DynFlags.hs 106 KB
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-- |
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-- Dynamic flags
--
--
-- (c) The University of Glasgow 2005
--

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-- Most flags are dynamic flags, which means they can change from
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-- 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.
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module DynFlags (
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        -- * Dynamic flags and associated configuration types
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        DynFlag(..),
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        WarningFlag(..),
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        ExtensionFlag(..),
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        LogAction,
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        glasgowExtsFlags,
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        dopt,
        dopt_set,
        dopt_unset,
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        wopt,
        wopt_set,
        wopt_unset,
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        xopt,
        xopt_set,
        xopt_unset,
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        DynFlags(..),
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        RtsOptsEnabled(..),
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        HscTarget(..), isObjectTarget, defaultObjectTarget,
        GhcMode(..), isOneShot,
        GhcLink(..), isNoLink,
        PackageFlag(..),
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        Option(..), showOpt,
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        DynLibLoader(..),
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        fFlags, fWarningFlags, fLangFlags, xFlags,
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        DPHBackend(..), dphPackageMaybe,
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        wayNames, dynFlagDependencies,
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        -- ** Safe Haskell
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        SafeHaskellMode(..),
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        safeHaskellOn, safeLanguageOn,
        safeDirectImpsReq, safeImplicitImpsReq,
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        -- ** System tool settings and locations
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        Settings(..),
        ghcUsagePath, ghciUsagePath, topDir, tmpDir, rawSettings,
        extraGccViaCFlags, systemPackageConfig,
        pgm_L, pgm_P, pgm_F, pgm_c, pgm_s, pgm_a, pgm_l, pgm_dll, pgm_T,
        pgm_sysman, pgm_windres, pgm_lo, pgm_lc,
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        opt_L, opt_P, opt_F, opt_c, opt_a, opt_l,
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        opt_windres, opt_lo, opt_lc,
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        -- ** Manipulating DynFlags
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        defaultDynFlags,                -- Settings -> DynFlags
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        initDynFlags,                   -- DynFlags -> IO DynFlags
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        defaultLogAction,
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        getOpts,                        -- DynFlags -> (DynFlags -> [a]) -> [a]
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        getVerbFlags,
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        updOptLevel,
        setTmpDir,
        setPackageName,
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        doingTickyProfiling,
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        -- ** Parsing DynFlags
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        parseDynamicFlagsCmdLine,
        parseDynamicFilePragma,
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        allFlags,
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        supportedLanguagesAndExtensions,
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        -- ** DynFlag C compiler options
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        picCCOpts,
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        -- * Configuration of the stg-to-stg passes
        StgToDo(..),
        getStgToDo,

        -- * Compiler configuration suitable for display to the user
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        compilerInfo
#ifdef GHCI
-- Only in stage 2 can we be sure that the RTS 
-- exposes the appropriate runtime boolean
        , rtsIsProfiled
#endif
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  ) where

#include "HsVersions.h"

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import Platform
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import Module
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import PackageConfig
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import PrelNames        ( mAIN )
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import StaticFlags
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import {-# SOURCE #-} Packages (PackageState)
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import DriverPhases     ( Phase(..), phaseInputExt )
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import Config
import CmdLineParser
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import Constants        ( mAX_CONTEXT_REDUCTION_DEPTH )
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import Panic
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import Util
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import Maybes           ( orElse )
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import SrcLoc
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import FastString
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import Outputable
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#ifdef GHCI
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import Foreign.C	( CInt )
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#endif
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import {-# SOURCE #-} ErrUtils ( Severity(..), Message, mkLocMessage )
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#ifdef GHCI
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import System.IO.Unsafe	( unsafePerformIO )
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#endif
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import Data.IORef
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import Control.Monad    ( when )
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import Data.Char
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import Data.List
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import Data.Map (Map)
import qualified Data.Map as Map
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import Data.Set (Set)
import qualified Data.Set as Set
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import System.FilePath
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import System.IO        ( stderr, hPutChar )
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-- -----------------------------------------------------------------------------
-- DynFlags

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-- | Enumerates the simple on-or-off dynamic flags
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data DynFlag

