path: root/compiler/iface/IfaceSyn.lhs

%
% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
%

\begin{code}
{-# OPTIONS -fno-warn-tabs #-}
-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and
-- detab the module (please do the detabbing in a separate patch). See
--     http://ghc.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
-- for details

module IfaceSyn (
        module IfaceType,

        IfaceDecl(..), IfaceSynTyConRhs(..), IfaceClassOp(..), IfaceAT(..), 
        IfaceConDecl(..), IfaceConDecls(..),
        IfaceExpr(..), IfaceAlt, IfaceLetBndr(..),
        IfaceBinding(..), IfaceConAlt(..),
        IfaceIdInfo(..), IfaceIdDetails(..), IfaceUnfolding(..),
        IfaceInfoItem(..), IfaceRule(..), IfaceAnnotation(..), IfaceAnnTarget,
        IfaceClsInst(..), IfaceFamInst(..), IfaceTickish(..), 
        IfaceBang(..), IfaceAxBranch(..),

        -- Misc
        ifaceDeclImplicitBndrs, visibleIfConDecls,
        ifaceDeclFingerprints,

        -- Free Names
        freeNamesIfDecl, freeNamesIfRule, freeNamesIfFamInst,

        -- Pretty printing
        pprIfaceExpr
    ) where

#include "HsVersions.h"

import IfaceType
import PprCore()            -- Printing DFunArgs
import Demand
import Annotations
import Class
import NameSet
import CoAxiom ( BranchIndex, Role )
import Name
import CostCentre
import Literal
import ForeignCall
import Serialized
import BasicTypes
import Outputable
import FastString
import Module
import TysWiredIn ( eqTyConName )
import Fingerprint
import Binary
import BooleanFormula ( BooleanFormula )

import Control.Monad
import System.IO.Unsafe

infixl 3 &&&
\end{code}


%************************************************************************
%*                                                                      *
    Data type declarations
%*                                                                      *
%************************************************************************

\begin{code}
data IfaceDecl
  = IfaceId { ifName      :: OccName,
              ifType      :: IfaceType,
              ifIdDetails :: IfaceIdDetails,
              ifIdInfo    :: IfaceIdInfo }

  | IfaceData { ifName       :: OccName,        -- Type constructor
                ifCType      :: Maybe CType,    -- C type for CAPI FFI
                ifTyVars     :: [IfaceTvBndr],  -- Type variables
                ifRoles      :: [Role],         -- Roles
                ifCtxt       :: IfaceContext,   -- The "stupid theta"
                ifCons       :: IfaceConDecls,  -- Includes new/data/data family info
                ifRec        :: RecFlag,        -- Recursive or not?
                ifPromotable :: Bool,           -- Promotable to kind level?
                ifGadtSyntax :: Bool,           -- True <=> declared using
                                                -- GADT syntax
                ifAxiom      :: Maybe IfExtName -- The axiom, for a newtype, 
                                                -- or data/newtype family instance
    }

  | IfaceSyn  { ifName    :: OccName,           -- Type constructor
                ifTyVars  :: [IfaceTvBndr],     -- Type variables
                ifRoles   :: [Role],            -- Roles
                ifSynKind :: IfaceKind,         -- Kind of the *rhs* (not of the tycon)
                ifSynRhs  :: IfaceSynTyConRhs }

  | IfaceClass { ifCtxt    :: IfaceContext,     -- Context...
                 ifName    :: OccName,          -- Name of the class TyCon
                 ifTyVars  :: [IfaceTvBndr],    -- Type variables
                 ifRoles   :: [Role],           -- Roles
                 ifFDs     :: [FunDep FastString], -- Functional dependencies
                 ifATs     :: [IfaceAT],      -- Associated type families
                 ifSigs    :: [IfaceClassOp],   -- Method signatures
                 ifMinDef  :: BooleanFormula OccName, -- Minimal complete definition
                 ifRec     :: RecFlag           -- Is newtype/datatype associated
                                                --   with the class recursive?
    }

  | IfaceAxiom { ifName       :: OccName,        -- Axiom name
                 ifTyCon      :: IfaceTyCon,     -- LHS TyCon
                 ifRole       :: Role,           -- Role of axiom
                 ifAxBranches :: [IfaceAxBranch] -- Branches
    }

  | IfaceForeign { ifName :: OccName,           -- Needs expanding when we move
                                                -- beyond .NET
                   ifExtName :: Maybe FastString }

-- A bit of magic going on here: there's no need to store the OccName
-- for a decl on the disk, since we can infer the namespace from the
-- context; however it is useful to have the OccName in the IfaceDecl
-- to avoid re-building it in various places.  So we build the OccName
-- when de-serialising.

instance Binary IfaceDecl where
    put_ bh (IfaceId name ty details idinfo) = do
        putByte bh 0
        put_ bh (occNameFS name)
        put_ bh ty
        put_ bh details
        put_ bh idinfo

    put_ _ (IfaceForeign _ _) = 
        error "Binary.put_(IfaceDecl): IfaceForeign"

    put_ bh (IfaceData a1 a2 a3 a4 a5 a6 a7 a8 a9 a10) = do
        putByte bh 2
        put_ bh (occNameFS a1)
        put_ bh a2
        put_ bh a3
        put_ bh a4
        put_ bh a5
        put_ bh a6
        put_ bh a7
        put_ bh a8
        put_ bh a9
        put_ bh a10

    put_ bh (IfaceSyn a1 a2 a3 a4 a5) = do
        putByte bh 3
        put_ bh (occNameFS a1)
        put_ bh a2
        put_ bh a3
        put_ bh a4
        put_ bh a5

    put_ bh (IfaceClass a1 a2 a3 a4 a5 a6 a7 a8 a9) = do
        putByte bh 4
        put_ bh a1
        put_ bh (occNameFS a2)
        put_ bh a3
        put_ bh a4
        put_ bh a5
        put_ bh a6
        put_ bh a7
        put_ bh a8
        put_ bh a9

    put_ bh (IfaceAxiom a1 a2 a3 a4) = do
        putByte bh 5
        put_ bh (occNameFS a1)
        put_ bh a2
        put_ bh a3
        put_ bh a4

    get bh = do
        h <- getByte bh
        case h of
            0 -> do name    <- get bh
                    ty      <- get bh
                    details <- get bh
                    idinfo  <- get bh
                    occ <- return $! mkOccNameFS varName name
                    return (IfaceId occ ty details idinfo)
            1 -> error "Binary.get(TyClDecl): ForeignType"
            2 -> do a1  <- get bh
                    a2  <- get bh
                    a3  <- get bh
                    a4  <- get bh
                    a5  <- get bh
                    a6  <- get bh
                    a7  <- get bh
                    a8  <- get bh
                    a9  <- get bh
                    a10 <- get bh
                    occ <- return $! mkOccNameFS tcName a1
                    return (IfaceData occ a2 a3 a4 a5 a6 a7 a8 a9 a10)
            3 -> do a1 <- get bh
                    a2 <- get bh
                    a3 <- get bh
                    a4 <- get bh
                    a5 <- get bh
                    occ <- return $! mkOccNameFS tcName a1
                    return (IfaceSyn occ a2 a3 a4 a5)
            4 -> do a1 <- get bh
                    a2 <- get bh
                    a3 <- get bh
                    a4 <- get bh
                    a5 <- get bh
                    a6 <- get bh
                    a7 <- get bh
                    a8 <- get bh
                    a9 <- get bh
                    occ <- return $! mkOccNameFS clsName a2
                    return (IfaceClass a1 occ a3 a4 a5 a6 a7 a8 a9)
            _ -> do a1 <- get bh
                    a2 <- get bh
                    a3 <- get bh
                    a4 <- get bh
                    occ <- return $! mkOccNameFS tcName a1
                    return (IfaceAxiom occ a2 a3 a4)

data IfaceSynTyConRhs
  = IfaceOpenSynFamilyTyCon
  | IfaceClosedSynFamilyTyCon IfExtName  -- name of associated axiom
  | IfaceAbstractClosedSynFamilyTyCon
  | IfaceSynonymTyCon IfaceType

