{-# LANGUAGE CPP          #-}
{-# LANGUAGE TypeFamilies #-}

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

{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998


Desugaring expressions.
-}

module GHC.HsToCore.Expr
   ( dsExpr, dsLExpr, dsLExprNoLP, dsLocalBinds
   , dsValBinds, dsLit, dsSyntaxExpr
   )
where

#include "GhclibHsVersions.h"

import GHC.Prelude

import GHC.HsToCore.Match
import GHC.HsToCore.Match.Literal
import GHC.HsToCore.Binds
import GHC.HsToCore.GuardedRHSs
import GHC.HsToCore.ListComp
import GHC.HsToCore.Utils
import GHC.HsToCore.Arrows
import GHC.HsToCore.Monad
import GHC.HsToCore.Pmc ( addTyCs, pmcGRHSs )
import GHC.Types.SourceText
import GHC.Types.Name
import GHC.Types.Name.Env
import GHC.Core.FamInstEnv( topNormaliseType )
import GHC.HsToCore.Quote
import GHC.Hs

-- NB: The desugarer, which straddles the source and Core worlds, sometimes
--     needs to see source types
import GHC.Tc.Utils.TcType
import GHC.Tc.Types.Evidence
import GHC.Tc.Utils.Monad
import GHC.Core.Type
import GHC.Core.Multiplicity
import GHC.Core.Coercion( Coercion )
import GHC.Core
import GHC.Core.Utils
import GHC.Core.Make

import GHC.Driver.Session
import GHC.Types.CostCentre
import GHC.Types.Id
import GHC.Types.Id.Make
import GHC.Types.Var.Env
import GHC.Unit.Module
import GHC.Core.ConLike
import GHC.Core.DataCon
import GHC.Core.TyCo.Ppr( pprWithTYPE )
import GHC.Builtin.Types
import GHC.Builtin.Names
import GHC.Types.Basic
import GHC.Data.Maybe
import GHC.Types.SrcLoc
import GHC.Utils.Misc
import GHC.Data.Bag
import GHC.Utils.Outputable as Outputable
import GHC.Utils.Panic
import GHC.Core.PatSyn
import Control.Monad

import qualified GHC.LanguageExtensions as LangExt

{-
************************************************************************
*                                                                      *
                dsLocalBinds, dsValBinds
*                                                                      *
************************************************************************
-}

dsLocalBinds :: LHsLocalBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsLocalBinds :: LHsLocalBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsLocalBinds (L _   (EmptyLocalBinds _))  CoreExpr
body = CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return CoreExpr
body
dsLocalBinds (L loc (HsValBinds _ binds)) CoreExpr
body = SrcSpan -> DsM CoreExpr -> DsM CoreExpr
forall a. SrcSpan -> DsM a -> DsM a
putSrcSpanDs SrcSpan
loc (DsM CoreExpr -> DsM CoreExpr) -> DsM CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$
                                                 HsValBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsValBinds HsValBinds GhcTc
binds CoreExpr
body
dsLocalBinds (L _ (HsIPBinds _ binds))    CoreExpr
body = HsIPBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsIPBinds  HsIPBinds GhcTc
binds CoreExpr
body

-------------------------
-- caller sets location
dsValBinds :: HsValBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsValBinds :: HsValBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsValBinds (XValBindsLR (NValBinds binds _)) CoreExpr
body
  = ((RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))
 -> CoreExpr -> DsM CoreExpr)
-> CoreExpr
-> [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
-> DsM CoreExpr
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> b -> m b) -> b -> t a -> m b
foldrM (RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))
-> CoreExpr -> DsM CoreExpr
(RecFlag, LHsBinds GhcTc) -> CoreExpr -> DsM CoreExpr
ds_val_bind CoreExpr
body [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
[(RecFlag, LHsBinds GhcTc)]
binds
dsValBinds (ValBinds {})       CoreExpr
_    = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsValBinds ValBindsIn"

-------------------------
dsIPBinds :: HsIPBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsIPBinds :: HsIPBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsIPBinds (IPBinds XIPBinds GhcTc
ev_binds [LIPBind GhcTc]
ip_binds) CoreExpr
body
  = do  { [CoreBind]
ds_binds <- TcEvBinds -> DsM [CoreBind]
dsTcEvBinds TcEvBinds
XIPBinds GhcTc
ev_binds
        ; let inner :: CoreExpr
inner = [CoreBind] -> CoreExpr -> CoreExpr
mkCoreLets [CoreBind]
ds_binds CoreExpr
body
                -- The dict bindings may not be in
                -- dependency order; hence Rec
        ; (Located (IPBind GhcTc) -> CoreExpr -> DsM CoreExpr)
-> CoreExpr -> [Located (IPBind GhcTc)] -> DsM CoreExpr
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> b -> m b) -> b -> t a -> m b
foldrM Located (IPBind GhcTc) -> CoreExpr -> DsM CoreExpr
LIPBind GhcTc -> CoreExpr -> DsM CoreExpr
ds_ip_bind CoreExpr
inner [Located (IPBind GhcTc)]
[LIPBind GhcTc]
ip_binds }
  where
    ds_ip_bind :: LIPBind GhcTc -> CoreExpr -> DsM CoreExpr
    ds_ip_bind :: LIPBind GhcTc -> CoreExpr -> DsM CoreExpr
ds_ip_bind (L _ (IPBind _ ~(Right n) e)) CoreExpr
body
      = do CoreExpr
e' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
e
           CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBind -> CoreExpr -> CoreExpr
forall b. Bind b -> Expr b -> Expr b
Let (CoreBndr -> CoreExpr -> CoreBind
forall b. b -> Expr b -> Bind b
NonRec CoreBndr
IdP GhcTc
n CoreExpr
e') CoreExpr
body)

-------------------------
-- caller sets location
ds_val_bind :: (RecFlag, LHsBinds GhcTc) -> CoreExpr -> DsM CoreExpr
-- Special case for bindings which bind unlifted variables
-- We need to do a case right away, rather than building
-- a tuple and doing selections.
-- Silently ignore INLINE and SPECIALISE pragmas...
ds_val_bind :: (RecFlag, LHsBinds GhcTc) -> CoreExpr -> DsM CoreExpr
ds_val_bind (RecFlag
NonRecursive, LHsBinds GhcTc
hsbinds) CoreExpr
body
  | [L SrcSpan
loc HsBindLR GhcTc GhcTc
bind] <- Bag (Located (HsBindLR GhcTc GhcTc))
-> [Located (HsBindLR GhcTc GhcTc)]
forall a. Bag a -> [a]
bagToList Bag (Located (HsBindLR GhcTc GhcTc))
LHsBinds GhcTc
hsbinds
        -- Non-recursive, non-overloaded bindings only come in ones
        -- ToDo: in some bizarre case it's conceivable that there
        --       could be dict binds in the 'binds'.  (See the notes
        --       below.  Then pattern-match would fail.  Urk.)
  , HsBindLR GhcTc GhcTc -> Bool
isUnliftedHsBind HsBindLR GhcTc GhcTc
bind
  = SrcSpan -> DsM CoreExpr -> DsM CoreExpr
forall a. SrcSpan -> DsM a -> DsM a
putSrcSpanDs SrcSpan
loc (DsM CoreExpr -> DsM CoreExpr) -> DsM CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$
     -- see Note [Strict binds checks] in GHC.HsToCore.Binds
    if HsBindLR GhcTc GhcTc -> Bool
forall idL idR. HsBindLR idL idR -> Bool
is_polymorphic HsBindLR GhcTc GhcTc
bind
    then SDoc -> DsM CoreExpr
errDsCoreExpr (HsBindLR GhcTc GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
poly_bind_err HsBindLR GhcTc GhcTc
bind)
            -- data Ptr a = Ptr Addr#
            -- f x = let p@(Ptr y) = ... in ...
            -- Here the binding for 'p' is polymorphic, but does
            -- not mix with an unlifted binding for 'y'.  You should
            -- use a bang pattern.  #6078.

    else do { Bool
-> IOEnv (Env DsGblEnv DsLclEnv) ()
-> IOEnv (Env DsGblEnv DsLclEnv) ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (HsBindLR GhcTc GhcTc -> Bool
forall (p :: Pass). HsBind (GhcPass p) -> Bool
looksLazyPatBind HsBindLR GhcTc GhcTc
bind) (IOEnv (Env DsGblEnv DsLclEnv) ()
 -> IOEnv (Env DsGblEnv DsLclEnv) ())
-> IOEnv (Env DsGblEnv DsLclEnv) ()
-> IOEnv (Env DsGblEnv DsLclEnv) ()
forall a b. (a -> b) -> a -> b
$
              WarningFlag -> SDoc -> IOEnv (Env DsGblEnv DsLclEnv) ()
warnIfSetDs WarningFlag
Opt_WarnUnbangedStrictPatterns (HsBindLR GhcTc GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
unlifted_must_be_bang HsBindLR GhcTc GhcTc
bind)
        -- Complain about a binding that looks lazy
        --    e.g.    let I# y = x in ...
        -- Remember, in checkStrictBinds we are going to do strict
        -- matching, so (for software engineering reasons) we insist
        -- that the strictness is manifest on each binding
        -- However, lone (unboxed) variables are ok


            ; HsBindLR GhcTc GhcTc -> CoreExpr -> DsM CoreExpr
dsUnliftedBind HsBindLR GhcTc GhcTc
bind CoreExpr
body }
  where
    is_polymorphic :: HsBindLR idL idR -> Bool
is_polymorphic (AbsBinds { abs_tvs :: forall idL idR. HsBindLR idL idR -> [CoreBndr]
abs_tvs = [CoreBndr]
tvs, abs_ev_vars :: forall idL idR. HsBindLR idL idR -> [CoreBndr]
abs_ev_vars = [CoreBndr]
evs })
                     = Bool -> Bool
not ([CoreBndr] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [CoreBndr]
tvs Bool -> Bool -> Bool
&& [CoreBndr] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [CoreBndr]
evs)
    is_polymorphic HsBindLR idL idR
_ = Bool
False

    unlifted_must_be_bang :: a -> SDoc
unlifted_must_be_bang a
bind
      = SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Pattern bindings containing unlifted types should use" SDoc -> SDoc -> SDoc
$$
              String -> SDoc
text String
"an outermost bang pattern:")
           Int
2 (a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
bind)

    poly_bind_err :: a -> SDoc
poly_bind_err a
bind
      = SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"You can't mix polymorphic and unlifted bindings:")
           Int
2 (a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
bind) SDoc -> SDoc -> SDoc
$$
        String -> SDoc
text String
"Probable fix: add a type signature"

ds_val_bind (RecFlag
is_rec, LHsBinds GhcTc
binds) CoreExpr
_body
  | (Located (HsBindLR GhcTc GhcTc) -> Bool)
-> Bag (Located (HsBindLR GhcTc GhcTc)) -> Bool
forall a. (a -> Bool) -> Bag a -> Bool
anyBag (HsBindLR GhcTc GhcTc -> Bool
isUnliftedHsBind (HsBindLR GhcTc GhcTc -> Bool)
-> (Located (HsBindLR GhcTc GhcTc) -> HsBindLR GhcTc GhcTc)
-> Located (HsBindLR GhcTc GhcTc)
-> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Located (HsBindLR GhcTc GhcTc) -> HsBindLR GhcTc GhcTc
forall l e. GenLocated l e -> e
unLoc) Bag (Located (HsBindLR GhcTc GhcTc))
LHsBinds GhcTc
binds  -- see Note [Strict binds checks] in GHC.HsToCore.Binds
  = ASSERT( isRec is_rec )
    SDoc -> DsM CoreExpr
errDsCoreExpr (SDoc -> DsM CoreExpr) -> SDoc -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$
    SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Recursive bindings for unlifted types aren't allowed:")
       Int
2 ([SDoc] -> SDoc
vcat ((Located (HsBindLR GhcTc GhcTc) -> SDoc)
-> [Located (HsBindLR GhcTc GhcTc)] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map Located (HsBindLR GhcTc GhcTc) -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Bag (Located (HsBindLR GhcTc GhcTc))
-> [Located (HsBindLR GhcTc GhcTc)]
forall a. Bag a -> [a]
bagToList Bag (Located (HsBindLR GhcTc GhcTc))
LHsBinds GhcTc
binds)))

-- Ordinary case for bindings; none should be unlifted
ds_val_bind (RecFlag
is_rec, LHsBinds GhcTc
binds) CoreExpr
body
  = do  { MASSERT( isRec is_rec || isSingletonBag binds )
               -- we should never produce a non-recursive list of multiple binds

        ; ([CoreBndr]
force_vars,[(CoreBndr, CoreExpr)]
prs) <- LHsBinds GhcTc -> DsM ([CoreBndr], [(CoreBndr, CoreExpr)])
dsLHsBinds LHsBinds GhcTc
binds
        ; let body' :: CoreExpr
body' = (CoreBndr -> CoreExpr -> CoreExpr)
-> CoreExpr -> [CoreBndr] -> CoreExpr
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr CoreBndr -> CoreExpr -> CoreExpr
seqVar CoreExpr
body [CoreBndr]
force_vars
        ; ASSERT2( not (any (isUnliftedType . idType . fst) prs), ppr is_rec $$ ppr binds )
          case [(CoreBndr, CoreExpr)]
prs of
            [] -> CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return CoreExpr
body
            [(CoreBndr, CoreExpr)]
_  -> CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBind -> CoreExpr -> CoreExpr
forall b. Bind b -> Expr b -> Expr b
Let ([(CoreBndr, CoreExpr)] -> CoreBind
forall b. [(b, Expr b)] -> Bind b
Rec [(CoreBndr, CoreExpr)]
prs) CoreExpr
body') }
        -- Use a Rec regardless of is_rec.
        -- Why? Because it allows the binds to be all
        -- mixed up, which is what happens in one rare case
        -- Namely, for an AbsBind with no tyvars and no dicts,
        --         but which does have dictionary bindings.
        -- See notes with GHC.Tc.Solver.inferLoop [NO TYVARS]
        -- It turned out that wrapping a Rec here was the easiest solution
        --
        -- NB The previous case dealt with unlifted bindings, so we
        --    only have to deal with lifted ones now; so Rec is ok

------------------
dsUnliftedBind :: HsBind GhcTc -> CoreExpr -> DsM CoreExpr
dsUnliftedBind :: HsBindLR GhcTc GhcTc -> CoreExpr -> DsM CoreExpr
dsUnliftedBind (AbsBinds { abs_tvs :: forall idL idR. HsBindLR idL idR -> [CoreBndr]
abs_tvs = [], abs_ev_vars :: forall idL idR. HsBindLR idL idR -> [CoreBndr]
abs_ev_vars = []
               , abs_exports :: forall idL idR. HsBindLR idL idR -> [ABExport idL]
abs_exports = [ABExport GhcTc]
exports
               , abs_ev_binds :: forall idL idR. HsBindLR idL idR -> [TcEvBinds]
abs_ev_binds = [TcEvBinds]
ev_binds
               , abs_binds :: forall idL idR. HsBindLR idL idR -> LHsBinds idL
abs_binds = LHsBinds GhcTc
lbinds }) CoreExpr
body
  = do { let body1 :: CoreExpr
body1 = (ABExport GhcTc -> CoreExpr -> CoreExpr)
-> CoreExpr -> [ABExport GhcTc] -> CoreExpr
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr ABExport GhcTc -> CoreExpr -> CoreExpr
forall p. (IdP p ~ CoreBndr) => ABExport p -> CoreExpr -> CoreExpr
bind_export CoreExpr
body [ABExport GhcTc]
exports
             bind_export :: ABExport p -> CoreExpr -> CoreExpr
bind_export ABExport p
export CoreExpr
b = CoreBndr -> CoreExpr -> CoreExpr -> CoreExpr
bindNonRec (ABExport p -> IdP p
forall p. ABExport p -> IdP p
abe_poly ABExport p
export) (CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var (ABExport p -> IdP p
forall p. ABExport p -> IdP p
abe_mono ABExport p
export)) CoreExpr
b
       ; CoreExpr
body2 <- (CoreExpr -> Located (HsBindLR GhcTc GhcTc) -> DsM CoreExpr)
-> CoreExpr -> Bag (Located (HsBindLR GhcTc GhcTc)) -> DsM CoreExpr
forall (t :: * -> *) (m :: * -> *) b a.
(Foldable t, Monad m) =>
(b -> a -> m b) -> b -> t a -> m b
foldlM (\CoreExpr
body Located (HsBindLR GhcTc GhcTc)
lbind -> HsBindLR GhcTc GhcTc -> CoreExpr -> DsM CoreExpr
dsUnliftedBind (Located (HsBindLR GhcTc GhcTc) -> HsBindLR GhcTc GhcTc
forall l e. GenLocated l e -> e
unLoc Located (HsBindLR GhcTc GhcTc)
lbind) CoreExpr
body)
                            CoreExpr
body1 Bag (Located (HsBindLR GhcTc GhcTc))
LHsBinds GhcTc
lbinds
       ; [CoreBind]
ds_binds <- [TcEvBinds] -> DsM [CoreBind]
dsTcEvBinds_s [TcEvBinds]
ev_binds
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return ([CoreBind] -> CoreExpr -> CoreExpr
mkCoreLets [CoreBind]
ds_binds CoreExpr
body2) }