   -- debugging flags
   = Opt_D_dump_cmm
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   | Opt_D_dump_raw_cmm
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   | Opt_D_dump_cmmz
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   | Opt_D_dump_cmmz_pretty
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   -- All of the cmmz subflags (there are a lot!)  Automatically
   -- enabled if you run -ddump-cmmz
   | Opt_D_dump_cmmz_cbe
   | Opt_D_dump_cmmz_proc
   | Opt_D_dump_cmmz_spills
   | Opt_D_dump_cmmz_rewrite
   | Opt_D_dump_cmmz_dead
   | Opt_D_dump_cmmz_stub
   | Opt_D_dump_cmmz_sp
   | Opt_D_dump_cmmz_procmap
   | Opt_D_dump_cmmz_split
   | Opt_D_dump_cmmz_lower
   | Opt_D_dump_cmmz_info
   | Opt_D_dump_cmmz_cafs
   -- end cmmz subflags
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   | Opt_D_dump_cps_cmm
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   | Opt_D_dump_cvt_cmm
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   | Opt_D_dump_asm
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   | Opt_D_dump_asm_native
   | Opt_D_dump_asm_liveness
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   | Opt_D_dump_asm_coalesce
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   | Opt_D_dump_asm_regalloc
   | Opt_D_dump_asm_regalloc_stages
   | Opt_D_dump_asm_conflicts
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   | Opt_D_dump_asm_stats
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   | Opt_D_dump_asm_expanded
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   | Opt_D_dump_llvm
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   | Opt_D_dump_core_stats
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   | Opt_D_dump_cpranal
   | Opt_D_dump_deriv
   | Opt_D_dump_ds
   | Opt_D_dump_flatC
   | Opt_D_dump_foreign
   | Opt_D_dump_inlinings
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   | Opt_D_dump_rule_firings
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   | Opt_D_dump_rule_rewrites
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   | Opt_D_dump_occur_anal
   | Opt_D_dump_parsed
   | Opt_D_dump_rn
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   | Opt_D_dump_core_pipeline -- TODO FIXME: dump after simplifier stats
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   | Opt_D_dump_simpl
   | Opt_D_dump_simpl_iterations
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   | Opt_D_dump_simpl_phases
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   | Opt_D_dump_spec
   | Opt_D_dump_prep
   | Opt_D_dump_stg
   | Opt_D_dump_stranal
   | 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
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   | Opt_D_dump_cs_trace	-- Constraint solver in type checker
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   | Opt_D_dump_tc_trace
   | Opt_D_dump_if_trace
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   | Opt_D_dump_vt_trace
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   | Opt_D_dump_splices
   | Opt_D_dump_BCOs
   | Opt_D_dump_vect
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   | Opt_D_dump_hpc
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   | Opt_D_dump_rtti
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   | Opt_D_source_stats
   | Opt_D_verbose_core2core
   | Opt_D_verbose_stg2stg
   | Opt_D_dump_hi
   | Opt_D_dump_hi_diffs
   | Opt_D_dump_minimal_imports
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   | Opt_D_dump_mod_cycles
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   | Opt_D_dump_view_pattern_commoning
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   | Opt_D_faststring_stats
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   | Opt_DumpToFile                     -- ^ Append dump output to files instead of stdout.
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   | Opt_D_no_debug_output
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   | Opt_DoCoreLinting
   | Opt_DoStgLinting
   | Opt_DoCmmLinting
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   | Opt_DoAsmLinting
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   | Opt_WarnIsError                    -- -Werror; makes warnings fatal
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   | Opt_PrintExplicitForalls

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   -- optimisation opts
   | Opt_Strictness
   | Opt_FullLaziness
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   | Opt_FloatIn
   | Opt_Specialise
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   | Opt_StaticArgumentTransformation
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   | Opt_CSE
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   | Opt_LiberateCase
   | Opt_SpecConstr
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   | Opt_DoLambdaEtaExpansion
   | Opt_IgnoreAsserts
   | Opt_DoEtaReduction
   | Opt_CaseMerge
   | Opt_UnboxStrictFields
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   | Opt_DictsCheap
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   | Opt_EnableRewriteRules		-- Apply rewrite rules during simplification
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   | Opt_Vectorise
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   | Opt_RegsGraph                      -- do graph coloring register allocation
   | Opt_RegsIterative                  -- do iterative coalescing graph coloring register allocation
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   -- Interface files
   | Opt_IgnoreInterfacePragmas
   | Opt_OmitInterfacePragmas
   | Opt_ExposeAllUnfoldings

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   -- profiling opts
   | Opt_AutoSccsOnAllToplevs
   | Opt_AutoSccsOnExportedToplevs
   | Opt_AutoSccsOnIndividualCafs