instance Binary IfaceSynTyConRhs where
    put_ bh IfaceOpenSynFamilyTyCon           = putByte bh 0
    put_ bh (IfaceClosedSynFamilyTyCon ax)    = putByte bh 1 >> put_ bh ax
    put_ bh IfaceAbstractClosedSynFamilyTyCon = putByte bh 2
    put_ bh (IfaceSynonymTyCon ty)            = putByte bh 3 >> put_ bh ty

    get bh = do { h <- getByte bh
                ; case h of
                    0 -> return IfaceOpenSynFamilyTyCon
                    1 -> do { ax <- get bh
                            ; return (IfaceClosedSynFamilyTyCon ax) }
                    2 -> return IfaceAbstractClosedSynFamilyTyCon
                    _ -> do { ty <- get bh
                            ; return (IfaceSynonymTyCon ty) } }

data IfaceClassOp = IfaceClassOp OccName DefMethSpec IfaceType
        -- Nothing    => no default method
        -- Just False => ordinary polymorphic default method
        -- Just True  => generic default method

instance Binary IfaceClassOp where
    put_ bh (IfaceClassOp n def ty) = do 
        put_ bh (occNameFS n)
        put_ bh def     
        put_ bh ty
    get bh = do
        n   <- get bh
        def <- get bh
        ty  <- get bh
        occ <- return $! mkOccNameFS varName n
        return (IfaceClassOp occ def ty)

data IfaceAT = IfaceAT IfaceDecl [IfaceAxBranch]
        -- Nothing => no default associated type instance
        -- Just ds => default associated type instance from these templates

instance Binary IfaceAT where
    put_ bh (IfaceAT dec defs) = do
        put_ bh dec
        put_ bh defs
    get bh = do
        dec  <- get bh
        defs <- get bh
        return (IfaceAT dec defs)

instance Outputable IfaceAxBranch where
  ppr = pprAxBranch Nothing

pprAxBranch :: Maybe IfaceTyCon -> IfaceAxBranch -> SDoc
pprAxBranch mtycon (IfaceAxBranch { ifaxbTyVars = tvs
                                  , ifaxbLHS = pat_tys
                                  , ifaxbRHS = ty
                                  , ifaxbIncomps = incomps })
  = ppr tvs <+> ppr_lhs <+> char '=' <+> ppr ty $+$
    nest 4 maybe_incomps
      where
        ppr_lhs
          | Just tycon <- mtycon
          = ppr (IfaceTyConApp tycon pat_tys)
          | otherwise
          = hsep (map ppr pat_tys)

        maybe_incomps
          | [] <- incomps
          = empty

          | otherwise
          = parens (ptext (sLit "incompatible indices:") <+> ppr incomps)

-- this is just like CoAxBranch
data IfaceAxBranch = IfaceAxBranch { ifaxbTyVars  :: [IfaceTvBndr]
                                   , ifaxbLHS     :: [IfaceType]
                                   , ifaxbRoles   :: [Role]
                                   , ifaxbRHS     :: IfaceType
                                   , ifaxbIncomps :: [BranchIndex] }
                                     -- See Note [Storing compatibility] in CoAxiom

instance Binary IfaceAxBranch where
    put_ bh (IfaceAxBranch a1 a2 a3 a4 a5) = do
        put_ bh a1
        put_ bh a2
        put_ bh a3
        put_ bh a4
        put_ bh a5
    get bh = do
        a1 <- get bh
        a2 <- get bh
        a3 <- get bh
        a4 <- get bh
        a5 <- get bh
        return (IfaceAxBranch a1 a2 a3 a4 a5)

data IfaceConDecls
  = IfAbstractTyCon Bool        -- c.f TyCon.AbstractTyCon
  | IfDataFamTyCon              -- Data family
  | IfDataTyCon [IfaceConDecl]  -- Data type decls
  | IfNewTyCon  IfaceConDecl    -- Newtype decls

instance Binary IfaceConDecls where
    put_ bh (IfAbstractTyCon d) = putByte bh 0 >> put_ bh d
    put_ bh IfDataFamTyCon     = putByte bh 1
    put_ bh (IfDataTyCon cs)    = putByte bh 2 >> put_ bh cs
    put_ bh (IfNewTyCon c)      = putByte bh 3 >> put_ bh c
    get bh = do
        h <- getByte bh
        case h of
            0 -> liftM IfAbstractTyCon $ get bh
            1 -> return IfDataFamTyCon
            2 -> liftM IfDataTyCon $ get bh
            _ -> liftM IfNewTyCon $ get bh

visibleIfConDecls :: IfaceConDecls -> [IfaceConDecl]
visibleIfConDecls (IfAbstractTyCon {}) = []
visibleIfConDecls IfDataFamTyCon      = []
visibleIfConDecls (IfDataTyCon cs)     = cs
visibleIfConDecls (IfNewTyCon c)       = [c]

data IfaceConDecl
  = IfCon {
        ifConOcc     :: OccName,                -- Constructor name
        ifConWrapper :: Bool,                   -- True <=> has a wrapper
        ifConInfix   :: Bool,                   -- True <=> declared infix
        ifConUnivTvs :: [IfaceTvBndr],          -- Universal tyvars
        ifConExTvs   :: [IfaceTvBndr],          -- Existential tyvars
        ifConEqSpec  :: [(OccName,IfaceType)],  -- Equality constraints
        ifConCtxt    :: IfaceContext,           -- Non-stupid context
        ifConArgTys  :: [IfaceType],            -- Arg types
        ifConFields  :: [OccName],              -- ...ditto... (field labels)
        ifConStricts :: [IfaceBang]}            -- Empty (meaning all lazy),
                                                -- or 1-1 corresp with arg tys

instance Binary IfaceConDecl where
    put_ bh (IfCon a1 a2 a3 a4 a5 a6 a7 a8 a9 a10) = do
        put_ bh a1
        put_ bh a2
        put_ bh a3
        put_ bh a4
        put_ bh a5
        put_ bh a6
        put_ bh a7
        put_ bh a8
        put_ bh a9
        put_ bh a10
    get bh = do
        a1 <- get bh
        a2 <- get bh
        a3 <- get bh
        a4 <- get bh
        a5 <- get bh
        a6 <- get bh
        a7 <- get bh
        a8 <- get bh
        a9 <- get bh
        a10 <- get bh
        return (IfCon a1 a2 a3 a4 a5 a6 a7 a8 a9 a10)

data IfaceBang
  = IfNoBang | IfStrict | IfUnpack | IfUnpackCo IfaceCoercion

instance Binary IfaceBang where
    put_ bh IfNoBang        = putByte bh 0
    put_ bh IfStrict        = putByte bh 1
    put_ bh IfUnpack        = putByte bh 2
    put_ bh (IfUnpackCo co) = putByte bh 3 >> put_ bh co

    get bh = do
            h <- getByte bh
            case h of
              0 -> do return IfNoBang
              1 -> do return IfStrict
              2 -> do return IfUnpack
              _ -> do { a <- get bh; return (IfUnpackCo a) }

data IfaceClsInst
  = IfaceClsInst { ifInstCls  :: IfExtName,                -- See comments with
                   ifInstTys  :: [Maybe IfaceTyCon],       -- the defn of ClsInst
                   ifDFun     :: IfExtName,                -- The dfun
                   ifOFlag    :: OverlapFlag,              -- Overlap flag
                   ifInstOrph :: Maybe OccName }           -- See Note [Orphans]
        -- There's always a separate IfaceDecl for the DFun, which gives
        -- its IdInfo with its full type and version number.
        -- The instance declarations taken together have a version number,
        -- and we don't want that to wobble gratuitously
        -- If this instance decl is *used*, we'll record a usage on the dfun;
        -- and if the head does not change it won't be used if it wasn't before

instance Binary IfaceClsInst where
    put_ bh (IfaceClsInst cls tys dfun flag orph) = do
        put_ bh cls
        put_ bh tys
        put_ bh dfun
        put_ bh flag
        put_ bh orph
    get bh = do
        cls  <- get bh
        tys  <- get bh
        dfun <- get bh
        flag <- get bh
        orph <- get bh
        return (IfaceClsInst cls tys dfun flag orph)