dsUnliftedBind (FunBind { fun_id :: forall idL idR. HsBindLR idL idR -> LIdP idL
fun_id = L l fun
                        , fun_matches :: forall idL idR. HsBindLR idL idR -> MatchGroup idR (LHsExpr idR)
fun_matches = MatchGroup GhcTc (LHsExpr GhcTc)
matches
                        , fun_ext :: forall idL idR. HsBindLR idL idR -> XFunBind idL idR
fun_ext = XFunBind GhcTc GhcTc
co_fn
                        , fun_tick :: forall idL idR. HsBindLR idL idR -> [Tickish CoreBndr]
fun_tick = [Tickish CoreBndr]
tick }) CoreExpr
body
               -- Can't be a bang pattern (that looks like a PatBind)
               -- so must be simply unboxed
  = do { ([CoreBndr]
args, CoreExpr
rhs) <- HsMatchContext GhcRn
-> Maybe (LHsExpr GhcTc)
-> MatchGroup GhcTc (LHsExpr GhcTc)
-> DsM ([CoreBndr], CoreExpr)
matchWrapper (LIdP GhcRn -> HsMatchContext GhcRn
forall p. LIdP p -> HsMatchContext p
mkPrefixFunRhs (SrcSpan -> Name -> GenLocated SrcSpan Name
forall l e. l -> e -> GenLocated l e
L SrcSpan
l (Name -> GenLocated SrcSpan Name)
-> Name -> GenLocated SrcSpan Name
forall a b. (a -> b) -> a -> b
$ CoreBndr -> Name
idName CoreBndr
fun))
                                     Maybe (LHsExpr GhcTc)
forall a. Maybe a
Nothing MatchGroup GhcTc (LHsExpr GhcTc)
matches
       ; MASSERT( null args ) -- Functions aren't lifted
       ; MASSERT( isIdHsWrapper co_fn )
       ; let rhs' :: CoreExpr
rhs' = [Tickish CoreBndr] -> CoreExpr -> CoreExpr
mkOptTickBox [Tickish CoreBndr]
tick CoreExpr
rhs
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBndr -> CoreExpr -> CoreExpr -> CoreExpr
bindNonRec CoreBndr
fun CoreExpr
rhs' CoreExpr
body) }

dsUnliftedBind (PatBind {pat_lhs :: forall idL idR. HsBindLR idL idR -> LPat idL
pat_lhs = LPat GhcTc
pat, pat_rhs :: forall idL idR. HsBindLR idL idR -> GRHSs idR (LHsExpr idR)
pat_rhs = GRHSs GhcTc (LHsExpr GhcTc)
grhss
                        , pat_ext :: forall idL idR. HsBindLR idL idR -> XPatBind idL idR
pat_ext = XPatBind GhcTc GhcTc
ty }) CoreExpr
body
  =     -- let C x# y# = rhs in body
        -- ==> case rhs of C x# y# -> body
    do { NonEmpty Nablas
match_nablas <- HsMatchContext GhcRn
-> GRHSs GhcTc (LHsExpr GhcTc) -> DsM (NonEmpty Nablas)
pmcGRHSs HsMatchContext GhcRn
forall p. HsMatchContext p
PatBindGuards GRHSs GhcTc (LHsExpr GhcTc)
grhss
       ; CoreExpr
rhs          <- GRHSs GhcTc (LHsExpr GhcTc)
-> Type -> NonEmpty Nablas -> DsM CoreExpr
dsGuarded GRHSs GhcTc (LHsExpr GhcTc)
grhss Type
XPatBind GhcTc GhcTc
ty NonEmpty Nablas
match_nablas
       ; let upat :: Pat GhcTc
upat = GenLocated SrcSpan (Pat GhcTc) -> Pat GhcTc
forall l e. GenLocated l e -> e
unLoc GenLocated SrcSpan (Pat GhcTc)
LPat GhcTc
pat
             eqn :: EquationInfo
eqn = EqnInfo :: [Pat GhcTc] -> Origin -> MatchResult CoreExpr -> EquationInfo
EqnInfo { eqn_pats :: [Pat GhcTc]
eqn_pats = [Pat GhcTc
upat],
                             eqn_orig :: Origin
eqn_orig = Origin
FromSource,
                             eqn_rhs :: MatchResult CoreExpr
eqn_rhs = CoreExpr -> MatchResult CoreExpr
cantFailMatchResult CoreExpr
body }
       ; CoreBndr
var    <- Type -> Pat GhcTc -> DsM CoreBndr
selectMatchVar Type
Many Pat GhcTc
upat
                    -- `var` will end up in a let binder, so the multiplicity
                    -- doesn't matter.
       ; CoreExpr
result <- HsMatchContext GhcRn
-> [CoreBndr] -> [EquationInfo] -> Type -> DsM CoreExpr
matchEquations HsMatchContext GhcRn
forall p. HsMatchContext p
PatBindRhs [CoreBndr
var] [EquationInfo
eqn] (CoreExpr -> Type
exprType CoreExpr
body)
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBndr -> CoreExpr -> CoreExpr -> CoreExpr
bindNonRec CoreBndr
var CoreExpr
rhs CoreExpr
result) }

dsUnliftedBind HsBindLR GhcTc GhcTc
bind CoreExpr
body = String -> SDoc -> DsM CoreExpr
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"dsLet: unlifted" (HsBindLR GhcTc GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsBindLR GhcTc GhcTc
bind SDoc -> SDoc -> SDoc
$$ CoreExpr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreExpr
body)

{-
************************************************************************
*                                                                      *
*              Variables, constructors, literals                       *
*                                                                      *
************************************************************************
-}


-- | Replace the body of the fucntion with this block to test the hsExprType
-- function in GHC.Tc.Utils.Zonk:
-- putSrcSpanDs loc $ do
--   { core_expr <- dsExpr e
--   ; MASSERT2( exprType core_expr `eqType` hsExprType e
--             , ppr e <+> dcolon <+> ppr (hsExprType e) $$
--                 ppr core_expr <+> dcolon <+> ppr (exprType core_expr) )
--   ; return core_expr }
dsLExpr :: LHsExpr GhcTc -> DsM CoreExpr
dsLExpr :: LHsExpr GhcTc -> DsM CoreExpr
dsLExpr (L loc e) =
  SrcSpan -> DsM CoreExpr -> DsM CoreExpr
forall a. SrcSpan -> DsM a -> DsM a
putSrcSpanDs SrcSpan
loc (DsM CoreExpr -> DsM CoreExpr) -> DsM CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
e

-- | Variant of 'dsLExpr' that ensures that the result is not levity
-- polymorphic. This should be used when the resulting expression will
-- be an argument to some other function.
-- See Note [Levity polymorphism checking] in "GHC.HsToCore.Monad"
-- See Note [Levity polymorphism invariants] in "GHC.Core"
dsLExprNoLP :: LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP :: LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP (L loc e)
  = SrcSpan -> DsM CoreExpr -> DsM CoreExpr
forall a. SrcSpan -> DsM a -> DsM a
putSrcSpanDs SrcSpan
loc (DsM CoreExpr -> DsM CoreExpr) -> DsM CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$
    do { CoreExpr
e' <- HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
e
       ; CoreExpr -> SDoc -> IOEnv (Env DsGblEnv DsLclEnv) ()
dsNoLevPolyExpr CoreExpr
e' (String -> SDoc
text String
"In the type of expression:" SDoc -> SDoc -> SDoc
<+> HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
e)
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return CoreExpr
e' }

dsExpr :: HsExpr GhcTc -> DsM CoreExpr
dsExpr :: HsExpr GhcTc -> DsM CoreExpr
dsExpr (HsVar    XVar GhcTc
_ (L _ id))           = CoreBndr -> DsM CoreExpr
dsHsVar CoreBndr
id
dsExpr (HsRecFld XRecFld GhcTc
_ (Unambiguous XUnambiguous GhcTc
id Located RdrName
_)) = CoreBndr -> DsM CoreExpr
dsHsVar CoreBndr
XUnambiguous GhcTc
id
dsExpr (HsRecFld XRecFld GhcTc
_ (Ambiguous   XAmbiguous GhcTc
id Located RdrName
_)) = CoreBndr -> DsM CoreExpr
dsHsVar CoreBndr
XAmbiguous GhcTc
id
dsExpr (HsUnboundVar XUnboundVar GhcTc
id OccName
_)             = CoreBndr -> DsM CoreExpr
dsHsVar CoreBndr
XUnboundVar GhcTc
id

dsExpr (HsPar XPar GhcTc
_ LHsExpr GhcTc
e)            = LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
e
dsExpr (ExprWithTySig XExprWithTySig GhcTc
_ LHsExpr GhcTc
e LHsSigWcType (NoGhcTc GhcTc)
_)  = LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
e

dsExpr (HsConLikeOut XConLikeOut GhcTc
_ ConLike
con)   = ConLike -> DsM CoreExpr
dsConLike ConLike
con
dsExpr (HsIPVar {})           = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsExpr: HsIPVar"
dsExpr (HsOverLabel{})        = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsExpr: HsOverLabel"

dsExpr (HsLit XLitE GhcTc
_ HsLit GhcTc
lit)
  = do { HsLit GhcTc -> IOEnv (Env DsGblEnv DsLclEnv) ()
warnAboutOverflowedLit HsLit GhcTc
lit
       ; HsLit GhcRn -> DsM CoreExpr
dsLit (HsLit GhcTc -> HsLit GhcRn
forall (p1 :: Pass) (p2 :: Pass).
HsLit (GhcPass p1) -> HsLit (GhcPass p2)
convertLit HsLit GhcTc
lit) }

dsExpr (HsOverLit XOverLitE GhcTc
_ HsOverLit GhcTc
lit)
  = do { HsOverLit GhcTc -> IOEnv (Env DsGblEnv DsLclEnv) ()
warnAboutOverflowedOverLit HsOverLit GhcTc
lit
       ; HsOverLit GhcTc -> DsM CoreExpr
dsOverLit HsOverLit GhcTc
lit }
dsExpr (XExpr (ExpansionExpr (HsExpanded _ b))) = HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
b
dsExpr hswrap :: HsExpr GhcTc
hswrap@(XExpr (WrapExpr (HsWrap co_fn e)))
  = do { CoreExpr
e' <- case HsExpr GhcTc
e of
                 HsVar XVar GhcTc
_ (L _ var) -> CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
varToCoreExpr CoreBndr
var
                 HsConLikeOut XConLikeOut GhcTc
_ (RealDataCon DataCon
dc) -> CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
varToCoreExpr (DataCon -> CoreBndr
dataConWrapId DataCon
dc)
                 XExpr (WrapExpr (HsWrap _ _)) -> String -> SDoc -> DsM CoreExpr
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"dsExpr: HsWrap inside HsWrap" (HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
hswrap)
                 HsPar XPar GhcTc
_ LHsExpr GhcTc
_ -> String -> SDoc -> DsM CoreExpr
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"dsExpr: HsPar inside HsWrap" (HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
hswrap)
                 HsExpr GhcTc
_ -> Origin -> Bag CoreBndr -> DsM CoreExpr -> DsM CoreExpr
forall a. Origin -> Bag CoreBndr -> DsM a -> DsM a
addTyCs Origin
FromSource (HsWrapper -> Bag CoreBndr
hsWrapDictBinders HsWrapper
co_fn) (DsM CoreExpr -> DsM CoreExpr) -> DsM CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$
                      HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
e
               -- See Note [Detecting forced eta expansion]
       ; CoreExpr -> CoreExpr
wrap' <- HsWrapper -> DsM (CoreExpr -> CoreExpr)
dsHsWrapper HsWrapper
co_fn
       ; DynFlags
dflags <- IOEnv (Env DsGblEnv DsLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       ; let wrapped_e :: CoreExpr
wrapped_e = CoreExpr -> CoreExpr
wrap' CoreExpr
e'
             wrapped_ty :: Type
wrapped_ty = CoreExpr -> Type
exprType CoreExpr
wrapped_e
       ; HsExpr GhcTc -> SDoc -> Type -> IOEnv (Env DsGblEnv DsLclEnv) ()
checkForcedEtaExpansion HsExpr GhcTc
e (HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
hswrap) Type
wrapped_ty -- See Note [Detecting forced eta expansion]
         -- Pass HsWrap, so that the user can see entire expression with -fprint-typechecker-elaboration
       ; DynFlags -> CoreExpr -> Type -> IOEnv (Env DsGblEnv DsLclEnv) ()
warnAboutIdentities DynFlags
dflags CoreExpr
e' Type
wrapped_ty
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return CoreExpr
wrapped_e }

dsExpr (NegApp XNegApp GhcTc
_ (L loc
                    (HsOverLit _ lit@(OverLit { ol_val = HsIntegral i})))
                SyntaxExpr GhcTc
neg_expr)
  = do { CoreExpr
expr' <- SrcSpan -> DsM CoreExpr -> DsM CoreExpr
forall a. SrcSpan -> DsM a -> DsM a
putSrcSpanDs SrcSpan
loc (DsM CoreExpr -> DsM CoreExpr) -> DsM CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ do
          { HsOverLit GhcTc -> IOEnv (Env DsGblEnv DsLclEnv) ()
warnAboutOverflowedOverLit
              (HsOverLit GhcTc
lit { ol_val :: OverLitVal
ol_val = IntegralLit -> OverLitVal
HsIntegral (IntegralLit -> IntegralLit
negateIntegralLit IntegralLit
i) })
          ; HsOverLit GhcTc -> DsM CoreExpr
dsOverLit HsOverLit GhcTc
lit }
       ; SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr SyntaxExpr GhcTc
neg_expr [CoreExpr
expr'] }

dsExpr (NegApp XNegApp GhcTc
_ LHsExpr GhcTc
expr SyntaxExpr GhcTc
neg_expr)
  = do { CoreExpr
expr' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
expr
       ; SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr SyntaxExpr GhcTc
neg_expr [CoreExpr
expr'] }

dsExpr (HsLam XLam GhcTc
_ MatchGroup GhcTc (LHsExpr GhcTc)
a_Match)
  = ([CoreBndr] -> CoreExpr -> CoreExpr)
-> ([CoreBndr], CoreExpr) -> CoreExpr
forall a b c. (a -> b -> c) -> (a, b) -> c
uncurry [CoreBndr] -> CoreExpr -> CoreExpr
forall b. [b] -> Expr b -> Expr b
mkLams (([CoreBndr], CoreExpr) -> CoreExpr)
-> DsM ([CoreBndr], CoreExpr) -> DsM CoreExpr
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> HsMatchContext GhcRn
-> Maybe (LHsExpr GhcTc)
-> MatchGroup GhcTc (LHsExpr GhcTc)
-> DsM ([CoreBndr], CoreExpr)
matchWrapper HsMatchContext GhcRn
forall p. HsMatchContext p
LambdaExpr Maybe (LHsExpr GhcTc)
forall a. Maybe a
Nothing MatchGroup GhcTc (LHsExpr GhcTc)
a_Match

dsExpr (HsLamCase XLamCase GhcTc
_ MatchGroup GhcTc (LHsExpr GhcTc)
matches)
  = do { ([CoreBndr
discrim_var], CoreExpr
matching_code) <- HsMatchContext GhcRn
-> Maybe (LHsExpr GhcTc)
-> MatchGroup GhcTc (LHsExpr GhcTc)
-> DsM ([CoreBndr], CoreExpr)
matchWrapper HsMatchContext GhcRn
forall p. HsMatchContext p
CaseAlt Maybe (LHsExpr GhcTc)
forall a. Maybe a
Nothing MatchGroup GhcTc (LHsExpr GhcTc)
matches
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ CoreBndr -> CoreExpr -> CoreExpr
forall b. b -> Expr b -> Expr b
Lam CoreBndr
discrim_var CoreExpr
matching_code }

dsExpr e :: HsExpr GhcTc
e@(HsApp XApp GhcTc
_ LHsExpr GhcTc
fun LHsExpr GhcTc
arg)
  = do { CoreExpr
fun' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
fun
       ; DsM CoreExpr -> (CoreExpr -> CoreExpr) -> DsM CoreExpr
forall a. DsM a -> (a -> CoreExpr) -> DsM CoreExpr
dsWhenNoErrs (LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
arg)
                      (\CoreExpr
arg' -> SDoc -> CoreExpr -> CoreExpr -> CoreExpr
mkCoreAppDs (String -> SDoc
text String
"HsApp" SDoc -> SDoc -> SDoc
<+> HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
e) CoreExpr
fun' CoreExpr
arg') }

dsExpr (HsAppType XAppTypeE GhcTc
ty LHsExpr GhcTc
e LHsWcType (NoGhcTc GhcTc)
_)
  = do { CoreExpr
e' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
e
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> CoreExpr -> CoreExpr
forall b. Expr b -> Expr b -> Expr b
App CoreExpr
e' (Type -> CoreExpr
forall b. Type -> Expr b
Type Type
XAppTypeE GhcTc
ty)) }