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   -- misc opts
   | Opt_Pp
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   | Opt_ForceRecomp
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   | Opt_ExcessPrecision
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   | Opt_EagerBlackHoling
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   | Opt_ReadUserPackageConf
   | Opt_NoHsMain
   | Opt_SplitObjs
   | Opt_StgStats
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   | Opt_HideAllPackages
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   | Opt_DistrustAllPackages
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   | Opt_PrintBindResult
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   | Opt_Haddock
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   | Opt_HaddockOptions
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   | Opt_Hpc_No_Auto
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   | Opt_BreakOnException
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   | Opt_BreakOnError
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   | Opt_PrintEvldWithShow
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   | Opt_PrintBindContents
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   | Opt_GenManifest
   | Opt_EmbedManifest
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   | Opt_EmitExternalCore
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   | Opt_SharedImplib
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   | Opt_BuildingCabalPackage
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   | Opt_SSE2
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   | Opt_SSE4_2
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   | Opt_GhciSandbox
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   | Opt_GhciHistory
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   | Opt_HelpfulErrors
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	-- temporary flags
   | Opt_RunCPS
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   | Opt_RunCPSZ
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   | Opt_AutoLinkPackages
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   | Opt_ImplicitImportQualified
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   | Opt_TryNewCodeGen
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   -- keeping stuff
   | Opt_KeepHiDiffs
   | Opt_KeepHcFiles
   | Opt_KeepSFiles
   | Opt_KeepTmpFiles
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   | Opt_KeepRawTokenStream
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   | Opt_KeepLlvmFiles
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   deriving (Eq, Show)
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data WarningFlag =
     Opt_WarnDuplicateExports
   | Opt_WarnHiShadows
   | Opt_WarnImplicitPrelude
   | Opt_WarnIncompletePatterns
   | Opt_WarnIncompleteUniPatterns
   | Opt_WarnIncompletePatternsRecUpd
   | Opt_WarnMissingFields
   | Opt_WarnMissingImportList
   | Opt_WarnMissingMethods
   | Opt_WarnMissingSigs
   | Opt_WarnMissingLocalSigs
   | Opt_WarnNameShadowing
   | Opt_WarnOverlappingPatterns
   | Opt_WarnTypeDefaults
   | Opt_WarnMonomorphism
   | Opt_WarnUnusedBinds
   | Opt_WarnUnusedImports
   | Opt_WarnUnusedMatches
   | Opt_WarnWarningsDeprecations
   | Opt_WarnDeprecatedFlags
   | Opt_WarnDodgyExports
   | Opt_WarnDodgyImports
   | Opt_WarnOrphans
   | Opt_WarnAutoOrphans
   | Opt_WarnIdentities
   | Opt_WarnTabs
   | Opt_WarnUnrecognisedPragmas
   | Opt_WarnDodgyForeignImports
   | Opt_WarnLazyUnliftedBindings
   | Opt_WarnUnusedDoBind
   | Opt_WarnWrongDoBind
   | Opt_WarnAlternativeLayoutRuleTransitional
   deriving (Eq, Show)

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data Language = Haskell98 | Haskell2010

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

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instance Outputable SafeHaskellMode where
    ppr Sf_None = ptext $ sLit "None"
    ppr Sf_SafeImports = ptext $ sLit "SafeImports"
    ppr Sf_Trustworthy = ptext $ sLit "Trustworthy"
    ppr Sf_Safe = ptext $ sLit "Safe"
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data ExtensionFlag
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   = Opt_Cpp
   | Opt_OverlappingInstances
   | Opt_UndecidableInstances
   | Opt_IncoherentInstances
   | Opt_MonomorphismRestriction
   | Opt_MonoPatBinds
   | Opt_MonoLocalBinds
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   | Opt_RelaxedPolyRec		-- Deprecated
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   | Opt_ExtendedDefaultRules           -- Use GHC's extended rules for defaulting
   | Opt_ForeignFunctionInterface
   | Opt_UnliftedFFITypes
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   | Opt_InterruptibleFFI
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   | Opt_GHCForeignImportPrim
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   | Opt_ParallelArrays                 -- Syntactic support for parallel arrays
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   | Opt_Arrows                         -- Arrow-notation syntax
   | Opt_TemplateHaskell
   | Opt_QuasiQuotes
   | Opt_ImplicitParams
   | Opt_ImplicitPrelude
   | Opt_ScopedTypeVariables
   | Opt_UnboxedTuples
   | Opt_BangPatterns
   | Opt_TypeFamilies
   | Opt_OverloadedStrings
   | Opt_DisambiguateRecordFields
   | Opt_RecordWildCards
   | Opt_RecordPuns
   | Opt_ViewPatterns
   | Opt_GADTs
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   | Opt_GADTSyntax
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   | Opt_NPlusKPatterns
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   | Opt_DoAndIfThenElse
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   | Opt_RebindableSyntax
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   | Opt_ConstraintKind
   
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   | Opt_StandaloneDeriving
   | Opt_DeriveDataTypeable
   | Opt_DeriveFunctor
   | Opt_DeriveTraversable
   | Opt_DeriveFoldable
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   | Opt_DeriveGeneric            -- Allow deriving Generic/1
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   | Opt_DefaultSignatures        -- Allow extra signatures for defmeths
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   | Opt_TypeSynonymInstances
   | Opt_FlexibleContexts
   | Opt_FlexibleInstances
   | Opt_ConstrainedClassMethods
   | Opt_MultiParamTypeClasses
   | Opt_FunctionalDependencies
   | Opt_UnicodeSyntax
   | Opt_PolymorphicComponents
   | Opt_ExistentialQuantification
   | Opt_MagicHash
   | Opt_EmptyDataDecls
   | Opt_KindSignatures
   | Opt_ParallelListComp
   | Opt_TransformListComp
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   | Opt_MonadComprehensions
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   | Opt_GeneralizedNewtypeDeriving
   | Opt_RecursiveDo
   | Opt_DoRec
   | Opt_PostfixOperators
   | Opt_TupleSections
   | Opt_PatternGuards
   | Opt_LiberalTypeSynonyms
   | Opt_Rank2Types
   | Opt_RankNTypes
   | Opt_ImpredicativeTypes
   | Opt_TypeOperators
   | Opt_PackageImports
   | Opt_ExplicitForAll
   | Opt_AlternativeLayoutRule
   | Opt_AlternativeLayoutRuleTransitional
   | Opt_DatatypeContexts
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   | Opt_NondecreasingIndentation
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   | Opt_RelaxedLayout
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   deriving (Eq, Show)