-- The ifFamInstTys field of IfaceFamInst contains a list of the rough
-- match types
data IfaceFamInst
  = IfaceFamInst { ifFamInstFam      :: IfExtName            -- Family name
                 , ifFamInstTys      :: [Maybe IfaceTyCon]   -- See above
                 , ifFamInstAxiom    :: IfExtName            -- The axiom
                 , ifFamInstOrph     :: Maybe OccName        -- Just like IfaceClsInst
                 }

instance Binary IfaceFamInst where
    put_ bh (IfaceFamInst fam tys name orph) = do
        put_ bh fam
        put_ bh tys
        put_ bh name
        put_ bh orph
    get bh = do
        fam      <- get bh
        tys      <- get bh
        name     <- get bh
        orph     <- get bh
        return (IfaceFamInst fam tys name orph)

data IfaceRule
  = IfaceRule {
        ifRuleName   :: RuleName,
        ifActivation :: Activation,
        ifRuleBndrs  :: [IfaceBndr],    -- Tyvars and term vars
        ifRuleHead   :: IfExtName,      -- Head of lhs
        ifRuleArgs   :: [IfaceExpr],    -- Args of LHS
        ifRuleRhs    :: IfaceExpr,
        ifRuleAuto   :: Bool,
        ifRuleOrph   :: Maybe OccName   -- Just like IfaceClsInst
    }

instance Binary IfaceRule where
    put_ bh (IfaceRule a1 a2 a3 a4 a5 a6 a7 a8) = do
        put_ bh a1
        put_ bh a2
        put_ bh a3
        put_ bh a4
        put_ bh a5
        put_ bh a6
        put_ bh a7
        put_ bh a8
    get bh = do
        a1 <- get bh
        a2 <- get bh
        a3 <- get bh
        a4 <- get bh
        a5 <- get bh
        a6 <- get bh
        a7 <- get bh
        a8 <- get bh
        return (IfaceRule a1 a2 a3 a4 a5 a6 a7 a8)

data IfaceAnnotation
  = IfaceAnnotation {
        ifAnnotatedTarget :: IfaceAnnTarget,
        ifAnnotatedValue :: Serialized
  }

instance Binary IfaceAnnotation where
    put_ bh (IfaceAnnotation a1 a2) = do
        put_ bh a1
        put_ bh a2
    get bh = do
        a1 <- get bh
        a2 <- get bh
        return (IfaceAnnotation a1 a2)

type IfaceAnnTarget = AnnTarget OccName

-- We only serialise the IdDetails of top-level Ids, and even then
-- we only need a very limited selection.  Notably, none of the
-- implicit ones are needed here, because they are not put it
-- interface files

data IfaceIdDetails
  = IfVanillaId
  | IfRecSelId IfaceTyCon Bool
  | IfDFunId Int          -- Number of silent args

instance Binary IfaceIdDetails where
    put_ bh IfVanillaId      = putByte bh 0
    put_ bh (IfRecSelId a b) = putByte bh 1 >> put_ bh a >> put_ bh b
    put_ bh (IfDFunId n)     = do { putByte bh 2; put_ bh n }
    get bh = do
        h <- getByte bh
        case h of
            0 -> return IfVanillaId
            1 -> do { a <- get bh; b <- get bh; return (IfRecSelId a b) }
            _ -> do { n <- get bh; return (IfDFunId n) }

data IfaceIdInfo
  = NoInfo                      -- When writing interface file without -O
  | HasInfo [IfaceInfoItem]     -- Has info, and here it is

instance Binary IfaceIdInfo where
    put_ bh NoInfo      = putByte bh 0
    put_ bh (HasInfo i) = putByte bh 1 >> lazyPut bh i -- NB lazyPut

    get bh = do
        h <- getByte bh
        case h of
            0 -> return NoInfo
            _ -> liftM HasInfo $ lazyGet bh    -- NB lazyGet

-- Here's a tricky case:
--   * Compile with -O module A, and B which imports A.f
--   * Change function f in A, and recompile without -O
--   * When we read in old A.hi we read in its IdInfo (as a thunk)
--      (In earlier GHCs we used to drop IdInfo immediately on reading,
--       but we do not do that now.  Instead it's discarded when the
--       ModIface is read into the various decl pools.)
--   * The version comparison sees that new (=NoInfo) differs from old (=HasInfo *)
--      and so gives a new version.

data IfaceInfoItem
  = HsArity         Arity
  | HsStrictness    StrictSig
  | HsInline        InlinePragma
  | HsUnfold        Bool             -- True <=> isStrongLoopBreaker is true
                    IfaceUnfolding   -- See Note [Expose recursive functions]
  | HsNoCafRefs

instance Binary IfaceInfoItem where
    put_ bh (HsArity aa)          = putByte bh 0 >> put_ bh aa
    put_ bh (HsStrictness ab)     = putByte bh 1 >> put_ bh ab
    put_ bh (HsUnfold lb ad)      = putByte bh 2 >> put_ bh lb >> put_ bh ad
    put_ bh (HsInline ad)         = putByte bh 3 >> put_ bh ad
    put_ bh HsNoCafRefs           = putByte bh 4
    get bh = do
        h <- getByte bh
        case h of
            0 -> liftM HsArity $ get bh
            1 -> liftM HsStrictness $ get bh
            2 -> do lb <- get bh
                    ad <- get bh
                    return (HsUnfold lb ad)
            3 -> liftM HsInline $ get bh
            _ -> return HsNoCafRefs

-- NB: Specialisations and rules come in separately and are
-- only later attached to the Id.  Partial reason: some are orphans.

data IfaceUnfolding
  = IfCoreUnfold Bool IfaceExpr -- True <=> INLINABLE, False <=> regular unfolding
                                -- Possibly could eliminate the Bool here, the information
                                -- is also in the InlinePragma.

  | IfCompulsory IfaceExpr      -- Only used for default methods, in fact

  | IfInlineRule Arity          -- INLINE pragmas
                 Bool           -- OK to inline even if *un*-saturated
                 Bool           -- OK to inline even if context is boring
                 IfaceExpr

  | IfDFunUnfold [IfaceBndr] [IfaceExpr]

instance Binary IfaceUnfolding where
    put_ bh (IfCoreUnfold s e) = do
        putByte bh 0
        put_ bh s
        put_ bh e
    put_ bh (IfInlineRule a b c d) = do
        putByte bh 1
        put_ bh a
        put_ bh b
        put_ bh c
        put_ bh d
    put_ bh (IfDFunUnfold as bs) = do
        putByte bh 2
        put_ bh as
        put_ bh bs
    put_ bh (IfCompulsory e) = do
        putByte bh 3
        put_ bh e
    get bh = do
        h <- getByte bh
        case h of
            0 -> do s <- get bh
                    e <- get bh
                    return (IfCoreUnfold s e)
            1 -> do a <- get bh
                    b <- get bh
                    c <- get bh
                    d <- get bh
                    return (IfInlineRule a b c d)
            2 -> do as <- get bh
                    bs <- get bh
                    return (IfDFunUnfold as bs)
            _ -> do e <- get bh
                    return (IfCompulsory e)

--------------------------------
data IfaceExpr
  = IfaceLcl    IfLclName
  | IfaceExt    IfExtName
  | IfaceType   IfaceType
  | IfaceCo     IfaceCoercion
  | IfaceTuple 	TupleSort [IfaceExpr]	-- Saturated; type arguments omitted
  | IfaceLam 	IfaceBndr IfaceExpr
  | IfaceApp 	IfaceExpr IfaceExpr
  | IfaceCase	IfaceExpr IfLclName [IfaceAlt]
  | IfaceECase  IfaceExpr IfaceType     -- See Note [Empty case alternatives]
  | IfaceLet	IfaceBinding  IfaceExpr
  | IfaceCast   IfaceExpr IfaceCoercion
  | IfaceLit    Literal
  | IfaceFCall  ForeignCall IfaceType
  | IfaceTick   IfaceTickish IfaceExpr    -- from Tick tickish E