{-
Note [Desugaring vars]
~~~~~~~~~~~~~~~~~~~~~~
In one situation we can get a *coercion* variable in a HsVar, namely
the support method for an equality superclass:
   class (a~b) => C a b where ...
   instance (blah) => C (T a) (T b) where ..
Then we get
   $dfCT :: forall ab. blah => C (T a) (T b)
   $dfCT ab blah = MkC ($c$p1C a blah) ($cop a blah)

   $c$p1C :: forall ab. blah => (T a ~ T b)
   $c$p1C ab blah = let ...; g :: T a ~ T b = ... } in g

That 'g' in the 'in' part is an evidence variable, and when
converting to core it must become a CO.


Note [Desugaring operator sections]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Desugaring left sections with -XPostfixOperators is straightforward: convert
(expr `op`) to (op expr).

Without -XPostfixOperators it's a bit more tricky. At first it looks as if we
can convert

    (expr `op`)

naively to

    \x -> op expr x

But no!  expr might be a redex, and we can lose laziness badly this
way.  Consider

    map (expr `op`) xs

for example. If expr were a redex then eta-expanding naively would
result in multiple evaluations where the user might only have expected one.

So we convert instead to

    let y = expr in \x -> op y x

Also, note that we must do this for both right and (perhaps surprisingly) left
sections. Why are left sections necessary? Consider the program (found in #18151),

    seq (True `undefined`) ()

according to the Haskell Report this should reduce to () (as it specifies
desugaring via eta expansion). However, if we fail to eta expand we will rather
bottom. Consequently, we must eta expand even in the case of a left section.

If `expr` is actually just a variable, say, then the simplifier
will inline `y`, eliminating the redundant `let`.

Note that this works even in the case that `expr` is unlifted. In this case
bindNonRec will automatically do the right thing, giving us:

    case expr of y -> (\x -> op y x)

See #18151.
-}

dsExpr e :: HsExpr GhcTc
e@(OpApp XOpApp GhcTc
_ LHsExpr GhcTc
e1 LHsExpr GhcTc
op LHsExpr GhcTc
e2)
  = -- for the type of y, we need the type of op's 2nd argument
    do { CoreExpr
op' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
op
       ; DsM [CoreExpr] -> ([CoreExpr] -> CoreExpr) -> DsM CoreExpr
forall a. DsM a -> (a -> CoreExpr) -> DsM CoreExpr
dsWhenNoErrs ((Located (HsExpr GhcTc) -> DsM CoreExpr)
-> [Located (HsExpr GhcTc)] -> DsM [CoreExpr]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Located (HsExpr GhcTc) -> DsM CoreExpr
LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP [Located (HsExpr GhcTc)
LHsExpr GhcTc
e1, Located (HsExpr GhcTc)
LHsExpr GhcTc
e2])
                      (\[CoreExpr]
exprs' -> SDoc -> CoreExpr -> [CoreExpr] -> CoreExpr
mkCoreAppsDs (String -> SDoc
text String
"opapp" SDoc -> SDoc -> SDoc
<+> HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
e) CoreExpr
op' [CoreExpr]
exprs') }

-- dsExpr (SectionL op expr)  ===  (expr `op`)  ~>  \y -> op expr y
--
-- See Note [Desugaring operator sections].
-- N.B. this also must handle postfix operator sections due to -XPostfixOperators.
dsExpr e :: HsExpr GhcTc
e@(SectionL XSectionL GhcTc
_ LHsExpr GhcTc
expr LHsExpr GhcTc
op) = do
  Bool
postfix_operators <- Extension -> TcRnIf DsGblEnv DsLclEnv Bool
forall gbl lcl. Extension -> TcRnIf gbl lcl Bool
xoptM Extension
LangExt.PostfixOperators
  if Bool
postfix_operators then
    -- Desugar (e !) to ((!) e)
    do { CoreExpr
op' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
op
       ; DsM CoreExpr -> (CoreExpr -> CoreExpr) -> DsM CoreExpr
forall a. DsM a -> (a -> CoreExpr) -> DsM CoreExpr
dsWhenNoErrs (LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
expr) ((CoreExpr -> CoreExpr) -> DsM CoreExpr)
-> (CoreExpr -> CoreExpr) -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ \CoreExpr
expr' ->
         SDoc -> CoreExpr -> CoreExpr -> CoreExpr
mkCoreAppDs (String -> SDoc
text String
"sectionl" SDoc -> SDoc -> SDoc
<+> Located (HsExpr GhcTc) -> SDoc
forall a. Outputable a => a -> SDoc
ppr Located (HsExpr GhcTc)
LHsExpr GhcTc
expr) CoreExpr
op' CoreExpr
expr' }
  else do
    CoreExpr
core_op <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
op
    CoreExpr
x_core <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
expr
    case Type -> ([Scaled Type], Type)
splitFunTys (CoreExpr -> Type
exprType CoreExpr
core_op) of
      -- Binary operator section
      (Scaled Type
x_ty:Scaled Type
y_ty:[Scaled Type]
_, Type
_) ->
        DsM [CoreBndr] -> ([CoreBndr] -> CoreExpr) -> DsM CoreExpr
forall a. DsM a -> (a -> CoreExpr) -> DsM CoreExpr
dsWhenNoErrs
          ([Scaled Type] -> DsM [CoreBndr]
newSysLocalsDsNoLP [Scaled Type
x_ty, Scaled Type
y_ty])
          (\[CoreBndr
x_id, CoreBndr
y_id] ->
            CoreBndr -> CoreExpr -> CoreExpr -> CoreExpr
bindNonRec CoreBndr
x_id CoreExpr
x_core
            (CoreExpr -> CoreExpr) -> CoreExpr -> CoreExpr
forall a b. (a -> b) -> a -> b
$ CoreBndr -> CoreExpr -> CoreExpr
forall b. b -> Expr b -> Expr b
Lam CoreBndr
y_id (SDoc -> CoreExpr -> [CoreExpr] -> CoreExpr
mkCoreAppsDs (String -> SDoc
text String
"sectionl" SDoc -> SDoc -> SDoc
<+> HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
e)
                                     CoreExpr
core_op [CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
x_id, CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
y_id]))

      -- Postfix operator section
      (Scaled Type
_:[Scaled Type]
_, Type
_) ->
        CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ SDoc -> CoreExpr -> CoreExpr -> CoreExpr
mkCoreAppDs (String -> SDoc
text String
"sectionl" SDoc -> SDoc -> SDoc
<+> HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
e) CoreExpr
core_op CoreExpr
x_core

      ([Scaled Type], Type)
_ -> String -> SDoc -> DsM CoreExpr
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"dsExpr(SectionL)" (HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
e)

-- dsExpr (SectionR op expr)  === (`op` expr)  ~>  \x -> op x expr
--
-- See Note [Desugaring operator sections].
dsExpr e :: HsExpr GhcTc
e@(SectionR XSectionR GhcTc
_ LHsExpr GhcTc
op LHsExpr GhcTc
expr) = do
    CoreExpr
core_op <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
op
    let (Scaled Type
x_ty:Scaled Type
y_ty:[Scaled Type]
_, Type
_) = Type -> ([Scaled Type], Type)
splitFunTys (CoreExpr -> Type
exprType CoreExpr
core_op)
    CoreExpr
y_core <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
expr
    DsM [CoreBndr] -> ([CoreBndr] -> CoreExpr) -> DsM CoreExpr
forall a. DsM a -> (a -> CoreExpr) -> DsM CoreExpr
dsWhenNoErrs ([Scaled Type] -> DsM [CoreBndr]
newSysLocalsDsNoLP [Scaled Type
x_ty, Scaled Type
y_ty])
                 (\[CoreBndr
x_id, CoreBndr
y_id] -> CoreBndr -> CoreExpr -> CoreExpr -> CoreExpr
bindNonRec CoreBndr
y_id CoreExpr
y_core (CoreExpr -> CoreExpr) -> CoreExpr -> CoreExpr
forall a b. (a -> b) -> a -> b
$
                                   CoreBndr -> CoreExpr -> CoreExpr
forall b. b -> Expr b -> Expr b
Lam CoreBndr
x_id (SDoc -> CoreExpr -> [CoreExpr] -> CoreExpr
mkCoreAppsDs (String -> SDoc
text String
"sectionr" SDoc -> SDoc -> SDoc
<+> HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
e)
                                                          CoreExpr
core_op [CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
x_id, CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
y_id]))

dsExpr (ExplicitTuple XExplicitTuple GhcTc
_ [LHsTupArg GhcTc]
tup_args Boxity
boxity)
  = do { let go :: ([CoreBndr], [CoreExpr])
-> GenLocated l (HsTupArg GhcTc)
-> IOEnv (Env DsGblEnv DsLclEnv) ([CoreBndr], [CoreExpr])
go ([CoreBndr]
lam_vars, [CoreExpr]
args) (L l
_ (Missing (Scaled mult ty)))
                    -- For every missing expression, we need
                    -- another lambda in the desugaring.
               = do { CoreBndr
lam_var <- Type -> Type -> DsM CoreBndr
newSysLocalDsNoLP Type
mult Type
ty
                    ; ([CoreBndr], [CoreExpr])
-> IOEnv (Env DsGblEnv DsLclEnv) ([CoreBndr], [CoreExpr])
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBndr
lam_var CoreBndr -> [CoreBndr] -> [CoreBndr]
forall a. a -> [a] -> [a]
: [CoreBndr]
lam_vars, CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
lam_var CoreExpr -> [CoreExpr] -> [CoreExpr]
forall a. a -> [a] -> [a]
: [CoreExpr]
args) }
             go ([CoreBndr]
lam_vars, [CoreExpr]
args) (L l
_ (Present XPresent GhcTc
_ LHsExpr GhcTc
expr))
                    -- Expressions that are present don't generate
                    -- lambdas, just arguments.
               = do { CoreExpr
core_expr <- LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
expr
                    ; ([CoreBndr], [CoreExpr])
-> IOEnv (Env DsGblEnv DsLclEnv) ([CoreBndr], [CoreExpr])
forall (m :: * -> *) a. Monad m => a -> m a
return ([CoreBndr]
lam_vars, CoreExpr
core_expr CoreExpr -> [CoreExpr] -> [CoreExpr]
forall a. a -> [a] -> [a]
: [CoreExpr]
args) }

       ; IOEnv (Env DsGblEnv DsLclEnv) ([CoreBndr], [CoreExpr])
-> (([CoreBndr], [CoreExpr]) -> CoreExpr) -> DsM CoreExpr
forall a. DsM a -> (a -> CoreExpr) -> DsM CoreExpr
dsWhenNoErrs ((([CoreBndr], [CoreExpr])
 -> GenLocated SrcSpan (HsTupArg GhcTc)
 -> IOEnv (Env DsGblEnv DsLclEnv) ([CoreBndr], [CoreExpr]))
-> ([CoreBndr], [CoreExpr])
-> [GenLocated SrcSpan (HsTupArg GhcTc)]
-> IOEnv (Env DsGblEnv DsLclEnv) ([CoreBndr], [CoreExpr])
forall (t :: * -> *) (m :: * -> *) b a.
(Foldable t, Monad m) =>
(b -> a -> m b) -> b -> t a -> m b
foldM ([CoreBndr], [CoreExpr])
-> GenLocated SrcSpan (HsTupArg GhcTc)
-> IOEnv (Env DsGblEnv DsLclEnv) ([CoreBndr], [CoreExpr])
forall l.
([CoreBndr], [CoreExpr])
-> GenLocated l (HsTupArg GhcTc)
-> IOEnv (Env DsGblEnv DsLclEnv) ([CoreBndr], [CoreExpr])
go ([], []) ([GenLocated SrcSpan (HsTupArg GhcTc)]
-> [GenLocated SrcSpan (HsTupArg GhcTc)]
forall a. [a] -> [a]
reverse [GenLocated SrcSpan (HsTupArg GhcTc)]
[LHsTupArg GhcTc]
tup_args))
                -- The reverse is because foldM goes left-to-right
                      (\([CoreBndr]
lam_vars, [CoreExpr]
args) ->
                        [CoreBndr] -> CoreExpr -> CoreExpr
mkCoreLams [CoreBndr]
lam_vars (CoreExpr -> CoreExpr) -> CoreExpr -> CoreExpr
forall a b. (a -> b) -> a -> b
$
                          Boxity -> [CoreExpr] -> CoreExpr
mkCoreTupBoxity Boxity
boxity [CoreExpr]
args) }
                        -- See Note [Don't flatten tuples from HsSyn] in GHC.Core.Make

dsExpr (ExplicitSum XExplicitSum GhcTc
types Int
alt Int
arity LHsExpr GhcTc
expr)
  = DsM CoreExpr -> (CoreExpr -> CoreExpr) -> DsM CoreExpr
forall a. DsM a -> (a -> CoreExpr) -> DsM CoreExpr
dsWhenNoErrs (LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
expr)
                 (\CoreExpr
core_expr -> DataCon -> [CoreExpr] -> CoreExpr
mkCoreConApps (Int -> Int -> DataCon
sumDataCon Int
alt Int
arity)
                                ((Type -> CoreExpr) -> [Type] -> [CoreExpr]
forall a b. (a -> b) -> [a] -> [b]
map (Type -> CoreExpr
forall b. Type -> Expr b
Type (Type -> CoreExpr) -> (Type -> Type) -> Type -> CoreExpr
forall b c a. (b -> c) -> (a -> b) -> a -> c
. HasDebugCallStack => Type -> Type
Type -> Type
getRuntimeRep) [Type]
XExplicitSum GhcTc
types [CoreExpr] -> [CoreExpr] -> [CoreExpr]
forall a. [a] -> [a] -> [a]
++
                                 (Type -> CoreExpr) -> [Type] -> [CoreExpr]
forall a b. (a -> b) -> [a] -> [b]
map Type -> CoreExpr
forall b. Type -> Expr b
Type [Type]
XExplicitSum GhcTc
types [CoreExpr] -> [CoreExpr] -> [CoreExpr]
forall a. [a] -> [a] -> [a]
++
                                 [CoreExpr
core_expr]) )

dsExpr (HsPragE XPragE GhcTc
_ HsPragE GhcTc
prag LHsExpr GhcTc
expr) =
  HsPragE GhcTc -> LHsExpr GhcTc -> DsM CoreExpr
ds_prag_expr HsPragE GhcTc
prag LHsExpr GhcTc
expr

dsExpr (HsCase XCase GhcTc
_ LHsExpr GhcTc
discrim MatchGroup GhcTc (LHsExpr GhcTc)
matches)
  = do { CoreExpr
core_discrim <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
discrim
       ; ([CoreBndr
discrim_var], CoreExpr
matching_code) <- HsMatchContext GhcRn
-> Maybe (LHsExpr GhcTc)
-> MatchGroup GhcTc (LHsExpr GhcTc)
-> DsM ([CoreBndr], CoreExpr)
matchWrapper HsMatchContext GhcRn
forall p. HsMatchContext p
CaseAlt (Located (HsExpr GhcTc) -> Maybe (Located (HsExpr GhcTc))
forall a. a -> Maybe a
Just Located (HsExpr GhcTc)
LHsExpr GhcTc
discrim) MatchGroup GhcTc (LHsExpr GhcTc)
matches
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBndr -> CoreExpr -> CoreExpr -> CoreExpr
bindNonRec CoreBndr
discrim_var CoreExpr
core_discrim CoreExpr
matching_code) }

-- Pepe: The binds are in scope in the body but NOT in the binding group
--       This is to avoid silliness in breakpoints
dsExpr (HsLet XLet GhcTc
_ LHsLocalBinds GhcTc
binds LHsExpr GhcTc
body) = do
    CoreExpr
body' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
body
    LHsLocalBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsLocalBinds LHsLocalBinds GhcTc
binds CoreExpr
body'

-- We need the `ListComp' form to use `deListComp' (rather than the "do" form)
-- because the interpretation of `stmts' depends on what sort of thing it is.
--
dsExpr (HsDo XDo GhcTc
res_ty HsStmtContext GhcRn
ListComp (L _ stmts)) = [ExprLStmt GhcTc] -> Type -> DsM CoreExpr
dsListComp [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
[ExprLStmt GhcTc]
stmts Type
XDo GhcTc
res_ty
dsExpr (HsDo XDo GhcTc
_ ctx :: HsStmtContext GhcRn
ctx@DoExpr{}      (L _ stmts)) = HsStmtContext GhcRn -> [ExprLStmt GhcTc] -> DsM CoreExpr
dsDo HsStmtContext GhcRn
ctx [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
[ExprLStmt GhcTc]
stmts
dsExpr (HsDo XDo GhcTc
_ ctx :: HsStmtContext GhcRn
ctx@HsStmtContext GhcRn
GhciStmtCtxt  (L _ stmts)) = HsStmtContext GhcRn -> [ExprLStmt GhcTc] -> DsM CoreExpr
dsDo HsStmtContext GhcRn
ctx [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
[ExprLStmt GhcTc]
stmts
dsExpr (HsDo XDo GhcTc
_ ctx :: HsStmtContext GhcRn
ctx@MDoExpr{}     (L _ stmts)) = HsStmtContext GhcRn -> [ExprLStmt GhcTc] -> DsM CoreExpr
dsDo HsStmtContext GhcRn
ctx [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
[ExprLStmt GhcTc]
stmts
dsExpr (HsDo XDo GhcTc
_ HsStmtContext GhcRn
MonadComp     (L _ stmts)) = [ExprLStmt GhcTc] -> DsM CoreExpr
dsMonadComp [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
[ExprLStmt GhcTc]
stmts

dsExpr (HsIf XIf GhcTc
_ LHsExpr GhcTc
guard_expr LHsExpr GhcTc
then_expr LHsExpr GhcTc
else_expr)
  = do { CoreExpr
pred <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
guard_expr
       ; CoreExpr
b1 <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
then_expr
       ; CoreExpr
b2 <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
else_expr
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ CoreExpr -> CoreExpr -> CoreExpr -> CoreExpr
mkIfThenElse CoreExpr
pred CoreExpr
b1 CoreExpr
b2 }

dsExpr (HsMultiIf XMultiIf GhcTc
res_ty [LGRHS GhcTc (LHsExpr GhcTc)]
alts)
  | [Located (GRHS GhcTc (Located (HsExpr GhcTc)))] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Located (GRHS GhcTc (Located (HsExpr GhcTc)))]
[LGRHS GhcTc (LHsExpr GhcTc)]
alts
  = DsM CoreExpr
mkErrorExpr

  | Bool
otherwise
  = do { let grhss :: GRHSs GhcTc (Located (HsExpr GhcTc))
grhss = XCGRHSs GhcTc (Located (HsExpr GhcTc))
-> [LGRHS GhcTc (Located (HsExpr GhcTc))]
-> LHsLocalBinds GhcTc
-> GRHSs GhcTc (Located (HsExpr GhcTc))
forall p body.
XCGRHSs p body -> [LGRHS p body] -> LHsLocalBinds p -> GRHSs p body
GRHSs NoExtField
XCGRHSs GhcTc (Located (HsExpr GhcTc))
noExtField [LGRHS GhcTc (Located (HsExpr GhcTc))]
[LGRHS GhcTc (LHsExpr GhcTc)]
alts (HsLocalBindsLR GhcTc GhcTc -> Located (HsLocalBindsLR GhcTc GhcTc)
forall e. e -> Located e
noLoc HsLocalBindsLR GhcTc GhcTc
forall (a :: Pass) (b :: Pass).
HsLocalBindsLR (GhcPass a) (GhcPass b)
emptyLocalBinds)
       ; NonEmpty Nablas
rhss_nablas  <- HsMatchContext GhcRn
-> GRHSs GhcTc (LHsExpr GhcTc) -> DsM (NonEmpty Nablas)
pmcGRHSs HsMatchContext GhcRn
forall p. HsMatchContext p
IfAlt GRHSs GhcTc (Located (HsExpr GhcTc))
GRHSs GhcTc (LHsExpr GhcTc)
grhss
       ; MatchResult CoreExpr
match_result <- HsMatchContext GhcRn
-> GRHSs GhcTc (LHsExpr GhcTc)
-> Type
-> NonEmpty Nablas
-> DsM (MatchResult CoreExpr)
dsGRHSs HsMatchContext GhcRn
forall p. HsMatchContext p
IfAlt GRHSs GhcTc (Located (HsExpr GhcTc))
GRHSs GhcTc (LHsExpr GhcTc)
grhss Type
XMultiIf GhcTc
res_ty NonEmpty Nablas
rhss_nablas
       ; CoreExpr
error_expr   <- DsM CoreExpr
mkErrorExpr
       ; MatchResult CoreExpr -> CoreExpr -> DsM CoreExpr
extractMatchResult MatchResult CoreExpr
match_result CoreExpr
error_expr }
  where
    mkErrorExpr :: DsM CoreExpr
mkErrorExpr = CoreBndr -> Type -> SDoc -> DsM CoreExpr
mkErrorAppDs CoreBndr
nON_EXHAUSTIVE_GUARDS_ERROR_ID Type
XMultiIf GhcTc
res_ty
                               (String -> SDoc
text String
"multi-way if")

{-
\noindent
\underline{\bf Various data construction things}
             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-}

dsExpr (ExplicitList XExplicitList GhcTc
elt_ty Maybe (SyntaxExpr GhcTc)
wit [LHsExpr GhcTc]
xs)
  = Type -> Maybe (SyntaxExpr GhcTc) -> [LHsExpr GhcTc] -> DsM CoreExpr
dsExplicitList Type
XExplicitList GhcTc
elt_ty Maybe (SyntaxExpr GhcTc)
wit [LHsExpr GhcTc]
xs

dsExpr (ArithSeq XArithSeq GhcTc
expr Maybe (SyntaxExpr GhcTc)
witness ArithSeqInfo GhcTc
seq)
  = case Maybe (SyntaxExpr GhcTc)
witness of
     Maybe (SyntaxExpr GhcTc)
Nothing -> HsExpr GhcTc -> ArithSeqInfo GhcTc -> DsM CoreExpr
dsArithSeq HsExpr GhcTc
XArithSeq GhcTc
expr ArithSeqInfo GhcTc
seq
     Just SyntaxExpr GhcTc
fl -> do { CoreExpr
newArithSeq <- HsExpr GhcTc -> ArithSeqInfo GhcTc -> DsM CoreExpr
dsArithSeq HsExpr GhcTc
XArithSeq GhcTc
expr ArithSeqInfo GhcTc
seq
                   ; SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr SyntaxExpr GhcTc
fl [CoreExpr
newArithSeq] }

{-
Static Pointers
~~~~~~~~~~~~~~~

