    {-
    (c) The University of Glasgow 2006
    (c) The AQUA Project, Glasgow University, 1998

    This module contains definitions for the IdInfo for things that
    have a standard form, namely:

    - data constructors
    - record selectors
    - method and superclass selectors
    - primitive operations
    -}

    {-# LANGUAGE CPP #-}

    {-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}

    module GHC.Types.Id.Make (
            mkDictFunId, mkDictFunTy, mkDictSelId, mkDictSelRhs,

            mkPrimOpId, mkFCallId,

            unwrapNewTypeBody, wrapFamInstBody,
            DataConBoxer(..), vanillaDataConBoxer,
            mkDataConRep, mkDataConWorkId,

            -- And some particular Ids; see below for why they are wired in
            wiredInIds, ghcPrimIds,
            realWorldPrimId,
            voidPrimId, voidArgId,
            nullAddrId, seqId, lazyId, lazyIdKey,
            coercionTokenId, magicDictId, coerceId,
            proxyHashId, noinlineId, noinlineIdName,
            coerceName, leftSectionName, rightSectionName,

            -- Re-export error Ids
            module GHC.Core.Opt.ConstantFold
        ) where

    #include "HsVersions.h"

    import GHC.Prelude

    import GHC.Builtin.Types.Prim
    import GHC.Builtin.Types
    import GHC.Core.Opt.ConstantFold
    import GHC.Core.Type
    import GHC.Core.Multiplicity
    import GHC.Core.TyCo.Rep
    import GHC.Core.FamInstEnv
    import GHC.Core.Coercion
    import GHC.Tc.Utils.TcType as TcType
    import GHC.Core.Make
    import GHC.Core.FVs     ( mkRuleInfo )
    import GHC.Core.Utils   ( exprType, mkCast, mkDefaultCase )
    import GHC.Core.Unfold.Make
    import GHC.Core.SimpleOpt
    import GHC.Types.Literal
    import GHC.Types.SourceText
    import GHC.Core.TyCon
    import GHC.Core.Class
    import GHC.Types.Name.Set
    import GHC.Types.Name
    import GHC.Builtin.PrimOps
    import GHC.Types.ForeignCall
    import GHC.Core.DataCon
    import GHC.Types.Id
    import GHC.Types.Id.Info
    import GHC.Types.Demand
    import GHC.Types.Cpr
    import GHC.Types.TyThing
    import GHC.Core
    import GHC.Types.Unique
    import GHC.Builtin.Uniques
    import GHC.Types.Unique.Supply
    import GHC.Builtin.Names
    import GHC.Types.Basic       hiding ( SuccessFlag(..) )
    import GHC.Utils.Misc
    import GHC.Driver.Session
    import GHC.Driver.Ppr
    import GHC.Utils.Outputable
    import GHC.Utils.Panic
    import GHC.Data.FastString
    import GHC.Data.List.SetOps
    import GHC.Types.Var (VarBndr(Bndr))
    import qualified GHC.LanguageExtensions as LangExt

    import Data.Maybe       ( maybeToList )

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Wired in Ids}
    *                                                                      *
    ************************************************************************

    Note [Wired-in Ids]
    ~~~~~~~~~~~~~~~~~~~
    A "wired-in" Id can be referred to directly in GHC (e.g. 'voidPrimId')
    rather than by looking it up its name in some environment or fetching
    it from an interface file.

    There are several reasons why an Id might appear in the wiredInIds:

    * ghcPrimIds: see Note [ghcPrimIds (aka pseudoops)]

    * magicIds: see Note [magicIds]

    * errorIds, defined in GHC.Core.Make.
      These error functions (e.g. rUNTIME_ERROR_ID) are wired in
      because the desugarer generates code that mentions them directly

    In all cases except ghcPrimIds, there is a definition site in a
    library module, which may be called (e.g. in higher order situations);
    but the wired-in version means that the details are never read from
    that module's interface file; instead, the full definition is right
    here.

    Note [ghcPrimIds (aka pseudoops)]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The ghcPrimIds

      * Are exported from GHC.Prim (see ghcPrimExports, used in ghcPrimInterface)
        See Note [GHC.Prim] in primops.txt.pp for the remaining items in GHC.Prim.

      * Can't be defined in Haskell, and hence no Haskell binding site,
        but have perfectly reasonable unfoldings in Core

      * Either have a CompulsoryUnfolding (hence always inlined), or
            of an EvaldUnfolding and void representation (e.g. realWorldPrimId)

      * Are (or should be) defined in primops.txt.pp as 'pseudoop'
        Reason: that's how we generate documentation for them

    Note [magicIds]
    ~~~~~~~~~~~~~~~
    The magicIds

      * Are exported from GHC.Magic

      * Can be defined in Haskell (and are, in ghc-prim:GHC/Magic.hs).
        This definition at least generates Haddock documentation for them.

      * May or may not have a CompulsoryUnfolding.

      * But have some special behaviour that can't be done via an
        unfolding from an interface file.

      * May have IdInfo that differs from what would be imported from GHC.Magic.hi.
        For example, 'lazy' gets a lazy strictness signature, per Note [lazyId magic].

      The two remaining identifiers in GHC.Magic, runRW# and inline, are not listed
      in magicIds: they have special behavior but they can be known-key and
      not wired-in.
      runRW#: see Note [Simplification of runRW#] in Prep, runRW# code in
      Simplifier, Note [Linting of runRW#].
      inline: see Note [inlineId magic]
    -}

    wiredInIds :: [Id]
    wiredInIds :: [Id]
    wiredInIds
      =  [Id]
    magicIds
      forall a. [a] -> [a] -> [a]
    ++ [Id]
    ghcPrimIds
      forall a. [a] -> [a] -> [a]
    ++ [Id]
    errorIds           -- Defined in GHC.Core.Make

    magicIds :: [Id]    -- See Note [magicIds]
    magicIds :: [Id]
    magicIds = [Id
    lazyId, Id
    oneShotId, Id
    noinlineId]

    ghcPrimIds :: [Id]  -- See Note [ghcPrimIds (aka pseudoops)]
    ghcPrimIds :: [Id]
    ghcPrimIds
      = [ Id
    realWorldPrimId
        , Id
    voidPrimId
        , Id
    nullAddrId
        , Id
    seqId
        , Id
    magicDictId
        , Id
    coerceId
        , Id
    proxyHashId
        , Id
    leftSectionId
        , Id
    rightSectionId
        ]

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Data constructors}
    *                                                                      *
    ************************************************************************

    The wrapper for a constructor is an ordinary top-level binding that evaluates
    any strict args, unboxes any args that are going to be flattened, and calls
    the worker.

    We're going to build a constructor that looks like:

            data (Data a, C b) =>  T a b = T1 !a !Int b

            T1 = /\ a b ->
                 \d1::Data a, d2::C b ->
                 \p q r -> case p of { p ->
                           case q of { q ->
                           Con T1 [a,b] [p,q,r]}}

    Notice that

    * d2 is thrown away --- a context in a data decl is used to make sure
      one *could* construct dictionaries at the site the constructor
      is used, but the dictionary isn't actually used.

    * We have to check that we can construct Data dictionaries for
      the types a and Int.  Once we've done that we can throw d1 away too.

    * We use (case p of q -> ...) to evaluate p, rather than "seq" because
      all that matters is that the arguments are evaluated.  "seq" is
      very careful to preserve evaluation order, which we don't need
      to be here.

      You might think that we could simply give constructors some strictness
      info, like PrimOps, and let CoreToStg do the let-to-case transformation.
      But we don't do that because in the case of primops and functions strictness
      is a *property* not a *requirement*.  In the case of constructors we need to
      do something active to evaluate the argument.

      Making an explicit case expression allows the simplifier to eliminate
      it in the (common) case where the constructor arg is already evaluated.

    Note [Wrappers for data instance tycons]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In the case of data instances, the wrapper also applies the coercion turning
    the representation type into the family instance type to cast the result of
    the wrapper.  For example, consider the declarations

      data family Map k :: * -> *
      data instance Map (a, b) v = MapPair (Map a (Pair b v))

    The tycon to which the datacon MapPair belongs gets a unique internal
    name of the form :R123Map, and we call it the representation tycon.
    In contrast, Map is the family tycon (accessible via
    tyConFamInst_maybe). A coercion allows you to move between
    representation and family type.  It is accessible from :R123Map via
    tyConFamilyCoercion_maybe and has kind

      Co123Map a b v :: {Map (a, b) v ~ :R123Map a b v}

    The wrapper and worker of MapPair get the types

            -- Wrapper
      $WMapPair :: forall a b v. Map a (Map a b v) -> Map (a, b) v
      $WMapPair a b v = MapPair a b v `cast` sym (Co123Map a b v)

            -- Worker
      MapPair :: forall a b v. Map a (Map a b v) -> :R123Map a b v

    This coercion is conditionally applied by wrapFamInstBody.

    It's a bit more complicated if the data instance is a GADT as well!

       data instance T [a] where
            T1 :: forall b. b -> T [Maybe b]

    Hence we translate to

            -- Wrapper
      $WT1 :: forall b. b -> T [Maybe b]
      $WT1 b v = T1 (Maybe b) b (Maybe b) v
                            `cast` sym (Co7T (Maybe b))

            -- Worker
      T1 :: forall c b. (c ~ Maybe b) => b -> :R7T c

            -- Coercion from family type to representation type
      Co7T a :: T [a] ~ :R7T a

    Newtype instances through an additional wrinkle into the mix. Consider the
    following example (adapted from #15318, comment:2):

      data family T a
      newtype instance T [a] = MkT [a]

    Within the newtype instance, there are three distinct types at play:

    1. The newtype's underlying type, [a].
    2. The instance's representation type, TList a (where TList is the
       representation tycon).
    3. The family type, T [a].

    We need two coercions in order to cast from (1) to (3):

    (a) A newtype coercion axiom:

          axiom coTList a :: TList a ~ [a]

        (Where TList is the representation tycon of the newtype instance.)

    (b) A data family instance coercion axiom:

          axiom coT a :: T [a] ~ TList a

    When we translate the newtype instance to Core, we obtain:

        -- Wrapper
      $WMkT :: forall a. [a] -> T [a]
      $WMkT a x = MkT a x |> Sym (coT a)

        -- Worker
      MkT :: forall a. [a] -> TList [a]
      MkT a x = x |> Sym (coTList a)

    Unlike for data instances, the worker for a newtype instance is actually an
    executable function which expands to a cast, but otherwise, the general
    strategy is essentially the same as for data instances. Also note that we have
    a wrapper, which is unusual for a newtype, but we make GHC produce one anyway
    for symmetry with the way data instances are handled.

    Note [Newtype datacons]
    ~~~~~~~~~~~~~~~~~~~~~~~
    The "data constructor" for a newtype should always be vanilla.  At one
    point this wasn't true, because the newtype arising from
         class C a => D a
    looked like
           newtype T:D a = D:D (C a)
    so the data constructor for T:C had a single argument, namely the
    predicate (C a).  But now we treat that as an ordinary argument, not
    part of the theta-type, so all is well.

    Note [Newtype workers]
    ~~~~~~~~~~~~~~~~~~~~~~
    A newtype does not really have a worker. Instead, newtype constructors
    just unfold into a cast. But we need *something* for, say, MkAge to refer
    to. So, we do this:

    * The Id used as the newtype worker will have a compulsory unfolding to
      a cast. See Note [Compulsory newtype unfolding]

    * This Id is labeled as a DataConWrapId. We don't want to use a DataConWorkId,
      as those have special treatment in the back end.

    * There is no top-level binding, because the compulsory unfolding
      means that it will be inlined (to a cast) at every call site.

    We probably should have a NewtypeWorkId, but these Ids disappear as soon as
    we desugar anyway, so it seems a step too far.

    Note [Compulsory newtype unfolding]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Newtype wrappers, just like workers, have compulsory unfoldings.
    This is needed so that two optimizations involving newtypes have the same
    effect whether a wrapper is present or not:

    (1) Case-of-known constructor.
        See Note [beta-reduction in exprIsConApp_maybe].

    (2) Matching against the map/coerce RULE. Suppose we have the RULE

        {-# RULE "map/coerce" map coerce = ... #-}

        As described in Note [Getting the map/coerce RULE to work],
        the occurrence of 'coerce' is transformed into:

        {-# RULE "map/coerce" forall (c :: T1 ~R# T2).
                              map ((\v -> v) `cast` c) = ... #-}

        We'd like 'map Age' to match the LHS. For this to happen, Age
        must be unfolded, otherwise we'll be stuck. This is tested in T16208.

    It also allows for the posssibility of levity polymorphic newtypes
    with wrappers (with -XUnliftedNewtypes):

      newtype N (a :: TYPE r) = MkN a

    With -XUnliftedNewtypes, this is allowed -- even though MkN is levity-
    polymorphic. It's OK because MkN evaporates in the compiled code, becoming
    just a cast. That is, it has a compulsory unfolding. As long as its
    argument is not levity-polymorphic (which it can't be, according to
    Note [Levity polymorphism invariants] in GHC.Core), and it's saturated,
    no levity-polymorphic code ends up in the code generator. The saturation
    condition is effectively checked by Note [Detecting forced eta expansion]
    in GHC.HsToCore.Expr.

    However, if we make a *wrapper* for a newtype, we get into trouble.
    The saturation condition is no longer checked (because hasNoBinding
    returns False) and indeed we generate a forbidden levity-polymorphic
    binding.

    The solution is simple, though: just make the newtype wrappers
    as ephemeral as the newtype workers. In other words, give the wrappers
    compulsory unfoldings and no bindings. The compulsory unfolding is given
    in wrap_unf in mkDataConRep, and the lack of a binding happens in
    GHC.Iface.Tidy.getTyConImplicitBinds, where we say that a newtype has no
    implicit bindings.

    Note [Records and linear types]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    All the fields, in a record constructor, are linear, because there is no syntax
    to specify the type of record field. There will be (see the proposal
    https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0111-linear-types.rst#records-and-projections
    ), but it isn't implemented yet.

    Projections of records can't be linear:

      data Foo = MkFoo { a :: A, b :: B }

    If we had

      a :: Foo %1 -> A

    We could write

      bad :: A %1 -> B %1 -> A
      bad x y = a (MkFoo { a=x, b=y })

    There is an exception: if `b` (more generally all the fields besides `a`) is
    unrestricted, then is perfectly possible to have a linear projection. Such a
    linear projection has as simple definition.

      data Bar = MkBar { c :: C, d # Many :: D }

      c :: Bar %1 -> C
      c MkBar{ c=x, d=_} = x

    The `# Many` syntax, for records, does not exist yet. But there is one important
    special case which already happens: when there is a single field (usually a
    newtype).

      newtype Baz = MkBaz { unbaz :: E }

    unbaz could be linear. And, in fact, it is linear in the proposal design.

    However, this hasn't been implemented yet.

    ************************************************************************
    *                                                                      *
    \subsection{Dictionary selectors}
    *                                                                      *
    ************************************************************************

    Selecting a field for a dictionary.  If there is just one field, then
    there's nothing to do.

    Dictionary selectors may get nested forall-types.  Thus:

            class Foo a where
              op :: forall b. Ord b => a -> b -> b

    Then the top-level type for op is

            op :: forall a. Foo a =>
                  forall b. Ord b =>
                  a -> b -> b

    Note [Type classes and linear types]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    Constraints, in particular type classes, don't have attached linearity
    information. Implicitly, they are all unrestricted. See the linear types proposal,
    https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0111-linear-types.rst .