instance Binary IfaceExpr where
    put_ bh (IfaceLcl aa) = do
        putByte bh 0
        put_ bh aa
    put_ bh (IfaceType ab) = do
        putByte bh 1
        put_ bh ab
    put_ bh (IfaceCo ab) = do
        putByte bh 2
        put_ bh ab
    put_ bh (IfaceTuple ac ad) = do
        putByte bh 3
        put_ bh ac
        put_ bh ad
    put_ bh (IfaceLam ae af) = do
        putByte bh 4
        put_ bh ae
        put_ bh af
    put_ bh (IfaceApp ag ah) = do
        putByte bh 5
        put_ bh ag
        put_ bh ah
    put_ bh (IfaceCase ai aj ak) = do
        putByte bh 6
        put_ bh ai
        put_ bh aj
        put_ bh ak
    put_ bh (IfaceLet al am) = do
        putByte bh 7
        put_ bh al
        put_ bh am
    put_ bh (IfaceTick an ao) = do
        putByte bh 8
        put_ bh an
        put_ bh ao
    put_ bh (IfaceLit ap) = do
        putByte bh 9
        put_ bh ap
    put_ bh (IfaceFCall as at) = do
        putByte bh 10
        put_ bh as
        put_ bh at
    put_ bh (IfaceExt aa) = do
        putByte bh 11
        put_ bh aa
    put_ bh (IfaceCast ie ico) = do
        putByte bh 12
        put_ bh ie
        put_ bh ico
    put_ bh (IfaceECase a b) = do
        putByte bh 13
        put_ bh a
        put_ bh b
    get bh = do
        h <- getByte bh
        case h of
            0 -> do aa <- get bh
                    return (IfaceLcl aa)
            1 -> do ab <- get bh
                    return (IfaceType ab)
            2 -> do ab <- get bh
                    return (IfaceCo ab)
            3 -> do ac <- get bh
                    ad <- get bh
                    return (IfaceTuple ac ad)
            4 -> do ae <- get bh
                    af <- get bh
                    return (IfaceLam ae af)
            5 -> do ag <- get bh
                    ah <- get bh
                    return (IfaceApp ag ah)
            6 -> do ai <- get bh
                    aj <- get bh
                    ak <- get bh
                    return (IfaceCase ai aj ak)
            7 -> do al <- get bh
                    am <- get bh
                    return (IfaceLet al am)
            8 -> do an <- get bh
                    ao <- get bh
                    return (IfaceTick an ao)
            9 -> do ap <- get bh
                    return (IfaceLit ap)
            10 -> do as <- get bh
                     at <- get bh
                     return (IfaceFCall as at)
            11 -> do aa <- get bh
                     return (IfaceExt aa)
            12 -> do ie <- get bh
                     ico <- get bh
                     return (IfaceCast ie ico)
            13 -> do a <- get bh
                     b <- get bh
                     return (IfaceECase a b)
            _ -> panic ("get IfaceExpr " ++ show h)

data IfaceTickish
  = IfaceHpcTick Module Int                -- from HpcTick x
  | IfaceSCC     CostCentre Bool Bool      -- from ProfNote
  -- no breakpoints: we never export these into interface files

instance Binary IfaceTickish where
    put_ bh (IfaceHpcTick m ix) = do
        putByte bh 0
        put_ bh m
        put_ bh ix
    put_ bh (IfaceSCC cc tick push) = do
        putByte bh 1
        put_ bh cc
        put_ bh tick
        put_ bh push

    get bh = do
        h <- getByte bh
        case h of
            0 -> do m <- get bh
                    ix <- get bh
                    return (IfaceHpcTick m ix)
            1 -> do cc <- get bh
                    tick <- get bh
                    push <- get bh
                    return (IfaceSCC cc tick push)
            _ -> panic ("get IfaceTickish " ++ show h)

type IfaceAlt = (IfaceConAlt, [IfLclName], IfaceExpr)
        -- Note: IfLclName, not IfaceBndr (and same with the case binder)
        -- We reconstruct the kind/type of the thing from the context
        -- thus saving bulk in interface files

data IfaceConAlt = IfaceDefault
                 | IfaceDataAlt IfExtName
                 | IfaceLitAlt Literal

instance Binary IfaceConAlt where
    put_ bh IfaceDefault      = putByte bh 0
    put_ bh (IfaceDataAlt aa) = putByte bh 1 >> put_ bh aa
    put_ bh (IfaceLitAlt ac)  = putByte bh 2 >> put_ bh ac
    get bh = do
        h <- getByte bh
        case h of
            0 -> return IfaceDefault
            1 -> liftM IfaceDataAlt $ get bh
            _ -> liftM IfaceLitAlt  $ get bh

data IfaceBinding
  = IfaceNonRec IfaceLetBndr IfaceExpr
  | IfaceRec    [(IfaceLetBndr, IfaceExpr)]

instance Binary IfaceBinding where
    put_ bh (IfaceNonRec aa ab) = putByte bh 0 >> put_ bh aa >> put_ bh ab
    put_ bh (IfaceRec ac)       = putByte bh 1 >> put_ bh ac
    get bh = do
        h <- getByte bh
        case h of
            0 -> do { aa <- get bh; ab <- get bh; return (IfaceNonRec aa ab) }
            _ -> do { ac <- get bh; return (IfaceRec ac) }

-- IfaceLetBndr is like IfaceIdBndr, but has IdInfo too
-- It's used for *non-top-level* let/rec binders
-- See Note [IdInfo on nested let-bindings]
data IfaceLetBndr = IfLetBndr IfLclName IfaceType IfaceIdInfo

instance Binary IfaceLetBndr where
    put_ bh (IfLetBndr a b c) = do
            put_ bh a
            put_ bh b
            put_ bh c
    get bh = do a <- get bh
                b <- get bh
                c <- get bh
                return (IfLetBndr a b c)
\end{code}

Note [Empty case alternatives]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In IfaceSyn an IfaceCase does not record the types of the alternatives,
unlike CorSyn Case.  But we need this type if the alternatives are empty.
Hence IfaceECase.  See Note [Empty case alternatives] in CoreSyn.

Note [Expose recursive functions]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For supercompilation we want to put *all* unfoldings in the interface
file, even for functions that are recursive (or big).  So we need to
know when an unfolding belongs to a loop-breaker so that we can refrain
from inlining it (except during supercompilation).

Note [IdInfo on nested let-bindings]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Occasionally we want to preserve IdInfo on nested let bindings. The one
that came up was a NOINLINE pragma on a let-binding inside an INLINE
function.  The user (Duncan Coutts) really wanted the NOINLINE control
to cross the separate compilation boundary.

In general we retain all info that is left by CoreTidy.tidyLetBndr, since
that is what is seen by importing module with --make

Note [Orphans]: the ifInstOrph and ifRuleOrph fields
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Class instances, rules, and family instances are divided into orphans
and non-orphans.  Roughly speaking, an instance/rule is an orphan if
its left hand side mentions nothing defined in this module.  Orphan-hood
has two major consequences

 * A non-orphan is not finger-printed separately.  Instead, for
   fingerprinting purposes it is treated as part of the entity it
   mentions on the LHS.  For example
      data T = T1 | T2
      instance Eq T where ....
   The instance (Eq T) is incorprated as part of T's fingerprint.

   In constrast, orphans are all fingerprinted together in the 
   mi_orph_hash field of the ModIface. 
  
   See MkIface.addFingerprints.

 * A module that contains orphans is called an "orphan module".  If
   the module being compiled depends (transitively) on an oprhan
   module M, then M.hi is read in regardless of whether M is oherwise
   needed. This is to ensure that we don't miss any instance decls in
   M.  But it's painful, because it means we need to keep track of all
   the orphan modules below us.

Orphan-hood is computed when we generate an IfaceInst, IfaceRule, or
IfaceFamInst respectively: 

 - If an instance is an orphan its ifInstOprh field is Nothing
   Otherwise ifInstOrph is (Just n) where n is the Name of a
   local class or tycon that witnesses its non-orphan-hood.
   This computation is done by MkIface.instanceToIfaceInst

 - Similarly for ifRuleOrph
   The computation is done by MkIface.coreRuleToIfaceRule

Note [When exactly is an instance decl an orphan?]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  (see MkIface.instanceToIfaceInst, which implements this)
Roughly speaking, an instance is an orphan if its head (after the =>)
mentions nothing defined in this module.  

Functional dependencies complicate the situation though. Consider

  module M where { class C a b | a -> b }

and suppose we are compiling module X:

  module X where
        import M
        data T = ...
        instance C Int T where ...

This instance is an orphan, because when compiling a third module Y we
might get a constraint (C Int v), and we'd want to improve v to T.  So
we must make sure X's instances are loaded, even if we do not directly
use anything from X.

More precisely, an instance is an orphan iff

  If there are no fundeps, then at least of the names in
  the instance head is locally defined.

  If there are fundeps, then for every fundep, at least one of the
  names free in a *non-determined* part of the instance head is
  defined in this module.