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-- | Contains not only a collection of 'DynFlag's but also a plethora of
-- information relating to the compilation of a single file or GHC session
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data DynFlags = DynFlags {
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  ghcMode               :: GhcMode,
  ghcLink               :: GhcLink,
  hscTarget             :: HscTarget,
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  hscOutName            :: String,      -- ^ Name of the output file
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  extCoreName           :: String,      -- ^ Name of the .hcr output file
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  verbosity             :: Int,         -- ^ Verbosity level: see Note [Verbosity levels]
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  optLevel              :: Int,         -- ^ Optimisation level
  simplPhases           :: Int,         -- ^ Number of simplifier phases
  maxSimplIterations    :: Int,         -- ^ Max simplifier iterations
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  shouldDumpSimplPhase  :: Maybe String,
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  ruleCheck             :: Maybe String,
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  strictnessBefore      :: [Int],       -- ^ Additional demand analysis
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  specConstrThreshold   :: Maybe Int,   -- ^ Threshold for SpecConstr
  specConstrCount       :: Maybe Int,   -- ^ Max number of specialisations for any one function
  liberateCaseThreshold :: Maybe Int,   -- ^ Threshold for LiberateCase
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  floatLamArgs          :: Maybe Int,   -- ^ Arg count for lambda floating
  			   	 	--   See CoreMonad.FloatOutSwitches
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  targetPlatform        :: Platform.Platform, -- ^ The platform we're compiling for. Used by the NCG.
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  cmdlineHcIncludes     :: [String],    -- ^ @\-\#includes@
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  importPaths           :: [FilePath],
  mainModIs             :: Module,
  mainFunIs             :: Maybe String,
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  ctxtStkDepth          :: Int,         -- ^ Typechecker context stack depth
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  dphBackend            :: DPHBackend,

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  thisPackage           :: PackageId,   -- ^ name of package currently being compiled
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  -- ways
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  ways                  :: [Way],       -- ^ Way flags from the command line
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  buildTag              :: String,      -- ^ The global \"way\" (e.g. \"p\" for prof)
  rtsBuildTag           :: String,      -- ^ The RTS \"way\"
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  -- For object splitting
  splitInfo             :: Maybe (String,Int),

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  -- paths etc.
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  objectDir             :: Maybe String,
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  dylibInstallName      :: Maybe String,
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  hiDir                 :: Maybe String,
  stubDir               :: Maybe String,
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  objectSuf             :: String,
  hcSuf                 :: String,
  hiSuf                 :: String,
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  outputFile            :: Maybe String,
  outputHi              :: Maybe String,
  dynLibLoader          :: DynLibLoader,
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  -- | This is set by 'DriverPipeline.runPipeline' based on where
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  --    its output is going.
  dumpPrefix            :: Maybe FilePath,
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  -- | Override the 'dumpPrefix' set by 'DriverPipeline.runPipeline'.
  --    Set by @-ddump-file-prefix@
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  dumpPrefixForce       :: Maybe FilePath,

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

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  rtsOpts               :: Maybe String,
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  rtsOptsEnabled        :: RtsOptsEnabled,
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  hpcDir                :: String,      -- ^ Path to store the .mix files
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  -- Plugins
  pluginModNames        :: [ModuleName],
  pluginModNameOpts     :: [(ModuleName,String)],

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

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  --  Package flags
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  extraPkgConfs         :: [FilePath],
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        -- ^ The @-package-conf@ flags given on the command line, in the order
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        -- they appeared.
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  packageFlags          :: [PackageFlag],
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        -- ^ The @-package@ and @-hide-package@ flags from the command-line
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  -- Package state
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  -- NB. do not modify this field, it is calculated by
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  -- Packages.initPackages and Packages.updatePackages.
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  pkgDatabase           :: Maybe [PackageConfig],
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  pkgState              :: PackageState,
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  -- Temporary files
  -- These have to be IORefs, because the defaultCleanupHandler needs to
  -- know what to clean when an exception happens
  filesToClean          :: IORef [FilePath],
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  dirsToClean           :: IORef (Map FilePath FilePath),
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  -- 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),

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  -- hsc dynamic flags
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  flags                 :: [DynFlag],
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  warningFlags          :: [WarningFlag],
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  -- Don't change this without updating extensionFlags:
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  language              :: Maybe Language,
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  -- | Safe Haskell mode
  safeHaskell           :: SafeHaskellMode,
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  -- Don't change this without updating extensionFlags:
  extensions            :: [OnOff ExtensionFlag],
  -- extensionFlags should always be equal to
  --     flattenExtensionFlags language extensions
  extensionFlags        :: [ExtensionFlag],
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  -- | Message output action: use "ErrUtils" instead of this if you can
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  log_action            :: LogAction,
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  haddockOptions :: Maybe String
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 }