    When translating to core `C => ...` is always translated to an unrestricted
    arrow `C # Many -> ...`.

    Therefore there is no loss of generality if we make all selectors unrestricted.

    -}

    mkDictSelId :: Name          -- Name of one of the *value* selectors
                                 -- (dictionary superclass or method)
                -> Class -> Id
    mkDictSelId :: Name -> Class -> Id
    mkDictSelId Name
    name Class
    clas
      = IdDetails -> Name -> Type -> IdInfo -> Id
    mkGlobalId (Class -> IdDetails
    ClassOpId Class
    clas) Name
    name Type
    sel_ty IdInfo
    info
      where
        tycon :: TyCon
    tycon          = Class -> TyCon
    classTyCon Class
    clas
        sel_names :: [Name]
    sel_names      = forall a b. (a -> b) -> [a] -> [b]
    map Id -> Name
    idName (Class -> [Id]
    classAllSelIds Class
    clas)
        new_tycon :: Bool
    new_tycon      = TyCon -> Bool
    isNewTyCon TyCon
    tycon
        [DataCon
    data_con]     = TyCon -> [DataCon]
    tyConDataCons TyCon
    tycon
        tyvars :: [InvisTVBinder]
    tyvars         = DataCon -> [InvisTVBinder]
    dataConUserTyVarBinders DataCon
    data_con
        n_ty_args :: Arity
    n_ty_args      = forall (t :: * -> *) a. Foldable t => t a -> Arity
    length [InvisTVBinder]
    tyvars
        arg_tys :: [Scaled Type]
    arg_tys        = DataCon -> [Scaled Type]
    dataConRepArgTys DataCon
    data_con  -- Includes the dictionary superclasses
        val_index :: Arity
    val_index      = forall a b. Eq a => String -> Assoc a b -> a -> b
    assoc String
    "MkId.mkDictSelId" ([Name]
    sel_names forall a b. [a] -> [b] -> [(a, b)]
    `zip` [Arity
    0..]) Name
    name

        sel_ty :: Type
    sel_ty = [InvisTVBinder] -> Type -> Type
    mkInvisForAllTys [InvisTVBinder]
    tyvars forall a b. (a -> b) -> a -> b
    $
                 Type -> Type -> Type
    mkInvisFunTyMany (Class -> [Type] -> Type
    mkClassPred Class
    clas ([Id] -> [Type]
    mkTyVarTys (forall tv argf. [VarBndr tv argf] -> [tv]
    binderVars [InvisTVBinder]
    tyvars))) forall a b. (a -> b) -> a -> b
    $
                 forall a. Scaled a -> a
    scaledThing (forall a. Outputable a => [a] -> Arity -> a
    getNth [Scaled Type]
    arg_tys Arity
    val_index)
                   -- See Note [Type classes and linear types]

        base_info :: IdInfo
    base_info = IdInfo
    noCafIdInfo
                    IdInfo -> Arity -> IdInfo
    `setArityInfo`          Arity
    1
                    IdInfo -> StrictSig -> IdInfo
    `setStrictnessInfo`     StrictSig
    strict_sig
                    IdInfo -> CprSig -> IdInfo
    `setCprInfo`            CprSig
    topCprSig
                    IdInfo -> Type -> IdInfo
    `setLevityInfoWithType` Type
    sel_ty

        info :: IdInfo
    info | Bool
    new_tycon
             = IdInfo
    base_info IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo` InlinePragma
    alwaysInlinePragma
                         IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`  Arity -> SimpleOpts -> CoreExpr -> Unfolding
    mkInlineUnfoldingWithArity Arity
    1
                                               SimpleOpts
    defaultSimpleOpts
                                               (Class -> Arity -> CoreExpr
    mkDictSelRhs Class
    clas Arity
    val_index)
                       -- See Note [Single-method classes] in GHC.Tc.TyCl.Instance
                       -- for why alwaysInlinePragma

             | Bool
    otherwise
             = IdInfo
    base_info IdInfo -> RuleInfo -> IdInfo
    `setRuleInfo` [CoreRule] -> RuleInfo
    mkRuleInfo [CoreRule
    rule]
                       -- Add a magic BuiltinRule, but no unfolding
                       -- so that the rule is always available to fire.
                       -- See Note [ClassOp/DFun selection] in GHC.Tc.TyCl.Instance

        -- This is the built-in rule that goes
        --      op (dfT d1 d2) --->  opT d1 d2
        rule :: CoreRule
    rule = BuiltinRule { ru_name :: RuleName
    ru_name = String -> RuleName
    fsLit String
    "Class op " RuleName -> RuleName -> RuleName
    `appendFS`
                                         OccName -> RuleName
    occNameFS (forall a. NamedThing a => a -> OccName
    getOccName Name
    name)
                           , ru_fn :: Name
    ru_fn    = Name
    name
                           , ru_nargs :: Arity
    ru_nargs = Arity
    n_ty_args forall a. Num a => a -> a -> a
    + Arity
    1
                           , ru_try :: RuleFun
    ru_try   = Arity -> Arity -> RuleFun
    dictSelRule Arity
    val_index Arity
    n_ty_args }

            -- The strictness signature is of the form U(AAAVAAAA) -> T
            -- where the V depends on which item we are selecting
            -- It's worth giving one, so that absence info etc is generated
            -- even if the selector isn't inlined

        strict_sig :: StrictSig
    strict_sig = [Demand] -> Divergence -> StrictSig
    mkClosedStrictSig [Demand
    arg_dmd] Divergence
    topDiv
        arg_dmd :: Demand
    arg_dmd | Bool
    new_tycon = Demand
    evalDmd
                | Bool
    otherwise = Card
    C_1N Card -> SubDemand -> Demand
    :*
                              [Demand] -> SubDemand
    Prod [ if Name
    name forall a. Eq a => a -> a -> Bool
    == Name
    sel_name then Demand
    evalDmd else Demand
    absDmd
                                   | Name
    sel_name <- [Name]
    sel_names ]

    mkDictSelRhs :: Class
                 -> Int         -- 0-indexed selector among (superclasses ++ methods)
                 -> CoreExpr
    mkDictSelRhs :: Class -> Arity -> CoreExpr
    mkDictSelRhs Class
    clas Arity
    val_index
      = forall b. [b] -> Expr b -> Expr b
    mkLams [Id]
    tyvars (forall b. b -> Expr b -> Expr b
    Lam Id
    dict_id CoreExpr
    rhs_body)
      where
        tycon :: TyCon
    tycon          = Class -> TyCon
    classTyCon Class
    clas
        new_tycon :: Bool
    new_tycon      = TyCon -> Bool
    isNewTyCon TyCon
    tycon
        [DataCon
    data_con]     = TyCon -> [DataCon]
    tyConDataCons TyCon
    tycon
        tyvars :: [Id]
    tyvars         = DataCon -> [Id]
    dataConUnivTyVars DataCon
    data_con
        arg_tys :: [Scaled Type]
    arg_tys        = DataCon -> [Scaled Type]
    dataConRepArgTys DataCon
    data_con  -- Includes the dictionary superclasses

        the_arg_id :: Id
    the_arg_id     = forall a. Outputable a => [a] -> Arity -> a
    getNth [Id]
    arg_ids Arity
    val_index
        pred :: Type
    pred           = Class -> [Type] -> Type
    mkClassPred Class
    clas ([Id] -> [Type]
    mkTyVarTys [Id]
    tyvars)
        dict_id :: Id
    dict_id        = Arity -> Type -> Id
    mkTemplateLocal Arity
    1 Type
    pred
        arg_ids :: [Id]
    arg_ids        = Arity -> [Type] -> [Id]
    mkTemplateLocalsNum Arity
    2 (forall a b. (a -> b) -> [a] -> [b]
    map forall a. Scaled a -> a
    scaledThing [Scaled Type]
    arg_tys)

        rhs_body :: CoreExpr
    rhs_body | Bool
    new_tycon = TyCon -> [Type] -> CoreExpr -> CoreExpr
    unwrapNewTypeBody TyCon
    tycon ([Id] -> [Type]
    mkTyVarTys [Id]
    tyvars)
                                                       (forall b. Id -> Expr b
    Var Id
    dict_id)
                 | Bool
    otherwise = CoreExpr -> Id -> AltCon -> [Id] -> CoreExpr -> CoreExpr
    mkSingleAltCase (forall b. Id -> Expr b
    Var Id
    dict_id) Id
    dict_id (DataCon -> AltCon
    DataAlt DataCon
    data_con)
                                               [Id]
    arg_ids (forall b. Id -> Expr b
    varToCoreExpr Id
    the_arg_id)
                                    -- varToCoreExpr needed for equality superclass selectors
                                    --   sel a b d = case x of { MkC _ (g:a~b) _ -> CO g }

    dictSelRule :: Int -> Arity -> RuleFun
    -- Tries to persuade the argument to look like a constructor
    -- application, using exprIsConApp_maybe, and then selects
    -- from it
    --       sel_i t1..tk (D t1..tk op1 ... opm) = opi
    --
    dictSelRule :: Arity -> Arity -> RuleFun
    dictSelRule Arity
    val_index Arity
    n_ty_args RuleOpts
    _ InScopeEnv
    id_unf Id
    _ [CoreExpr]
    args
      | (CoreExpr
    dict_arg : [CoreExpr]
    _) <- forall a. Arity -> [a] -> [a]
    drop Arity
    n_ty_args [CoreExpr]
    args
      , Just (InScopeSet
    _, [FloatBind]
    floats, DataCon
    _, [Type]
    _, [CoreExpr]
    con_args) <- HasDebugCallStack =>
    InScopeEnv
    -> CoreExpr
    -> Maybe (InScopeSet, [FloatBind], DataCon, [Type], [CoreExpr])
    exprIsConApp_maybe InScopeEnv
    id_unf CoreExpr
    dict_arg
      = forall a. a -> Maybe a
    Just ([FloatBind] -> CoreExpr -> CoreExpr
    wrapFloats [FloatBind]
    floats forall a b. (a -> b) -> a -> b
    $ forall a. Outputable a => [a] -> Arity -> a
    getNth [CoreExpr]
    con_args Arity
    val_index)
      | Bool
    otherwise
      = forall a. Maybe a
    Nothing

    {-
    ************************************************************************
    *                                                                      *
            Data constructors
    *                                                                      *
    ************************************************************************
    -}

    mkDataConWorkId :: Name -> DataCon -> Id
    mkDataConWorkId :: Name -> DataCon -> Id
    mkDataConWorkId Name
    wkr_name DataCon
    data_con
      | TyCon -> Bool
    isNewTyCon TyCon
    tycon
      = IdDetails -> Name -> Type -> IdInfo -> Id
    mkGlobalId (DataCon -> IdDetails
    DataConWrapId DataCon
    data_con) Name
    wkr_name Type
    wkr_ty IdInfo
    nt_work_info
          -- See Note [Newtype workers]

      | Bool
    otherwise
      = IdDetails -> Name -> Type -> IdInfo -> Id
    mkGlobalId (DataCon -> IdDetails
    DataConWorkId DataCon
    data_con) Name
    wkr_name Type
    wkr_ty IdInfo
    alg_wkr_info

      where
        tycon :: TyCon
    tycon  = DataCon -> TyCon
    dataConTyCon DataCon
    data_con  -- The representation TyCon
        wkr_ty :: Type
    wkr_ty = DataCon -> Type
    dataConRepType DataCon
    data_con

        ----------- Workers for data types --------------
        alg_wkr_info :: IdInfo
    alg_wkr_info = IdInfo
    noCafIdInfo
                       IdInfo -> Arity -> IdInfo
    `setArityInfo`          Arity
    wkr_arity
                       IdInfo -> CprSig -> IdInfo
    `setCprInfo`            Arity -> Cpr -> CprSig
    mkCprSig Arity
    wkr_arity (DataCon -> Cpr
    dataConCPR DataCon
    data_con)
                       IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo`     InlinePragma
    wkr_inline_prag
                       IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`      Unfolding
    evaldUnfolding  -- Record that it's evaluated,
                                                               -- even if arity = 0
                       IdInfo -> Type -> IdInfo
    `setLevityInfoWithType` Type
    wkr_ty
                         -- NB: unboxed tuples have workers, so we can't use
                         -- setNeverLevPoly

        wkr_inline_prag :: InlinePragma
    wkr_inline_prag = InlinePragma
    defaultInlinePragma { inl_rule :: RuleMatchInfo
    inl_rule = RuleMatchInfo
    ConLike }
        wkr_arity :: Arity
    wkr_arity = DataCon -> Arity
    dataConRepArity DataCon
    data_con
        ----------- Workers for newtypes --------------
        univ_tvs :: [Id]
    univ_tvs = DataCon -> [Id]
    dataConUnivTyVars DataCon
    data_con
        arg_tys :: [Scaled Type]
    arg_tys  = DataCon -> [Scaled Type]
    dataConRepArgTys  DataCon
    data_con  -- Should be same as dataConOrigArgTys
        nt_work_info :: IdInfo
    nt_work_info = IdInfo
    noCafIdInfo          -- The NoCaf-ness is set by noCafIdInfo
                      IdInfo -> Arity -> IdInfo
    `setArityInfo` Arity
    1      -- Arity 1
                      IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo`     InlinePragma
    dataConWrapperInlinePragma
                      IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`      Unfolding
    newtype_unf
                      IdInfo -> Type -> IdInfo
    `setLevityInfoWithType` Type
    wkr_ty
        id_arg1 :: Id
    id_arg1      = Arity -> Scaled Type -> Id
    mkScaledTemplateLocal Arity
    1 (forall a. [a] -> a
    head [Scaled Type]
    arg_tys)
        res_ty_args :: [Type]
    res_ty_args  = [Id] -> [Type]
    mkTyCoVarTys [Id]
    univ_tvs
        newtype_unf :: Unfolding
    newtype_unf  = ASSERT2( isVanillaDataCon data_con &&
                                isSingleton arg_tys
                              , ppr data_con  )
                                  -- Note [Newtype datacons]
                       SimpleOpts -> CoreExpr -> Unfolding
    mkCompulsoryUnfolding SimpleOpts
    defaultSimpleOpts forall a b. (a -> b) -> a -> b
    $
                       forall b. [b] -> Expr b -> Expr b
    mkLams [Id]
    univ_tvs forall a b. (a -> b) -> a -> b
    $ forall b. b -> Expr b -> Expr b
    Lam Id
    id_arg1 forall a b. (a -> b) -> a -> b
    $
                       TyCon -> [Type] -> CoreExpr -> CoreExpr
    wrapNewTypeBody TyCon
    tycon [Type]
    res_ty_args (forall b. Id -> Expr b
    Var Id
    id_arg1)

    dataConCPR :: DataCon -> Cpr
    dataConCPR :: DataCon -> Cpr
    dataConCPR DataCon
    con
      | TyCon -> Bool
    isDataTyCon TyCon
    tycon     -- Real data types only; that is,
                              -- not unboxed tuples or newtypes
      , forall (t :: * -> *) a. Foldable t => t a -> Bool
    null (DataCon -> [Id]
    dataConExTyCoVars DataCon
    con)  -- No existentials
      , Arity
    wkr_arity forall a. Ord a => a -> a -> Bool
    > Arity
    0
      , Arity
    wkr_arity forall a. Ord a => a -> a -> Bool
    <= Arity
    mAX_CPR_SIZE
      = Arity -> Cpr
    flatConCpr (DataCon -> Arity
    dataConTag DataCon
    con)
      | Bool
    otherwise
      = Cpr
    topCpr
      where
        tycon :: TyCon
    tycon     = DataCon -> TyCon
    dataConTyCon DataCon
    con
        wkr_arity :: Arity
    wkr_arity = DataCon -> Arity
    dataConRepArity DataCon
    con

        mAX_CPR_SIZE :: Arity
        mAX_CPR_SIZE :: Arity
    mAX_CPR_SIZE = Arity
    10
        -- We do not treat very big tuples as CPR-ish:
        --      a) for a start we get into trouble because there aren't
        --         "enough" unboxed tuple types (a tiresome restriction,
        --         but hard to fix),
        --      b) more importantly, big unboxed tuples get returned mainly
        --         on the stack, and are often then allocated in the heap
        --         by the caller.  So doing CPR for them may in fact make
        --         things worse.