See Note [Grand plan for static forms] in GHC.Iface.Tidy.StaticPtrTable for an overview.

    g = ... static f ...
==>
    g = ... makeStatic loc f ...
-}

dsExpr (HsStatic XStatic GhcTc
_ expr :: LHsExpr GhcTc
expr@(L loc _)) = do
    CoreExpr
expr_ds <- LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
expr
    let ty :: Type
ty = CoreExpr -> Type
exprType CoreExpr
expr_ds
    CoreBndr
makeStaticId <- Name -> DsM CoreBndr
dsLookupGlobalId Name
makeStaticName

    DynFlags
dflags <- IOEnv (Env DsGblEnv DsLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
    let platform :: Platform
platform = DynFlags -> Platform
targetPlatform DynFlags
dflags
    let (Int
line, Int
col) = case SrcSpan
loc of
           RealSrcSpan RealSrcSpan
r Maybe BufSpan
_ ->
                            ( RealSrcLoc -> Int
srcLocLine (RealSrcLoc -> Int) -> RealSrcLoc -> Int
forall a b. (a -> b) -> a -> b
$ RealSrcSpan -> RealSrcLoc
realSrcSpanStart RealSrcSpan
r
                            , RealSrcLoc -> Int
srcLocCol  (RealSrcLoc -> Int) -> RealSrcLoc -> Int
forall a b. (a -> b) -> a -> b
$ RealSrcSpan -> RealSrcLoc
realSrcSpanStart RealSrcSpan
r
                            )
           SrcSpan
_             -> (Int
0, Int
0)
        srcLoc :: CoreExpr
srcLoc = DataCon -> [CoreExpr] -> CoreExpr
mkCoreConApps (Boxity -> Int -> DataCon
tupleDataCon Boxity
Boxed Int
2)
                     [ Type -> CoreExpr
forall b. Type -> Expr b
Type Type
intTy              , Type -> CoreExpr
forall b. Type -> Expr b
Type Type
intTy
                     , Platform -> Int -> CoreExpr
mkIntExprInt Platform
platform Int
line, Platform -> Int -> CoreExpr
mkIntExprInt Platform
platform Int
col
                     ]

    SrcSpan -> DsM CoreExpr -> DsM CoreExpr
forall a. SrcSpan -> DsM a -> DsM a
putSrcSpanDs SrcSpan
loc (DsM CoreExpr -> DsM CoreExpr) -> DsM CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$
      CoreExpr -> [CoreExpr] -> CoreExpr
mkCoreApps (CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
makeStaticId) [ Type -> CoreExpr
forall b. Type -> Expr b
Type Type
ty, CoreExpr
srcLoc, CoreExpr
expr_ds ]

{-
\noindent
\underline{\bf Record construction and update}
             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For record construction we do this (assuming T has three arguments)
\begin{verbatim}
        T { op2 = e }
==>
        let err = /\a -> recConErr a
        T (recConErr t1 "M.hs/230/op1")
          e
          (recConErr t1 "M.hs/230/op3")
\end{verbatim}
@recConErr@ then converts its argument string into a proper message
before printing it as
\begin{verbatim}
        M.hs, line 230: missing field op1 was evaluated
\end{verbatim}

We also handle @C{}@ as valid construction syntax for an unlabelled
constructor @C@, setting all of @C@'s fields to bottom.
-}

dsExpr (RecordCon { rcon_flds :: forall p. HsExpr p -> HsRecordBinds p
rcon_flds = HsRecordBinds GhcTc
rbinds
                  , rcon_ext :: forall p. HsExpr p -> XRecordCon p
rcon_ext = RecordConTc { rcon_con_expr = con_expr
                                           , rcon_con_like = con_like }})
  = do { CoreExpr
con_expr' <- HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
con_expr
       ; let
             ([Scaled Type]
arg_tys, Type
_) = Type -> ([Scaled Type], Type)
tcSplitFunTys (CoreExpr -> Type
exprType CoreExpr
con_expr')
             -- A newtype in the corner should be opaque;
             -- hence TcType.tcSplitFunTys

             mk_arg :: (Type, FieldLbl Name) -> DsM CoreExpr
mk_arg (Type
arg_ty, FieldLbl Name
fl)
               = case [LHsRecField GhcTc (Located (HsExpr GhcTc))]
-> Name -> [Located (HsExpr GhcTc)]
forall arg. [LHsRecField GhcTc arg] -> Name -> [arg]
findField (HsRecFields GhcTc (Located (HsExpr GhcTc))
-> [LHsRecField GhcTc (Located (HsExpr GhcTc))]
forall p arg. HsRecFields p arg -> [LHsRecField p arg]
rec_flds HsRecFields GhcTc (Located (HsExpr GhcTc))
HsRecordBinds GhcTc
rbinds) (FieldLbl Name -> Name
forall a. FieldLbl a -> a
flSelector FieldLbl Name
fl) of
                   (Located (HsExpr GhcTc)
rhs:[Located (HsExpr GhcTc)]
rhss) -> ASSERT( null rhss )
                                 LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP Located (HsExpr GhcTc)
LHsExpr GhcTc
rhs
                   []         -> CoreBndr -> Type -> SDoc -> DsM CoreExpr
mkErrorAppDs CoreBndr
rEC_CON_ERROR_ID Type
arg_ty (FieldLabelString -> SDoc
forall a. Outputable a => a -> SDoc
ppr (FieldLbl Name -> FieldLabelString
forall a. FieldLbl a -> FieldLabelString
flLabel FieldLbl Name
fl))
             unlabelled_bottom :: Type -> DsM CoreExpr
unlabelled_bottom Type
arg_ty = CoreBndr -> Type -> SDoc -> DsM CoreExpr
mkErrorAppDs CoreBndr
rEC_CON_ERROR_ID Type
arg_ty SDoc
Outputable.empty

             labels :: [FieldLbl Name]
labels = ConLike -> [FieldLbl Name]
conLikeFieldLabels ConLike
con_like

       ; [CoreExpr]
con_args <- if [FieldLbl Name] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [FieldLbl Name]
labels
                     then (Type -> DsM CoreExpr) -> [Type] -> DsM [CoreExpr]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Type -> DsM CoreExpr
unlabelled_bottom ((Scaled Type -> Type) -> [Scaled Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map Scaled Type -> Type
forall a. Scaled a -> a
scaledThing [Scaled Type]
arg_tys)
                     else ((Type, FieldLbl Name) -> DsM CoreExpr)
-> [(Type, FieldLbl Name)] -> DsM [CoreExpr]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (Type, FieldLbl Name) -> DsM CoreExpr
mk_arg (String -> [Type] -> [FieldLbl Name] -> [(Type, FieldLbl Name)]
forall a b. String -> [a] -> [b] -> [(a, b)]
zipEqual String
"dsExpr:RecordCon" ((Scaled Type -> Type) -> [Scaled Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map Scaled Type -> Type
forall a. Scaled a -> a
scaledThing [Scaled Type]
arg_tys) [FieldLbl Name]
labels)

       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> [CoreExpr] -> CoreExpr
mkCoreApps CoreExpr
con_expr' [CoreExpr]
con_args) }

{-
Record update is a little harder. Suppose we have the decl:
\begin{verbatim}
        data T = T1 {op1, op2, op3 :: Int}
               | T2 {op4, op2 :: Int}
               | T3
\end{verbatim}
Then we translate as follows:
\begin{verbatim}
        r { op2 = e }
===>
        let op2 = e in
        case r of
          T1 op1 _ op3 -> T1 op1 op2 op3
          T2 op4 _     -> T2 op4 op2
          other        -> recUpdError "M.hs/230"
\end{verbatim}
It's important that we use the constructor Ids for @T1@, @T2@ etc on the
RHSs, and do not generate a Core constructor application directly, because the constructor
might do some argument-evaluation first; and may have to throw away some
dictionaries.