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data Settings = Settings {
  sGhcUsagePath          :: FilePath,    -- Filled in by SysTools
  sGhciUsagePath         :: FilePath,    -- ditto
  sTopDir                :: FilePath,
  sTmpDir                :: String,      -- no trailing '/'
  -- You shouldn't need to look things up in rawSettings directly.
  -- They should have their own fields instead.
  sRawSettings           :: [(String, String)],
  sExtraGccViaCFlags     :: [String],
  sSystemPackageConfig   :: FilePath,
  -- commands for particular phases
  sPgm_L                 :: String,
  sPgm_P                 :: (String,[Option]),
  sPgm_F                 :: String,
  sPgm_c                 :: (String,[Option]),
  sPgm_s                 :: (String,[Option]),
  sPgm_a                 :: (String,[Option]),
  sPgm_l                 :: (String,[Option]),
  sPgm_dll               :: (String,[Option]),
  sPgm_T                 :: String,
  sPgm_sysman            :: String,
  sPgm_windres           :: String,
  sPgm_lo                :: (String,[Option]), -- LLVM: opt llvm optimiser
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  sPgm_lc                :: (String,[Option]), -- LLVM: llc static compiler
  -- options for particular phases
  sOpt_L                 :: [String],
  sOpt_P                 :: [String],
  sOpt_F                 :: [String],
  sOpt_c                 :: [String],
  sOpt_a                 :: [String],
  sOpt_l                 :: [String],
  sOpt_windres           :: [String],
  sOpt_lo                :: [String], -- LLVM: llvm optimiser
  sOpt_lc                :: [String]  -- LLVM: llc static compiler

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 }

ghcUsagePath          :: DynFlags -> FilePath
ghcUsagePath dflags = sGhcUsagePath (settings dflags)
ghciUsagePath         :: DynFlags -> FilePath
ghciUsagePath dflags = sGhciUsagePath (settings dflags)
topDir                :: DynFlags -> FilePath
topDir dflags = sTopDir (settings dflags)
tmpDir                :: DynFlags -> String
tmpDir dflags = sTmpDir (settings dflags)
rawSettings           :: DynFlags -> [(String, String)]
rawSettings dflags = sRawSettings (settings dflags)
extraGccViaCFlags     :: DynFlags -> [String]
extraGccViaCFlags dflags = sExtraGccViaCFlags (settings dflags)
systemPackageConfig   :: DynFlags -> FilePath
systemPackageConfig dflags = sSystemPackageConfig (settings dflags)
pgm_L                 :: DynFlags -> String
pgm_L dflags = sPgm_L (settings dflags)
pgm_P                 :: DynFlags -> (String,[Option])
pgm_P dflags = sPgm_P (settings dflags)
pgm_F                 :: DynFlags -> String
pgm_F dflags = sPgm_F (settings dflags)
pgm_c                 :: DynFlags -> (String,[Option])
pgm_c dflags = sPgm_c (settings dflags)
pgm_s                 :: DynFlags -> (String,[Option])
pgm_s dflags = sPgm_s (settings dflags)
pgm_a                 :: DynFlags -> (String,[Option])
pgm_a dflags = sPgm_a (settings dflags)
pgm_l                 :: DynFlags -> (String,[Option])
pgm_l dflags = sPgm_l (settings dflags)
pgm_dll               :: DynFlags -> (String,[Option])
pgm_dll dflags = sPgm_dll (settings dflags)
pgm_T                 :: DynFlags -> String
pgm_T dflags = sPgm_T (settings dflags)
pgm_sysman            :: DynFlags -> String
pgm_sysman dflags = sPgm_sysman (settings dflags)
pgm_windres           :: DynFlags -> String
pgm_windres dflags = sPgm_windres (settings dflags)
pgm_lo                :: DynFlags -> (String,[Option])
pgm_lo dflags = sPgm_lo (settings dflags)
pgm_lc                :: DynFlags -> (String,[Option])
pgm_lc dflags = sPgm_lc (settings dflags)
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opt_L                 :: DynFlags -> [String]
opt_L dflags = sOpt_L (settings dflags)
opt_P                 :: DynFlags -> [String]
opt_P dflags = sOpt_P (settings dflags)
opt_F                 :: DynFlags -> [String]
opt_F dflags = sOpt_F (settings dflags)
opt_c                 :: DynFlags -> [String]
opt_c dflags = sOpt_c (settings dflags)
opt_a                 :: DynFlags -> [String]
opt_a dflags = sOpt_a (settings dflags)
opt_l                 :: DynFlags -> [String]
opt_l dflags = sOpt_l (settings dflags)
opt_windres           :: DynFlags -> [String]
opt_windres dflags = sOpt_windres (settings dflags)
opt_lo                :: DynFlags -> [String]
opt_lo dflags = sOpt_lo (settings dflags)
opt_lc                :: DynFlags -> [String]
opt_lc dflags = sOpt_lc (settings dflags)
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wayNames :: DynFlags -> [WayName]
wayNames = map wayName . ways