    {-
    -------------------------------------------------
    --         Data constructor representation
    --
    -- This is where we decide how to wrap/unwrap the
    -- constructor fields
    --
    --------------------------------------------------
    -}

    type Unboxer = Var -> UniqSM ([Var], CoreExpr -> CoreExpr)
      -- Unbox: bind rep vars by decomposing src var

    data Boxer = UnitBox | Boxer (TCvSubst -> UniqSM ([Var], CoreExpr))
      -- Box:   build src arg using these rep vars

    -- | Data Constructor Boxer
    newtype DataConBoxer = DCB ([Type] -> [Var] -> UniqSM ([Var], [CoreBind]))
                           -- Bind these src-level vars, returning the
                           -- rep-level vars to bind in the pattern

    vanillaDataConBoxer :: DataConBoxer
    -- No transformation on arguments needed
    vanillaDataConBoxer :: DataConBoxer
    vanillaDataConBoxer = ([Type] -> [Id] -> UniqSM ([Id], [CoreBind])) -> DataConBoxer
    DCB (\[Type]
    _tys [Id]
    args -> forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id]
    args, []))

    {-
    Note [Inline partially-applied constructor wrappers]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    We allow the wrapper to inline when partially applied to avoid
    boxing values unnecessarily. For example, consider

       data Foo a = Foo !Int a

       instance Traversable Foo where
         traverse f (Foo i a) = Foo i <$> f a

    This desugars to

       traverse f foo = case foo of
            Foo i# a -> let i = I# i#
                        in map ($WFoo i) (f a)

    If the wrapper `$WFoo` is not inlined, we get a fruitless reboxing of `i`.
    But if we inline the wrapper, we get

       map (\a. case i of I# i# a -> Foo i# a) (f a)

    and now case-of-known-constructor eliminates the redundant allocation.

    -}

    mkDataConRep :: DynFlags
                 -> FamInstEnvs
                 -> Name
                 -> Maybe [HsImplBang]
                    -- See Note [Bangs on imported data constructors]
                 -> DataCon
                 -> UniqSM DataConRep
    mkDataConRep :: DynFlags
    -> FamInstEnvs
    -> Name
    -> Maybe [HsImplBang]
    -> DataCon
    -> UniqSM DataConRep
    mkDataConRep DynFlags
    dflags FamInstEnvs
    fam_envs Name
    wrap_name Maybe [HsImplBang]
    mb_bangs DataCon
    data_con
      | Bool -> Bool
    not Bool
    wrapper_reqd
      = forall (m :: * -> *) a. Monad m => a -> m a
    return DataConRep
    NoDataConRep

      | Bool
    otherwise
      = do { [Id]
    wrap_args <- forall (t :: * -> *) (m :: * -> *) a b.
    (Traversable t, Monad m) =>
    (a -> m b) -> t a -> m (t b)
    mapM Scaled Type -> UniqSM Id
    newLocal [Scaled Type]
    wrap_arg_tys
           ; CoreExpr
    wrap_body <- [(Id, Unboxer)] -> CoreExpr -> UniqSM CoreExpr
    mk_rep_app ([Id]
    wrap_args forall a b. [a] -> [b] -> [(a, b)]
    `zip` forall b a. [b] -> [a] -> [a]
    dropList [EqSpec]
    eq_spec [Unboxer]
    unboxers)
                                     CoreExpr
    initial_wrap_app

           ; let wrap_id :: Id
    wrap_id = IdDetails -> Name -> Type -> IdInfo -> Id
    mkGlobalId (DataCon -> IdDetails
    DataConWrapId DataCon
    data_con) Name
    wrap_name Type
    wrap_ty IdInfo
    wrap_info
                 wrap_info :: IdInfo
    wrap_info = IdInfo
    noCafIdInfo
                             IdInfo -> Arity -> IdInfo
    `setArityInfo`         Arity
    wrap_arity
                                 -- It's important to specify the arity, so that partial
                                 -- applications are treated as values
                             IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo`    InlinePragma
    wrap_prag
                             IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`     Unfolding
    wrap_unf
                             IdInfo -> StrictSig -> IdInfo
    `setStrictnessInfo`    StrictSig
    wrap_sig
                             IdInfo -> CprSig -> IdInfo
    `setCprInfo`           Arity -> Cpr -> CprSig
    mkCprSig Arity
    wrap_arity (DataCon -> Cpr
    dataConCPR DataCon
    data_con)
                                 -- We need to get the CAF info right here because GHC.Iface.Tidy
                                 -- does not tidy the IdInfo of implicit bindings (like the wrapper)
                                 -- so it not make sure that the CAF info is sane
                             IdInfo -> Type -> IdInfo
    `setLevityInfoWithType` Type
    wrap_ty

                 wrap_sig :: StrictSig
    wrap_sig = [Demand] -> Divergence -> StrictSig
    mkClosedStrictSig [Demand]
    wrap_arg_dmds Divergence
    topDiv

                 wrap_arg_dmds :: [Demand]
    wrap_arg_dmds =
                   forall a. Arity -> a -> [a]
    replicate (forall (t :: * -> *) a. Foldable t => t a -> Arity
    length [Type]
    theta) Demand
    topDmd forall a. [a] -> [a] -> [a]
    ++ forall a b. (a -> b) -> [a] -> [b]
    map HsImplBang -> Demand
    mk_dmd [HsImplBang]
    arg_ibangs
                   -- Don't forget the dictionary arguments when building
                   -- the strictness signature (#14290).

                 mk_dmd :: HsImplBang -> Demand
    mk_dmd HsImplBang
    str | HsImplBang -> Bool
    isBanged HsImplBang
    str = Demand
    evalDmd
                            | Bool
    otherwise    = Demand
    topDmd

                 wrap_prag :: InlinePragma
    wrap_prag = InlinePragma
    dataConWrapperInlinePragma
                             InlinePragma -> Activation -> InlinePragma
    `setInlinePragmaActivation` Activation
    activateDuringFinal
                             -- See Note [Activation for data constructor wrappers]

                 -- The wrapper will usually be inlined (see wrap_unf), so its
                 -- strictness and CPR info is usually irrelevant. But this is
                 -- not always the case; GHC may choose not to inline it. In
                 -- particular, the wrapper constructor is not inlined inside
                 -- an INLINE rhs or when it is not applied to any arguments.
                 -- See Note [Inline partially-applied constructor wrappers]
                 -- Passing Nothing here allows the wrapper to inline when
                 -- unsaturated.
                 wrap_unf :: Unfolding
    wrap_unf | TyCon -> Bool
    isNewTyCon TyCon
    tycon = SimpleOpts -> CoreExpr -> Unfolding
    mkCompulsoryUnfolding SimpleOpts
    defaultSimpleOpts CoreExpr
    wrap_rhs
                            -- See Note [Compulsory newtype unfolding]
                          | Bool
    otherwise        = SimpleOpts -> CoreExpr -> Unfolding
    mkInlineUnfolding SimpleOpts
    defaultSimpleOpts CoreExpr
    wrap_rhs
                 wrap_rhs :: CoreExpr
    wrap_rhs = forall b. [b] -> Expr b -> Expr b
    mkLams [Id]
    wrap_tvs forall a b. (a -> b) -> a -> b
    $
                            forall b. [b] -> Expr b -> Expr b
    mkLams [Id]
    wrap_args forall a b. (a -> b) -> a -> b
    $
                            TyCon -> [Type] -> CoreExpr -> CoreExpr
    wrapFamInstBody TyCon
    tycon [Type]
    res_ty_args forall a b. (a -> b) -> a -> b
    $
                            CoreExpr
    wrap_body

           ; forall (m :: * -> *) a. Monad m => a -> m a
    return (DCR { dcr_wrap_id :: Id
    dcr_wrap_id = Id
    wrap_id
                         , dcr_boxer :: DataConBoxer
    dcr_boxer   = [Boxer] -> DataConBoxer
    mk_boxer [Boxer]
    boxers
                         , dcr_arg_tys :: [Scaled Type]
    dcr_arg_tys = [Scaled Type]
    rep_tys
                         , dcr_stricts :: [StrictnessMark]
    dcr_stricts = [StrictnessMark]
    rep_strs
                           -- For newtypes, dcr_bangs is always [HsLazy].
                           -- See Note [HsImplBangs for newtypes].
                         , dcr_bangs :: [HsImplBang]
    dcr_bangs   = [HsImplBang]
    arg_ibangs }) }

      where
        ([Id]
    univ_tvs, [Id]
    ex_tvs, [EqSpec]
    eq_spec, [Type]
    theta, [Scaled Type]
    orig_arg_tys, Type
    _orig_res_ty)
          = DataCon -> ([Id], [Id], [EqSpec], [Type], [Scaled Type], Type)
    dataConFullSig DataCon
    data_con
        wrap_tvs :: [Id]
    wrap_tvs     = DataCon -> [Id]
    dataConUserTyVars DataCon
    data_con
        res_ty_args :: [Type]
    res_ty_args  = TCvSubst -> [Id] -> [Type]
    substTyVars ([(Id, Type)] -> TCvSubst
    mkTvSubstPrs (forall a b. (a -> b) -> [a] -> [b]
    map EqSpec -> (Id, Type)
    eqSpecPair [EqSpec]
    eq_spec)) [Id]
    univ_tvs

        tycon :: TyCon
    tycon        = DataCon -> TyCon
    dataConTyCon DataCon
    data_con       -- The representation TyCon (not family)
        wrap_ty :: Type
    wrap_ty      = DataCon -> Type
    dataConWrapperType DataCon
    data_con
        ev_tys :: [Type]
    ev_tys       = [EqSpec] -> [Type]
    eqSpecPreds [EqSpec]
    eq_spec forall a. [a] -> [a] -> [a]
    ++ [Type]
    theta
        all_arg_tys :: [Scaled Type]
    all_arg_tys  = forall a b. (a -> b) -> [a] -> [b]
    map forall a. a -> Scaled a
    unrestricted [Type]
    ev_tys forall a. [a] -> [a] -> [a]
    ++ [Scaled Type]
    orig_arg_tys
        ev_ibangs :: [HsImplBang]
    ev_ibangs    = forall a b. (a -> b) -> [a] -> [b]
    map (forall a b. a -> b -> a
    const HsImplBang
    HsLazy) [Type]
    ev_tys
        orig_bangs :: [HsSrcBang]
    orig_bangs   = DataCon -> [HsSrcBang]
    dataConSrcBangs DataCon
    data_con

        wrap_arg_tys :: [Scaled Type]
    wrap_arg_tys = (forall a b. (a -> b) -> [a] -> [b]
    map forall a. a -> Scaled a
    unrestricted [Type]
    theta) forall a. [a] -> [a] -> [a]
    ++ [Scaled Type]
    orig_arg_tys
        wrap_arity :: Arity
    wrap_arity   = forall a. (a -> Bool) -> [a] -> Arity
    count Id -> Bool
    isCoVar [Id]
    ex_tvs forall a. Num a => a -> a -> a
    + forall (t :: * -> *) a. Foldable t => t a -> Arity
    length [Scaled Type]
    wrap_arg_tys
                 -- The wrap_args are the arguments *other than* the eq_spec
                 -- Because we are going to apply the eq_spec args manually in the
                 -- wrapper

        new_tycon :: Bool
    new_tycon = TyCon -> Bool
    isNewTyCon TyCon
    tycon
        arg_ibangs :: [HsImplBang]
    arg_ibangs
          | Bool
    new_tycon
          = forall a b. (a -> b) -> [a] -> [b]
    map (forall a b. a -> b -> a
    const HsImplBang
    HsLazy) [Scaled Type]
    orig_arg_tys -- See Note [HsImplBangs for newtypes]
                                            -- orig_arg_tys should be a singleton, but
                                            -- if a user declared a wrong newtype we
                                            -- detect this later (see test T2334A)
          | Bool
    otherwise
          = case Maybe [HsImplBang]
    mb_bangs of
              Maybe [HsImplBang]
    Nothing    -> forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
    zipWith (DynFlags -> FamInstEnvs -> Scaled Type -> HsSrcBang -> HsImplBang
    dataConSrcToImplBang DynFlags
    dflags FamInstEnvs
    fam_envs)
                                    [Scaled Type]
    orig_arg_tys [HsSrcBang]
    orig_bangs
              Just [HsImplBang]
    bangs -> [HsImplBang]
    bangs

        ([[(Scaled Type, StrictnessMark)]]
    rep_tys_w_strs, [(Unboxer, Boxer)]
    wrappers)
          = forall a b. [(a, b)] -> ([a], [b])
    unzip (forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
    zipWith Scaled Type
    -> HsImplBang
    -> ([(Scaled Type, StrictnessMark)], (Unboxer, Boxer))
    dataConArgRep [Scaled Type]
    all_arg_tys ([HsImplBang]
    ev_ibangs forall a. [a] -> [a] -> [a]
    ++ [HsImplBang]
    arg_ibangs))

        ([Unboxer]
    unboxers, [Boxer]
    boxers) = forall a b. [(a, b)] -> ([a], [b])
    unzip [(Unboxer, Boxer)]
    wrappers
        ([Scaled Type]
    rep_tys, [StrictnessMark]
    rep_strs) = forall a b. [(a, b)] -> ([a], [b])
    unzip (forall (t :: * -> *) a. Foldable t => t [a] -> [a]
    concat [[(Scaled Type, StrictnessMark)]]
    rep_tys_w_strs)

        wrapper_reqd :: Bool
    wrapper_reqd =
            (Bool -> Bool
    not Bool
    new_tycon
                         -- (Most) newtypes have only a worker, with the exception
                         -- of some newtypes written with GADT syntax. See below.
             Bool -> Bool -> Bool
    && (forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    any HsImplBang -> Bool
    isBanged ([HsImplBang]
    ev_ibangs forall a. [a] -> [a] -> [a]
    ++ [HsImplBang]
    arg_ibangs)
                         -- Some forcing/unboxing (includes eq_spec)
                 Bool -> Bool -> Bool
    || (Bool -> Bool
    not forall a b. (a -> b) -> a -> b
    $ forall (t :: * -> *) a. Foldable t => t a -> Bool
    null [EqSpec]
    eq_spec))) -- GADT
          Bool -> Bool -> Bool
    || TyCon -> Bool
    isFamInstTyCon TyCon
    tycon -- Cast result
          Bool -> Bool -> Bool
    || DataCon -> Bool
    dataConUserTyVarsArePermuted DataCon
    data_con
                         -- If the data type was written with GADT syntax and
                         -- orders the type variables differently from what the
                         -- worker expects, it needs a data con wrapper to reorder
                         -- the type variables.
                         -- See Note [Data con wrappers and GADT syntax].