Note [Update for GADTs]
~~~~~~~~~~~~~~~~~~~~~~~
Consider
   data T a b where
     MkT :: { foo :: a } -> T a Int

   upd :: T s t -> s -> T s t
   upd z y = z { foo = y}

We need to get this:
   $WMkT :: a -> T a Int
   MkT   :: (b ~# Int) => a -> T a b

   upd = /\s t. \(z::T s t) (y::s) ->
         case z of
            MkT (co :: t ~# Int) _ -> $WMkT @s y |> T (Refl s) (Sym co)

Note the final cast
   T (Refl s) (Sym co) :: T s Int ~ T s t
which uses co, bound by the GADT match.  This is the wrap_co coercion
in wrapped_rhs. How do we produce it?

* Start with raw materials
    tc, the tycon:                                       T
    univ_tvs, the universally quantified tyvars of MkT:  a,b
  NB: these are in 1-1 correspondence with the tyvars of tc

* Form univ_cos, a coercion for each of tc's args: (Refl s) (Sym co)
  We replaced
     a  by  (Refl s)    since 's' instantiates 'a'
     b  by  (Sym co)   since 'b' is in the data-con's EqSpec

* Then form the coercion T (Refl s) (Sym co)

It gets more complicated when data families are involved (#18809).
Consider
    data family F x
    data instance F (a,b) where
      MkF :: { foo :: Int } -> F (Int,b)

    bar :: F (s,t) -> Int -> F (s,t)
    bar z y = z { foo = y}

We have
    data R:FPair a b where
      MkF :: { foo :: Int } -> R:FPair Int b

    $WMkF :: Int -> F (Int,b)
    MkF :: forall a b. (a ~# Int) => Int -> R:FPair a b

    bar :: F (s,t) -> Int -> F (s,t)
    bar = /\s t. \(z::F (s,t)) \(y::Int) ->
         case z |> co1 of
            MkF (co2::s ~# Int) _ -> $WMkF @t y |> co3

(Side note: here (z |> co1) is built by typechecking the scrutinee, so
we ignore it here.  In general the scrutinee is an aribtrary expression.)

The question is: what is co3, the cast for the RHS?
      co3 :: F (Int,t) ~ F (s,t)
Again, we can construct it using co2, bound by the GADT match.
We do /exactly/ the same as the non-family case up to building
univ_cos.  But that gives us
     rep_tc:   R:FPair
     univ_cos: (Sym co2)   (Refl t)
But then we use mkTcFamilyTyConAppCo to "lift" this to the coercion
we want, namely
     F (Sym co2, Refl t) :: F (Int,t) ~ F (s,t)

-}

dsExpr expr :: HsExpr GhcTc
expr@(RecordUpd { rupd_expr :: forall p. HsExpr p -> LHsExpr p
rupd_expr = LHsExpr GhcTc
record_expr, rupd_flds :: forall p. HsExpr p -> [LHsRecUpdField p]
rupd_flds = [LHsRecUpdField GhcTc]
fields
                       , rupd_ext :: forall p. HsExpr p -> XRecordUpd p
rupd_ext = RecordUpdTc
                           { rupd_cons = cons_to_upd
                           , rupd_in_tys = in_inst_tys
                           , rupd_out_tys = out_inst_tys
                           , rupd_wrap = dict_req_wrap }} )
  | [Located
   (HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc)))]
-> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Located
   (HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc)))]
[LHsRecUpdField GhcTc]
fields
  = LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
record_expr
  | Bool
otherwise
  = ASSERT2( notNull cons_to_upd, ppr expr )

    do  { CoreExpr
record_expr' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
record_expr
        ; [(Name, CoreBndr, CoreExpr)]
field_binds' <- (Located
   (HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc)))
 -> IOEnv (Env DsGblEnv DsLclEnv) (Name, CoreBndr, CoreExpr))
-> [Located
      (HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc)))]
-> IOEnv (Env DsGblEnv DsLclEnv) [(Name, CoreBndr, CoreExpr)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Located
  (HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc)))
-> IOEnv (Env DsGblEnv DsLclEnv) (Name, CoreBndr, CoreExpr)
LHsRecUpdField GhcTc
-> IOEnv (Env DsGblEnv DsLclEnv) (Name, CoreBndr, CoreExpr)
ds_field [Located
   (HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc)))]
[LHsRecUpdField GhcTc]
fields
        ; let upd_fld_env :: NameEnv Id -- Maps field name to the LocalId of the field binding
              upd_fld_env :: NameEnv CoreBndr
upd_fld_env = [(Name, CoreBndr)] -> NameEnv CoreBndr
forall a. [(Name, a)] -> NameEnv a
mkNameEnv [(Name
f,CoreBndr
l) | (Name
f,CoreBndr
l,CoreExpr
_) <- [(Name, CoreBndr, CoreExpr)]
field_binds']

        -- It's important to generate the match with matchWrapper,
        -- and the right hand sides with applications of the wrapper Id
        -- so that everything works when we are doing fancy unboxing on the
        -- constructor arguments.
        ; [Located (Match GhcTc (Located (HsExpr GhcTc)))]
alts <- (ConLike
 -> IOEnv
      (Env DsGblEnv DsLclEnv)
      (Located (Match GhcTc (Located (HsExpr GhcTc)))))
-> [ConLike]
-> IOEnv
     (Env DsGblEnv DsLclEnv)
     [Located (Match GhcTc (Located (HsExpr GhcTc)))]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (NameEnv CoreBndr
-> ConLike
-> IOEnv
     (Env DsGblEnv DsLclEnv)
     (Located (Match GhcTc (Located (HsExpr GhcTc))))
mk_alt NameEnv CoreBndr
upd_fld_env) [ConLike]
cons_to_upd
        ; ([CoreBndr
discrim_var], CoreExpr
matching_code)
                <- HsMatchContext GhcRn
-> Maybe (LHsExpr GhcTc)
-> MatchGroup GhcTc (LHsExpr GhcTc)
-> DsM ([CoreBndr], CoreExpr)
matchWrapper HsMatchContext GhcRn
forall p. HsMatchContext p
RecUpd (Located (HsExpr GhcTc) -> Maybe (Located (HsExpr GhcTc))
forall a. a -> Maybe a
Just Located (HsExpr GhcTc)
LHsExpr GhcTc
record_expr) -- See Note [Scrutinee in Record updates]
                                      (MG :: forall p body.
XMG p body -> XRec p [LMatch p body] -> Origin -> MatchGroup p body
MG { mg_alts :: XRec GhcTc [LMatch GhcTc (Located (HsExpr GhcTc))]
mg_alts = [Located (Match GhcTc (Located (HsExpr GhcTc)))]
-> Located [Located (Match GhcTc (Located (HsExpr GhcTc)))]
forall e. e -> Located e
noLoc [Located (Match GhcTc (Located (HsExpr GhcTc)))]
alts
                                          , mg_ext :: XMG GhcTc (Located (HsExpr GhcTc))
mg_ext = [Scaled Type] -> Type -> MatchGroupTc
MatchGroupTc [Type -> Scaled Type
forall a. a -> Scaled a
unrestricted Type
in_ty] Type
out_ty
                                          , mg_origin :: Origin
mg_origin = Origin
FromSource
                                          })
                                     -- FromSource is not strictly right, but we
                                     -- want incomplete pattern-match warnings

        ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return ([(Name, CoreBndr, CoreExpr)] -> CoreExpr -> CoreExpr
forall a. [(a, CoreBndr, CoreExpr)] -> CoreExpr -> CoreExpr
add_field_binds [(Name, CoreBndr, CoreExpr)]
field_binds' (CoreExpr -> CoreExpr) -> CoreExpr -> CoreExpr
forall a b. (a -> b) -> a -> b
$
                  CoreBndr -> CoreExpr -> CoreExpr -> CoreExpr
bindNonRec CoreBndr
discrim_var CoreExpr
record_expr' CoreExpr
matching_code) }
  where
    ds_field :: LHsRecUpdField GhcTc -> DsM (Name, Id, CoreExpr)
      -- Clone the Id in the HsRecField, because its Name is that
      -- of the record selector, and we must not make that a local binder
      -- else we shadow other uses of the record selector
      -- Hence 'lcl_id'.  Cf #2735
    ds_field :: LHsRecUpdField GhcTc
-> IOEnv (Env DsGblEnv DsLclEnv) (Name, CoreBndr, CoreExpr)
ds_field (L SrcSpan
_ HsRecUpdField GhcTc
rec_field)
      = do { CoreExpr
rhs <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr (HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc))
-> Located (HsExpr GhcTc)
forall id arg. HsRecField' id arg -> arg
hsRecFieldArg HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc))
HsRecUpdField GhcTc
rec_field)
           ; let fld_id :: CoreBndr
fld_id = GenLocated SrcSpan CoreBndr -> CoreBndr
forall l e. GenLocated l e -> e
unLoc (HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc))
-> GenLocated SrcSpan CoreBndr
forall arg.
HsRecField' (AmbiguousFieldOcc GhcTc) arg
-> GenLocated SrcSpan CoreBndr
hsRecUpdFieldId HsRecField' (AmbiguousFieldOcc GhcTc) (Located (HsExpr GhcTc))
HsRecUpdField GhcTc
rec_field)
           ; CoreBndr
lcl_id <- Type -> Type -> DsM CoreBndr
newSysLocalDs (CoreBndr -> Type
idMult CoreBndr
fld_id) (CoreBndr -> Type
idType CoreBndr
fld_id)
           ; (Name, CoreBndr, CoreExpr)
-> IOEnv (Env DsGblEnv DsLclEnv) (Name, CoreBndr, CoreExpr)
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBndr -> Name
idName CoreBndr
fld_id, CoreBndr
lcl_id, CoreExpr
rhs) }

    add_field_binds :: [(a, CoreBndr, CoreExpr)] -> CoreExpr -> CoreExpr
add_field_binds [] CoreExpr
expr = CoreExpr
expr
    add_field_binds ((a
_,CoreBndr
b,CoreExpr
r):[(a, CoreBndr, CoreExpr)]
bs) CoreExpr
expr = CoreBndr -> CoreExpr -> CoreExpr -> CoreExpr
bindNonRec CoreBndr
b CoreExpr
r ([(a, CoreBndr, CoreExpr)] -> CoreExpr -> CoreExpr
add_field_binds [(a, CoreBndr, CoreExpr)]
bs CoreExpr
expr)

        -- Awkwardly, for families, the match goes
        -- from instance type to family type
    (Type
in_ty, Type
out_ty) =
      case ([ConLike] -> ConLike
forall a. [a] -> a
head [ConLike]
cons_to_upd) of
        RealDataCon DataCon
data_con ->
          let tycon :: TyCon
tycon = DataCon -> TyCon
dataConTyCon DataCon
data_con in
          (TyCon -> [Type] -> Type
mkTyConApp TyCon
tycon [Type]
in_inst_tys, TyCon -> [Type] -> Type
mkFamilyTyConApp TyCon
tycon [Type]
out_inst_tys)
        PatSynCon PatSyn
pat_syn ->
          ( PatSyn -> [Type] -> Type
patSynInstResTy PatSyn
pat_syn [Type]
in_inst_tys
          , PatSyn -> [Type] -> Type
patSynInstResTy PatSyn
pat_syn [Type]
out_inst_tys)
    mk_alt :: NameEnv CoreBndr
-> ConLike
-> IOEnv
     (Env DsGblEnv DsLclEnv)
     (Located (Match GhcTc (Located (HsExpr GhcTc))))
mk_alt NameEnv CoreBndr
upd_fld_env ConLike
con
      = do { let ([CoreBndr]
univ_tvs, [CoreBndr]
ex_tvs, [EqSpec]
eq_spec,
                  [Type]
prov_theta, [Type]
_req_theta, [Scaled Type]
arg_tys, Type
_) = ConLike
-> ([CoreBndr], [CoreBndr], [EqSpec], [Type], [Type],
    [Scaled Type], Type)
conLikeFullSig ConLike
con
                 arg_tys' :: [Scaled Type]
arg_tys' = (Scaled Type -> Scaled Type) -> [Scaled Type] -> [Scaled Type]
forall a b. (a -> b) -> [a] -> [b]
map (Type -> Scaled Type -> Scaled Type
forall a. Type -> Scaled a -> Scaled a
scaleScaled Type
Many) [Scaled Type]
arg_tys
                   -- Record updates consume the source record with multiplicity
                   -- Many. Therefore all the fields need to be scaled thus.
                 user_tvs :: [CoreBndr]
user_tvs  = [VarBndr CoreBndr Specificity] -> [CoreBndr]
forall tv argf. [VarBndr tv argf] -> [tv]
binderVars ([VarBndr CoreBndr Specificity] -> [CoreBndr])
-> [VarBndr CoreBndr Specificity] -> [CoreBndr]
forall a b. (a -> b) -> a -> b
$ ConLike -> [VarBndr CoreBndr Specificity]
conLikeUserTyVarBinders ConLike
con
                 in_subst :: TCvSubst
in_subst  = [CoreBndr] -> [Type] -> TCvSubst
HasDebugCallStack => [CoreBndr] -> [Type] -> TCvSubst
zipTvSubst [CoreBndr]
univ_tvs [Type]
in_inst_tys
                 out_subst :: TCvSubst
out_subst = [CoreBndr] -> [Type] -> TCvSubst
HasDebugCallStack => [CoreBndr] -> [Type] -> TCvSubst
zipTvSubst [CoreBndr]
univ_tvs [Type]
out_inst_tys

                -- I'm not bothering to clone the ex_tvs
           ; [CoreBndr]
eqs_vars   <- (Type -> DsM CoreBndr) -> [Type] -> DsM [CoreBndr]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Type -> DsM CoreBndr
newPredVarDs (HasCallStack => TCvSubst -> [Type] -> [Type]
TCvSubst -> [Type] -> [Type]
substTheta TCvSubst
in_subst ([EqSpec] -> [Type]
eqSpecPreds [EqSpec]
eq_spec))
           ; [CoreBndr]
theta_vars <- (Type -> DsM CoreBndr) -> [Type] -> DsM [CoreBndr]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Type -> DsM CoreBndr
newPredVarDs (HasCallStack => TCvSubst -> [Type] -> [Type]
TCvSubst -> [Type] -> [Type]
substTheta TCvSubst
in_subst [Type]
prov_theta)
           ; [CoreBndr]
arg_ids    <- [Scaled Type] -> DsM [CoreBndr]
newSysLocalsDs (TCvSubst -> [Scaled Type] -> [Scaled Type]
substScaledTysUnchecked TCvSubst
in_subst [Scaled Type]
arg_tys')
           ; let field_labels :: [FieldLbl Name]
field_labels = ConLike -> [FieldLbl Name]
conLikeFieldLabels ConLike
con
                 val_args :: [Located (HsExpr GhcTc)]
val_args = String
-> (FieldLbl Name -> CoreBndr -> Located (HsExpr GhcTc))
-> [FieldLbl Name]
-> [CoreBndr]
-> [Located (HsExpr GhcTc)]
forall a b c. String -> (a -> b -> c) -> [a] -> [b] -> [c]
zipWithEqual String
"dsExpr:RecordUpd" FieldLbl Name -> CoreBndr -> Located (HsExpr GhcTc)
FieldLbl Name -> CoreBndr -> LHsExpr GhcTc
mk_val_arg
                                         [FieldLbl Name]
field_labels [CoreBndr]
arg_ids
                 mk_val_arg :: FieldLbl Name -> CoreBndr -> LHsExpr GhcTc
mk_val_arg FieldLbl Name
fl CoreBndr
pat_arg_id
                     = IdP GhcTc -> LHsExpr GhcTc
forall (id :: Pass). IdP (GhcPass id) -> LHsExpr (GhcPass id)
nlHsVar (NameEnv CoreBndr -> Name -> Maybe CoreBndr
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv NameEnv CoreBndr
upd_fld_env (FieldLbl Name -> Name
forall a. FieldLbl a -> a
flSelector FieldLbl Name
fl) Maybe CoreBndr -> CoreBndr -> CoreBndr
forall a. Maybe a -> a -> a
`orElse` CoreBndr
pat_arg_id)

                 inst_con :: Located (HsExpr GhcTc)
inst_con = HsExpr GhcTc -> Located (HsExpr GhcTc)
forall e. e -> Located e
noLoc (HsExpr GhcTc -> Located (HsExpr GhcTc))
-> HsExpr GhcTc -> Located (HsExpr GhcTc)
forall a b. (a -> b) -> a -> b
$ HsWrapper -> HsExpr GhcTc -> HsExpr GhcTc
mkHsWrap HsWrapper
wrap (XConLikeOut GhcTc -> ConLike -> HsExpr GhcTc
forall p. XConLikeOut p -> ConLike -> HsExpr p
HsConLikeOut NoExtField
XConLikeOut GhcTc
noExtField ConLike
con)
                        -- Reconstruct with the WrapId so that unpacking happens
                 wrap :: HsWrapper
wrap = [CoreBndr] -> HsWrapper
mkWpEvVarApps [CoreBndr]
theta_vars                                HsWrapper -> HsWrapper -> HsWrapper
<.>
                        HsWrapper
dict_req_wrap                                           HsWrapper -> HsWrapper -> HsWrapper
<.>
                        [Type] -> HsWrapper
mkWpTyApps    [ TCvSubst -> CoreBndr -> Maybe Type
lookupTyVar TCvSubst
out_subst CoreBndr
tv
                                          Maybe Type -> Type -> Type
forall a. Maybe a -> a -> a
`orElse` CoreBndr -> Type
mkTyVarTy CoreBndr
tv
                                      | CoreBndr
tv <- [CoreBndr]
user_tvs ]
                          -- Be sure to use user_tvs (which may be ordered
                          -- differently than `univ_tvs ++ ex_tvs) above.
                          -- See Note [DataCon user type variable binders]
                          -- in GHC.Core.DataCon.
                 rhs :: Located (HsExpr GhcTc)
rhs = (Located (HsExpr GhcTc)
 -> Located (HsExpr GhcTc) -> Located (HsExpr GhcTc))
-> Located (HsExpr GhcTc)
-> [Located (HsExpr GhcTc)]
-> Located (HsExpr GhcTc)
forall (t :: * -> *) b a.
Foldable t =>
(b -> a -> b) -> b -> t a -> b
foldl' (\Located (HsExpr GhcTc)
a Located (HsExpr GhcTc)
b -> LHsExpr GhcTc -> LHsExpr GhcTc -> LHsExpr GhcTc
forall (id :: Pass).
IsPass id =>
LHsExpr (GhcPass id)
-> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)
nlHsApp Located (HsExpr GhcTc)
LHsExpr GhcTc
a Located (HsExpr GhcTc)
LHsExpr GhcTc
b) Located (HsExpr GhcTc)
inst_con [Located (HsExpr GhcTc)]
val_args

                        -- Tediously wrap the application in a cast
                        -- Note [Update for GADTs]
                 wrapped_rhs :: Located (HsExpr GhcTc)
wrapped_rhs =
                  case ConLike
con of
                    RealDataCon DataCon
data_con
                      | [EqSpec] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [EqSpec]
eq_spec -> Located (HsExpr GhcTc)
rhs
                      | Bool
otherwise    -> HsWrapper -> LHsExpr GhcTc -> LHsExpr GhcTc
mkLHsWrap (TcCoercionN -> HsWrapper