(Note that these conditions hold trivially if the class is locally
defined.)  

Note [Versioning of instances]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
See [http://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/RecompilationAvoidance#Instances]

\begin{code}
-- -----------------------------------------------------------------------------
-- Utils on IfaceSyn

ifaceDeclImplicitBndrs :: IfaceDecl -> [OccName]
--  *Excludes* the 'main' name, but *includes* the implicitly-bound names
-- Deeply revolting, because it has to predict what gets bound,
-- especially the question of whether there's a wrapper for a datacon
-- See Note [Implicit TyThings] in HscTypes

-- N.B. the set of names returned here *must* match the set of
-- TyThings returned by HscTypes.implicitTyThings, in the sense that
-- TyThing.getOccName should define a bijection between the two lists.
-- This invariant is used in LoadIface.loadDecl (see note [Tricky iface loop])
-- The order of the list does not matter.
ifaceDeclImplicitBndrs IfaceData {ifCons = IfAbstractTyCon {}}  = []

-- Newtype
ifaceDeclImplicitBndrs (IfaceData {ifName = tc_occ,
                              ifCons = IfNewTyCon (
                                        IfCon { ifConOcc = con_occ })})
  =   -- implicit newtype coercion
    (mkNewTyCoOcc tc_occ) : -- JPM: newtype coercions shouldn't be implicit
      -- data constructor and worker (newtypes don't have a wrapper)
    [con_occ, mkDataConWorkerOcc con_occ]


ifaceDeclImplicitBndrs (IfaceData {ifName = _tc_occ,
                              ifCons = IfDataTyCon cons })
  = -- for each data constructor in order,
    --    data constructor, worker, and (possibly) wrapper
    concatMap dc_occs cons
  where
    dc_occs con_decl
        | has_wrapper = [con_occ, work_occ, wrap_occ]
        | otherwise   = [con_occ, work_occ]
        where
          con_occ  = ifConOcc con_decl            -- DataCon namespace
          wrap_occ = mkDataConWrapperOcc con_occ  -- Id namespace
          work_occ = mkDataConWorkerOcc con_occ   -- Id namespace
          has_wrapper = ifConWrapper con_decl     -- This is the reason for
                                                  -- having the ifConWrapper field!

ifaceDeclImplicitBndrs (IfaceClass {ifCtxt = sc_ctxt, ifName = cls_tc_occ,
                               ifSigs = sigs, ifATs = ats })
  = --   (possibly) newtype coercion
    co_occs ++
    --    data constructor (DataCon namespace)
    --    data worker (Id namespace)
    --    no wrapper (class dictionaries never have a wrapper)
    [dc_occ, dcww_occ] ++
    -- associated types
    [ifName at | IfaceAT at _ <- ats ] ++
    -- superclass selectors
    [mkSuperDictSelOcc n cls_tc_occ | n <- [1..n_ctxt]] ++
    -- operation selectors
    [op | IfaceClassOp op  _ _ <- sigs]
  where
    n_ctxt = length sc_ctxt
    n_sigs = length sigs
    co_occs | is_newtype = [mkNewTyCoOcc cls_tc_occ]
            | otherwise  = []
    dcww_occ = mkDataConWorkerOcc dc_occ
    dc_occ = mkClassDataConOcc cls_tc_occ
    is_newtype = n_sigs + n_ctxt == 1 -- Sigh

ifaceDeclImplicitBndrs _ = []

-- -----------------------------------------------------------------------------
-- The fingerprints of an IfaceDecl

       -- We better give each name bound by the declaration a
       -- different fingerprint!  So we calculate the fingerprint of
       -- each binder by combining the fingerprint of the whole
       -- declaration with the name of the binder. (#5614, #7215)
ifaceDeclFingerprints :: Fingerprint -> IfaceDecl -> [(OccName,Fingerprint)]
ifaceDeclFingerprints hash decl
  = (ifName decl, hash) :
    [ (occ, computeFingerprint' (hash,occ))
    | occ <- ifaceDeclImplicitBndrs decl ]
  where
     computeFingerprint' =
       unsafeDupablePerformIO
        . computeFingerprint (panic "ifaceDeclFingerprints")

----------------------------- Printing IfaceDecl ------------------------------

instance Outputable IfaceDecl where
  ppr = pprIfaceDecl

pprIfaceDecl :: IfaceDecl -> SDoc
pprIfaceDecl (IfaceId {ifName = var, ifType = ty,
                       ifIdDetails = details, ifIdInfo = info})
  = sep [ ppr var <+> dcolon <+> ppr ty,
          nest 2 (ppr details),
          nest 2 (ppr info) ]

pprIfaceDecl (IfaceForeign {ifName = tycon})
  = hsep [ptext (sLit "foreign import type dotnet"), ppr tycon]

pprIfaceDecl (IfaceSyn {ifName = tycon,
                        ifTyVars = tyvars,
                        ifSynRhs = IfaceSynonymTyCon mono_ty})
  = hang (ptext (sLit "type") <+> pprIfaceDeclHead [] tycon tyvars)
       4 (vcat [equals <+> ppr mono_ty])

pprIfaceDecl (IfaceSyn {ifName = tycon, ifTyVars = tyvars,
                        ifSynRhs = IfaceOpenSynFamilyTyCon, ifSynKind = kind })
  = hang (ptext (sLit "type family") <+> pprIfaceDeclHead [] tycon tyvars)
       4 (dcolon <+> ppr kind)

-- this case handles both abstract and instantiated closed family tycons
pprIfaceDecl (IfaceSyn {ifName = tycon, ifTyVars = tyvars,
                        ifSynRhs = _closedSynFamilyTyCon, ifSynKind = kind })
  = hang (ptext (sLit "closed type family") <+> pprIfaceDeclHead [] tycon tyvars)
       4 (dcolon <+> ppr kind)

pprIfaceDecl (IfaceData {ifName = tycon, ifCType = cType,
                         ifCtxt = context,
                         ifTyVars = tyvars, ifRoles = roles, ifCons = condecls,
                         ifRec = isrec, ifPromotable = is_prom,
                         ifAxiom = mbAxiom})
  = hang (pp_nd <+> pprIfaceDeclHead context tycon tyvars)
       4 (vcat [ pprCType cType
               , pprRoles roles
               , pprRec isrec <> comma <+> pp_prom 
               , pp_condecls tycon condecls
               , pprAxiom mbAxiom])
  where
    pp_prom | is_prom   = ptext (sLit "Promotable")
            | otherwise = ptext (sLit "Not promotable")
    pp_nd = case condecls of
                IfAbstractTyCon dis -> ptext (sLit "abstract") <> parens (ppr dis)
                IfDataFamTyCon     -> ptext (sLit "data family")
                IfDataTyCon _       -> ptext (sLit "data")
                IfNewTyCon _        -> ptext (sLit "newtype")

pprIfaceDecl (IfaceClass {ifCtxt = context, ifName = clas, ifTyVars = tyvars,
                          ifRoles = roles, ifFDs = fds, ifATs = ats, ifSigs = sigs,
                          ifRec = isrec})
  = hang (ptext (sLit "class") <+> pprIfaceDeclHead context clas tyvars <+> pprFundeps fds)
       4 (vcat [pprRoles roles,
                pprRec isrec,
                sep (map ppr ats),
                sep (map ppr sigs)])

pprIfaceDecl (IfaceAxiom {ifName = name, ifTyCon = tycon, ifAxBranches = branches })
  = hang (ptext (sLit "axiom") <+> ppr name <> colon)
       2 (vcat $ map (pprAxBranch $ Just tycon) branches)

pprCType :: Maybe CType -> SDoc
pprCType Nothing = ptext (sLit "No C type associated")
pprCType (Just cType) = ptext (sLit "C type:") <+> ppr cType

pprRoles :: [Role] -> SDoc
pprRoles []    = empty
pprRoles roles = text "Roles:" <+> ppr roles

pprRec :: RecFlag -> SDoc
pprRec isrec = ptext (sLit "RecFlag") <+> ppr isrec

pprAxiom :: Maybe Name -> SDoc
pprAxiom Nothing   = ptext (sLit "FamilyInstance: none")
pprAxiom (Just ax) = ptext (sLit "FamilyInstance:") <+> ppr ax