        initial_wrap_app :: CoreExpr
    initial_wrap_app = forall b. Id -> Expr b
    Var (DataCon -> Id
    dataConWorkId DataCon
    data_con)
                           forall b. Expr b -> [Type] -> Expr b
    `mkTyApps`  [Type]
    res_ty_args
                           forall b. Expr b -> [Id] -> Expr b
    `mkVarApps` [Id]
    ex_tvs
                           forall b. Expr b -> [Coercion] -> Expr b
    `mkCoApps`  forall a b. (a -> b) -> [a] -> [b]
    map (Role -> Type -> Coercion
    mkReflCo Role
    Nominal forall b c a. (b -> c) -> (a -> b) -> a -> c
    . EqSpec -> Type
    eqSpecType) [EqSpec]
    eq_spec

        mk_boxer :: [Boxer] -> DataConBoxer
        mk_boxer :: [Boxer] -> DataConBoxer
    mk_boxer [Boxer]
    boxers = ([Type] -> [Id] -> UniqSM ([Id], [CoreBind])) -> DataConBoxer
    DCB (\ [Type]
    ty_args [Id]
    src_vars ->
                          do { let ([Id]
    ex_vars, [Id]
    term_vars) = forall b a. [b] -> [a] -> ([a], [a])
    splitAtList [Id]
    ex_tvs [Id]
    src_vars
                                   subst1 :: TCvSubst
    subst1 = HasDebugCallStack => [Id] -> [Type] -> TCvSubst
    zipTvSubst [Id]
    univ_tvs [Type]
    ty_args
                                   subst2 :: TCvSubst
    subst2 = TCvSubst -> [Id] -> [Type] -> TCvSubst
    extendTCvSubstList TCvSubst
    subst1 [Id]
    ex_tvs
                                                               ([Id] -> [Type]
    mkTyCoVarTys [Id]
    ex_vars)
                             ; ([Id]
    rep_ids, [CoreBind]
    binds) <- TCvSubst -> [Boxer] -> [Id] -> UniqSM ([Id], [CoreBind])
    go TCvSubst
    subst2 [Boxer]
    boxers [Id]
    term_vars
                             ; forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id]
    ex_vars forall a. [a] -> [a] -> [a]
    ++ [Id]
    rep_ids, [CoreBind]
    binds) } )

        go :: TCvSubst -> [Boxer] -> [Id] -> UniqSM ([Id], [CoreBind])
    go TCvSubst
    _ [] [Id]
    src_vars = ASSERT2( null src_vars, ppr data_con ) return ([], [])
        go TCvSubst
    subst (Boxer
    UnitBox : [Boxer]
    boxers) (Id
    src_var : [Id]
    src_vars)
          = do { ([Id]
    rep_ids2, [CoreBind]
    binds) <- TCvSubst -> [Boxer] -> [Id] -> UniqSM ([Id], [CoreBind])
    go TCvSubst
    subst [Boxer]
    boxers [Id]
    src_vars
               ; forall (m :: * -> *) a. Monad m => a -> m a
    return (Id
    src_var forall a. a -> [a] -> [a]
    : [Id]
    rep_ids2, [CoreBind]
    binds) }
        go TCvSubst
    subst (Boxer TCvSubst -> UniqSM ([Id], CoreExpr)
    boxer : [Boxer]
    boxers) (Id
    src_var : [Id]
    src_vars)
          = do { ([Id]
    rep_ids1, CoreExpr
    arg)  <- TCvSubst -> UniqSM ([Id], CoreExpr)
    boxer TCvSubst
    subst
               ; ([Id]
    rep_ids2, [CoreBind]
    binds) <- TCvSubst -> [Boxer] -> [Id] -> UniqSM ([Id], [CoreBind])
    go TCvSubst
    subst [Boxer]
    boxers [Id]
    src_vars
               ; forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id]
    rep_ids1 forall a. [a] -> [a] -> [a]
    ++ [Id]
    rep_ids2, forall b. b -> Expr b -> Bind b
    NonRec Id
    src_var CoreExpr
    arg forall a. a -> [a] -> [a]
    : [CoreBind]
    binds) }
        go TCvSubst
    _ (Boxer
    _:[Boxer]
    _) [] = forall a. HasCallStack => String -> SDoc -> a
    pprPanic String
    "mk_boxer" (forall a. Outputable a => a -> SDoc
    ppr DataCon
    data_con)

        mk_rep_app :: [(Id,Unboxer)] -> CoreExpr -> UniqSM CoreExpr
        mk_rep_app :: [(Id, Unboxer)] -> CoreExpr -> UniqSM CoreExpr
    mk_rep_app [] CoreExpr
    con_app
          = forall (m :: * -> *) a. Monad m => a -> m a
    return CoreExpr
    con_app
        mk_rep_app ((Id
    wrap_arg, Unboxer
    unboxer) : [(Id, Unboxer)]
    prs) CoreExpr
    con_app
          = do { ([Id]
    rep_ids, CoreExpr -> CoreExpr
    unbox_fn) <- Unboxer
    unboxer Id
    wrap_arg
               ; CoreExpr
    expr <- [(Id, Unboxer)] -> CoreExpr -> UniqSM CoreExpr
    mk_rep_app [(Id, Unboxer)]
    prs (forall b. Expr b -> [Id] -> Expr b
    mkVarApps CoreExpr
    con_app [Id]
    rep_ids)
               ; forall (m :: * -> *) a. Monad m => a -> m a
    return (CoreExpr -> CoreExpr
    unbox_fn CoreExpr
    expr) }

    dataConWrapperInlinePragma :: InlinePragma
    -- See Note [DataCon wrappers are conlike]
    dataConWrapperInlinePragma :: InlinePragma
    dataConWrapperInlinePragma = InlinePragma
    alwaysInlinePragma { inl_rule :: RuleMatchInfo
    inl_rule = RuleMatchInfo
    ConLike
                                                    , inl_inline :: InlineSpec
    inl_inline = InlineSpec
    Inline }

    {- Note [Activation for data constructor wrappers]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The Activation on a data constructor wrapper allows it to inline only in Phase
    0. This way rules have a chance to fire if they mention a data constructor on
    the left
       RULE "foo"  f (K a b) = ...
    Since the LHS of rules are simplified with InitialPhase, we won't
    inline the wrapper on the LHS either.

    On the other hand, this means that exprIsConApp_maybe must be able to deal
    with wrappers so that case-of-constructor is not delayed; see
    Note [exprIsConApp_maybe on data constructors with wrappers] for details.

    It used to activate in phases 2 (afterInitial) and later, but it makes it
    awkward to write a RULE[1] with a constructor on the left: it would work if a
    constructor has no wrapper, but whether a constructor has a wrapper depends, for
    instance, on the order of type argument of that constructors. Therefore changing
    the order of type argument could make previously working RULEs fail.

    See also https://gitlab.haskell.org/ghc/ghc/issues/15840 .

    Note [DataCon wrappers are conlike]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    DataCon workers are clearly ConLike --- they are the “Con” in
    “ConLike”, after all --- but what about DataCon wrappers? Should they
    be marked ConLike, too?

    Yes, absolutely! As described in Note [CONLIKE pragma] in
    GHC.Types.Basic, isConLike influences GHC.Core.Utils.exprIsExpandable,
    which is used by both RULE matching and the case-of-known-constructor
    optimization. It’s crucial that both of those things can see
    applications of DataCon wrappers:

      * User-defined RULEs match on wrappers, not workers, so we might
        need to look through an unfolding built from a DataCon wrapper to
        determine if a RULE matches.

      * Likewise, if we have something like
            let x = $WC a b in ... case x of { C y z -> e } ...
        we still want to apply case-of-known-constructor.

    Therefore, it’s important that we consider DataCon wrappers conlike.
    This is especially true now that we don’t inline DataCon wrappers
    until the final simplifier phase; see Note [Activation for data
    constructor wrappers].

    For further reading, see:
      * Note [Conlike is interesting] in GHC.Core.Op.Simplify.Utils
      * Note [Lone variables] in GHC.Core.Unfold
      * Note [exprIsConApp_maybe on data constructors with wrappers]
        in GHC.Core.SimpleOpt
      * #18012

    Note [Bangs on imported data constructors]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    We pass Maybe [HsImplBang] to mkDataConRep to make use of HsImplBangs
    from imported modules.

    - Nothing <=> use HsSrcBangs
    - Just bangs <=> use HsImplBangs

    For imported types we can't work it all out from the HsSrcBangs,
    because we want to be very sure to follow what the original module
    (where the data type was declared) decided, and that depends on what
    flags were enabled when it was compiled. So we record the decisions in
    the interface file.

    The HsImplBangs passed are in 1-1 correspondence with the
    dataConOrigArgTys of the DataCon.

    Note [Data con wrappers and unlifted types]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Consider
       data T = MkT !Int#

    We certainly do not want to make a wrapper
       $WMkT x = case x of y { DEFAULT -> MkT y }

    For a start, it's still to generate a no-op.  But worse, since wrappers
    are currently injected at TidyCore, we don't even optimise it away!
    So the stupid case expression stays there.  This actually happened for
    the Integer data type (see #1600 comment:66)!

    Note [Data con wrappers and GADT syntax]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Consider these two very similar data types:

      data T1 a b = MkT1 b

      data T2 a b where
        MkT2 :: forall b a. b -> T2 a b

    Despite their similar appearance, T2 will have a data con wrapper but T1 will
    not. What sets them apart? The types of their constructors, which are:

      MkT1 :: forall a b. b -> T1 a b
      MkT2 :: forall b a. b -> T2 a b

    MkT2's use of GADT syntax allows it to permute the order in which `a` and `b`
    would normally appear. See Note [DataCon user type variable binders] in GHC.Core.DataCon
    for further discussion on this topic.

    The worker data cons for T1 and T2, however, both have types such that `a` is
    expected to come before `b` as arguments. Because MkT2 permutes this order, it
    needs a data con wrapper to swizzle around the type variables to be in the
    order the worker expects.

    A somewhat surprising consequence of this is that *newtypes* can have data con
    wrappers! After all, a newtype can also be written with GADT syntax:

      newtype T3 a b where
        MkT3 :: forall b a. b -> T3 a b

    Again, this needs a wrapper data con to reorder the type variables. It does
    mean that this newtype constructor requires another level of indirection when
    being called, but the inliner should make swift work of that.

    Note [HsImplBangs for newtypes]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Most of the time, we use the dataConSrctoImplBang function to decide what
    strictness/unpackedness to use for the fields of a data type constructor. But
    there is an exception to this rule: newtype constructors. You might not think
    that newtypes would pose a challenge, since newtypes are seemingly forbidden
    from having strictness annotations in the first place. But consider this
    (from #16141):

      {-# LANGUAGE StrictData #-}
      {-# OPTIONS_GHC -O #-}
      newtype T a b where
        MkT :: forall b a. Int -> T a b

    Because StrictData (plus optimization) is enabled, invoking
    dataConSrcToImplBang would sneak in and unpack the field of type Int to Int#!
    This would be disastrous, since the wrapper for `MkT` uses a coercion involving
    Int, not Int#.

    Bottom line: dataConSrcToImplBang should never be invoked for newtypes. In the
    case of a newtype constructor, we simply hardcode its dcr_bangs field to
    [HsLazy].
    -}

    -------------------------
    newLocal :: Scaled Type -> UniqSM Var
    newLocal :: Scaled Type -> UniqSM Id
    newLocal (Scaled Type
    w Type
    ty) = do { Unique
    uniq <- forall (m :: * -> *). MonadUnique m => m Unique
    getUniqueM
                                ; forall (m :: * -> *) a. Monad m => a -> m a
    return (RuleName -> Unique -> Type -> Type -> Id
    mkSysLocalOrCoVar (String -> RuleName
    fsLit String
    "dt") Unique
    uniq Type
    w Type
    ty) }
                     -- We should not have "OrCoVar" here, this is a bug (#17545)

    -- | Unpack/Strictness decisions from source module.
    --
    -- This function should only ever be invoked for data constructor fields, and
    -- never on the field of a newtype constructor.
    -- See @Note [HsImplBangs for newtypes]@.
    dataConSrcToImplBang
       :: DynFlags
       -> FamInstEnvs
       -> Scaled Type
       -> HsSrcBang
       -> HsImplBang

    dataConSrcToImplBang :: DynFlags -> FamInstEnvs -> Scaled Type -> HsSrcBang -> HsImplBang
    dataConSrcToImplBang DynFlags
    dflags FamInstEnvs
    fam_envs Scaled Type
    arg_ty
                         (HsSrcBang SourceText
    ann SrcUnpackedness
    unpk SrcStrictness
    NoSrcStrict)
      | Extension -> DynFlags -> Bool
    xopt Extension
    LangExt.StrictData DynFlags
    dflags -- StrictData => strict field
      = DynFlags -> FamInstEnvs -> Scaled Type -> HsSrcBang -> HsImplBang
    dataConSrcToImplBang DynFlags
    dflags FamInstEnvs
    fam_envs Scaled Type
    arg_ty
                      (SourceText -> SrcUnpackedness -> SrcStrictness -> HsSrcBang
    HsSrcBang SourceText
    ann SrcUnpackedness
    unpk SrcStrictness
    SrcStrict)
      | Bool
    otherwise -- no StrictData => lazy field
      = HsImplBang
    HsLazy

    dataConSrcToImplBang DynFlags
    _ FamInstEnvs
    _ Scaled Type
    _ (HsSrcBang SourceText
    _ SrcUnpackedness
    _ SrcStrictness
    SrcLazy)
      = HsImplBang
    HsLazy

    dataConSrcToImplBang DynFlags
    dflags FamInstEnvs
    fam_envs Scaled Type
    arg_ty
                         (HsSrcBang SourceText
    _ SrcUnpackedness
    unpk_prag SrcStrictness
    SrcStrict)
      | HasDebugCallStack => Type -> Bool
    isUnliftedType (forall a. Scaled a -> a
    scaledThing Scaled Type
    arg_ty)
      = HsImplBang
    HsLazy  -- For !Int#, say, use HsLazy
                -- See Note [Data con wrappers and unlifted types]

      | Bool -> Bool
    not (GeneralFlag -> DynFlags -> Bool
    gopt GeneralFlag
    Opt_OmitInterfacePragmas DynFlags
    dflags) -- Don't unpack if -fomit-iface-pragmas
              -- Don't unpack if we aren't optimising; rather arbitrarily,
              -- we use -fomit-iface-pragmas as the indication
      , let mb_co :: Maybe (Coercion, Type)
    mb_co   = FamInstEnvs -> Type -> Maybe (Coercion, Type)
    topNormaliseType_maybe FamInstEnvs
    fam_envs (forall a. Scaled a -> a
    scaledThing Scaled Type
    arg_ty)
                         -- Unwrap type families and newtypes
            arg_ty' :: Scaled Type
    arg_ty' = case Maybe (Coercion, Type)
    mb_co of { Just (Coercion
    _,Type
    ty) -> forall a b. Scaled a -> b -> Scaled b
    scaledSet Scaled Type
    arg_ty Type
    ty; Maybe (Coercion, Type)
    Nothing -> Scaled Type
    arg_ty }
      , DynFlags -> FamInstEnvs -> Type -> Bool
    isUnpackableType DynFlags
    dflags FamInstEnvs
    fam_envs (forall a. Scaled a -> a
    scaledThing Scaled Type
    arg_ty')
      , ([(Scaled Type, StrictnessMark)]
    rep_tys, (Unboxer, Boxer)
    _) <- Scaled Type -> ([(Scaled Type, StrictnessMark)], (Unboxer, Boxer))
    dataConArgUnpack Scaled Type
    arg_ty'
      , case SrcUnpackedness
    unpk_prag of
          SrcUnpackedness
    NoSrcUnpack ->
            GeneralFlag -> DynFlags -> Bool
    gopt GeneralFlag
    Opt_UnboxStrictFields DynFlags
    dflags
                Bool -> Bool -> Bool
    || (GeneralFlag -> DynFlags -> Bool
    gopt GeneralFlag
    Opt_UnboxSmallStrictFields DynFlags
    dflags
                    Bool -> Bool -> Bool
    && [(Scaled Type, StrictnessMark)]
    rep_tys forall a. [a] -> Arity -> Bool
    `lengthAtMost` Arity
    1) -- See Note [Unpack one-wide fields]
          SrcUnpackedness
    srcUnpack -> SrcUnpackedness -> Bool
    isSrcUnpacked SrcUnpackedness
    srcUnpack
      = case Maybe (Coercion, Type)
    mb_co of
          Maybe (Coercion, Type)
    Nothing     -> Maybe Coercion -> HsImplBang
    HsUnpack forall a. Maybe a
    Nothing
          Just (Coercion
    co,Type
    _) -> Maybe Coercion -> HsImplBang
    HsUnpack (forall a. a -> Maybe a
    Just Coercion
    co)

      | Bool
    otherwise -- Record the strict-but-no-unpack decision
      = HsImplBang
    HsStrict