mkWpCastN TcCoercionN
wrap_co) Located (HsExpr GhcTc)
LHsExpr GhcTc
rhs
                                     -- This wrap is the punchline: Note [Update for GADTs]
                      where
                        rep_tc :: TyCon
rep_tc   = DataCon -> TyCon
dataConTyCon DataCon
data_con
                        wrap_co :: TcCoercionN
wrap_co  = TyCon -> [TcCoercionN] -> TcCoercionN
mkTcFamilyTyConAppCo TyCon
rep_tc [TcCoercionN]
univ_cos
                        univ_cos :: [TcCoercionN]
univ_cos = String
-> (CoreBndr -> Type -> TcCoercionN)
-> [CoreBndr]
-> [Type]
-> [TcCoercionN]
forall a b c. String -> (a -> b -> c) -> [a] -> [b] -> [c]
zipWithEqual String
"dsExpr:upd" CoreBndr -> Type -> TcCoercionN
mk_univ_co [CoreBndr]
univ_tvs [Type]
out_inst_tys

                        mk_univ_co :: TyVar   -- Universal tyvar from the DataCon
                                   -> Type    -- Corresponding instantiating type
                                   -> Coercion
                        mk_univ_co :: CoreBndr -> Type -> TcCoercionN
mk_univ_co CoreBndr
univ_tv Type
inst_ty
                          = case VarEnv TcCoercionN -> CoreBndr -> Maybe TcCoercionN
forall a. VarEnv a -> CoreBndr -> Maybe a
lookupVarEnv VarEnv TcCoercionN
eq_spec_env CoreBndr
univ_tv of
                               Just TcCoercionN
co -> TcCoercionN
co
                               Maybe TcCoercionN
Nothing -> Type -> TcCoercionN
mkTcNomReflCo Type
inst_ty

                        eq_spec_env :: VarEnv Coercion
                        eq_spec_env :: VarEnv TcCoercionN
eq_spec_env = [(CoreBndr, TcCoercionN)] -> VarEnv TcCoercionN
forall a. [(CoreBndr, a)] -> VarEnv a
mkVarEnv [ (EqSpec -> CoreBndr
eqSpecTyVar EqSpec
spec, TcCoercionN -> TcCoercionN
mkTcSymCo (CoreBndr -> TcCoercionN
mkTcCoVarCo CoreBndr
eqs_var))
                                               | (EqSpec
spec,CoreBndr
eqs_var) <- String -> [EqSpec] -> [CoreBndr] -> [(EqSpec, CoreBndr)]
forall a b. String -> [a] -> [b] -> [(a, b)]
zipEqual String
"dsExpr:upd2" [EqSpec]
eq_spec [CoreBndr]
eqs_vars ]

                    -- eq_spec is always null for a PatSynCon
                    PatSynCon PatSyn
_ -> Located (HsExpr GhcTc)
rhs


                 req_wrap :: HsWrapper
req_wrap = HsWrapper
dict_req_wrap HsWrapper -> HsWrapper -> HsWrapper
<.> [Type] -> HsWrapper
mkWpTyApps [Type]
in_inst_tys

                 pat :: GenLocated SrcSpan (Pat GhcTc)
pat = Pat GhcTc -> GenLocated SrcSpan (Pat GhcTc)
forall e. e -> Located e
noLoc (Pat GhcTc -> GenLocated SrcSpan (Pat GhcTc))
-> Pat GhcTc -> GenLocated SrcSpan (Pat GhcTc)
forall a b. (a -> b) -> a -> b
$ ConPat :: forall p.
XConPat p -> XRec p (ConLikeP p) -> HsConPatDetails p -> Pat p
ConPat { pat_con :: XRec GhcTc (ConLikeP GhcTc)
pat_con = ConLike -> Located ConLike
forall e. e -> Located e
noLoc ConLike
con
                                      , pat_args :: HsConPatDetails GhcTc
pat_args = [GenLocated SrcSpan (Pat GhcTc)]
-> HsConDetails
     (GenLocated SrcSpan (Pat GhcTc))
     (HsRecFields GhcTc (GenLocated SrcSpan (Pat GhcTc)))
forall arg rec. [arg] -> HsConDetails arg rec
PrefixCon ([GenLocated SrcSpan (Pat GhcTc)]
 -> HsConDetails
      (GenLocated SrcSpan (Pat GhcTc))
      (HsRecFields GhcTc (GenLocated SrcSpan (Pat GhcTc))))
-> [GenLocated SrcSpan (Pat GhcTc)]
-> HsConDetails
     (GenLocated SrcSpan (Pat GhcTc))
     (HsRecFields GhcTc (GenLocated SrcSpan (Pat GhcTc)))
forall a b. (a -> b) -> a -> b
$ (CoreBndr -> GenLocated SrcSpan (Pat GhcTc))
-> [CoreBndr] -> [GenLocated SrcSpan (Pat GhcTc)]
forall a b. (a -> b) -> [a] -> [b]
map CoreBndr -> GenLocated SrcSpan (Pat GhcTc)
forall (id :: Pass). IdP (GhcPass id) -> LPat (GhcPass id)
nlVarPat [CoreBndr]
arg_ids
                                      , pat_con_ext :: XConPat GhcTc
pat_con_ext = ConPatTc :: [Type]
-> [CoreBndr] -> [CoreBndr] -> TcEvBinds -> HsWrapper -> ConPatTc
ConPatTc
                                        { cpt_tvs :: [CoreBndr]
cpt_tvs = [CoreBndr]
ex_tvs
                                        , cpt_dicts :: [CoreBndr]
cpt_dicts = [CoreBndr]
eqs_vars [CoreBndr] -> [CoreBndr] -> [CoreBndr]
forall a. [a] -> [a] -> [a]
++ [CoreBndr]
theta_vars
                                        , cpt_binds :: TcEvBinds
cpt_binds = TcEvBinds
emptyTcEvBinds
                                        , cpt_arg_tys :: [Type]
cpt_arg_tys = [Type]
in_inst_tys
                                        , cpt_wrap :: HsWrapper
cpt_wrap = HsWrapper
req_wrap
                                        }
                                      }
           ; Located (Match GhcTc (Located (HsExpr GhcTc)))
-> IOEnv
     (Env DsGblEnv DsLclEnv)
     (Located (Match GhcTc (Located (HsExpr GhcTc))))
forall (m :: * -> *) a. Monad m => a -> m a
return (HsMatchContext (NoGhcTc GhcTc)
-> [LPat GhcTc]
-> Located (HsExpr GhcTc)
-> LMatch GhcTc (Located (HsExpr GhcTc))
forall (p :: Pass) (body :: * -> *).
HsMatchContext (NoGhcTc (GhcPass p))
-> [LPat (GhcPass p)]
-> Located (body (GhcPass p))
-> LMatch (GhcPass p) (Located (body (GhcPass p)))
mkSimpleMatch HsMatchContext (NoGhcTc GhcTc)
forall p. HsMatchContext p
RecUpd [GenLocated SrcSpan (Pat GhcTc)
LPat GhcTc
pat] Located (HsExpr GhcTc)
wrapped_rhs) }

{- Note [Scrutinee in Record updates]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider #17783:

  data PartialRec = No
                  | Yes { a :: Int, b :: Bool }
  update No = No
  update r@(Yes {}) = r { b = False }

In the context of pattern-match checking, the occurrence of @r@ in
@r { b = False }@ is to be treated as if it was a scrutinee, as can be seen by
the following desugaring:

  r { b = False } ==> case r of Yes a b -> Yes a False

Thus, we pass @r@ as the scrutinee expression to @matchWrapper@ above.
-}

-- Here is where we desugar the Template Haskell brackets and escapes

-- Template Haskell stuff

dsExpr (HsRnBracketOut XRnBracketOut GhcTc
_ HsBracket GhcRn
_ [PendingRnSplice]
_)  = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsExpr HsRnBracketOut"
dsExpr (HsTcBracketOut XTcBracketOut GhcTc
_ Maybe QuoteWrapper
hs_wrapper HsBracket GhcRn
x [PendingTcSplice]
ps) = Maybe QuoteWrapper
-> HsBracket GhcRn -> [PendingTcSplice] -> DsM CoreExpr
dsBracket Maybe QuoteWrapper
hs_wrapper HsBracket GhcRn
x [PendingTcSplice]
ps
dsExpr (HsSpliceE XSpliceE GhcTc
_ HsSplice GhcTc
s)         = String -> SDoc -> DsM CoreExpr
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"dsExpr:splice" (HsSplice GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsSplice GhcTc
s)

-- Arrow notation extension
dsExpr (HsProc XProc GhcTc
_ LPat GhcTc
pat LHsCmdTop GhcTc
cmd) = LPat GhcTc -> LHsCmdTop GhcTc -> DsM CoreExpr
dsProcExpr LPat GhcTc
pat LHsCmdTop GhcTc
cmd

-- Hpc Support

dsExpr (HsTick XTick GhcTc
_ Tickish (IdP GhcTc)
tickish LHsExpr GhcTc
e) = do
  CoreExpr
e' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
e
  CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (Tickish CoreBndr -> CoreExpr -> CoreExpr
forall b. Tickish CoreBndr -> Expr b -> Expr b
Tick Tickish CoreBndr
Tickish (IdP GhcTc)
tickish CoreExpr
e')

-- There is a problem here. The then and else branches
-- have no free variables, so they are open to lifting.
-- We need someway of stopping this.
-- This will make no difference to binary coverage
-- (did you go here: YES or NO), but will effect accurate
-- tick counting.

dsExpr (HsBinTick XBinTick GhcTc
_ Int
ixT Int
ixF LHsExpr GhcTc
e) = do
  CoreExpr
e2 <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
e
  do { ASSERT(exprType e2 `eqType` boolTy)
       Int -> Int -> CoreExpr -> DsM CoreExpr
mkBinaryTickBox Int
ixT Int
ixF CoreExpr
e2
     }

-- HsSyn constructs that just shouldn't be here:
dsExpr (HsBracket     {})  = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsExpr:HsBracket"
dsExpr (HsDo          {})  = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsExpr:HsDo"

ds_prag_expr :: HsPragE GhcTc -> LHsExpr GhcTc -> DsM CoreExpr
ds_prag_expr :: HsPragE GhcTc -> LHsExpr GhcTc -> DsM CoreExpr
ds_prag_expr (HsPragSCC XSCC GhcTc
_ SourceText
_ StringLiteral
cc) LHsExpr GhcTc
expr = do
    DynFlags
dflags <- IOEnv (Env DsGblEnv DsLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
    if DynFlags -> Bool
sccProfilingEnabled DynFlags
dflags
      then do
        Module
mod_name <- IOEnv (Env DsGblEnv DsLclEnv) Module
forall (m :: * -> *). HasModule m => m Module
getModule
        Bool
count <- GeneralFlag -> TcRnIf DsGblEnv DsLclEnv Bool
forall gbl lcl. GeneralFlag -> TcRnIf gbl lcl Bool
goptM GeneralFlag
Opt_ProfCountEntries
        let nm :: FieldLabelString
nm = StringLiteral -> FieldLabelString
sl_fs StringLiteral
cc
        CCFlavour
flavour <- CostCentreIndex -> CCFlavour
ExprCC (CostCentreIndex -> CCFlavour)
-> IOEnv (Env DsGblEnv DsLclEnv) CostCentreIndex
-> IOEnv (Env DsGblEnv DsLclEnv) CCFlavour
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> FieldLabelString -> IOEnv (Env DsGblEnv DsLclEnv) CostCentreIndex
getCCIndexDsM FieldLabelString
nm
        Tickish CoreBndr -> CoreExpr -> CoreExpr
forall b. Tickish CoreBndr -> Expr b -> Expr b
Tick (CostCentre -> Bool -> Bool -> Tickish CoreBndr
forall id. CostCentre -> Bool -> Bool -> Tickish id
ProfNote (FieldLabelString -> Module -> SrcSpan -> CCFlavour -> CostCentre
mkUserCC FieldLabelString
nm Module
mod_name (Located (HsExpr GhcTc) -> SrcSpan
forall l e. GenLocated l e -> l
getLoc Located (HsExpr GhcTc)
LHsExpr GhcTc
expr) CCFlavour
flavour) Bool
count Bool
True)
               (CoreExpr -> CoreExpr) -> DsM CoreExpr -> DsM CoreExpr
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
expr
      else LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
expr

------------------------------
dsSyntaxExpr :: SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr :: SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr (SyntaxExprTc { syn_expr      = expr
                           , syn_arg_wraps = arg_wraps
                           , syn_res_wrap  = res_wrap })
             [CoreExpr]
arg_exprs
  = do { CoreExpr
fun            <- HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
expr
       ; [CoreExpr -> CoreExpr]
core_arg_wraps <- (HsWrapper -> DsM (CoreExpr -> CoreExpr))
-> [HsWrapper]
-> IOEnv (Env DsGblEnv DsLclEnv) [CoreExpr -> CoreExpr]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM HsWrapper -> DsM (CoreExpr -> CoreExpr)
dsHsWrapper [HsWrapper]
arg_wraps
       ; CoreExpr -> CoreExpr
core_res_wrap  <- HsWrapper -> DsM (CoreExpr -> CoreExpr)
dsHsWrapper HsWrapper
res_wrap
       ; let wrapped_args :: [CoreExpr]
wrapped_args = String
-> ((CoreExpr -> CoreExpr) -> CoreExpr -> CoreExpr)
-> [CoreExpr -> CoreExpr]
-> [CoreExpr]
-> [CoreExpr]
forall a b c. String -> (a -> b -> c) -> [a] -> [b] -> [c]
zipWithEqual String
"dsSyntaxExpr" (CoreExpr -> CoreExpr) -> CoreExpr -> CoreExpr
forall a b. (a -> b) -> a -> b
($) [CoreExpr -> CoreExpr]
core_arg_wraps [CoreExpr]
arg_exprs
       ; IOEnv (Env DsGblEnv DsLclEnv) ()
-> (() -> CoreExpr) -> DsM CoreExpr
forall a. DsM a -> (a -> CoreExpr) -> DsM CoreExpr
dsWhenNoErrs ((CoreExpr -> SDoc -> IOEnv (Env DsGblEnv DsLclEnv) ())
-> [CoreExpr] -> [SDoc] -> IOEnv (Env DsGblEnv DsLclEnv) ()
forall (m :: * -> *) a b c.
Applicative m =>
(a -> b -> m c) -> [a] -> [b] -> m ()
zipWithM_ CoreExpr -> SDoc -> IOEnv (Env DsGblEnv DsLclEnv) ()
dsNoLevPolyExpr [CoreExpr]
wrapped_args [ Int -> SDoc
mk_doc Int
n | Int
n <- [Int
1..] ])
                      (\()
_ -> CoreExpr -> CoreExpr
core_res_wrap (CoreExpr -> [CoreExpr] -> CoreExpr
forall b. Expr b -> [Expr b] -> Expr b
mkApps CoreExpr
fun [CoreExpr]
wrapped_args)) }
  where
    mk_doc :: Int -> SDoc
mk_doc Int
n = String -> SDoc
text String
"In the" SDoc -> SDoc -> SDoc
<+> Int -> SDoc
speakNth Int
n SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"argument of" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (HsExpr GhcTc -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsExpr GhcTc
expr)
dsSyntaxExpr SyntaxExpr GhcTc
NoSyntaxExprTc [CoreExpr]
_ = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsSyntaxExpr"

findField :: [LHsRecField GhcTc arg] -> Name -> [arg]
findField :: [LHsRecField GhcTc arg] -> Name -> [arg]
findField [LHsRecField GhcTc arg]
rbinds Name
sel
  = [HsRecField' (FieldOcc GhcTc) arg -> arg
forall id arg. HsRecField' id arg -> arg
hsRecFieldArg HsRecField' (FieldOcc GhcTc) arg
fld | L SrcSpan
_ HsRecField' (FieldOcc GhcTc) arg
fld <- [LHsRecField GhcTc arg]
rbinds
                       , Name
sel Name -> Name -> Bool
forall a. Eq a => a -> a -> Bool
== CoreBndr -> Name
idName (GenLocated SrcSpan CoreBndr -> CoreBndr
forall l e. GenLocated l e -> e
unLoc (GenLocated SrcSpan CoreBndr -> CoreBndr)
-> GenLocated SrcSpan CoreBndr -> CoreBndr
forall a b. (a -> b) -> a -> b
$ HsRecField' (FieldOcc GhcTc) arg -> GenLocated SrcSpan CoreBndr
forall arg. HsRecField GhcTc arg -> GenLocated SrcSpan CoreBndr
hsRecFieldId HsRecField' (FieldOcc GhcTc) arg
fld) ]

{-
%--------------------------------------------------------------------

Note [Desugaring explicit lists]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Explicit lists are desugared in a cleverer way to prevent some
fruitless allocations.  Essentially, whenever we see a list literal
[x_1, ..., x_n] we generate the corresponding expression in terms of
build:

Explicit lists (literals) are desugared to allow build/foldr fusion when
beneficial. This is a bit of a trade-off,

 * build/foldr fusion can generate far larger code than the corresponding
   cons-chain (e.g. see #11707)

 * even when it doesn't produce more code, build can still fail to fuse,
   requiring that the simplifier do more work to bring the expression
   back into cons-chain form; this costs compile time

 * when it works, fusion can be a significant win. Allocations are reduced
   by up to 25% in some nofib programs. Specifically,

        Program           Size    Allocs   Runtime  CompTime
        rewrite          +0.0%    -26.3%      0.02     -1.8%
           ansi          -0.3%    -13.8%      0.00     +0.0%
           lift          +0.0%     -8.7%      0.00     -2.3%

At the moment we use a simple heuristic to determine whether build will be
fruitful: for small lists we assume the benefits of fusion will be worthwhile;
for long lists we assume that the benefits will be outweighted by the cost of
code duplication. This magic length threshold is @maxBuildLength@. Also, fusion
won't work at all if rewrite rules are disabled, so we don't use the build-based
desugaring in this case.

We used to have a more complex heuristic which would try to break the list into
"static" and "dynamic" parts and only build-desugar the dynamic part.
Unfortunately, determining "static-ness" reliably is a bit tricky and the
heuristic at times produced surprising behavior (see #11710) so it was dropped.
-}

{- | The longest list length which we will desugar using @build@.

This is essentially a magic number and its setting is unfortunate rather
arbitrary. The idea here, as mentioned in Note [Desugaring explicit lists],
is to avoid deforesting large static data into large(r) code. Ideally we'd
want a smaller threshold with larger consumers and vice-versa, but we have no
way of knowing what will be consuming our list in the desugaring impossible to
set generally correctly.

The effect of reducing this number will be that 'build' fusion is applied
less often. From a runtime performance perspective, applying 'build' more
liberally on "moderately" sized lists should rarely hurt and will often it can
only expose further optimization opportunities; if no fusion is possible it will
eventually get rule-rewritten back to a list). We do, however, pay in compile
time.
-}
maxBuildLength :: Int
maxBuildLength :: Int
maxBuildLength = Int
32

