :: UnitId,   -- ^ key of package currently being compiled

  -- ways
  ways                  :: [Way],       -- ^ Way flags from the command line
  buildTag              :: String,      -- ^ The global \"way\" (e.g. \"p\" for prof)
  rtsBuildTag           :: String,      -- ^ The RTS \"way\"

  -- For object splitting
  splitInfo             :: Maybe (String,Int),

  -- paths etc.
  objectDir             :: Maybe String,
  dylibInstallName      :: Maybe String,
  hiDir                 :: Maybe String,
  stubDir               :: Maybe String,
  dumpDir               :: Maybe String,

  objectSuf             :: String,
  hcSuf                 :: String,
  hiSuf                 :: String,

  canGenerateDynamicToo :: IORef Bool,
  dynObjectSuf          :: String,
  dynHiSuf              :: String,

  -- Packages.isDllName needs to know whether a call is within a
  -- single DLL or not. Normally it does this by seeing if the call
  -- is to the same package, but for the ghc package, we split the
  -- package between 2 DLLs. The dllSplit tells us which sets of
  -- modules are in which package.
  dllSplitFile          :: Maybe FilePath,
  dllSplit              :: Maybe [Set String],

  outputFile            :: Maybe String,
  dynOutputFile         :: Maybe String,
  outputHi              :: Maybe String,
  dynLibLoader          :: DynLibLoader,

  -- | This is set by 'DriverPipeline.runPipeline' based on where
  --    its output is going.
  dumpPrefix            :: Maybe FilePath,

  -- | Override the 'dumpPrefix' set by 'DriverPipeline.runPipeline'.
  --    Set by @-ddump-file-prefix@
  dumpPrefixForce       :: Maybe FilePath,

  ldInputs              :: [Option],

  includePaths          :: [String],
  libraryPaths          :: [String],
  frameworkPaths        :: [String],    -- used on darwin only
  cmdlineFrameworks     :: [String],    -- ditto

  rtsOpts               :: Maybe String,
  rtsOptsEnabled        :: RtsOptsEnabled,
  rtsOptsSuggestions    :: Bool,

  hpcDir                :: String,      -- ^ Path to store the .mix files

  -- Plugins
  pluginModNames        :: [ModuleName],
  pluginModNameOpts     :: [(ModuleName,String)],
  frontendPluginOpts    :: [String],

  -- GHC API hooks
  hooks                 :: Hooks,

  --  For ghc -M
  depMakefile           :: FilePath,
  depIncludePkgDeps     :: Bool,
  depExcludeMods        :: [ModuleName],
  depSuffixes           :: [String],

  --  Package flags
  extraPkgConfs         :: [PkgConfRef] -> [PkgConfRef],
        -- ^ The @-package-db@ flags given on the command line, in the order
        -- they appeared.

  ignorePackageFlags    :: [IgnorePackageFlag],
        -- ^ The @-ignore-package@ flags from the command line
  packageFlags          :: [PackageFlag],
        -- ^ The @-package@ and @-hide-package@ flags from the command-line
  pluginPackageFlags    :: [PackageFlag],
        -- ^ The @-plugin-package-id@ flags from command line
  trustFlags            :: [TrustFlag],
        -- ^ The @-trust@ and @-distrust@ flags
  packageEnv            :: Maybe FilePath,
        -- ^ Filepath to the package environment file (if overriding default)

  -- Package state
  -- NB. do not modify this field, it is calculated by
  -- Packages.initPackages
  pkgDatabase           :: Maybe [(FilePath, [PackageConfig])],
  pkgState              :: PackageState,

  -- Temporary files
  -- These have to be IORefs, because the defaultCleanupHandler needs to
  -- know what to clean when an exception happens
  filesToClean          :: IORef [FilePath],
  dirsToClean           :: IORef (Map FilePath FilePath),
  filesToNotIntermediateClean :: IORef [FilePath],
  -- The next available suffix to uniquely name a temp file, updated atomically
  nextTempSuffix        :: IORef Int,

  -- Names of files which were generated from -ddump-to-file; used to
  -- track which ones we need to truncate because it's our first run
  -- through
  generatedDumps        :: IORef (Set FilePath),

  -- hsc dynamic flags
  dumpFlags             :: IntSet,
  generalFlags          :: IntSet,
  warningFlags          :: IntSet,
  -- Don't change this without updating extensionFlags:
  language              :: Maybe Language,
  -- | Safe Haskell mode
  safeHaskell           :: SafeHaskellMode,
  safeInfer             :: Bool,
  safeInferred          :: Bool,
  -- We store the location of where some extension and flags were turned on so
  -- we can produce accurate error messages when Safe Haskell fails due to
  -- them.
  thOnLoc               :: SrcSpan,
  newDerivOnLoc         :: SrcSpan,
  overlapInstLoc        :: SrcSpan,
  incoherentOnLoc       :: SrcSpan,
  pkgTrustOnLoc         :: SrcSpan,
  warnSafeOnLoc         :: SrcSpan,
  warnUnsafeOnLoc       :: SrcSpan,
  trustworthyOnLoc      :: SrcSpan,
  -- Don't change this without updating extensionFlags:
  extensions            :: [OnOff LangExt.Extension],
  -- extensionFlags should always be equal to
  --     flattenExtensionFlags language extensions
  -- LangExt.Extension is defined in libraries/ghc-boot so that it can be used
  -- by template-haskell
  extensionFlags        :: IntSet,