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-- | The target code type of the compilation (if any).
--
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-- Whenever you change the target, also make sure to set 'ghcLink' to
-- something sensible.
--
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-- 'HscNothing' can be used to avoid generating any output, however, note
-- that:
--
--  * This will not run the desugaring step, thus no warnings generated in
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--    this step will be output.  In particular, this includes warnings related
--    to pattern matching.  You can run the desugarer manually using
--    'GHC.desugarModule'.
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--
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--  * If a program uses Template Haskell the typechecker may try to run code
--    from an imported module.  This will fail if no code has been generated
--    for this module.  You can use 'GHC.needsTemplateHaskell' to detect
--    whether this might be the case and choose to either switch to a
--    different target or avoid typechecking such modules.  (The latter may
--    preferable for security reasons.)
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--
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data HscTarget
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  = HscC           -- ^ Generate C code.
  | HscAsm         -- ^ Generate assembly using the native code generator.
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  | HscLlvm        -- ^ Generate assembly using the llvm code generator.
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  | HscInterpreted -- ^ Generate bytecode.  (Requires 'LinkInMemory')
  | HscNothing     -- ^ Don't generate any code.  See notes above.
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  deriving (Eq, Show)

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showHscTargetFlag :: HscTarget -> String
showHscTargetFlag HscC           = "-fvia-c"
showHscTargetFlag HscAsm         = "-fasm"
showHscTargetFlag HscLlvm        = "-fllvm"
showHscTargetFlag HscInterpreted = "-fbyte-code"
showHscTargetFlag HscNothing     = "-fno-code"

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-- | Will this target result in an object file on the disk?
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isObjectTarget :: HscTarget -> Bool
isObjectTarget HscC     = True
isObjectTarget HscAsm   = True
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isObjectTarget HscLlvm  = True
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isObjectTarget _        = False

-- | The 'GhcMode' tells us whether we're doing multi-module
-- compilation (controlled via the "GHC" API) or one-shot
-- (single-module) compilation.  This makes a difference primarily to
-- the "Finder": in one-shot mode we look for interface files for
-- imported modules, but in multi-module mode we look for source files
-- in order to check whether they need to be recompiled.
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data GhcMode
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  = CompManager         -- ^ @\-\-make@, GHCi, etc.
  | OneShot             -- ^ @ghc -c Foo.hs@
  | MkDepend            -- ^ @ghc -M@, see "Finder" for why we need this
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  deriving Eq

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instance Outputable GhcMode where
  ppr CompManager = ptext (sLit "CompManager")
  ppr OneShot     = ptext (sLit "OneShot")
  ppr MkDepend    = ptext (sLit "MkDepend")

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isOneShot :: GhcMode -> Bool
isOneShot OneShot = True
isOneShot _other  = False

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-- | What to do in the link step, if there is one.
data GhcLink
  = NoLink              -- ^ Don't link at all
  | LinkBinary          -- ^ Link object code into a binary
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  | LinkInMemory        -- ^ Use the in-memory dynamic linker (works for both
                        --   bytecode and object code).
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  | LinkDynLib          -- ^ Link objects into a dynamic lib (DLL on Windows, DSO on ELF platforms)
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  deriving (Eq, Show)
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isNoLink :: GhcLink -> Bool
isNoLink NoLink = True
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isNoLink _      = False
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-- Is it worth evaluating this Bool and caching it in the DynFlags value
-- during initDynFlags?
doingTickyProfiling :: DynFlags -> Bool
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doingTickyProfiling _ = opt_Ticky
  -- XXX -ticky is a static flag, because it implies -debug which is also
  -- static.  If the way flags were made dynamic, we could fix this.
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data PackageFlag
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  = ExposePackage   String
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  | ExposePackageId String
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  | HidePackage     String
  | IgnorePackage   String
  | TrustPackage    String
  | DistrustPackage String
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  deriving Eq
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defaultHscTarget :: HscTarget
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defaultHscTarget = defaultObjectTarget

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-- | The 'HscTarget' value corresponding to the default way to create
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-- object files on the current platform.
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defaultObjectTarget :: HscTarget
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defaultObjectTarget
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  | cGhcUnregisterised    == "YES"      =  HscC
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  | cGhcWithNativeCodeGen == "YES"      =  HscAsm
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  | otherwise                           =  HscLlvm
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data DynLibLoader
  = Deployable
  | SystemDependent
  deriving Eq