dsExplicitList :: Type -> Maybe (SyntaxExpr GhcTc) -> [LHsExpr GhcTc]
               -> DsM CoreExpr
-- See Note [Desugaring explicit lists]
dsExplicitList :: Type -> Maybe (SyntaxExpr GhcTc) -> [LHsExpr GhcTc] -> DsM CoreExpr
dsExplicitList Type
elt_ty Maybe (SyntaxExpr GhcTc)
Nothing [LHsExpr GhcTc]
xs
  = do { DynFlags
dflags <- IOEnv (Env DsGblEnv DsLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       ; [CoreExpr]
xs' <- (Located (HsExpr GhcTc) -> DsM CoreExpr)
-> [Located (HsExpr GhcTc)] -> DsM [CoreExpr]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Located (HsExpr GhcTc) -> DsM CoreExpr
LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP [Located (HsExpr GhcTc)]
[LHsExpr GhcTc]
xs
       ; if [CoreExpr]
xs' [CoreExpr] -> Int -> Bool
forall a. [a] -> Int -> Bool
`lengthExceeds` Int
maxBuildLength
                -- Don't generate builds if the list is very long.
         Bool -> Bool -> Bool
|| [CoreExpr] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [CoreExpr]
xs'
                -- Don't generate builds when the [] constructor will do
         Bool -> Bool -> Bool
|| Bool -> Bool
not (GeneralFlag -> DynFlags -> Bool
gopt GeneralFlag
Opt_EnableRewriteRules DynFlags
dflags)  -- Rewrite rules off
                -- Don't generate a build if there are no rules to eliminate it!
                -- See Note [Desugaring RULE left hand sides] in GHC.HsToCore
         then CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ Type -> [CoreExpr] -> CoreExpr
mkListExpr Type
elt_ty [CoreExpr]
xs'
         else Type
-> ((CoreBndr, Type) -> (CoreBndr, Type) -> DsM CoreExpr)
-> DsM CoreExpr
forall (m :: * -> *).
(MonadFail m, MonadThings m, MonadUnique m) =>
Type
-> ((CoreBndr, Type) -> (CoreBndr, Type) -> m CoreExpr)
-> m CoreExpr
mkBuildExpr Type
elt_ty ([CoreExpr] -> (CoreBndr, Type) -> (CoreBndr, Type) -> DsM CoreExpr
forall (m :: * -> *) (t :: * -> *) b b b.
(Monad m, Foldable t) =>
t (Arg b) -> (CoreBndr, b) -> (CoreBndr, b) -> m (Arg b)
mk_build_list [CoreExpr]
xs') }
  where
    mk_build_list :: t (Arg b) -> (CoreBndr, b) -> (CoreBndr, b) -> m (Arg b)
mk_build_list t (Arg b)
xs' (CoreBndr
cons, b
_) (CoreBndr
nil, b
_)
      = Arg b -> m (Arg b)
forall (m :: * -> *) a. Monad m => a -> m a
return ((Arg b -> Arg b -> Arg b) -> Arg b -> t (Arg b) -> Arg b
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (Arg b -> Arg b -> Arg b
forall b. Expr b -> Expr b -> Expr b
App (Arg b -> Arg b -> Arg b)
-> (Arg b -> Arg b) -> Arg b -> Arg b -> Arg b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Arg b -> Arg b -> Arg b
forall b. Expr b -> Expr b -> Expr b
App (CoreBndr -> Arg b
forall b. CoreBndr -> Expr b
Var CoreBndr
cons)) (CoreBndr -> Arg b
forall b. CoreBndr -> Expr b
Var CoreBndr
nil) t (Arg b)
xs')

dsExplicitList Type
elt_ty (Just SyntaxExpr GhcTc
fln) [LHsExpr GhcTc]
xs
  = do { CoreExpr
list <- Type -> Maybe (SyntaxExpr GhcTc) -> [LHsExpr GhcTc] -> DsM CoreExpr
dsExplicitList Type
elt_ty Maybe (SyntaxExpr GhcTc)
forall a. Maybe a
Nothing [LHsExpr GhcTc]
xs
       ; DynFlags
dflags <- IOEnv (Env DsGblEnv DsLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       ; let platform :: Platform
platform = DynFlags -> Platform
targetPlatform DynFlags
dflags
       ; SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr SyntaxExpr GhcTc
fln [Platform -> Int -> CoreExpr
mkIntExprInt Platform
platform ([Located (HsExpr GhcTc)] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Located (HsExpr GhcTc)]
[LHsExpr GhcTc]
xs), CoreExpr
list] }

dsArithSeq :: PostTcExpr -> (ArithSeqInfo GhcTc) -> DsM CoreExpr
dsArithSeq :: HsExpr GhcTc -> ArithSeqInfo GhcTc -> DsM CoreExpr
dsArithSeq HsExpr GhcTc
expr (From LHsExpr GhcTc
from)
  = CoreExpr -> CoreExpr -> CoreExpr
forall b. Expr b -> Expr b -> Expr b
App (CoreExpr -> CoreExpr -> CoreExpr)
-> DsM CoreExpr -> DsM (CoreExpr -> CoreExpr)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
expr DsM (CoreExpr -> CoreExpr) -> DsM CoreExpr -> DsM CoreExpr
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
from
dsArithSeq HsExpr GhcTc
expr (FromTo LHsExpr GhcTc
from LHsExpr GhcTc
to)
  = do FamInstEnvs
fam_envs <- DsM FamInstEnvs
dsGetFamInstEnvs
       DynFlags
dflags <- IOEnv (Env DsGblEnv DsLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       FamInstEnvs
-> DynFlags
-> LHsExpr GhcTc
-> Maybe (LHsExpr GhcTc)
-> LHsExpr GhcTc
-> IOEnv (Env DsGblEnv DsLclEnv) ()
warnAboutEmptyEnumerations FamInstEnvs
fam_envs DynFlags
dflags LHsExpr GhcTc
from Maybe (LHsExpr GhcTc)
forall a. Maybe a
Nothing LHsExpr GhcTc
to
       CoreExpr
expr' <- HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
expr
       CoreExpr
from' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
from
       CoreExpr
to'   <- LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
to
       CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ CoreExpr -> [CoreExpr] -> CoreExpr
forall b. Expr b -> [Expr b] -> Expr b
mkApps CoreExpr
expr' [CoreExpr
from', CoreExpr
to']
dsArithSeq HsExpr GhcTc
expr (FromThen LHsExpr GhcTc
from LHsExpr GhcTc
thn)
  = CoreExpr -> [CoreExpr] -> CoreExpr
forall b. Expr b -> [Expr b] -> Expr b
mkApps (CoreExpr -> [CoreExpr] -> CoreExpr)
-> DsM CoreExpr
-> IOEnv (Env DsGblEnv DsLclEnv) ([CoreExpr] -> CoreExpr)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
expr IOEnv (Env DsGblEnv DsLclEnv) ([CoreExpr] -> CoreExpr)
-> DsM [CoreExpr] -> DsM CoreExpr
forall (f :: * -> *) a b. Applicative f => f (a -> b) -> f a -> f b
<*> (Located (HsExpr GhcTc) -> DsM CoreExpr)
-> [Located (HsExpr GhcTc)] -> DsM [CoreExpr]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Located (HsExpr GhcTc) -> DsM CoreExpr
LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP [Located (HsExpr GhcTc)
LHsExpr GhcTc
from, Located (HsExpr GhcTc)
LHsExpr GhcTc
thn]
dsArithSeq HsExpr GhcTc
expr (FromThenTo LHsExpr GhcTc
from LHsExpr GhcTc
thn LHsExpr GhcTc
to)
  = do FamInstEnvs
fam_envs <- DsM FamInstEnvs
dsGetFamInstEnvs
       DynFlags
dflags <- IOEnv (Env DsGblEnv DsLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
       FamInstEnvs
-> DynFlags
-> LHsExpr GhcTc
-> Maybe (LHsExpr GhcTc)
-> LHsExpr GhcTc
-> IOEnv (Env DsGblEnv DsLclEnv) ()
warnAboutEmptyEnumerations FamInstEnvs
fam_envs DynFlags
dflags LHsExpr GhcTc
from (Located (HsExpr GhcTc) -> Maybe (Located (HsExpr GhcTc))
forall a. a -> Maybe a
Just Located (HsExpr GhcTc)
LHsExpr GhcTc
thn) LHsExpr GhcTc
to
       CoreExpr
expr' <- HsExpr GhcTc -> DsM CoreExpr
dsExpr HsExpr GhcTc
expr
       CoreExpr
from' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
from
       CoreExpr
thn'  <- LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
thn
       CoreExpr
to'   <- LHsExpr GhcTc -> DsM CoreExpr
dsLExprNoLP LHsExpr GhcTc
to
       CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ CoreExpr -> [CoreExpr] -> CoreExpr
forall b. Expr b -> [Expr b] -> Expr b
mkApps CoreExpr
expr' [CoreExpr
from', CoreExpr
thn', CoreExpr
to']

{-
Desugar 'do' and 'mdo' expressions (NOT list comprehensions, they're
handled in GHC.HsToCore.ListComp).  Basically does the translation given in the
Haskell 98 report:
-}

dsDo :: HsStmtContext GhcRn -> [ExprLStmt GhcTc] -> DsM CoreExpr
dsDo :: HsStmtContext GhcRn -> [ExprLStmt GhcTc] -> DsM CoreExpr
dsDo HsStmtContext GhcRn
ctx [ExprLStmt GhcTc]
stmts
  = [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> DsM CoreExpr
goL [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
[ExprLStmt GhcTc]
stmts
  where
    goL :: [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> DsM CoreExpr
goL [] = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsDo"
    goL ((L SrcSpan
loc StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
stmt):[Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
lstmts) = SrcSpan -> DsM CoreExpr -> DsM CoreExpr
forall a. SrcSpan -> DsM a -> DsM a
putSrcSpanDs SrcSpan
loc (SrcSpan
-> StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
-> [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> DsM CoreExpr
go SrcSpan
loc StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
stmt [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
lstmts)

    go :: SrcSpan
-> StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
-> [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> DsM CoreExpr
go SrcSpan
_ (LastStmt XLastStmt GhcTc GhcTc (Located (HsExpr GhcTc))
_ Located (HsExpr GhcTc)
body Maybe Bool
_ SyntaxExpr GhcTc
_) [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts
      = ASSERT( null stmts ) dsLExpr body
        -- The 'return' op isn't used for 'do' expressions

    go SrcSpan
_ (BodyStmt XBodyStmt GhcTc GhcTc (Located (HsExpr GhcTc))
_ Located (HsExpr GhcTc)
rhs SyntaxExpr GhcTc
then_expr SyntaxExpr GhcTc
_) [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts
      = do { CoreExpr
rhs2 <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr Located (HsExpr GhcTc)
LHsExpr GhcTc
rhs
           ; LHsExpr GhcTc -> Type -> IOEnv (Env DsGblEnv DsLclEnv) ()
warnDiscardedDoBindings Located (HsExpr GhcTc)
LHsExpr GhcTc
rhs (CoreExpr -> Type
exprType CoreExpr
rhs2)
           ; CoreExpr
rest <- [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> DsM CoreExpr
goL [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts
           ; SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr SyntaxExpr GhcTc
then_expr [CoreExpr
rhs2, CoreExpr
rest] }

    go SrcSpan
_ (LetStmt XLetStmt GhcTc GhcTc (Located (HsExpr GhcTc))
_ LHsLocalBinds GhcTc
binds) [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts
      = do { CoreExpr
rest <- [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> DsM CoreExpr
goL [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts
           ; LHsLocalBinds GhcTc -> CoreExpr -> DsM CoreExpr
dsLocalBinds LHsLocalBinds GhcTc
binds CoreExpr
rest }

    go SrcSpan
_ (BindStmt XBindStmt GhcTc GhcTc (Located (HsExpr GhcTc))
xbs LPat GhcTc
pat Located (HsExpr GhcTc)
rhs) [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts
      = do  { CoreExpr
body     <- [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> DsM CoreExpr
goL [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts
            ; CoreExpr
rhs'     <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr Located (HsExpr GhcTc)
LHsExpr GhcTc
rhs
            ; CoreBndr
var   <- Type -> LPat GhcTc -> DsM CoreBndr
selectSimpleMatchVarL (XBindStmtTc -> Type
xbstc_boundResultMult XBindStmtTc
XBindStmt GhcTc GhcTc (Located (HsExpr GhcTc))
xbs) LPat GhcTc
pat
            ; MatchResult CoreExpr
match <- CoreBndr
-> Maybe CoreExpr
-> HsMatchContext GhcRn
-> LPat GhcTc
-> Type
-> MatchResult CoreExpr
-> DsM (MatchResult CoreExpr)
matchSinglePatVar CoreBndr
var Maybe CoreExpr
forall a. Maybe a
Nothing (HsStmtContext GhcRn -> HsMatchContext GhcRn
forall p. HsStmtContext p -> HsMatchContext p
StmtCtxt HsStmtContext GhcRn
ctx) LPat GhcTc
pat
                         (XBindStmtTc -> Type
xbstc_boundResultType XBindStmtTc
XBindStmt GhcTc GhcTc (Located (HsExpr GhcTc))
xbs) (CoreExpr -> MatchResult CoreExpr
cantFailMatchResult CoreExpr
body)
            ; CoreExpr
match_code <- HsStmtContext GhcRn
-> LPat GhcTc
-> MatchResult CoreExpr
-> Maybe (SyntaxExpr GhcTc)
-> DsM CoreExpr
dsHandleMonadicFailure HsStmtContext GhcRn
ctx LPat GhcTc
pat MatchResult CoreExpr
match (XBindStmtTc -> Maybe (SyntaxExpr GhcTc)
xbstc_failOp XBindStmtTc
XBindStmt GhcTc GhcTc (Located (HsExpr GhcTc))
xbs)
            ; SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr (XBindStmtTc -> SyntaxExpr GhcTc
xbstc_bindOp XBindStmtTc
XBindStmt GhcTc GhcTc (Located (HsExpr GhcTc))
xbs) [CoreExpr
rhs', CoreBndr -> CoreExpr -> CoreExpr
forall b. b -> Expr b -> Expr b
Lam CoreBndr
var CoreExpr
match_code] }

    go SrcSpan
_ (ApplicativeStmt XApplicativeStmt GhcTc GhcTc (Located (HsExpr GhcTc))
body_ty [(SyntaxExpr GhcTc, ApplicativeArg GhcTc)]
args Maybe (SyntaxExpr GhcTc)
mb_join) [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts
      = do {
             let
               ([(GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc)]
pats, [DsM CoreExpr]
rhss) = [((GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc),
  DsM CoreExpr)]
-> ([(GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc)],
    [DsM CoreExpr])
forall a b. [(a, b)] -> ([a], [b])
unzip (((SyntaxExprTc, ApplicativeArg GhcTc)
 -> ((GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc),
     DsM CoreExpr))
-> [(SyntaxExprTc, ApplicativeArg GhcTc)]
-> [((GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc),
     DsM CoreExpr)]
forall a b. (a -> b) -> [a] -> [b]
map (ApplicativeArg GhcTc
-> ((GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc),
    DsM CoreExpr)
do_arg (ApplicativeArg GhcTc
 -> ((GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc),
     DsM CoreExpr))
-> ((SyntaxExprTc, ApplicativeArg GhcTc) -> ApplicativeArg GhcTc)
-> (SyntaxExprTc, ApplicativeArg GhcTc)
-> ((GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc),
    DsM CoreExpr)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (SyntaxExprTc, ApplicativeArg GhcTc) -> ApplicativeArg GhcTc
forall a b. (a, b) -> b
snd) [(SyntaxExprTc, ApplicativeArg GhcTc)]
[(SyntaxExpr GhcTc, ApplicativeArg GhcTc)]
args)

               do_arg :: ApplicativeArg GhcTc
-> ((GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc),
    DsM CoreExpr)
do_arg (ApplicativeArgOne XApplicativeArgOne GhcTc
fail_op LPat GhcTc
pat LHsExpr GhcTc
expr Bool
_) =
                 ((GenLocated SrcSpan (Pat GhcTc)
LPat GhcTc
pat, Maybe SyntaxExprTc
XApplicativeArgOne GhcTc
fail_op), LHsExpr GhcTc -> DsM CoreExpr
dsLExpr LHsExpr GhcTc
expr)
               do_arg (ApplicativeArgMany XApplicativeArgMany GhcTc
_ [ExprLStmt GhcTc]
stmts HsExpr GhcTc
ret LPat GhcTc
pat HsStmtContext GhcRn
_) =
                 ((GenLocated SrcSpan (Pat GhcTc)
LPat GhcTc
pat, Maybe SyntaxExprTc
forall a. Maybe a
Nothing), HsStmtContext GhcRn -> [ExprLStmt GhcTc] -> DsM CoreExpr
dsDo HsStmtContext GhcRn
ctx ([Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
[ExprLStmt GhcTc]
stmts [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
forall a. [a] -> [a] -> [a]
++ [StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
-> Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
forall e. e -> Located e
noLoc (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
 -> Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))))
-> StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
-> Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
forall a b. (a -> b) -> a -> b
$ Located (HsExpr GhcTc)
-> StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
forall (idR :: Pass) (bodyR :: * -> *) (idL :: Pass).
IsPass idR =>
Located (bodyR (GhcPass idR))
-> StmtLR
     (GhcPass idL) (GhcPass idR) (Located (bodyR (GhcPass idR)))
mkLastStmt (HsExpr GhcTc -> Located (HsExpr GhcTc)
forall e. e -> Located e
noLoc HsExpr GhcTc
ret)]))

           ; [CoreExpr]
rhss' <- [DsM CoreExpr] -> DsM [CoreExpr]
forall (t :: * -> *) (m :: * -> *) a.
(Traversable t, Monad m) =>
t (m a) -> m (t a)
sequence [DsM CoreExpr]
rhss

           ; CoreExpr
body' <- LHsExpr GhcTc -> DsM CoreExpr
dsLExpr (LHsExpr GhcTc -> DsM CoreExpr) -> LHsExpr GhcTc -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ HsExpr GhcTc -> Located (HsExpr GhcTc)
forall e. e -> Located e
noLoc (HsExpr GhcTc -> Located (HsExpr GhcTc))
-> HsExpr GhcTc -> Located (HsExpr GhcTc)
forall a b. (a -> b) -> a -> b
$ XDo GhcTc
-> HsStmtContext GhcRn
-> XRec GhcTc [ExprLStmt GhcTc]
-> HsExpr GhcTc
forall p.
XDo p -> HsStmtContext GhcRn -> XRec p [ExprLStmt p] -> HsExpr p
HsDo XApplicativeStmt GhcTc GhcTc (Located (HsExpr GhcTc))
XDo GhcTc
body_ty HsStmtContext GhcRn
ctx ([Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> Located [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