    -- | Wrappers/Workers and representation following Unpack/Strictness
    -- decisions
    dataConArgRep
      :: Scaled Type
      -> HsImplBang
      -> ([(Scaled Type,StrictnessMark)] -- Rep types
         ,(Unboxer,Boxer))

    dataConArgRep :: Scaled Type
    -> HsImplBang
    -> ([(Scaled Type, StrictnessMark)], (Unboxer, Boxer))
    dataConArgRep Scaled Type
    arg_ty HsImplBang
    HsLazy
      = ([(Scaled Type
    arg_ty, StrictnessMark
    NotMarkedStrict)], (Unboxer
    unitUnboxer, Boxer
    unitBoxer))

    dataConArgRep Scaled Type
    arg_ty HsImplBang
    HsStrict
      = ([(Scaled Type
    arg_ty, StrictnessMark
    MarkedStrict)], (Unboxer
    seqUnboxer, Boxer
    unitBoxer))

    dataConArgRep Scaled Type
    arg_ty (HsUnpack Maybe Coercion
    Nothing)
      | ([(Scaled Type, StrictnessMark)]
    rep_tys, (Unboxer, Boxer)
    wrappers) <- Scaled Type -> ([(Scaled Type, StrictnessMark)], (Unboxer, Boxer))
    dataConArgUnpack Scaled Type
    arg_ty
      = ([(Scaled Type, StrictnessMark)]
    rep_tys, (Unboxer, Boxer)
    wrappers)

    dataConArgRep (Scaled Type
    w Type
    _) (HsUnpack (Just Coercion
    co))
      | let co_rep_ty :: Type
    co_rep_ty = Coercion -> Type
    coercionRKind Coercion
    co
      , ([(Scaled Type, StrictnessMark)]
    rep_tys, (Unboxer, Boxer)
    wrappers) <- Scaled Type -> ([(Scaled Type, StrictnessMark)], (Unboxer, Boxer))
    dataConArgUnpack (forall a. Type -> a -> Scaled a
    Scaled Type
    w Type
    co_rep_ty)
      = ([(Scaled Type, StrictnessMark)]
    rep_tys, Coercion -> Type -> (Unboxer, Boxer) -> (Unboxer, Boxer)
    wrapCo Coercion
    co Type
    co_rep_ty (Unboxer, Boxer)
    wrappers)

    -------------------------
    wrapCo :: Coercion -> Type -> (Unboxer, Boxer) -> (Unboxer, Boxer)
    wrapCo :: Coercion -> Type -> (Unboxer, Boxer) -> (Unboxer, Boxer)
    wrapCo Coercion
    co Type
    rep_ty (Unboxer
    unbox_rep, Boxer
    box_rep)  -- co :: arg_ty ~ rep_ty
      = (Unboxer
    unboxer, Boxer
    boxer)
      where
        unboxer :: Unboxer
    unboxer Id
    arg_id = do { Id
    rep_id <- Scaled Type -> UniqSM Id
    newLocal (forall a. Type -> a -> Scaled a
    Scaled (Id -> Type
    idMult Id
    arg_id) Type
    rep_ty)
                            ; ([Id]
    rep_ids, CoreExpr -> CoreExpr
    rep_fn) <- Unboxer
    unbox_rep Id
    rep_id
                            ; let co_bind :: CoreBind
    co_bind = forall b. b -> Expr b -> Bind b
    NonRec Id
    rep_id (forall b. Id -> Expr b
    Var Id
    arg_id forall b. Expr b -> Coercion -> Expr b
    `Cast` Coercion
    co)
                            ; forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id]
    rep_ids, forall b. Bind b -> Expr b -> Expr b
    Let CoreBind
    co_bind forall b c a. (b -> c) -> (a -> b) -> a -> c
    . CoreExpr -> CoreExpr
    rep_fn) }
        boxer :: Boxer
    boxer = (TCvSubst -> UniqSM ([Id], CoreExpr)) -> Boxer
    Boxer forall a b. (a -> b) -> a -> b
    $ \ TCvSubst
    subst ->
                do { ([Id]
    rep_ids, CoreExpr
    rep_expr)
                        <- case Boxer
    box_rep of
                             Boxer
    UnitBox -> do { Id
    rep_id <- Scaled Type -> UniqSM Id
    newLocal (forall a. a -> Scaled a
    linear forall a b. (a -> b) -> a -> b
    $ HasCallStack => TCvSubst -> Type -> Type
    TcType.substTy TCvSubst
    subst Type
    rep_ty)
                                           ; forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id
    rep_id], forall b. Id -> Expr b
    Var Id
    rep_id) }
                             Boxer TCvSubst -> UniqSM ([Id], CoreExpr)
    boxer -> TCvSubst -> UniqSM ([Id], CoreExpr)
    boxer TCvSubst
    subst
                   ; let sco :: Coercion
    sco = TCvSubst -> Coercion -> Coercion
    substCoUnchecked TCvSubst
    subst Coercion
    co
                   ; forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id]
    rep_ids, CoreExpr
    rep_expr forall b. Expr b -> Coercion -> Expr b
    `Cast` Coercion -> Coercion
    mkSymCo Coercion
    sco) }

    ------------------------
    seqUnboxer :: Unboxer
    seqUnboxer :: Unboxer
    seqUnboxer Id
    v = forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id
    v], CoreExpr -> Id -> CoreExpr -> CoreExpr
    mkDefaultCase (forall b. Id -> Expr b
    Var Id
    v) Id
    v)

    unitUnboxer :: Unboxer
    unitUnboxer :: Unboxer
    unitUnboxer Id
    v = forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id
    v], \CoreExpr
    e -> CoreExpr
    e)

    unitBoxer :: Boxer
    unitBoxer :: Boxer
    unitBoxer = Boxer
    UnitBox

    -------------------------
    dataConArgUnpack
       :: Scaled Type
       ->  ( [(Scaled Type, StrictnessMark)]   -- Rep types
           , (Unboxer, Boxer) )

    dataConArgUnpack :: Scaled Type -> ([(Scaled Type, StrictnessMark)], (Unboxer, Boxer))
    dataConArgUnpack (Scaled Type
    arg_mult Type
    arg_ty)
      | Just (TyCon
    tc, [Type]
    tc_args) <- HasDebugCallStack => Type -> Maybe (TyCon, [Type])
    splitTyConApp_maybe Type
    arg_ty
      , Just DataCon
    con <- TyCon -> Maybe DataCon
    tyConSingleAlgDataCon_maybe TyCon
    tc
          -- NB: check for an *algebraic* data type
          -- A recursive newtype might mean that
          -- 'arg_ty' is a newtype
      , let rep_tys :: [Scaled Type]
    rep_tys = forall a b. (a -> b) -> [a] -> [b]
    map (forall a. Type -> Scaled a -> Scaled a
    scaleScaled Type
    arg_mult) forall a b. (a -> b) -> a -> b
    $ DataCon -> [Type] -> [Scaled Type]
    dataConInstArgTys DataCon
    con [Type]
    tc_args
      = ASSERT( null (dataConExTyCoVars con) )
          -- Note [Unpacking GADTs and existentials]
        ( [Scaled Type]
    rep_tys forall a b. [a] -> [b] -> [(a, b)]
    `zip` DataCon -> [StrictnessMark]
    dataConRepStrictness DataCon
    con
        ,( \ Id
    arg_id ->
           do { [Id]
    rep_ids <- forall (t :: * -> *) (m :: * -> *) a b.
    (Traversable t, Monad m) =>
    (a -> m b) -> t a -> m (t b)
    mapM Scaled Type -> UniqSM Id
    newLocal [Scaled Type]
    rep_tys
              ; let r_mult :: Type
    r_mult = Id -> Type
    idMult Id
    arg_id
              ; let rep_ids' :: [Id]
    rep_ids' = forall a b. (a -> b) -> [a] -> [b]
    map (Type -> Id -> Id
    scaleIdBy Type
    r_mult) [Id]
    rep_ids
              ; let unbox_fn :: CoreExpr -> CoreExpr
    unbox_fn CoreExpr
    body
                      = CoreExpr -> Id -> AltCon -> [Id] -> CoreExpr -> CoreExpr
    mkSingleAltCase (forall b. Id -> Expr b
    Var Id
    arg_id) Id
    arg_id
                                 (DataCon -> AltCon
    DataAlt DataCon
    con) [Id]
    rep_ids' CoreExpr
    body
              ; forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id]
    rep_ids, CoreExpr -> CoreExpr
    unbox_fn) }
         , (TCvSubst -> UniqSM ([Id], CoreExpr)) -> Boxer
    Boxer forall a b. (a -> b) -> a -> b
    $ \ TCvSubst
    subst ->
           do { [Id]
    rep_ids <- forall (t :: * -> *) (m :: * -> *) a b.
    (Traversable t, Monad m) =>
    (a -> m b) -> t a -> m (t b)
    mapM (Scaled Type -> UniqSM Id
    newLocal forall b c a. (b -> c) -> (a -> b) -> a -> c
    . HasCallStack => TCvSubst -> Scaled Type -> Scaled Type
    TcType.substScaledTyUnchecked TCvSubst
    subst) [Scaled Type]
    rep_tys
              ; forall (m :: * -> *) a. Monad m => a -> m a
    return ([Id]
    rep_ids, forall b. Id -> Expr b
    Var (DataCon -> Id
    dataConWorkId DataCon
    con)
                                 forall b. Expr b -> [Type] -> Expr b
    `mkTyApps` (TCvSubst -> [Type] -> [Type]
    substTysUnchecked TCvSubst
    subst [Type]
    tc_args)
                                 forall b. Expr b -> [Id] -> Expr b
    `mkVarApps` [Id]
    rep_ids ) } ) )
      | Bool
    otherwise
      = forall a. HasCallStack => String -> SDoc -> a
    pprPanic String
    "dataConArgUnpack" (forall a. Outputable a => a -> SDoc
    ppr Type
    arg_ty)
        -- An interface file specified Unpacked, but we couldn't unpack it

    isUnpackableType :: DynFlags -> FamInstEnvs -> Type -> Bool
    -- True if we can unpack the UNPACK the argument type
    -- See Note [Recursive unboxing]
    -- We look "deeply" inside rather than relying on the DataCons
    -- we encounter on the way, because otherwise we might well
    -- end up relying on ourselves!
    isUnpackableType :: DynFlags -> FamInstEnvs -> Type -> Bool
    isUnpackableType DynFlags
    dflags FamInstEnvs
    fam_envs Type
    ty
      | Just DataCon
    data_con <- Type -> Maybe DataCon
    unpackable_type Type
    ty
      = NameSet -> DataCon -> Bool
    ok_con_args NameSet
    emptyNameSet DataCon
    data_con
      | Bool
    otherwise
      = Bool
    False
      where
        ok_con_args :: NameSet -> DataCon -> Bool
    ok_con_args NameSet
    dcs DataCon
    con
           | Name
    dc_name Name -> NameSet -> Bool
    `elemNameSet` NameSet
    dcs
           = Bool
    False
           | Bool
    otherwise
           = forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
    all (NameSet -> (Scaled Type, HsSrcBang) -> Bool
    ok_arg NameSet
    dcs')
                 (DataCon -> [Scaled Type]
    dataConOrigArgTys DataCon
    con forall a b. [a] -> [b] -> [(a, b)]
    `zip` DataCon -> [HsSrcBang]
    dataConSrcBangs DataCon
    con)
              -- NB: dataConSrcBangs gives the *user* request;
              -- We'd get a black hole if we used dataConImplBangs
           where
             dc_name :: Name
    dc_name = forall a. NamedThing a => a -> Name
    getName DataCon
    con
             dcs' :: NameSet
    dcs' = NameSet
    dcs NameSet -> Name -> NameSet
    `extendNameSet` Name
    dc_name

        ok_arg :: NameSet -> (Scaled Type, HsSrcBang) -> Bool
    ok_arg NameSet
    dcs (Scaled Type
    _ Type
    ty, HsSrcBang
    bang)
          = Bool -> Bool
    not (HsSrcBang -> Bool
    attempt_unpack HsSrcBang
    bang) Bool -> Bool -> Bool
    || NameSet -> Type -> Bool
    ok_ty NameSet
    dcs Type
    norm_ty
          where
            norm_ty :: Type
    norm_ty = FamInstEnvs -> Type -> Type
    topNormaliseType FamInstEnvs
    fam_envs Type
    ty

        ok_ty :: NameSet -> Type -> Bool
    ok_ty NameSet
    dcs Type
    ty
          | Just DataCon
    data_con <- Type -> Maybe DataCon
    unpackable_type Type
    ty
          = NameSet -> DataCon -> Bool
    ok_con_args NameSet
    dcs DataCon
    data_con
          | Bool
    otherwise
          = Bool
    True        -- NB True here, in contrast to False at top level

        attempt_unpack :: HsSrcBang -> Bool
    attempt_unpack (HsSrcBang SourceText
    _ SrcUnpackedness
    SrcUnpack SrcStrictness
    NoSrcStrict)
          = Extension -> DynFlags -> Bool
    xopt Extension
    LangExt.StrictData DynFlags
    dflags
        attempt_unpack (HsSrcBang SourceText
    _ SrcUnpackedness
    SrcUnpack SrcStrictness
    SrcStrict)
          = Bool
    True
        attempt_unpack (HsSrcBang SourceText
    _  SrcUnpackedness
    NoSrcUnpack SrcStrictness
    SrcStrict)
          = Bool
    True  -- Be conservative
        attempt_unpack (HsSrcBang SourceText
    _  SrcUnpackedness
    NoSrcUnpack SrcStrictness
    NoSrcStrict)
          = Extension -> DynFlags -> Bool
    xopt Extension
    LangExt.StrictData DynFlags
    dflags -- Be conservative
        attempt_unpack HsSrcBang
    _ = Bool
    False

        unpackable_type :: Type -> Maybe DataCon
        -- Works just on a single level
        unpackable_type :: Type -> Maybe DataCon
    unpackable_type Type
    ty
          | Just (TyCon
    tc, [Type]
    _) <- HasDebugCallStack => Type -> Maybe (TyCon, [Type])
    splitTyConApp_maybe Type
    ty
          , Just DataCon
    data_con <- TyCon -> Maybe DataCon
    tyConSingleAlgDataCon_maybe TyCon
    tc
          , forall (t :: * -> *) a. Foldable t => t a -> Bool
    null (DataCon -> [Id]
    dataConExTyCoVars DataCon
    data_con)
              -- See Note [Unpacking GADTs and existentials]
          = forall a. a -> Maybe a
    Just DataCon
    data_con
          | Bool
    otherwise
          = forall a. Maybe a
    Nothing

    {-
    Note [Unpacking GADTs and existentials]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    There is nothing stopping us unpacking a data type with equality
    components, like
      data Equal a b where
        Equal :: Equal a a

    And it'd be fine to unpack a product type with existential components
    too, but that would require a bit more plumbing, so currently we don't.