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data RtsOptsEnabled = RtsOptsNone | RtsOptsSafeOnly | RtsOptsAll
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  deriving (Show)
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-- | Used by 'GHC.newSession' to partially initialize a new 'DynFlags' value
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initDynFlags :: DynFlags -> IO DynFlags
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initDynFlags dflags = do
 -- someday these will be dynamic flags
 ways <- readIORef v_Ways
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 refFilesToClean <- newIORef []
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 refDirsToClean <- newIORef Map.empty
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 refGeneratedDumps <- newIORef Set.empty
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 return dflags{
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        ways            = ways,
        buildTag        = mkBuildTag (filter (not . wayRTSOnly) ways),
        rtsBuildTag     = mkBuildTag ways,
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        filesToClean    = refFilesToClean,
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        dirsToClean     = refDirsToClean,
        generatedDumps   = refGeneratedDumps
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        }
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-- | The normal 'DynFlags'. Note that they is not suitable for use in this form
-- and must be fully initialized by 'GHC.newSession' first.
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defaultDynFlags :: Settings -> DynFlags
defaultDynFlags mySettings =
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     DynFlags {
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        ghcMode                 = CompManager,
        ghcLink                 = LinkBinary,
        hscTarget               = defaultHscTarget,
        hscOutName              = "",
        extCoreName             = "",
        verbosity               = 0,
        optLevel                = 0,
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        simplPhases             = 2,
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        maxSimplIterations      = 4,
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        shouldDumpSimplPhase    = Nothing,
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        ruleCheck               = Nothing,
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        specConstrThreshold     = Just 2000,
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        specConstrCount         = Just 3,
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        liberateCaseThreshold   = Just 2000,
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        floatLamArgs            = Just 0,	-- Default: float only if no fvs
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        strictnessBefore        = [],

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        targetPlatform          = defaultTargetPlatform,
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        cmdlineHcIncludes       = [],
        importPaths             = ["."],
        mainModIs               = mAIN,
        mainFunIs               = Nothing,
        ctxtStkDepth            = mAX_CONTEXT_REDUCTION_DEPTH,

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        dphBackend              = DPHNone,
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        thisPackage             = mainPackageId,

        objectDir               = Nothing,
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        dylibInstallName        = Nothing,
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        hiDir                   = Nothing,
        stubDir                 = Nothing,

        objectSuf               = phaseInputExt StopLn,
        hcSuf                   = phaseInputExt HCc,
        hiSuf                   = "hi",

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        pluginModNames          = [],
        pluginModNameOpts       = [],

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        outputFile              = Nothing,
        outputHi                = Nothing,
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        dynLibLoader            = SystemDependent,
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        dumpPrefix              = Nothing,
        dumpPrefixForce         = Nothing,
        includePaths            = [],
        libraryPaths            = [],
        frameworkPaths          = [],
        cmdlineFrameworks       = [],
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        rtsOpts                 = Nothing,
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        rtsOptsEnabled          = RtsOptsSafeOnly,
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        hpcDir                  = ".hpc",

        extraPkgConfs           = [],
        packageFlags            = [],
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        pkgDatabase             = Nothing,
        pkgState                = panic "no package state yet: call GHC.setSessionDynFlags",
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        ways                    = panic "defaultDynFlags: No ways",
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        buildTag                = panic "defaultDynFlags: No buildTag",
        rtsBuildTag             = panic "defaultDynFlags: No rtsBuildTag",
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        splitInfo               = Nothing,
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        settings                = mySettings,
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        -- ghc -M values
        depMakefile       = "Makefile",
        depIncludePkgDeps = False,
        depExcludeMods    = [],
        depSuffixes       = [],
        -- end of ghc -M values
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        filesToClean   = panic "defaultDynFlags: No filesToClean",
        dirsToClean    = panic "defaultDynFlags: No dirsToClean",
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        generatedDumps = panic "defaultDynFlags: No generatedDumps",
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        haddockOptions = Nothing,
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        flags = defaultFlags,
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        warningFlags = standardWarnings,
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        language = Nothing,
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        safeHaskell = Sf_None,
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        extensions = [],
        extensionFlags = flattenExtensionFlags Nothing [],
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        log_action = defaultLogAction
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      }

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type LogAction = Severity -> SrcSpan -> PprStyle -> Message -> IO ()

defaultLogAction :: LogAction
defaultLogAction severity srcSpan style msg
 = case severity of
   SevOutput -> printSDoc msg style
   SevInfo   -> printErrs msg style
   SevFatal  -> printErrs msg style
   _         -> do hPutChar stderr '\n'
                   printErrs (mkLocMessage srcSpan msg) style
                   -- careful (#2302): printErrs prints in UTF-8, whereas
                   -- converting to string first and using hPutStr would
                   -- just emit the low 8 bits of each unicode char.