instance Outputable IfaceClassOp where
   ppr (IfaceClassOp n dm ty) = ppr n <+> ppr dm <+> dcolon <+> ppr ty

instance Outputable IfaceAT where
   ppr (IfaceAT d defs) = hang (ppr d) 2 (vcat (map ppr defs))

pprIfaceDeclHead :: IfaceContext -> OccName -> [IfaceTvBndr] -> SDoc
pprIfaceDeclHead context thing tyvars
  = hsep [pprIfaceContext context, parenSymOcc thing (ppr thing),
          pprIfaceTvBndrs tyvars]

pp_condecls :: OccName -> IfaceConDecls -> SDoc
pp_condecls _  (IfAbstractTyCon {}) = empty
pp_condecls _  IfDataFamTyCon      = empty
pp_condecls tc (IfNewTyCon c)   = equals <+> pprIfaceConDecl tc c
pp_condecls tc (IfDataTyCon cs) = equals <+> sep (punctuate (ptext (sLit " |"))
                                                            (map (pprIfaceConDecl tc) cs))

mkIfaceEqPred :: IfaceType -> IfaceType -> IfacePredType
-- IA0_NOTE: This is wrong, but only used for pretty-printing.
mkIfaceEqPred ty1 ty2 = IfaceTyConApp (IfaceTc eqTyConName) [ty1, ty2]

pprIfaceConDecl :: OccName -> IfaceConDecl -> SDoc
pprIfaceConDecl tc
        (IfCon { ifConOcc = name, ifConInfix = is_infix, ifConWrapper = has_wrap,
                 ifConUnivTvs = univ_tvs, ifConExTvs = ex_tvs,
                 ifConEqSpec = eq_spec, ifConCtxt = ctxt, ifConArgTys = arg_tys,
                 ifConStricts = strs, ifConFields = fields })
  = sep [main_payload,
         if is_infix then ptext (sLit "Infix") else empty,
         if has_wrap then ptext (sLit "HasWrapper") else empty,
         ppUnless (null strs) $
            nest 4 (ptext (sLit "Stricts:") <+> hsep (map ppr_bang strs)),
         ppUnless (null fields) $
            nest 4 (ptext (sLit "Fields:") <+> hsep (map ppr fields))]
  where
    ppr_bang IfNoBang = char '_'        -- Want to see these
    ppr_bang IfStrict = char '!'
    ppr_bang IfUnpack = ptext (sLit "!!")
    ppr_bang (IfUnpackCo co) = ptext (sLit "!!") <> pprParendIfaceCoercion co

    main_payload = ppr name <+> dcolon <+>
                   pprIfaceForAllPart (univ_tvs ++ ex_tvs) (eq_ctxt ++ ctxt) pp_tau

    eq_ctxt = [(mkIfaceEqPred (IfaceTyVar (occNameFS tv)) ty)
              | (tv,ty) <- eq_spec]

        -- A bit gruesome this, but we can't form the full con_tau, and ppr it,
        -- because we don't have a Name for the tycon, only an OccName
    pp_tau = case map pprParendIfaceType arg_tys ++ [pp_res_ty] of
                (t:ts) -> fsep (t : map (arrow <+>) ts)
                []     -> panic "pp_con_taus"

    pp_res_ty = ppr tc <+> fsep [ppr tv | (tv,_) <- univ_tvs]

instance Outputable IfaceRule where
  ppr (IfaceRule { ifRuleName = name, ifActivation = act, ifRuleBndrs = bndrs,
                   ifRuleHead = fn, ifRuleArgs = args, ifRuleRhs = rhs })
    = sep [hsep [doubleQuotes (ftext name), ppr act,
                 ptext (sLit "forall") <+> pprIfaceBndrs bndrs],
           nest 2 (sep [ppr fn <+> sep (map pprParendIfaceExpr args),
                        ptext (sLit "=") <+> ppr rhs])
      ]

instance Outputable IfaceClsInst where
  ppr (IfaceClsInst {ifDFun = dfun_id, ifOFlag = flag,
                  ifInstCls = cls, ifInstTys = mb_tcs})
    = hang (ptext (sLit "instance") <+> ppr flag
                <+> ppr cls <+> brackets (pprWithCommas ppr_rough mb_tcs))
         2 (equals <+> ppr dfun_id)

instance Outputable IfaceFamInst where
  ppr (IfaceFamInst {ifFamInstFam = fam, ifFamInstTys = mb_tcs,
                     ifFamInstAxiom = tycon_ax})
    = hang (ptext (sLit "family instance") <+>
            ppr fam <+> pprWithCommas (brackets . ppr_rough) mb_tcs)
         2 (equals <+> ppr tycon_ax)

ppr_rough :: Maybe IfaceTyCon -> SDoc
ppr_rough Nothing   = dot
ppr_rough (Just tc) = ppr tc
\end{code}


----------------------------- Printing IfaceExpr ------------------------------------

\begin{code}
instance Outputable IfaceExpr where
    ppr e = pprIfaceExpr noParens e

pprParendIfaceExpr :: IfaceExpr -> SDoc
pprParendIfaceExpr = pprIfaceExpr parens

-- | Pretty Print an IfaceExpre
--
-- The first argument should be a function that adds parens in context that need
-- an atomic value (e.g. function args)
pprIfaceExpr :: (SDoc -> SDoc) -> IfaceExpr -> SDoc

pprIfaceExpr _       (IfaceLcl v)       = ppr v
pprIfaceExpr _       (IfaceExt v)       = ppr v
pprIfaceExpr _       (IfaceLit l)       = ppr l
pprIfaceExpr _       (IfaceFCall cc ty) = braces (ppr cc <+> ppr ty)
pprIfaceExpr _       (IfaceType ty)     = char '@' <+> pprParendIfaceType ty
pprIfaceExpr _       (IfaceCo co)       = text "@~" <+> pprParendIfaceCoercion co

pprIfaceExpr add_par app@(IfaceApp _ _) = add_par (pprIfaceApp app [])
pprIfaceExpr _       (IfaceTuple c as)  = tupleParens c (interpp'SP as)

pprIfaceExpr add_par i@(IfaceLam _ _)
  = add_par (sep [char '\\' <+> sep (map ppr bndrs) <+> arrow,
                  pprIfaceExpr noParens body])
  where
    (bndrs,body) = collect [] i
    collect bs (IfaceLam b e) = collect (b:bs) e
    collect bs e              = (reverse bs, e)

pprIfaceExpr add_par (IfaceECase scrut ty)
  = add_par (sep [ ptext (sLit "case") <+> pprIfaceExpr noParens scrut 
                 , ptext (sLit "ret_ty") <+> pprParendIfaceType ty
                 , ptext (sLit "of {}") ])

pprIfaceExpr add_par (IfaceCase scrut bndr [(con, bs, rhs)])
  = add_par (sep [ptext (sLit "case") 
			<+> pprIfaceExpr noParens scrut <+> ptext (sLit "of") 
			<+> ppr bndr <+> char '{' <+> ppr_con_bs con bs <+> arrow,
  		  pprIfaceExpr noParens rhs <+> char '}'])

pprIfaceExpr add_par (IfaceCase scrut bndr alts)
  = add_par (sep [ptext (sLit "case") 
		 	<+> pprIfaceExpr noParens scrut <+> ptext (sLit "of") 
			<+> ppr bndr <+> char '{',
  		  nest 2 (sep (map ppr_alt alts)) <+> char '}'])

pprIfaceExpr _       (IfaceCast expr co)
  = sep [pprParendIfaceExpr expr,
         nest 2 (ptext (sLit "`cast`")),
         pprParendIfaceCoercion co]

pprIfaceExpr add_par (IfaceLet (IfaceNonRec b rhs) body)
  = add_par (sep [ptext (sLit "let {"),
                  nest 2 (ppr_bind (b, rhs)),
                  ptext (sLit "} in"),
                  pprIfaceExpr noParens body])

pprIfaceExpr add_par (IfaceLet (IfaceRec pairs) body)
  = add_par (sep [ptext (sLit "letrec {"),
                  nest 2 (sep (map ppr_bind pairs)),
                  ptext (sLit "} in"),
                  pprIfaceExpr noParens body])

pprIfaceExpr add_par (IfaceTick tickish e)
  = add_par (pprIfaceTickish tickish <+> pprIfaceExpr noParens e)

ppr_alt :: (IfaceConAlt, [IfLclName], IfaceExpr) -> SDoc
ppr_alt (con, bs, rhs) = sep [ppr_con_bs con bs,
                         arrow <+> pprIfaceExpr noParens rhs]

ppr_con_bs :: IfaceConAlt -> [IfLclName] -> SDoc
ppr_con_bs con bs = ppr con <+> hsep (map ppr bs)

ppr_bind :: (IfaceLetBndr, IfaceExpr) -> SDoc
ppr_bind (IfLetBndr b ty info, rhs)
  = sep [hang (ppr b <+> dcolon <+> ppr ty) 2 (ppr info),
         equals <+> pprIfaceExpr noParens rhs]