    So for now we require: null (dataConExTyCoVars data_con)
    See #14978

    Note [Unpack one-wide fields]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The flag UnboxSmallStrictFields ensures that any field that can
    (safely) be unboxed to a word-sized unboxed field, should be so unboxed.
    For example:

        data A = A Int#
        newtype B = B A
        data C = C !B
        data D = D !C
        data E = E !()
        data F = F !D
        data G = G !F !F

    All of these should have an Int# as their representation, except
    G which should have two Int#s.

    However

        data T = T !(S Int)
        data S = S !a

    Here we can represent T with an Int#.

    Note [Recursive unboxing]
    ~~~~~~~~~~~~~~~~~~~~~~~~~
    Consider
      data R = MkR {-# UNPACK #-} !S Int
      data S = MkS {-# UNPACK #-} !Int
    The representation arguments of MkR are the *representation* arguments
    of S (plus Int); the rep args of MkS are Int#.  This is all fine.

    But be careful not to try to unbox this!
            data T = MkT {-# UNPACK #-} !T Int
    Because then we'd get an infinite number of arguments.

    Here is a more complicated case:
            data S = MkS {-# UNPACK #-} !T Int
            data T = MkT {-# UNPACK #-} !S Int
    Each of S and T must decide independently whether to unpack
    and they had better not both say yes. So they must both say no.

    Also behave conservatively when there is no UNPACK pragma
            data T = MkS !T Int
    with -funbox-strict-fields or -funbox-small-strict-fields
    we need to behave as if there was an UNPACK pragma there.

    But it's the *argument* type that matters. This is fine:
            data S = MkS S !Int
    because Int is non-recursive.

    ************************************************************************
    *                                                                      *
            Wrapping and unwrapping newtypes and type families
    *                                                                      *
    ************************************************************************
    -}

    wrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
    -- The wrapper for the data constructor for a newtype looks like this:
    --      newtype T a = MkT (a,Int)
    --      MkT :: forall a. (a,Int) -> T a
    --      MkT = /\a. \(x:(a,Int)). x `cast` sym (CoT a)
    -- where CoT is the coercion TyCon associated with the newtype
    --
    -- The call (wrapNewTypeBody T [a] e) returns the
    -- body of the wrapper, namely
    --      e `cast` (CoT [a])
    --
    -- If a coercion constructor is provided in the newtype, then we use
    -- it, otherwise the wrap/unwrap are both no-ops

    wrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
    wrapNewTypeBody TyCon
    tycon [Type]
    args CoreExpr
    result_expr
      = ASSERT( isNewTyCon tycon )
        CoreExpr -> Coercion -> CoreExpr
    mkCast CoreExpr
    result_expr (Coercion -> Coercion
    mkSymCo Coercion
    co)
      where
        co :: Coercion
    co = Role -> CoAxiom Unbranched -> [Type] -> [Coercion] -> Coercion
    mkUnbranchedAxInstCo Role
    Representational (TyCon -> CoAxiom Unbranched
    newTyConCo TyCon
    tycon) [Type]
    args []

    -- When unwrapping, we do *not* apply any family coercion, because this will
    -- be done via a CoPat by the type checker.  We have to do it this way as
    -- computing the right type arguments for the coercion requires more than just
    -- a splitting operation (cf, GHC.Tc.Gen.Pat.tcConPat).

    unwrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
    unwrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
    unwrapNewTypeBody TyCon
    tycon [Type]
    args CoreExpr
    result_expr
      = ASSERT( isNewTyCon tycon )
        CoreExpr -> Coercion -> CoreExpr
    mkCast CoreExpr
    result_expr (Role -> CoAxiom Unbranched -> [Type] -> [Coercion] -> Coercion
    mkUnbranchedAxInstCo Role
    Representational (TyCon -> CoAxiom Unbranched
    newTyConCo TyCon
    tycon) [Type]
    args [])

    -- If the type constructor is a representation type of a data instance, wrap
    -- the expression into a cast adjusting the expression type, which is an
    -- instance of the representation type, to the corresponding instance of the
    -- family instance type.
    -- See Note [Wrappers for data instance tycons]
    wrapFamInstBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
    wrapFamInstBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
    wrapFamInstBody TyCon
    tycon [Type]
    args CoreExpr
    body
      | Just CoAxiom Unbranched
    co_con <- TyCon -> Maybe (CoAxiom Unbranched)
    tyConFamilyCoercion_maybe TyCon
    tycon
      = CoreExpr -> Coercion -> CoreExpr
    mkCast CoreExpr
    body (Coercion -> Coercion
    mkSymCo (Role -> CoAxiom Unbranched -> [Type] -> [Coercion] -> Coercion
    mkUnbranchedAxInstCo Role
    Representational CoAxiom Unbranched
    co_con [Type]
    args []))
      | Bool
    otherwise
      = CoreExpr
    body

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Primitive operations}
    *                                                                      *
    ************************************************************************
    -}

    mkPrimOpId :: PrimOp -> Id
    mkPrimOpId :: PrimOp -> Id
    mkPrimOpId PrimOp
    prim_op
      = Id
    id
      where
        ([Id]
    tyvars,[Type]
    arg_tys,Type
    res_ty, Arity
    arity, StrictSig
    strict_sig) = PrimOp -> ([Id], [Type], Type, Arity, StrictSig)
    primOpSig PrimOp
    prim_op
        ty :: Type
    ty   = [Id] -> Type -> Type
    mkSpecForAllTys [Id]
    tyvars ([Type] -> Type -> Type
    mkVisFunTysMany [Type]
    arg_tys Type
    res_ty)
        name :: Name
    name = Module -> OccName -> Unique -> TyThing -> BuiltInSyntax -> Name
    mkWiredInName Module
    gHC_PRIM (PrimOp -> OccName
    primOpOcc PrimOp
    prim_op)
                             (Arity -> Unique
    mkPrimOpIdUnique (PrimOp -> Arity
    primOpTag PrimOp
    prim_op))
                             (Id -> TyThing
    AnId Id
    id) BuiltInSyntax
    UserSyntax
        id :: Id
    id   = IdDetails -> Name -> Type -> IdInfo -> Id
    mkGlobalId (PrimOp -> IdDetails
    PrimOpId PrimOp
    prim_op) Name
    name Type
    ty IdInfo
    info

        -- PrimOps don't ever construct a product, but we want to preserve bottoms
        cpr :: Cpr
    cpr
          | Divergence -> Bool
    isDeadEndDiv (forall a b. (a, b) -> b
    snd (StrictSig -> ([Demand], Divergence)
    splitStrictSig StrictSig
    strict_sig)) = Cpr
    botCpr
          | Bool
    otherwise                                      = Cpr
    topCpr

        info :: IdInfo
    info = IdInfo
    noCafIdInfo
               IdInfo -> RuleInfo -> IdInfo
    `setRuleInfo`           [CoreRule] -> RuleInfo
    mkRuleInfo (forall a. Maybe a -> [a]
    maybeToList forall a b. (a -> b) -> a -> b
    $ Name -> PrimOp -> Maybe CoreRule
    primOpRules Name
    name PrimOp
    prim_op)
               IdInfo -> Arity -> IdInfo
    `setArityInfo`          Arity
    arity
               IdInfo -> StrictSig -> IdInfo
    `setStrictnessInfo`     StrictSig
    strict_sig
               IdInfo -> CprSig -> IdInfo
    `setCprInfo`            Arity -> Cpr -> CprSig
    mkCprSig Arity
    arity Cpr
    cpr
               IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo`     InlinePragma
    neverInlinePragma
               IdInfo -> Type -> IdInfo
    `setLevityInfoWithType` Type
    res_ty
                   -- We give PrimOps a NOINLINE pragma so that we don't
                   -- get silly warnings from Desugar.dsRule (the inline_shadows_rule
                   -- test) about a RULE conflicting with a possible inlining
                   -- cf #7287

    -- For each ccall we manufacture a separate CCallOpId, giving it
    -- a fresh unique, a type that is correct for this particular ccall,
    -- and a CCall structure that gives the correct details about calling
    -- convention etc.
    --
    -- The *name* of this Id is a local name whose OccName gives the full
    -- details of the ccall, type and all.  This means that the interface
    -- file reader can reconstruct a suitable Id

    mkFCallId :: DynFlags -> Unique -> ForeignCall -> Type -> Id
    mkFCallId :: DynFlags -> Unique -> ForeignCall -> Type -> Id
    mkFCallId DynFlags
    dflags Unique
    uniq ForeignCall
    fcall Type
    ty
      = ASSERT( noFreeVarsOfType ty )
        -- A CCallOpId should have no free type variables;
        -- when doing substitutions won't substitute over it
        IdDetails -> Name -> Type -> IdInfo -> Id
    mkGlobalId (ForeignCall -> IdDetails
    FCallId ForeignCall
    fcall) Name
    name Type
    ty IdInfo
    info
      where
        occ_str :: String
    occ_str = DynFlags -> SDoc -> String
    showSDoc DynFlags
    dflags (SDoc -> SDoc
    braces (forall a. Outputable a => a -> SDoc
    ppr ForeignCall
    fcall SDoc -> SDoc -> SDoc
    <+> forall a. Outputable a => a -> SDoc
    ppr Type
    ty))
        -- The "occurrence name" of a ccall is the full info about the
        -- ccall; it is encoded, but may have embedded spaces etc!

        name :: Name
    name = Unique -> String -> Name
    mkFCallName Unique
    uniq String
    occ_str

        info :: IdInfo
    info = IdInfo
    noCafIdInfo
               IdInfo -> Arity -> IdInfo
    `setArityInfo`          Arity
    arity
               IdInfo -> StrictSig -> IdInfo
    `setStrictnessInfo`     StrictSig
    strict_sig
               IdInfo -> CprSig -> IdInfo
    `setCprInfo`            CprSig
    topCprSig
               IdInfo -> Type -> IdInfo
    `setLevityInfoWithType` Type
    ty

        ([TyBinder]
    bndrs, Type
    _) = Type -> ([TyBinder], Type)
    tcSplitPiTys Type
    ty
        arity :: Arity
    arity      = forall a. (a -> Bool) -> [a] -> Arity
    count TyBinder -> Bool
    isAnonTyCoBinder [TyBinder]
    bndrs
        strict_sig :: StrictSig
    strict_sig = [Demand] -> Divergence -> StrictSig
    mkClosedStrictSig (forall a. Arity -> a -> [a]
    replicate Arity
    arity Demand
    topDmd) Divergence
    topDiv
        -- the call does not claim to be strict in its arguments, since they
        -- may be lifted (foreign import prim) and the called code doesn't
        -- necessarily force them. See #11076.
    {-
    ************************************************************************
    *                                                                      *
    \subsection{DictFuns and default methods}
    *                                                                      *
    ************************************************************************

    Note [Dict funs and default methods]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Dict funs and default methods are *not* ImplicitIds.  Their definition
    involves user-written code, so we can't figure out their strictness etc
    based on fixed info, as we can for constructors and record selectors (say).

    NB: See also Note [Exported LocalIds] in GHC.Types.Id
    -}

    mkDictFunId :: Name      -- Name to use for the dict fun;
                -> [TyVar]
                -> ThetaType
                -> Class
                -> [Type]
                -> Id
    -- Implements the DFun Superclass Invariant (see GHC.Tc.TyCl.Instance)
    -- See Note [Dict funs and default methods]

    mkDictFunId :: Name -> [Id] -> [Type] -> Class -> [Type] -> Id
    mkDictFunId Name
    dfun_name [Id]
    tvs [Type]
    theta Class
    clas [Type]
    tys
      = IdDetails -> Name -> Type -> Id
    mkExportedLocalId (Bool -> IdDetails
    DFunId Bool
    is_nt)
                          Name
    dfun_name
                          Type
    dfun_ty
      where
        is_nt :: Bool
    is_nt = TyCon -> Bool
    isNewTyCon (Class -> TyCon
    classTyCon Class
    clas)
        dfun_ty :: Type
    dfun_ty = [Id] -> [Type] -> Class -> [Type] -> Type
    mkDictFunTy [Id]
    tvs [Type]
    theta Class
    clas [Type]
    tys

    mkDictFunTy :: [TyVar] -> ThetaType -> Class -> [Type] -> Type
    mkDictFunTy :: [Id] -> [Type] -> Class -> [Type] -> Type
    mkDictFunTy [Id]
    tvs [Type]
    theta Class
    clas [Type]
    tys
     = [Id] -> [Type] -> Type -> Type
    mkSpecSigmaTy [Id]
    tvs [Type]
    theta (Class -> [Type] -> Type
    mkClassPred Class
    clas [Type]
    tys)

    {-
    ************************************************************************
    *                                                                      *
    \subsection{Un-definable}
    *                                                                      *
    ************************************************************************

    These Ids can't be defined in Haskell.  They could be defined in
    unfoldings in the wired-in GHC.Prim interface file, but we'd have to
    ensure that they were definitely, definitely inlined, because there is
    no curried identifier for them.  That's what mkCompulsoryUnfolding
    does. Alternatively, we could add the definitions to mi_decls of ghcPrimIface
    but it's not clear if this would be simpler.

    coercionToken# is not listed in ghcPrimIds, since its type uses (~#)
    which is not supposed to be used in expressions (GHC throws an assertion
    failure when trying.)
    -}

    nullAddrName, seqName,
       realWorldName, voidPrimIdName, coercionTokenName,
       magicDictName, coerceName, proxyName,
       leftSectionName, rightSectionName :: Name
    nullAddrName :: Name
    nullAddrName      = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "nullAddr#")      Unique
    nullAddrIdKey      Id
    nullAddrId
    seqName :: Name
    seqName           = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "seq")            Unique
    seqIdKey           Id
    seqId
    realWorldName :: Name
    realWorldName     = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "realWorld#")     Unique
    realWorldPrimIdKey Id
    realWorldPrimId
    voidPrimIdName :: Name
    voidPrimIdName    = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "void#")          Unique
    voidPrimIdKey      Id
    voidPrimId
    coercionTokenName :: Name
    coercionTokenName = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "coercionToken#") Unique
    coercionTokenIdKey Id
    coercionTokenId
    magicDictName :: Name
    magicDictName     = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "magicDict")      Unique
    magicDictKey       Id
    magicDictId
    coerceName :: Name
    coerceName        = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "coerce")         Unique
    coerceKey          Id
    coerceId
    proxyName :: Name
    proxyName         = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "proxy#")         Unique
    proxyHashKey       Id
    proxyHashId
    leftSectionName :: Name
    leftSectionName   = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "leftSection")    Unique
    leftSectionKey     Id
    leftSectionId
    rightSectionName :: Name
    rightSectionName  = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_PRIM  (String -> RuleName
    fsLit String
    "rightSection")   Unique
    rightSectionKey    Id
    rightSectionId

