    -- \section[Hooks]{Low level API hooks}

    -- NB: this module is SOURCE-imported by DynFlags, and should primarily
    --     refer to *types*, rather than *code*

    {-# LANGUAGE RankNTypes, TypeFamilies #-}

    module GHC.Driver.Hooks
       ( Hooks
       , HasHooks (..)
       , ContainsHooks (..)
       , emptyHooks
         -- the hooks:
       , DsForeignsHook
       , dsForeignsHook
       , tcForeignImportsHook
       , tcForeignExportsHook
       , hscFrontendHook
       , hscCompileCoreExprHook
       , ghcPrimIfaceHook
       , runPhaseHook
       , runMetaHook
       , linkHook
       , runRnSpliceHook
       , getValueSafelyHook
       , createIservProcessHook
       , stgToCmmHook
       , cmmToRawCmmHook
       )
    where

    import GHC.Prelude

    import GHC.Driver.Env
    import GHC.Driver.Session
    import GHC.Driver.Pipeline.Phases

    import GHC.Hs.Decls
    import GHC.Hs.Binds
    import GHC.Hs.Expr
    import GHC.Hs.Extension

    import GHC.Types.Name.Reader
    import GHC.Types.Name
    import GHC.Types.Id
    import GHC.Types.SrcLoc
    import GHC.Types.Basic
    import GHC.Types.CostCentre
    import GHC.Types.IPE
    import GHC.Types.Meta
    import GHC.Types.HpcInfo

    import GHC.Unit.Module
    import GHC.Unit.Module.ModSummary
    import GHC.Unit.Module.ModIface
    import GHC.Unit.Home.ModInfo

    import GHC.Core
    import GHC.Core.TyCon
    import GHC.Core.Type

    import GHC.Tc.Types
    import GHC.Stg.Syntax
    import GHC.StgToCmm.Types (ModuleLFInfos)
    import GHC.StgToCmm.Config
    import GHC.Cmm

    import GHCi.RemoteTypes

    import GHC.Data.Stream
    import GHC.Data.Bag

    import qualified Data.Kind
    import System.Process
    import GHC.Linker.Types

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Hooks}
    *                                                                      *
    ************************************************************************
    -}

    -- | Hooks can be used by GHC API clients to replace parts of
    --   the compiler pipeline. If a hook is not installed, GHC
    --   uses the default built-in behaviour