------------------
pprIfaceTickish :: IfaceTickish -> SDoc
pprIfaceTickish (IfaceHpcTick m ix)
  = braces (text "tick" <+> ppr m <+> ppr ix)
pprIfaceTickish (IfaceSCC cc tick scope)
  = braces (pprCostCentreCore cc <+> ppr tick <+> ppr scope)

------------------
pprIfaceApp :: IfaceExpr -> [SDoc] -> SDoc
pprIfaceApp (IfaceApp fun arg) args = pprIfaceApp fun $
                                          nest 2 (pprParendIfaceExpr arg) : args
pprIfaceApp fun                args = sep (pprParendIfaceExpr fun : args)

------------------
instance Outputable IfaceConAlt where
    ppr IfaceDefault      = text "DEFAULT"
    ppr (IfaceLitAlt l)   = ppr l
    ppr (IfaceDataAlt d)  = ppr d

------------------
instance Outputable IfaceIdDetails where
  ppr IfVanillaId       = empty
  ppr (IfRecSelId tc b) = ptext (sLit "RecSel") <+> ppr tc
                          <+> if b then ptext (sLit "<naughty>") else empty
  ppr (IfDFunId ns)     = ptext (sLit "DFunId") <> brackets (int ns)

instance Outputable IfaceIdInfo where
  ppr NoInfo       = empty
  ppr (HasInfo is) = ptext (sLit "{-") <+> pprWithCommas ppr is
                     <+> ptext (sLit "-}")

instance Outputable IfaceInfoItem where
  ppr (HsUnfold lb unf)     = ptext (sLit "Unfolding")
                              <> ppWhen lb (ptext (sLit "(loop-breaker)"))
                              <> colon <+> ppr unf
  ppr (HsInline prag)       = ptext (sLit "Inline:") <+> ppr prag
  ppr (HsArity arity)       = ptext (sLit "Arity:") <+> int arity
  ppr (HsStrictness str) = ptext (sLit "Strictness:") <+> pprIfaceStrictSig str
  ppr HsNoCafRefs           = ptext (sLit "HasNoCafRefs")

instance Outputable IfaceUnfolding where
  ppr (IfCompulsory e)     = ptext (sLit "<compulsory>") <+> parens (ppr e)
  ppr (IfCoreUnfold s e)   = (if s then ptext (sLit "<stable>") else empty)
                              <+> parens (ppr e)
  ppr (IfInlineRule a uok bok e) = sep [ptext (sLit "InlineRule")
                                            <+> ppr (a,uok,bok),
                                        pprParendIfaceExpr e]
  ppr (IfDFunUnfold bs es) = hang (ptext (sLit "DFun:") <+> sep (map ppr bs) <> dot)
                                2 (sep (map pprParendIfaceExpr es))

-- -----------------------------------------------------------------------------
-- | Finding the Names in IfaceSyn

-- This is used for dependency analysis in MkIface, so that we
-- fingerprint a declaration before the things that depend on it.  It
-- is specific to interface-file fingerprinting in the sense that we
-- don't collect *all* Names: for example, the DFun of an instance is
-- recorded textually rather than by its fingerprint when
-- fingerprinting the instance, so DFuns are not dependencies.

freeNamesIfDecl :: IfaceDecl -> NameSet
freeNamesIfDecl (IfaceId _s t d i) =
  freeNamesIfType t &&&
  freeNamesIfIdInfo i &&&
  freeNamesIfIdDetails d
freeNamesIfDecl IfaceForeign{} =
  emptyNameSet
freeNamesIfDecl d@IfaceData{} =
  freeNamesIfTvBndrs (ifTyVars d) &&&
  maybe emptyNameSet unitNameSet (ifAxiom d) &&&
  freeNamesIfContext (ifCtxt d) &&&
  freeNamesIfConDecls (ifCons d)
freeNamesIfDecl d@IfaceSyn{} =
  freeNamesIfTvBndrs (ifTyVars d) &&&
  freeNamesIfSynRhs (ifSynRhs d) &&&
  freeNamesIfKind (ifSynKind d) -- IA0_NOTE: because of promotion, we
                                -- return names in the kind signature
freeNamesIfDecl d@IfaceClass{} =
  freeNamesIfTvBndrs (ifTyVars d) &&&
  freeNamesIfContext (ifCtxt d) &&&
  fnList freeNamesIfAT     (ifATs d) &&&
  fnList freeNamesIfClsSig (ifSigs d)
freeNamesIfDecl d@IfaceAxiom{} =
  freeNamesIfTc (ifTyCon d) &&&
  fnList freeNamesIfAxBranch (ifAxBranches d)

freeNamesIfAxBranch :: IfaceAxBranch -> NameSet
freeNamesIfAxBranch (IfaceAxBranch { ifaxbTyVars = tyvars
                                   , ifaxbLHS    = lhs
                                   , ifaxbRHS    = rhs }) =
  freeNamesIfTvBndrs tyvars &&&
  fnList freeNamesIfType lhs &&&
  freeNamesIfType rhs

freeNamesIfIdDetails :: IfaceIdDetails -> NameSet
freeNamesIfIdDetails (IfRecSelId tc _) = freeNamesIfTc tc
freeNamesIfIdDetails _                 = emptyNameSet

-- All other changes are handled via the version info on the tycon
freeNamesIfSynRhs :: IfaceSynTyConRhs -> NameSet
freeNamesIfSynRhs (IfaceSynonymTyCon ty)            = freeNamesIfType ty
freeNamesIfSynRhs IfaceOpenSynFamilyTyCon           = emptyNameSet
freeNamesIfSynRhs (IfaceClosedSynFamilyTyCon ax)    = unitNameSet ax
freeNamesIfSynRhs IfaceAbstractClosedSynFamilyTyCon = emptyNameSet

freeNamesIfContext :: IfaceContext -> NameSet
freeNamesIfContext = fnList freeNamesIfType

freeNamesIfAT :: IfaceAT -> NameSet
freeNamesIfAT (IfaceAT decl defs)
  = freeNamesIfDecl decl &&&
    fnList freeNamesIfAxBranch defs

freeNamesIfClsSig :: IfaceClassOp -> NameSet
freeNamesIfClsSig (IfaceClassOp _n _dm ty) = freeNamesIfType ty

freeNamesIfConDecls :: IfaceConDecls -> NameSet
freeNamesIfConDecls (IfDataTyCon c) = fnList freeNamesIfConDecl c
freeNamesIfConDecls (IfNewTyCon c)  = freeNamesIfConDecl c
freeNamesIfConDecls _               = emptyNameSet

freeNamesIfConDecl :: IfaceConDecl -> NameSet
freeNamesIfConDecl c =
  freeNamesIfTvBndrs (ifConUnivTvs c) &&&
  freeNamesIfTvBndrs (ifConExTvs c) &&&
  freeNamesIfContext (ifConCtxt c) &&&
  fnList freeNamesIfType (ifConArgTys c) &&&
  fnList freeNamesIfType (map snd (ifConEqSpec c)) -- equality constraints

freeNamesIfKind :: IfaceType -> NameSet
freeNamesIfKind = freeNamesIfType

freeNamesIfType :: IfaceType -> NameSet
freeNamesIfType (IfaceTyVar _)        = emptyNameSet
freeNamesIfType (IfaceAppTy s t)      = freeNamesIfType s &&& freeNamesIfType t
freeNamesIfType (IfaceTyConApp tc ts) =
   freeNamesIfTc tc &&& fnList freeNamesIfType ts
freeNamesIfType (IfaceLitTy _)        = emptyNameSet
freeNamesIfType (IfaceForAllTy tv t)  =
   freeNamesIfTvBndr tv &&& freeNamesIfType t
freeNamesIfType (IfaceFunTy s t)      = freeNamesIfType s &&& freeNamesIfType t