    -- Names listed in magicIds; see Note [magicIds]
    lazyIdName, oneShotName, noinlineIdName :: Name
    lazyIdName :: Name
    lazyIdName        = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_MAGIC (String -> RuleName
    fsLit String
    "lazy")           Unique
    lazyIdKey          Id
    lazyId
    oneShotName :: Name
    oneShotName       = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_MAGIC (String -> RuleName
    fsLit String
    "oneShot")        Unique
    oneShotKey         Id
    oneShotId
    noinlineIdName :: Name
    noinlineIdName    = Module -> RuleName -> Unique -> Id -> Name
    mkWiredInIdName Module
    gHC_MAGIC (String -> RuleName
    fsLit String
    "noinline")       Unique
    noinlineIdKey      Id
    noinlineId

    ------------------------------------------------
    proxyHashId :: Id
    proxyHashId :: Id
    proxyHashId
      = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    proxyName Type
    ty
           (IdInfo
    noCafIdInfo IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo` Unfolding
    evaldUnfolding -- Note [evaldUnfoldings]
                        HasDebugCallStack => IdInfo -> Type -> IdInfo
    `setNeverLevPoly`  Type
    ty)
      where
        -- proxy# :: forall {k} (a:k). Proxy# k a
        --
        -- The visibility of the `k` binder is Inferred to match the type of the
        -- Proxy data constructor (#16293).
        [Id
    kv,Id
    tv] = [Type] -> ([Type] -> [Type]) -> [Id]
    mkTemplateKiTyVars [Type
    liftedTypeKind] forall a. a -> a
    id
        kv_ty :: Type
    kv_ty   = Id -> Type
    mkTyVarTy Id
    kv
        tv_ty :: Type
    tv_ty   = Id -> Type
    mkTyVarTy Id
    tv
        ty :: Type
    ty      = Id -> Type -> Type
    mkInfForAllTy Id
    kv forall a b. (a -> b) -> a -> b
    $ Id -> Type -> Type
    mkSpecForAllTy Id
    tv forall a b. (a -> b) -> a -> b
    $ Type -> Type -> Type
    mkProxyPrimTy Type
    kv_ty Type
    tv_ty

    ------------------------------------------------
    nullAddrId :: Id
    -- nullAddr# :: Addr#
    -- The reason it is here is because we don't provide
    -- a way to write this literal in Haskell.
    nullAddrId :: Id
    nullAddrId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    nullAddrName Type
    addrPrimTy IdInfo
    info
      where
        info :: IdInfo
    info = IdInfo
    noCafIdInfo IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo` InlinePragma
    alwaysInlinePragma
                           IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`  SimpleOpts -> CoreExpr -> Unfolding
    mkCompulsoryUnfolding SimpleOpts
    defaultSimpleOpts (forall b. Literal -> Expr b
    Lit Literal
    nullAddrLit)
                           HasDebugCallStack => IdInfo -> Type -> IdInfo
    `setNeverLevPoly`   Type
    addrPrimTy

    ------------------------------------------------
    seqId :: Id     -- See Note [seqId magic]
    seqId :: Id
    seqId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    seqName Type
    ty IdInfo
    info
      where
        info :: IdInfo
    info = IdInfo
    noCafIdInfo IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo` InlinePragma
    inline_prag
                           IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`  SimpleOpts -> CoreExpr -> Unfolding
    mkCompulsoryUnfolding SimpleOpts
    defaultSimpleOpts CoreExpr
    rhs

        inline_prag :: InlinePragma
    inline_prag
             = InlinePragma
    alwaysInlinePragma InlinePragma -> Activation -> InlinePragma
    `setInlinePragmaActivation` SourceText -> Arity -> Activation
    ActiveAfter
                     SourceText
    NoSourceText Arity
    0
                      -- Make 'seq' not inline-always, so that simpleOptExpr
                      -- (see GHC.Core.Subst.simple_app) won't inline 'seq' on the
                      -- LHS of rules.  That way we can have rules for 'seq';
                      -- see Note [seqId magic]

        -- seq :: forall (r :: RuntimeRep) a (b :: TYPE r). a -> b -> b
        ty :: Type
    ty  =
          Id -> Type -> Type
    mkInfForAllTy Id
    runtimeRep2TyVar
          forall a b. (a -> b) -> a -> b
    $ [Id] -> Type -> Type
    mkSpecForAllTys [Id
    alphaTyVar, Id
    openBetaTyVar]
          forall a b. (a -> b) -> a -> b
    $ Type -> Type -> Type
    mkVisFunTyMany Type
    alphaTy (Type -> Type -> Type
    mkVisFunTyMany Type
    openBetaTy Type
    openBetaTy)

        [Id
    x,Id
    y] = [Type] -> [Id]
    mkTemplateLocals [Type
    alphaTy, Type
    openBetaTy]
        rhs :: CoreExpr
    rhs = forall b. [b] -> Expr b -> Expr b
    mkLams ([Id
    runtimeRep2TyVar, Id
    alphaTyVar, Id
    openBetaTyVar, Id
    x, Id
    y]) forall a b. (a -> b) -> a -> b
    $
              forall b. Expr b -> b -> Type -> [Alt b] -> Expr b
    Case (forall b. Id -> Expr b
    Var Id
    x) Id
    x Type
    openBetaTy [forall b. AltCon -> [b] -> Expr b -> Alt b
    Alt AltCon
    DEFAULT [] (forall b. Id -> Expr b
    Var Id
    y)]

    ------------------------------------------------
    lazyId :: Id    -- See Note [lazyId magic]
    lazyId :: Id
    lazyId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    lazyIdName Type
    ty IdInfo
    info
      where
        info :: IdInfo
    info = IdInfo
    noCafIdInfo HasDebugCallStack => IdInfo -> Type -> IdInfo
    `setNeverLevPoly` Type
    ty
        ty :: Type
    ty  = [Id] -> Type -> Type
    mkSpecForAllTys [Id
    alphaTyVar] (Type -> Type -> Type
    mkVisFunTyMany Type
    alphaTy Type
    alphaTy)

    noinlineId :: Id -- See Note [noinlineId magic]
    noinlineId :: Id
    noinlineId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    noinlineIdName Type
    ty IdInfo
    info
      where
        info :: IdInfo
    info = IdInfo
    noCafIdInfo HasDebugCallStack => IdInfo -> Type -> IdInfo
    `setNeverLevPoly` Type
    ty
        ty :: Type
    ty  = [Id] -> Type -> Type
    mkSpecForAllTys [Id
    alphaTyVar] (Type -> Type -> Type
    mkVisFunTyMany Type
    alphaTy Type
    alphaTy)

    oneShotId :: Id -- See Note [The oneShot function]
    oneShotId :: Id
    oneShotId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    oneShotName Type
    ty IdInfo
    info
      where
        info :: IdInfo
    info = IdInfo
    noCafIdInfo IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo` InlinePragma
    alwaysInlinePragma
                           IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`  SimpleOpts -> CoreExpr -> Unfolding
    mkCompulsoryUnfolding SimpleOpts
    defaultSimpleOpts CoreExpr
    rhs
        ty :: Type
    ty  = [Id] -> Type -> Type
    mkInfForAllTys  [ Id
    runtimeRep1TyVar, Id
    runtimeRep2TyVar ] forall a b. (a -> b) -> a -> b
    $
              [Id] -> Type -> Type
    mkSpecForAllTys [ Id
    openAlphaTyVar, Id
    openBetaTyVar ]      forall a b. (a -> b) -> a -> b
    $
              Type -> Type -> Type
    mkVisFunTyMany Type
    fun_ty Type
    fun_ty
        fun_ty :: Type
    fun_ty = Type -> Type -> Type
    mkVisFunTyMany Type
    openAlphaTy Type
    openBetaTy
        [Id
    body, Id
    x] = [Type] -> [Id]
    mkTemplateLocals [Type
    fun_ty, Type
    openAlphaTy]
        x' :: Id
    x' = Id -> Id
    setOneShotLambda Id
    x  -- Here is the magic bit!
        rhs :: CoreExpr
    rhs = forall b. [b] -> Expr b -> Expr b
    mkLams [ Id
    runtimeRep1TyVar, Id
    runtimeRep2TyVar
                     , Id
    openAlphaTyVar, Id
    openBetaTyVar
                     , Id
    body, Id
    x'] forall a b. (a -> b) -> a -> b
    $
              forall b. Id -> Expr b
    Var Id
    body forall b. Expr b -> Expr b -> Expr b
    `App` forall b. Id -> Expr b
    Var Id
    x'

    ----------------------------------------------------------------------
    {- Note [Wired-in Ids for rebindable syntax]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    The functions leftSectionId, rightSectionId are
    wired in here ONLY because they are use in a levity-polymorphic way
    by the rebindable syntax mechanism. See GHC.Rename.Expr
    Note [Handling overloaded and rebindable constructs].

    Alas, we can't currenly give Haskell definitions for
    levity-polymorphic functions.

    They have Compulsory unfoldings to so that the levity polymorphism
    does not linger for long.
    -}

    -- See Note [Left and right sections] in GHC.Rename.Expr
    -- See Note [Wired-in Ids for rebindable syntax]
    --   leftSection :: forall r1 r2 n (a:Type r1) (b:TYPE r2).
    --                  (a %n-> b) -> a %n-> b
    --   leftSection f x = f x
    -- Important that it is eta-expanded, so that (leftSection undefined `seq` ())
    --   is () and not undefined
    -- Important that is is multiplicity-polymorphic (test linear/should_compile/OldList)
    leftSectionId :: Id
    leftSectionId :: Id
    leftSectionId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    leftSectionName Type
    ty IdInfo
    info
      where
        info :: IdInfo
    info = IdInfo
    noCafIdInfo IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo` InlinePragma
    alwaysInlinePragma
                           IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`  SimpleOpts -> CoreExpr -> Unfolding
    mkCompulsoryUnfolding SimpleOpts
    defaultSimpleOpts CoreExpr
    rhs
        ty :: Type
    ty  = [Id] -> Type -> Type
    mkInfForAllTys  [Id
    runtimeRep1TyVar,Id
    runtimeRep2TyVar, Id
    multiplicityTyVar1] forall a b. (a -> b) -> a -> b
    $
              [Id] -> Type -> Type
    mkSpecForAllTys [Id
    openAlphaTyVar,  Id
    openBetaTyVar]    forall a b. (a -> b) -> a -> b
    $
              CoreExpr -> Type
    exprType CoreExpr
    body
        [Id
    f,Id
    x] = [Type] -> [Id]
    mkTemplateLocals [Type -> Type -> Type -> Type
    mkVisFunTy Type
    mult Type
    openAlphaTy Type
    openBetaTy, Type
    openAlphaTy]

        mult :: Type
    mult = Id -> Type
    mkTyVarTy Id
    multiplicityTyVar1 :: Mult
        xmult :: Id
    xmult = Id -> Type -> Id
    setIdMult Id
    x Type
    mult

        rhs :: CoreExpr
    rhs  = forall b. [b] -> Expr b -> Expr b
    mkLams [ Id
    runtimeRep1TyVar, Id
    runtimeRep2TyVar, Id
    multiplicityTyVar1
                      , Id
    openAlphaTyVar,   Id
    openBetaTyVar   ] CoreExpr
    body
        body :: CoreExpr
    body = forall b. [b] -> Expr b -> Expr b
    mkLams [Id
    f,Id
    xmult] forall a b. (a -> b) -> a -> b
    $ forall b. Expr b -> Expr b -> Expr b
    App (forall b. Id -> Expr b
    Var Id
    f) (forall b. Id -> Expr b
    Var Id
    xmult)

    -- See Note [Left and right sections] in GHC.Rename.Expr
    -- See Note [Wired-in Ids for rebindable syntax]
    --   rightSection :: forall r1 r2 r3 (a:TYPE r1) (b:TYPE r2) (c:TYPE r3).
    --                   (a %n1 -> b %n2-> c) -> b %n2-> a %n1-> c
    --   rightSection f y x = f x y
    -- Again, multiplicity polymorphism is important
    rightSectionId :: Id
    rightSectionId :: Id
    rightSectionId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    rightSectionName Type
    ty IdInfo
    info
      where
        info :: IdInfo
    info = IdInfo
    noCafIdInfo IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo` InlinePragma
    alwaysInlinePragma
                           IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`  SimpleOpts -> CoreExpr -> Unfolding
    mkCompulsoryUnfolding SimpleOpts
    defaultSimpleOpts CoreExpr
    rhs
        ty :: Type
    ty  = [Id] -> Type -> Type
    mkInfForAllTys  [Id
    runtimeRep1TyVar,Id
    runtimeRep2TyVar,Id
    runtimeRep3TyVar
                              , Id
    multiplicityTyVar1, Id
    multiplicityTyVar2 ] forall a b. (a -> b) -> a -> b
    $
              [Id] -> Type -> Type
    mkSpecForAllTys [Id
    openAlphaTyVar,  Id
    openBetaTyVar,   Id
    openGammaTyVar ]  forall a b. (a -> b) -> a -> b
    $
              CoreExpr -> Type
    exprType CoreExpr
    body
        mult1 :: Type
    mult1 = Id -> Type
    mkTyVarTy Id
    multiplicityTyVar1
        mult2 :: Type
    mult2 = Id -> Type
    mkTyVarTy Id
    multiplicityTyVar2

        [Id
    f,Id
    x,Id
    y] = [Type] -> [Id]
    mkTemplateLocals [ [Scaled Type] -> Type -> Type
    mkVisFunTys [ forall a. Type -> a -> Scaled a
    Scaled Type
    mult1 Type
    openAlphaTy
                                                 , forall a. Type -> a -> Scaled a
    Scaled Type
    mult2 Type
    openBetaTy ] Type
    openGammaTy
                                   , Type
    openAlphaTy, Type
    openBetaTy ]
        xmult :: Id
    xmult = Id -> Type -> Id
    setIdMult Id
    x Type
    mult1
        ymult :: Id
    ymult = Id -> Type -> Id
    setIdMult Id
    y Type
    mult2
        rhs :: CoreExpr
    rhs  = forall b. [b] -> Expr b -> Expr b
    mkLams [ Id
    runtimeRep1TyVar, Id
    runtimeRep2TyVar, Id
    runtimeRep3TyVar
                      , Id
    multiplicityTyVar1, Id
    multiplicityTyVar2
                      , Id
    openAlphaTyVar,   Id
    openBetaTyVar,    Id
    openGammaTyVar ] CoreExpr
    body
        body :: CoreExpr
    body = forall b. [b] -> Expr b -> Expr b
    mkLams [Id
    f,Id
    ymult,Id
    xmult] forall a b. (a -> b) -> a -> b
    $ forall b. Expr b -> [Id] -> Expr b
    mkVarApps (forall b. Id -> Expr b
    Var Id
    f) [Id
    xmult,Id
    ymult]

    --------------------------------------------------------------------------------
    magicDictId :: Id  -- See Note [magicDictId magic]
    magicDictId :: Id
    magicDictId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    magicDictName Type
    ty IdInfo
    info
      where
      info :: IdInfo
    info = IdInfo
    noCafIdInfo IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo` InlinePragma
    neverInlinePragma
                         HasDebugCallStack => IdInfo -> Type -> IdInfo
    `setNeverLevPoly`   Type
    ty
      ty :: Type
    ty   = [Id] -> Type -> Type
    mkSpecForAllTys [Id
    alphaTyVar] Type
    alphaTy