    emptyHooks :: Hooks
    emptyHooks :: Hooks
    emptyHooks = Hooks
      { dsForeignsHook :: Maybe DsForeignsHook
    dsForeignsHook         = Maybe DsForeignsHook
    forall a. Maybe a
    Nothing
      , tcForeignImportsHook :: Maybe
      ([LForeignDecl GhcRn]
       -> TcM ([Id], [LForeignDecl GhcTc], Bag GlobalRdrElt))
    tcForeignImportsHook   = Maybe
      ([LForeignDecl GhcRn]
       -> TcM ([Id], [LForeignDecl GhcTc], Bag GlobalRdrElt))
    Maybe
      ([GenLocated SrcSpanAnnA (ForeignDecl GhcRn)]
       -> TcM
            ([Id], [GenLocated SrcSpanAnnA (ForeignDecl GhcTc)],
             Bag GlobalRdrElt))
    forall a. Maybe a
    Nothing
      , tcForeignExportsHook :: Maybe
      ([LForeignDecl GhcRn]
       -> TcM (LHsBinds GhcTc, [LForeignDecl GhcTc], Bag GlobalRdrElt))
    tcForeignExportsHook   = Maybe
      ([LForeignDecl GhcRn]
       -> TcM (LHsBinds GhcTc, [LForeignDecl GhcTc], Bag GlobalRdrElt))
    Maybe
      ([GenLocated SrcSpanAnnA (ForeignDecl GhcRn)]
       -> TcM
            (Bag (GenLocated SrcSpanAnnA (HsBindLR GhcTc GhcTc)),
             [GenLocated SrcSpanAnnA (ForeignDecl GhcTc)], Bag GlobalRdrElt))
    forall a. Maybe a
    Nothing
      , hscFrontendHook :: Maybe (ModSummary -> Hsc FrontendResult)
    hscFrontendHook        = Maybe (ModSummary -> Hsc FrontendResult)
    forall a. Maybe a
    Nothing
      , hscCompileCoreExprHook :: Maybe
      (HscEnv
       -> SrcSpan
       -> CoreExpr
       -> IO (ForeignHValue, [Linkable], PkgsLoaded))
    hscCompileCoreExprHook = Maybe
      (HscEnv
       -> SrcSpan
       -> CoreExpr
       -> IO (ForeignHValue, [Linkable], PkgsLoaded))
    forall a. Maybe a
    Nothing
      , ghcPrimIfaceHook :: Maybe ModIface
    ghcPrimIfaceHook       = Maybe ModIface
    forall a. Maybe a
    Nothing
      , runPhaseHook :: Maybe PhaseHook
    runPhaseHook           = Maybe PhaseHook
    forall a. Maybe a
    Nothing
      , runMetaHook :: Maybe (MetaHook TcM)
    runMetaHook            = Maybe (MetaHook TcM)
    Maybe
      (MetaRequest
       -> GenLocated SrcSpanAnnA (HsExpr GhcTc) -> TcM MetaResult)
    forall a. Maybe a
    Nothing
      , linkHook :: Maybe
      (GhcLink -> DynFlags -> Bool -> HomePackageTable -> IO SuccessFlag)
    linkHook               = Maybe
      (GhcLink -> DynFlags -> Bool -> HomePackageTable -> IO SuccessFlag)
    forall a. Maybe a
    Nothing
      , runRnSpliceHook :: Maybe (HsSplice GhcRn -> RnM (HsSplice GhcRn))
    runRnSpliceHook        = Maybe (HsSplice GhcRn -> RnM (HsSplice GhcRn))
    forall a. Maybe a
    Nothing
      , getValueSafelyHook :: Maybe
      (HscEnv
       -> Name
       -> Type
       -> IO (Either Type (HValue, [Linkable], PkgsLoaded)))
    getValueSafelyHook     = Maybe
      (HscEnv
       -> Name
       -> Type
       -> IO (Either Type (HValue, [Linkable], PkgsLoaded)))
    forall a. Maybe a
    Nothing
      , createIservProcessHook :: Maybe (CreateProcess -> IO ProcessHandle)
    createIservProcessHook = Maybe (CreateProcess -> IO ProcessHandle)
    forall a. Maybe a
    Nothing
      , stgToCmmHook :: Maybe
      (StgToCmmConfig
       -> InfoTableProvMap
       -> [TyCon]
       -> CollectedCCs
       -> [CgStgTopBinding]
       -> HpcInfo
       -> Stream IO CmmGroup ModuleLFInfos)
    stgToCmmHook           = Maybe
      (StgToCmmConfig
       -> InfoTableProvMap
       -> [TyCon]
       -> CollectedCCs
       -> [CgStgTopBinding]
       -> HpcInfo
       -> Stream IO CmmGroup ModuleLFInfos)
    forall a. Maybe a
    Nothing
      , cmmToRawCmmHook :: forall a.
    Maybe
      (DynFlags
       -> Maybe Module
       -> Stream IO CmmGroupSRTs a
       -> IO (Stream IO RawCmmGroup a))
    cmmToRawCmmHook        = Maybe
      (DynFlags
       -> Maybe Module
       -> Stream IO CmmGroupSRTs a
       -> IO (Stream IO RawCmmGroup a))
    forall a. Maybe a
    forall a.
    Maybe
      (DynFlags
       -> Maybe Module
       -> Stream IO CmmGroupSRTs a
       -> IO (Stream IO RawCmmGroup a))
    Nothing
      }

    {- Note [The Decoupling Abstract Data Hack]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The "Abstract Data" idea is due to Richard Eisenberg in
    https://gitlab.haskell.org/ghc/ghc/-/merge_requests/1957, where the pattern is
    described in more detail.