freeNamesIfCoercion :: IfaceCoercion -> NameSet
freeNamesIfCoercion (IfaceReflCo _ t) = freeNamesIfType t
freeNamesIfCoercion (IfaceFunCo _ c1 c2)
  = freeNamesIfCoercion c1 &&& freeNamesIfCoercion c2
freeNamesIfCoercion (IfaceTyConAppCo _ tc cos)
  = freeNamesIfTc tc &&& fnList freeNamesIfCoercion cos
freeNamesIfCoercion (IfaceAppCo c1 c2)
  = freeNamesIfCoercion c1 &&& freeNamesIfCoercion c2
freeNamesIfCoercion (IfaceForAllCo tv co)
  = freeNamesIfTvBndr tv &&& freeNamesIfCoercion co
freeNamesIfCoercion (IfaceCoVarCo _)
  = emptyNameSet
freeNamesIfCoercion (IfaceAxiomInstCo ax _ cos)
  = unitNameSet ax &&& fnList freeNamesIfCoercion cos
freeNamesIfCoercion (IfaceUnivCo _ t1 t2)
  = freeNamesIfType t1 &&& freeNamesIfType t2
freeNamesIfCoercion (IfaceSymCo c)
  = freeNamesIfCoercion c
freeNamesIfCoercion (IfaceTransCo c1 c2)
  = freeNamesIfCoercion c1 &&& freeNamesIfCoercion c2
freeNamesIfCoercion (IfaceNthCo _ co)
  = freeNamesIfCoercion co
freeNamesIfCoercion (IfaceLRCo _ co)
  = freeNamesIfCoercion co
freeNamesIfCoercion (IfaceInstCo co ty)
  = freeNamesIfCoercion co &&& freeNamesIfType ty
freeNamesIfCoercion (IfaceSubCo co)
  = freeNamesIfCoercion co
freeNamesIfCoercion (IfaceAxiomRuleCo _ax tys cos)
  -- the axiom is just a string, so we don't count it as a name.
  = fnList freeNamesIfType tys &&&
    fnList freeNamesIfCoercion cos

freeNamesIfTvBndrs :: [IfaceTvBndr] -> NameSet
freeNamesIfTvBndrs = fnList freeNamesIfTvBndr

freeNamesIfBndr :: IfaceBndr -> NameSet
freeNamesIfBndr (IfaceIdBndr b) = freeNamesIfIdBndr b
freeNamesIfBndr (IfaceTvBndr b) = freeNamesIfTvBndr b

freeNamesIfLetBndr :: IfaceLetBndr -> NameSet
-- Remember IfaceLetBndr is used only for *nested* bindings
-- The IdInfo can contain an unfolding (in the case of
-- local INLINE pragmas), so look there too
freeNamesIfLetBndr (IfLetBndr _name ty info) = freeNamesIfType ty
                                             &&& freeNamesIfIdInfo info

freeNamesIfTvBndr :: IfaceTvBndr -> NameSet
freeNamesIfTvBndr (_fs,k) = freeNamesIfKind k
    -- kinds can have Names inside, because of promotion

freeNamesIfIdBndr :: IfaceIdBndr -> NameSet
freeNamesIfIdBndr = freeNamesIfTvBndr

freeNamesIfIdInfo :: IfaceIdInfo -> NameSet
freeNamesIfIdInfo NoInfo      = emptyNameSet
freeNamesIfIdInfo (HasInfo i) = fnList freeNamesItem i

freeNamesItem :: IfaceInfoItem -> NameSet
freeNamesItem (HsUnfold _ u) = freeNamesIfUnfold u
freeNamesItem _              = emptyNameSet

freeNamesIfUnfold :: IfaceUnfolding -> NameSet
freeNamesIfUnfold (IfCoreUnfold _ e)     = freeNamesIfExpr e
freeNamesIfUnfold (IfCompulsory e)       = freeNamesIfExpr e
freeNamesIfUnfold (IfInlineRule _ _ _ e) = freeNamesIfExpr e
freeNamesIfUnfold (IfDFunUnfold bs es)   = fnList freeNamesIfBndr bs &&& fnList freeNamesIfExpr es

freeNamesIfExpr :: IfaceExpr -> NameSet
freeNamesIfExpr (IfaceExt v)      = unitNameSet v
freeNamesIfExpr (IfaceFCall _ ty) = freeNamesIfType ty
freeNamesIfExpr (IfaceType ty)    = freeNamesIfType ty
freeNamesIfExpr (IfaceCo co)      = freeNamesIfCoercion co
freeNamesIfExpr (IfaceTuple _ as) = fnList freeNamesIfExpr as
freeNamesIfExpr (IfaceLam b body) = freeNamesIfBndr b &&& freeNamesIfExpr body
freeNamesIfExpr (IfaceApp f a)    = freeNamesIfExpr f &&& freeNamesIfExpr a
freeNamesIfExpr (IfaceCast e co)  = freeNamesIfExpr e &&& freeNamesIfCoercion co
freeNamesIfExpr (IfaceTick _ e)   = freeNamesIfExpr e
freeNamesIfExpr (IfaceECase e ty) = freeNamesIfExpr e &&& freeNamesIfType ty
freeNamesIfExpr (IfaceCase s _ alts)
  = freeNamesIfExpr s 
    &&& fnList fn_alt alts &&& fn_cons alts
  where
    fn_alt (_con,_bs,r) = freeNamesIfExpr r

    -- Depend on the data constructors.  Just one will do!
    -- Note [Tracking data constructors]
    fn_cons []                            = emptyNameSet
    fn_cons ((IfaceDefault    ,_,_) : xs) = fn_cons xs
    fn_cons ((IfaceDataAlt con,_,_) : _ ) = unitNameSet con
    fn_cons (_                      : _ ) = emptyNameSet

freeNamesIfExpr (IfaceLet (IfaceNonRec bndr rhs) body)
  = freeNamesIfLetBndr bndr &&& freeNamesIfExpr rhs &&& freeNamesIfExpr body

freeNamesIfExpr (IfaceLet (IfaceRec as) x)
  = fnList fn_pair as &&& freeNamesIfExpr x
  where
    fn_pair (bndr, rhs) = freeNamesIfLetBndr bndr &&& freeNamesIfExpr rhs

freeNamesIfExpr _ = emptyNameSet

freeNamesIfTc :: IfaceTyCon -> NameSet
freeNamesIfTc (IfaceTc tc) = unitNameSet tc
-- ToDo: shouldn't we include IfaceIntTc & co.?

freeNamesIfRule :: IfaceRule -> NameSet
freeNamesIfRule (IfaceRule { ifRuleBndrs = bs, ifRuleHead = f
                           , ifRuleArgs = es, ifRuleRhs = rhs })
  = unitNameSet f &&&
    fnList freeNamesIfBndr bs &&&
    fnList freeNamesIfExpr es &&&
    freeNamesIfExpr rhs
    
freeNamesIfFamInst :: IfaceFamInst -> NameSet
freeNamesIfFamInst (IfaceFamInst { ifFamInstFam = famName
                                 , ifFamInstAxiom = axName })
  = unitNameSet famName &&&
    unitNameSet axName

-- helpers
(&&&) :: NameSet -> NameSet -> NameSet
(&&&) = unionNameSets

fnList :: (a -> NameSet) -> [a] -> NameSet
fnList f = foldr (&&&) emptyNameSet . map f
\end{code}

Note [Tracking data constructors]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In a case expression
   case e of { C a -> ...; ... }
You might think that we don't need to include the datacon C
in the free names, because its type will probably show up in
the free names of 'e'.  But in rare circumstances this may
not happen.   Here's the one that bit me:

   module DynFlags where
     import {-# SOURCE #-} Packages( PackageState )
     data DynFlags = DF ... PackageState ...

   module Packages where
     import DynFlags
     data PackageState = PS ...
     lookupModule (df :: DynFlags)
        = case df of
              DF ...p... -> case p of
                               PS ... -> ...

Now, lookupModule depends on DynFlags, but the transitive dependency
on the *locally-defined* type PackageState is not visible. We need
to take account of the use of the data constructor PS in the pattern match.