    --------------------------------------------------------------------------------

    coerceId :: Id
    coerceId :: Id
    coerceId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    coerceName Type
    ty IdInfo
    info
      where
        info :: IdInfo
    info = IdInfo
    noCafIdInfo IdInfo -> InlinePragma -> IdInfo
    `setInlinePragInfo` InlinePragma
    alwaysInlinePragma
                           IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo`  SimpleOpts -> CoreExpr -> Unfolding
    mkCompulsoryUnfolding SimpleOpts
    defaultSimpleOpts CoreExpr
    rhs
        eqRTy :: Type
    eqRTy     = TyCon -> [Type] -> Type
    mkTyConApp TyCon
    coercibleTyCon [ Type -> Type
    tYPE Type
    r , Type
    a, Type
    b ]
        eqRPrimTy :: Type
    eqRPrimTy = TyCon -> [Type] -> Type
    mkTyConApp TyCon
    eqReprPrimTyCon [ Type -> Type
    tYPE Type
    r, Type -> Type
    tYPE Type
    r, Type
    a, Type
    b ]
        ty :: Type
    ty        = [InvisTVBinder] -> Type -> Type
    mkInvisForAllTys [ forall var argf. var -> argf -> VarBndr var argf
    Bndr Id
    rv Specificity
    InferredSpec
                                     , forall var argf. var -> argf -> VarBndr var argf
    Bndr Id
    av Specificity
    SpecifiedSpec
                                     , forall var argf. var -> argf -> VarBndr var argf
    Bndr Id
    bv Specificity
    SpecifiedSpec
                                     ] forall a b. (a -> b) -> a -> b
    $
                    Type -> Type -> Type
    mkInvisFunTyMany Type
    eqRTy forall a b. (a -> b) -> a -> b
    $
                    Type -> Type -> Type
    mkVisFunTyMany Type
    a Type
    b

        bndrs :: [Id]
    bndrs@[Id
    rv,Id
    av,Id
    bv] = Type -> (Type -> [Type]) -> [Id]
    mkTemplateKiTyVar Type
    runtimeRepTy
                            (\Type
    r -> [Type -> Type
    tYPE Type
    r, Type -> Type
    tYPE Type
    r])

        [Type
    r, Type
    a, Type
    b] = [Id] -> [Type]
    mkTyVarTys [Id]
    bndrs

        [Id
    eqR,Id
    x,Id
    eq] = [Type] -> [Id]
    mkTemplateLocals [Type
    eqRTy, Type
    a, Type
    eqRPrimTy]
        rhs :: CoreExpr
    rhs = forall b. [b] -> Expr b -> Expr b
    mkLams ([Id]
    bndrs forall a. [a] -> [a] -> [a]
    ++ [Id
    eqR, Id
    x]) forall a b. (a -> b) -> a -> b
    $
              CoreExpr -> Scaled Type -> Type -> [Alt Id] -> CoreExpr
    mkWildCase (forall b. Id -> Expr b
    Var Id
    eqR) (forall a. a -> Scaled a
    unrestricted Type
    eqRTy) Type
    b forall a b. (a -> b) -> a -> b
    $
              [forall b. AltCon -> [b] -> Expr b -> Alt b
    Alt (DataCon -> AltCon
    DataAlt DataCon
    coercibleDataCon) [Id
    eq] (forall b. Expr b -> Coercion -> Expr b
    Cast (forall b. Id -> Expr b
    Var Id
    x) (Id -> Coercion
    mkCoVarCo Id
    eq))]

    {-
    Note [seqId magic]
    ~~~~~~~~~~~~~~~~~~
    'GHC.Prim.seq' is special in several ways.

    a) Its fixity is set in GHC.Iface.Load.ghcPrimIface

    b) It has quite a bit of desugaring magic.
       See GHC.HsToCore.Utils Note [Desugaring seq] (1) and (2) and (3)

    c) There is some special rule handing: Note [User-defined RULES for seq]

    Historical note:
        In GHC.Tc.Gen.Expr we used to need a special typing rule for 'seq', to handle calls
        whose second argument had an unboxed type, e.g.  x `seq` 3#

        However, with levity polymorphism we can now give seq the type seq ::
        forall (r :: RuntimeRep) a (b :: TYPE r). a -> b -> b which handles this
        case without special treatment in the typechecker.

    Note [User-defined RULES for seq]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Roman found situations where he had
          case (f n) of _ -> e
    where he knew that f (which was strict in n) would terminate if n did.
    Notice that the result of (f n) is discarded. So it makes sense to
    transform to
          case n of _ -> e

    Rather than attempt some general analysis to support this, I've added
    enough support that you can do this using a rewrite rule:

      RULE "f/seq" forall n.  seq (f n) = seq n

    You write that rule.  When GHC sees a case expression that discards
    its result, it mentally transforms it to a call to 'seq' and looks for
    a RULE.  (This is done in GHC.Core.Opt.Simplify.trySeqRules.)  As usual, the
    correctness of the rule is up to you.

    VERY IMPORTANT: to make this work, we give the RULE an arity of 1, not 2.
    If we wrote
      RULE "f/seq" forall n e.  seq (f n) e = seq n e
    with rule arity 2, then two bad things would happen:

      - The magical desugaring done in Note [seqId magic] item (b)
        for saturated application of 'seq' would turn the LHS into
        a case expression!

      - The code in GHC.Core.Opt.Simplify.rebuildCase would need to actually supply
        the value argument, which turns out to be awkward.

    See also: Note [User-defined RULES for seq] in GHC.Core.Opt.Simplify.

    Note [lazyId magic]
    ~~~~~~~~~~~~~~~~~~~
    lazy :: forall a. a -> a

    'lazy' is used to make sure that a sub-expression, and its free variables,
    are truly used call-by-need, with no code motion.  Key examples:

    * pseq:    pseq a b = a `seq` lazy b
      We want to make sure that the free vars of 'b' are not evaluated
      before 'a', even though the expression is plainly strict in 'b'.

    * catch:   catch a b = catch# (lazy a) b
      Again, it's clear that 'a' will be evaluated strictly (and indeed
      applied to a state token) but we want to make sure that any exceptions
      arising from the evaluation of 'a' are caught by the catch (see
      #11555).

    Implementing 'lazy' is a bit tricky:

    * It must not have a strictness signature: by being a built-in Id,
      all the info about lazyId comes from here, not from GHC.Magic.hi.
      This is important, because the strictness analyser will spot it as
      strict!

    * It must not have an unfolding: it gets "inlined" by a HACK in
      CorePrep. It's very important to do this inlining *after* unfoldings
      are exposed in the interface file.  Otherwise, the unfolding for
      (say) pseq in the interface file will not mention 'lazy', so if we
      inline 'pseq' we'll totally miss the very thing that 'lazy' was
      there for in the first place. See #3259 for a real world
      example.

    * Suppose CorePrep sees (catch# (lazy e) b).  At all costs we must
      avoid using call by value here:
         case e of r -> catch# r b
      Avoiding that is the whole point of 'lazy'.  So in CorePrep (which
      generate the 'case' expression for a call-by-value call) we must
      spot the 'lazy' on the arg (in CorePrep.cpeApp), and build a 'let'
      instead.

    * lazyId is defined in GHC.Base, so we don't *have* to inline it.  If it
      appears un-applied, we'll end up just calling it.

    Note [noinlineId magic]
    ~~~~~~~~~~~~~~~~~~~~~~~
    'noinline' is used to make sure that a function f is never inlined,
    e.g., as in 'noinline f x'.  We won't inline f because we never inline
    lone variables (see Note [Lone variables] in GHC.Core.Unfold

    You might think that we could implement noinline like this:
       {-# NOINLINE #-}
       noinline :: forall a. a -> a
       noinline x = x

    But actually we give 'noinline' a wired-in name for three distinct reasons:

    1. We don't want to leave a (useless) call to noinline in the final program,
       to be executed at runtime. So we have a little bit of magic to
       optimize away 'noinline' after we are done running the simplifier.
       This is done in GHC.CoreToStg.Prep.cpeApp.

    2. 'noinline' sometimes gets inserted automatically when we serialize an
       expression to the interface format, in GHC.CoreToIface.toIfaceVar.
       See Note [Inlining and hs-boot files] in GHC.CoreToIface

    3. Given foo :: Eq a => [a] -> Bool, the expression
         noinline foo x xs
       where x::Int, will naturally desugar to
          noinline @Int (foo @Int dEqInt) x xs
       But now it's entirely possible htat (foo @Int dEqInt) will inline foo,
       since 'foo' is no longer a lone variable -- see #18995

       Solution: in the desugarer, rewrite
          noinline (f x y)  ==>  noinline f x y
       This is done in GHC.HsToCore.Utils.mkCoreAppDs.

    Note that noinline as currently implemented can hide some simplifications since
    it hides strictness from the demand analyser. Specifically, the demand analyser
    will treat 'noinline f x' as lazy in 'x', even if the demand signature of 'f'
    specifies that it is strict in its argument. We considered fixing this this by adding a
    special case to the demand analyser to address #16588. However, the special
    case seemed like a large and expensive hammer to address a rare case and
    consequently we rather opted to use a more minimal solution.

    Note [The oneShot function]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
    In the context of making left-folds fuse somewhat okish (see ticket #7994
    and Note [Left folds via right fold]) it was determined that it would be useful
    if library authors could explicitly tell the compiler that a certain lambda is
    called at most once. The oneShot function allows that.

    'oneShot' is levity-polymorphic, i.e. the type variables can refer to unlifted
    types as well (#10744); e.g.
       oneShot (\x:Int# -> x +# 1#)

    Like most magic functions it has a compulsory unfolding, so there is no need
    for a real definition somewhere. We have one in GHC.Magic for the convenience
    of putting the documentation there.

    It uses `setOneShotLambda` on the lambda's binder. That is the whole magic:

    A typical call looks like
         oneShot (\y. e)
    after unfolding the definition `oneShot = \f \x[oneshot]. f x` we get
         (\f \x[oneshot]. f x) (\y. e)
     --> \x[oneshot]. ((\y.e) x)
     --> \x[oneshot] e[x/y]
    which is what we want.

    It is only effective if the one-shot info survives as long as possible; in
    particular it must make it into the interface in unfoldings. See Note [Preserve
    OneShotInfo] in GHC.Core.Tidy.

    Also see https://gitlab.haskell.org/ghc/ghc/wikis/one-shot.

    Note [magicDictId magic]
    ~~~~~~~~~~~~~~~~~~~~~~~~~
    The identifier `magicDict` is just a place-holder, which is used to
    implement a primitive that we cannot define in Haskell but we can write
    in Core.  It is declared with a place-holder type:

        magicDict :: forall a. a

    The intention is that the identifier will be used in a very specific way,
    to create dictionaries for classes with a single method.  Consider a class
    like this:

       class C a where
         f :: T a

    We are going to use `magicDict`, in conjunction with a built-in Prelude
    rule, to cast values of type `T a` into dictionaries for `C a`.  To do
    this, we define a function like this in the library:

      data WrapC a b = WrapC (C a => Proxy a -> b)

      withT :: (C a => Proxy a -> b)
            ->  T a -> Proxy a -> b
      withT f x y = magicDict (WrapC f) x y

    The purpose of `WrapC` is to avoid having `f` instantiated.
    Also, it avoids impredicativity, because `magicDict`'s type
    cannot be instantiated with a forall.  The field of `WrapC` contains
    a `Proxy` parameter which is used to link the type of the constraint,
    `C a`, with the type of the `Wrap` value being made.

    Next, we add a built-in Prelude rule (see GHC.Core.Opt.ConstantFold),
    which will replace the RHS of this definition with the appropriate
    definition in Core.  The rewrite rule works as follows:

      magicDict @t (wrap @a @b f) x y
    ---->
      f (x `cast` co a) y

    The `co` coercion is the newtype-coercion extracted from the type-class.
    The type class is obtained by looking at the type of wrap.

    In the constant folding rule it's very import to make sure to strip all ticks
    from the expression as if there's an occurence of
    magicDict we *must* convert it for correctness. See #19667 for where this went
    wrong in GHCi.

    -------------------------------------------------------------
    @realWorld#@ used to be a magic literal, \tr{void#}.  If things get
    nasty as-is, change it back to a literal (@Literal@).

    voidArgId is a Local Id used simply as an argument in functions
    where we just want an arg to avoid having a thunk of unlifted type.
    E.g.
            x = \ void :: Void# -> (# p, q #)

    This comes up in strictness analysis

    Note [evaldUnfoldings]
    ~~~~~~~~~~~~~~~~~~~~~~
    The evaldUnfolding makes it look that some primitive value is
    evaluated, which in turn makes Simplify.interestingArg return True,
    which in turn makes INLINE things applied to said value likely to be
    inlined.
    -}

    realWorldPrimId :: Id   -- :: State# RealWorld
    realWorldPrimId :: Id
    realWorldPrimId = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    realWorldName Type
    realWorldStatePrimTy
                         (IdInfo
    noCafIdInfo IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo` Unfolding
    evaldUnfolding    -- Note [evaldUnfoldings]
                                      IdInfo -> OneShotInfo -> IdInfo
    `setOneShotInfo`   OneShotInfo
    stateHackOneShot
                                      HasDebugCallStack => IdInfo -> Type -> IdInfo
    `setNeverLevPoly`  Type
    realWorldStatePrimTy)

    voidPrimId :: Id     -- Global constant :: Void#
                         -- The type Void# is now the same as (# #) (ticket #18441),
                         -- this identifier just signifies the (# #) datacon
                         -- and is kept for backwards compatibility.
                         -- We cannot define it in normal Haskell, since it's
                         -- a top-level unlifted value.
    voidPrimId :: Id
    voidPrimId  = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    voidPrimIdName Type
    unboxedUnitTy
                    (IdInfo
    noCafIdInfo IdInfo -> Unfolding -> IdInfo
    `setUnfoldingInfo` SimpleOpts -> CoreExpr -> Unfolding
    mkCompulsoryUnfolding SimpleOpts
    defaultSimpleOpts forall {b}. Expr b
    rhs
                                 HasDebugCallStack => IdInfo -> Type -> IdInfo
    `setNeverLevPoly`  Type
    unboxedUnitTy)
        where rhs :: Expr b
    rhs = forall b. Id -> Expr b
    Var (DataCon -> Id
    dataConWorkId DataCon
    unboxedUnitDataCon)

    voidArgId :: Id       -- Local lambda-bound :: Void#
    voidArgId :: Id
    voidArgId = RuleName -> Unique -> Type -> Type -> Id
    mkSysLocal (String -> RuleName
    fsLit String
    "void") Unique
    voidArgIdKey Type
    Many Type
    unboxedUnitTy

    coercionTokenId :: Id         -- :: () ~# ()
    coercionTokenId :: Id
    coercionTokenId -- See Note [Coercion tokens] in "GHC.CoreToStg"
      = Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    coercionTokenName
                     (TyCon -> [Type] -> Type
    mkTyConApp TyCon
    eqPrimTyCon [Type
    liftedTypeKind, Type
    liftedTypeKind, Type
    unitTy, Type
    unitTy])
                     IdInfo
    noCafIdInfo

    pcMiscPrelId :: Name -> Type -> IdInfo -> Id
    pcMiscPrelId :: Name -> Type -> IdInfo -> Id
    pcMiscPrelId Name
    name Type
    ty IdInfo
    info
      = Name -> Type -> IdInfo -> Id
    mkVanillaGlobalWithInfo Name
    name Type
    ty IdInfo
    info