    Here we use it as a temporary measure to break the dependency from the Parser on
    the Desugarer until the parser is free of DynFlags. We introduced a nullary type
    family @DsForeignsook@, whose single definition is in GHC.HsToCore.Types, where
    we instantiate it to

       [LForeignDecl GhcTc] -> DsM (ForeignStubs, OrdList (Id, CoreExpr))

    In doing so, the Hooks module (which is an hs-boot dependency of DynFlags) can
    be decoupled from its use of the DsM definition in GHC.HsToCore.Types. Since
    both DsM and the definition of @ForeignsHook@ live in the same module, there is
    virtually no difference for plugin authors that want to write a foreign hook.
    -}

    -- See Note [The Decoupling Abstract Data Hack]
    type family DsForeignsHook :: Data.Kind.Type

    data Hooks = Hooks
      { Hooks -> Maybe DsForeignsHook
    dsForeignsHook         :: !(Maybe DsForeignsHook)
      -- ^ Actual type:
      -- @Maybe ([LForeignDecl GhcTc] -> DsM (ForeignStubs, OrdList (Id, CoreExpr)))@
      , Hooks
    -> Maybe
         ([LForeignDecl GhcRn]
          -> TcM ([Id], [LForeignDecl GhcTc], Bag GlobalRdrElt))
    tcForeignImportsHook   :: !(Maybe ([LForeignDecl GhcRn]
                              -> TcM ([Id], [LForeignDecl GhcTc], Bag GlobalRdrElt)))
      , Hooks
    -> Maybe
         ([LForeignDecl GhcRn]
          -> TcM (LHsBinds GhcTc, [LForeignDecl GhcTc], Bag GlobalRdrElt))
    tcForeignExportsHook   :: !(Maybe ([LForeignDecl GhcRn]
                -> TcM (LHsBinds GhcTc, [LForeignDecl GhcTc], Bag GlobalRdrElt)))
      , Hooks -> Maybe (ModSummary -> Hsc FrontendResult)
    hscFrontendHook        :: !(Maybe (ModSummary -> Hsc FrontendResult))
      , Hooks
    -> Maybe
         (HscEnv
          -> SrcSpan
          -> CoreExpr
          -> IO (ForeignHValue, [Linkable], PkgsLoaded))
    hscCompileCoreExprHook :: !(Maybe (HscEnv -> SrcSpan -> CoreExpr -> IO (ForeignHValue, [Linkable], PkgsLoaded)))
      , Hooks -> Maybe ModIface
    ghcPrimIfaceHook       :: !(Maybe ModIface)
      , Hooks -> Maybe PhaseHook
    runPhaseHook           :: !(Maybe PhaseHook)
      , Hooks -> Maybe (MetaHook TcM)
    runMetaHook            :: !(Maybe (MetaHook TcM))
      , Hooks
    -> Maybe
         (GhcLink -> DynFlags -> Bool -> HomePackageTable -> IO SuccessFlag)
    linkHook               :: !(Maybe (GhcLink -> DynFlags -> Bool
                                             -> HomePackageTable -> IO SuccessFlag))
      , Hooks -> Maybe (HsSplice GhcRn -> RnM (HsSplice GhcRn))
    runRnSpliceHook        :: !(Maybe (HsSplice GhcRn -> RnM (HsSplice GhcRn)))
      , Hooks
    -> Maybe
         (HscEnv
          -> Name
          -> Type
          -> IO (Either Type (HValue, [Linkable], PkgsLoaded)))
    getValueSafelyHook     :: !(Maybe (HscEnv -> Name -> Type
                                             -> IO (Either Type (HValue, [Linkable], PkgsLoaded))))
      , Hooks -> Maybe (CreateProcess -> IO ProcessHandle)
    createIservProcessHook :: !(Maybe (CreateProcess -> IO ProcessHandle))
      , Hooks
    -> Maybe
         (StgToCmmConfig
          -> InfoTableProvMap
          -> [TyCon]
          -> CollectedCCs
          -> [CgStgTopBinding]
          -> HpcInfo
          -> Stream IO CmmGroup ModuleLFInfos)
    stgToCmmHook           :: !(Maybe (StgToCmmConfig -> InfoTableProvMap -> [TyCon] -> CollectedCCs
                                     -> [CgStgTopBinding] -> HpcInfo -> Stream IO CmmGroup ModuleLFInfos))
      , Hooks
    -> forall a.
       Maybe
         (DynFlags
          -> Maybe Module
          -> Stream IO CmmGroupSRTs a
          -> IO (Stream IO RawCmmGroup a))
    cmmToRawCmmHook        :: !(forall a . Maybe (DynFlags -> Maybe Module -> Stream IO CmmGroupSRTs a
                                     -> IO (Stream IO RawCmmGroup a)))
      }

    class HasHooks m where
        getHooks :: m Hooks

    class ContainsHooks a where
        extractHooks :: a -> Hooks