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{-
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Note [Verbosity levels]
~~~~~~~~~~~~~~~~~~~~~~~
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    0   |   print errors & warnings only
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    1   |   minimal verbosity: print "compiling M ... done." for each module.
    2   |   equivalent to -dshow-passes
    3   |   equivalent to existing "ghc -v"
    4   |   "ghc -v -ddump-most"
    5   |   "ghc -v -ddump-all"
-}

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data OnOff a = On a
             | Off a

-- OnOffs accumulate in reverse order, so we use foldr in order to
-- process them in the right order
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flattenExtensionFlags :: Maybe Language -> [OnOff ExtensionFlag]
                      -> [ExtensionFlag]
flattenExtensionFlags ml = foldr f defaultExtensionFlags
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    where f (On f)  flags = f : delete f flags
          f (Off f) flags =     delete f flags
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          defaultExtensionFlags = languageExtensions ml

languageExtensions :: Maybe Language -> [ExtensionFlag]
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languageExtensions Nothing
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    -- Nothing => the default case
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    = Opt_NondecreasingIndentation -- This has been on by default for some time
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    : delete Opt_DatatypeContexts  -- The Haskell' committee decided to
                                   -- remove datatype contexts from the
                                   -- language:
   -- http://www.haskell.org/pipermail/haskell-prime/2011-January/003335.html
      (languageExtensions (Just Haskell2010))
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   -- NB: MonoPatBinds is no longer the default

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languageExtensions (Just Haskell98)
    = [Opt_ImplicitPrelude,
       Opt_MonomorphismRestriction,
       Opt_NPlusKPatterns,
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       Opt_DatatypeContexts,
       Opt_NondecreasingIndentation
           -- strictly speaking non-standard, but we always had this
           -- on implicitly before the option was added in 7.1, and
           -- turning it off breaks code, so we're keeping it on for
           -- backwards compatibility.  Cabal uses -XHaskell98 by
           -- default unless you specify another language.
      ]
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languageExtensions (Just Haskell2010)
    = [Opt_ImplicitPrelude,
       Opt_MonomorphismRestriction,
       Opt_DatatypeContexts,
       Opt_EmptyDataDecls,
       Opt_ForeignFunctionInterface,
       Opt_PatternGuards,
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       Opt_DoAndIfThenElse,
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       Opt_RelaxedPolyRec]
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-- | Test whether a 'DynFlag' is set
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dopt :: DynFlag -> DynFlags -> Bool
dopt f dflags  = f `elem` (flags dflags)
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-- | Set a 'DynFlag'
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dopt_set :: DynFlags -> DynFlag -> DynFlags
dopt_set dfs f = dfs{ flags = f : flags dfs }
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-- | Unset a 'DynFlag'
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dopt_unset :: DynFlags -> DynFlag -> DynFlags
dopt_unset dfs f = dfs{ flags = filter (/= f) (flags dfs) }
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-- | Test whether a 'WarningFlag' is set
wopt :: WarningFlag -> DynFlags -> Bool
wopt f dflags  = f `elem` (warningFlags dflags)

-- | Set a 'WarningFlag'
wopt_set :: DynFlags -> WarningFlag -> DynFlags
wopt_set dfs f = dfs{ warningFlags = f : warningFlags dfs }

-- | Unset a 'WarningFlag'
wopt_unset :: DynFlags -> WarningFlag -> DynFlags
wopt_unset dfs f = dfs{ warningFlags = filter (/= f) (warningFlags dfs) }

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-- | Test whether a 'ExtensionFlag' is set
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xopt :: ExtensionFlag -> DynFlags -> Bool
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xopt f dflags = f `elem` extensionFlags dflags
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-- | Set a 'ExtensionFlag'
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xopt_set :: DynFlags -> ExtensionFlag -> DynFlags
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xopt_set dfs f
    = let onoffs = On f : extensions dfs
      in dfs { extensions = onoffs,
               extensionFlags = flattenExtensionFlags (language dfs) onoffs }
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-- | Unset a 'ExtensionFlag'
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xopt_unset :: DynFlags -> ExtensionFlag -> DynFlags
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xopt_unset dfs f
    = let onoffs = Off f : extensions dfs
      in dfs { extensions = onoffs,
               extensionFlags = flattenExtensionFlags (language dfs) onoffs }
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-- | Set the Haskell language standard to use
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setLanguage :: Language -> DynP ()
setLanguage l = upd f
    where f dfs = let mLang = Just l
                      oneoffs = extensions dfs
                  in dfs {
                         language = mLang,
                         extensionFlags = flattenExtensionFlags mLang oneoffs
                     }
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-- | Some modules have dependencies on others through the DynFlags rather than textual imports
dynFlagDependencies :: DynFlags -> [ModuleName]
dynFlagDependencies = pluginModNames

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-- | Is the Safe Haskell safe language in use
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safeLanguageOn :: DynFlags -> Bool
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safeLanguageOn dflags = safeHaskell dflags == Sf_Safe
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-- | Test if Safe Haskell is on in some form
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safeHaskellOn :: DynFlags -> Bool
safeHaskellOn dflags = safeHaskell dflags /= Sf_None

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-- | Set a 'Safe Haskell' flag
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setSafeHaskell :: SafeHaskellMode -> DynP ()
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setSafeHaskell s = updM f
    where f dfs = do
              let sf = safeHaskell dfs
              safeM <- combineSafeFlags sf s
              return $ dfs { safeHaskell = safeM }
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-- | Are all direct imports required to be safe for this Safe Haskell mode?
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-- Direct imports are when the code explicitly imports a module
safeDirectImpsReq :: DynFlags -> Bool
safeDirectImpsReq = safeLanguageOn

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-- | Are all implicit imports required to be safe for this Safe Haskell mode?
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-- Implicit imports are things in the prelude. e.g System.IO when print is used.
safeImplicitImpsReq :: DynFlags -> Bool
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safeImplicitImpsReq = safeLanguageOn
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-- | Combine two Safe Haskell modes correctly. Used for dealing with multiple flags.
-- This makes Safe Haskell very much a monoid but for now I prefer this as I don't
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-- want to export this functionality from the module but do want to export the
-- type constructors.
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