forall e. e -> Located e
noLoc [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts)

           ; let match_args :: (GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc)
-> ([CoreBndr], CoreExpr) -> DsM ([CoreBndr], CoreExpr)
match_args (GenLocated SrcSpan (Pat GhcTc)
pat, Maybe SyntaxExprTc
fail_op) ([CoreBndr]
vs,CoreExpr
body)
                   = do { CoreBndr
var   <- Type -> LPat GhcTc -> DsM CoreBndr
selectSimpleMatchVarL Type
Many GenLocated SrcSpan (Pat GhcTc)
LPat GhcTc
pat
                        ; MatchResult CoreExpr
match <- CoreBndr
-> Maybe CoreExpr
-> HsMatchContext GhcRn
-> LPat GhcTc
-> Type
-> MatchResult CoreExpr
-> DsM (MatchResult CoreExpr)
matchSinglePatVar CoreBndr
var Maybe CoreExpr
forall a. Maybe a
Nothing (HsStmtContext GhcRn -> HsMatchContext GhcRn
forall p. HsStmtContext p -> HsMatchContext p
StmtCtxt HsStmtContext GhcRn
ctx) GenLocated SrcSpan (Pat GhcTc)
LPat GhcTc
pat
                                   Type
XApplicativeStmt GhcTc GhcTc (Located (HsExpr GhcTc))
body_ty (CoreExpr -> MatchResult CoreExpr
cantFailMatchResult CoreExpr
body)
                        ; CoreExpr
match_code <- HsStmtContext GhcRn
-> LPat GhcTc
-> MatchResult CoreExpr
-> Maybe (SyntaxExpr GhcTc)
-> DsM CoreExpr
dsHandleMonadicFailure HsStmtContext GhcRn
ctx GenLocated SrcSpan (Pat GhcTc)
LPat GhcTc
pat MatchResult CoreExpr
match Maybe SyntaxExprTc
Maybe (SyntaxExpr GhcTc)
fail_op
                        ; ([CoreBndr], CoreExpr) -> DsM ([CoreBndr], CoreExpr)
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBndr
varCoreBndr -> [CoreBndr] -> [CoreBndr]
forall a. a -> [a] -> [a]
:[CoreBndr]
vs, CoreExpr
match_code)
                        }

           ; ([CoreBndr]
vars, CoreExpr
body) <- ((GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc)
 -> ([CoreBndr], CoreExpr) -> DsM ([CoreBndr], CoreExpr))
-> ([CoreBndr], CoreExpr)
-> [(GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc)]
-> DsM ([CoreBndr], CoreExpr)
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> b -> m b) -> b -> t a -> m b
foldrM (GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc)
-> ([CoreBndr], CoreExpr) -> DsM ([CoreBndr], CoreExpr)
match_args ([],CoreExpr
body') [(GenLocated SrcSpan (Pat GhcTc), Maybe SyntaxExprTc)]
pats
           ; let fun' :: CoreExpr
fun' = [CoreBndr] -> CoreExpr -> CoreExpr
forall b. [b] -> Expr b -> Expr b
mkLams [CoreBndr]
vars CoreExpr
body
           ; let mk_ap_call :: CoreExpr -> (SyntaxExprTc, CoreExpr) -> DsM CoreExpr
mk_ap_call CoreExpr
l (SyntaxExprTc
op,CoreExpr
r) = SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr SyntaxExprTc
SyntaxExpr GhcTc
op [CoreExpr
l,CoreExpr
r]
           ; CoreExpr
expr <- (CoreExpr -> (SyntaxExprTc, CoreExpr) -> DsM CoreExpr)
-> CoreExpr -> [(SyntaxExprTc, CoreExpr)] -> DsM CoreExpr
forall (t :: * -> *) (m :: * -> *) b a.
(Foldable t, Monad m) =>
(b -> a -> m b) -> b -> t a -> m b
foldlM CoreExpr -> (SyntaxExprTc, CoreExpr) -> DsM CoreExpr
mk_ap_call CoreExpr
fun' ([SyntaxExprTc] -> [CoreExpr] -> [(SyntaxExprTc, CoreExpr)]
forall a b. [a] -> [b] -> [(a, b)]
zip (((SyntaxExprTc, ApplicativeArg GhcTc) -> SyntaxExprTc)
-> [(SyntaxExprTc, ApplicativeArg GhcTc)] -> [SyntaxExprTc]
forall a b. (a -> b) -> [a] -> [b]
map (SyntaxExprTc, ApplicativeArg GhcTc) -> SyntaxExprTc
forall a b. (a, b) -> a
fst [(SyntaxExprTc, ApplicativeArg GhcTc)]
[(SyntaxExpr GhcTc, ApplicativeArg GhcTc)]
args) [CoreExpr]
rhss')
           ; case Maybe (SyntaxExpr GhcTc)
mb_join of
               Maybe (SyntaxExpr GhcTc)
Nothing -> CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return CoreExpr
expr
               Just SyntaxExpr GhcTc
join_op -> SyntaxExpr GhcTc -> [CoreExpr] -> DsM CoreExpr
dsSyntaxExpr SyntaxExpr GhcTc
join_op [CoreExpr
expr] }

    go SrcSpan
loc (RecStmt { recS_stmts :: forall idL idR body. StmtLR idL idR body -> [LStmtLR idL idR body]
recS_stmts = [LStmtLR GhcTc GhcTc (Located (HsExpr GhcTc))]
rec_stmts, recS_later_ids :: forall idL idR body. StmtLR idL idR body -> [IdP idR]
recS_later_ids = [IdP GhcTc]
later_ids
                    , recS_rec_ids :: forall idL idR body. StmtLR idL idR body -> [IdP idR]
recS_rec_ids = [IdP GhcTc]
rec_ids, recS_ret_fn :: forall idL idR body. StmtLR idL idR body -> SyntaxExpr idR
recS_ret_fn = SyntaxExpr GhcTc
return_op
                    , recS_mfix_fn :: forall idL idR body. StmtLR idL idR body -> SyntaxExpr idR
recS_mfix_fn = SyntaxExpr GhcTc
mfix_op, recS_bind_fn :: forall idL idR body. StmtLR idL idR body -> SyntaxExpr idR
recS_bind_fn = SyntaxExpr GhcTc
bind_op
                    , recS_ext :: forall idL idR body. StmtLR idL idR body -> XRecStmt idL idR body
recS_ext = RecStmtTc
                        { recS_bind_ty = bind_ty
                        , recS_rec_rets = rec_rets
                        , recS_ret_ty = body_ty} }) [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts
      = [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> DsM CoreExpr
goL (Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
new_bind_stmt Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
-> [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
forall a. a -> [a] -> [a]
: [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
stmts)  -- rec_ids can be empty; eg  rec { print 'x' }
      where
        new_bind_stmt :: Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
new_bind_stmt = SrcSpan
-> StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
-> Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
 -> Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))))
-> StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
-> Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
forall a b. (a -> b) -> a -> b
$ XBindStmt GhcTc GhcTc (Located (HsExpr GhcTc))
-> LPat GhcTc
-> Located (HsExpr GhcTc)
-> StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
forall idL idR body.
XBindStmt idL idR body -> LPat idL -> body -> StmtLR idL idR body
BindStmt
          XBindStmtTc :: SyntaxExpr GhcTc
-> Type -> Type -> Maybe (SyntaxExpr GhcTc) -> XBindStmtTc
XBindStmtTc
            { xbstc_bindOp :: SyntaxExpr GhcTc
xbstc_bindOp = SyntaxExpr GhcTc
bind_op
            , xbstc_boundResultType :: Type
xbstc_boundResultType = Type
bind_ty
            , xbstc_boundResultMult :: Type
xbstc_boundResultMult = Type
Many
            , xbstc_failOp :: Maybe (SyntaxExpr GhcTc)
xbstc_failOp = Maybe (SyntaxExpr GhcTc)
forall a. Maybe a
Nothing -- Tuple cannot fail
            }
          ([LPat GhcTc] -> LPat GhcTc
mkBigLHsPatTupId [GenLocated SrcSpan (Pat GhcTc)]
[LPat GhcTc]
later_pats)
          Located (HsExpr GhcTc)
LHsExpr GhcTc
mfix_app

        tup_ids :: [CoreBndr]
tup_ids      = [CoreBndr]
[IdP GhcTc]
rec_ids [CoreBndr] -> [CoreBndr] -> [CoreBndr]
forall a. [a] -> [a] -> [a]
++ (CoreBndr -> Bool) -> [CoreBndr] -> [CoreBndr]
forall a. (a -> Bool) -> [a] -> [a]
filterOut (CoreBndr -> [CoreBndr] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [CoreBndr]
[IdP GhcTc]
rec_ids) [CoreBndr]
[IdP GhcTc]
later_ids
        tup_ty :: Type
tup_ty       = [Type] -> Type
mkBigCoreTupTy ((CoreBndr -> Type) -> [CoreBndr] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map CoreBndr -> Type
idType [CoreBndr]
tup_ids) -- Deals with singleton case
        rec_tup_pats :: [GenLocated SrcSpan (Pat GhcTc)]
rec_tup_pats = (CoreBndr -> GenLocated SrcSpan (Pat GhcTc))
-> [CoreBndr] -> [GenLocated SrcSpan (Pat GhcTc)]
forall a b. (a -> b) -> [a] -> [b]
map CoreBndr -> GenLocated SrcSpan (Pat GhcTc)
forall (id :: Pass). IdP (GhcPass id) -> LPat (GhcPass id)
nlVarPat [CoreBndr]
tup_ids
        later_pats :: [GenLocated SrcSpan (Pat GhcTc)]
later_pats   = [GenLocated SrcSpan (Pat GhcTc)]
rec_tup_pats
        rets :: [Located (HsExpr GhcTc)]
rets         = (HsExpr GhcTc -> Located (HsExpr GhcTc))
-> [HsExpr GhcTc] -> [Located (HsExpr GhcTc)]
forall a b. (a -> b) -> [a] -> [b]
map HsExpr GhcTc -> Located (HsExpr GhcTc)
forall e. e -> Located e
noLoc [HsExpr GhcTc]
rec_rets
        mfix_app :: LHsExpr GhcTc
mfix_app     = SyntaxExprTc -> [LHsExpr GhcTc] -> LHsExpr GhcTc
nlHsSyntaxApps SyntaxExprTc
SyntaxExpr GhcTc
mfix_op [Located (HsExpr GhcTc)
LHsExpr GhcTc
mfix_arg]
        mfix_arg :: Located (HsExpr GhcTc)
mfix_arg     = HsExpr GhcTc -> Located (HsExpr GhcTc)
forall e. e -> Located e
noLoc (HsExpr GhcTc -> Located (HsExpr GhcTc))
-> HsExpr GhcTc -> Located (HsExpr GhcTc)
forall a b. (a -> b) -> a -> b
$ XLam GhcTc -> MatchGroup GhcTc (LHsExpr GhcTc) -> HsExpr GhcTc
forall p. XLam p -> MatchGroup p (LHsExpr p) -> HsExpr p
HsLam NoExtField
XLam GhcTc
noExtField
                           (MG :: forall p body.
XMG p body -> XRec p [LMatch p body] -> Origin -> MatchGroup p body
MG { mg_alts :: XRec GhcTc [LMatch GhcTc (Located (HsExpr GhcTc))]
mg_alts = [Located (Match GhcTc (Located (HsExpr GhcTc)))]
-> Located [Located (Match GhcTc (Located (HsExpr GhcTc)))]
forall e. e -> Located e
noLoc [HsMatchContext (NoGhcTc GhcTc)
-> [LPat GhcTc]
-> Located (HsExpr GhcTc)
-> LMatch GhcTc (Located (HsExpr GhcTc))
forall (p :: Pass) (body :: * -> *).
HsMatchContext (NoGhcTc (GhcPass p))
-> [LPat (GhcPass p)]
-> Located (body (GhcPass p))
-> LMatch (GhcPass p) (Located (body (GhcPass p)))
mkSimpleMatch
                                                    HsMatchContext (NoGhcTc GhcTc)
forall p. HsMatchContext p
LambdaExpr
                                                    [GenLocated SrcSpan (Pat GhcTc)
LPat GhcTc
mfix_pat] Located (HsExpr GhcTc)
body]
                               , mg_ext :: XMG GhcTc (Located (HsExpr GhcTc))
mg_ext = [Scaled Type] -> Type -> MatchGroupTc
MatchGroupTc [Type -> Scaled Type
forall a. a -> Scaled a
unrestricted Type
tup_ty] Type
body_ty
                               , mg_origin :: Origin
mg_origin = Origin
Generated })
        mfix_pat :: GenLocated SrcSpan (Pat GhcTc)
mfix_pat     = Pat GhcTc -> GenLocated SrcSpan (Pat GhcTc)
forall e. e -> Located e
noLoc (Pat GhcTc -> GenLocated SrcSpan (Pat GhcTc))
-> Pat GhcTc -> GenLocated SrcSpan (Pat GhcTc)
forall a b. (a -> b) -> a -> b
$ XLazyPat GhcTc -> LPat GhcTc -> Pat GhcTc
forall p. XLazyPat p -> LPat p -> Pat p
LazyPat NoExtField
XLazyPat GhcTc
noExtField (LPat GhcTc -> Pat GhcTc) -> LPat GhcTc -> Pat GhcTc
forall a b. (a -> b) -> a -> b
$ [LPat GhcTc] -> LPat GhcTc
mkBigLHsPatTupId [GenLocated SrcSpan (Pat GhcTc)]
[LPat GhcTc]
rec_tup_pats
        body :: Located (HsExpr GhcTc)
body         = HsExpr GhcTc -> Located (HsExpr GhcTc)
forall e. e -> Located e
noLoc (HsExpr GhcTc -> Located (HsExpr GhcTc))
-> HsExpr GhcTc -> Located (HsExpr GhcTc)
forall a b. (a -> b) -> a -> b
$ XDo GhcTc
-> HsStmtContext GhcRn
-> XRec GhcTc [ExprLStmt GhcTc]
-> HsExpr GhcTc
forall p.
XDo p -> HsStmtContext GhcRn -> XRec p [ExprLStmt p] -> HsExpr p
HsDo Type
XDo GhcTc
body_ty
                                HsStmtContext GhcRn
ctx ([Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> Located [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
forall e. e -> Located e
noLoc ([Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
[LStmtLR GhcTc GhcTc (Located (HsExpr GhcTc))]
rec_stmts [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
-> [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
forall a. [a] -> [a] -> [a]
++ [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
ret_stmt]))
        ret_app :: LHsExpr GhcTc
ret_app      = SyntaxExprTc -> [LHsExpr GhcTc] -> LHsExpr GhcTc
nlHsSyntaxApps SyntaxExprTc
SyntaxExpr GhcTc
return_op [[LHsExpr GhcTc] -> LHsExpr GhcTc
mkBigLHsTupId [Located (HsExpr GhcTc)]
[LHsExpr GhcTc]
rets]
        ret_stmt :: Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
ret_stmt     = StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
-> Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
forall e. e -> Located e
noLoc (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
 -> Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))))
-> StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
-> Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))
forall a b. (a -> b) -> a -> b
$ Located (HsExpr GhcTc)
-> StmtLR GhcTc GhcTc (Located (HsExpr GhcTc))
forall (idR :: Pass) (bodyR :: * -> *) (idL :: Pass).
IsPass idR =>
Located (bodyR (GhcPass idR))
-> StmtLR
     (GhcPass idL) (GhcPass idR) (Located (bodyR (GhcPass idR)))
mkLastStmt Located (HsExpr GhcTc)
LHsExpr GhcTc
ret_app
                     -- This LastStmt will be desugared with dsDo,
                     -- which ignores the return_op in the LastStmt,
                     -- so we must apply the return_op explicitly

    go SrcSpan
_ (ParStmt   {}) [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
_ = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsDo ParStmt"
    go SrcSpan
_ (TransStmt {}) [Located (StmtLR GhcTc GhcTc (Located (HsExpr GhcTc)))]
_ = String -> DsM CoreExpr
forall a. String -> a
panic String
"dsDo TransStmt"

{-
************************************************************************
*                                                                      *
   Desugaring Variables
*                                                                      *
************************************************************************
-}

dsHsVar :: Id -> DsM CoreExpr
dsHsVar :: CoreBndr -> DsM CoreExpr
dsHsVar CoreBndr
var
  | let bad_tys :: [Type]
bad_tys = CoreBndr -> Type -> [Type]
badUseOfLevPolyPrimop CoreBndr
var Type
ty
  , Bool -> Bool
not ([Type] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Type]
bad_tys)
  = do { SDoc -> Type -> [Type] -> IOEnv (Env DsGblEnv DsLclEnv) ()
levPolyPrimopErr (CoreBndr -> SDoc
forall a. Outputable a => a -> SDoc
ppr CoreBndr
var) Type
ty [Type]
bad_tys
       ; CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return CoreExpr
unitExpr }  -- return something eminently safe

  | Bool
otherwise
  = CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
varToCoreExpr CoreBndr
var)   -- See Note [Desugaring vars]
  where
    ty :: Type
ty = CoreBndr -> Type
idType CoreBndr
var

dsConLike :: ConLike -> DsM CoreExpr
dsConLike :: ConLike -> DsM CoreExpr
dsConLike (RealDataCon DataCon
dc) = CoreBndr -> DsM CoreExpr
dsHsVar (DataCon -> CoreBndr
dataConWrapId DataCon
dc)
dsConLike (PatSynCon PatSyn
ps)   = CoreExpr -> DsM CoreExpr
forall (m :: * -> *) a. Monad m => a -> m a
return (CoreExpr -> DsM CoreExpr) -> CoreExpr -> DsM CoreExpr
forall a b. (a -> b) -> a -> b
$ case PatSyn -> Maybe (CoreBndr, Bool)
patSynBuilder PatSyn
ps of
  Just (CoreBndr
id, Bool
add_void)
    | Bool
add_void  -> SDoc -> CoreExpr -> CoreExpr -> CoreExpr
mkCoreApp (String -> SDoc
text String
"dsConLike" SDoc -> SDoc -> SDoc
<+> PatSyn -> SDoc
forall a. Outputable a => a -> SDoc
ppr PatSyn
ps) (CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
id) (CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
voidPrimId)
    | Bool
otherwise -> CoreBndr -> CoreExpr
forall b. CoreBndr -> Expr b
Var CoreBndr
id
  Maybe (CoreBndr, Bool)
_ -> String -> SDoc -> CoreExpr
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"dsConLike" (PatSyn -> SDoc
forall a. Outputable a => a -> SDoc
ppr PatSyn
ps)

{-
************************************************************************
*                                                                      *
\subsection{Errors and contexts}
*                                                                      *
************************************************************************
-}

-- Warn about certain types of values discarded in monadic bindings (#3263)
warnDiscardedDoBindings :: LHsExpr GhcTc -> Type -> DsM ()
warnDiscardedDoBindings :: LHsExpr GhcTc -> Type -> IOEnv (Env DsGblEnv DsLclEnv) ()
warnDiscardedDoBindings LHsExpr GhcTc
rhs Type
rhs_ty
  | Just (Type
m_ty, Type
elt_ty) <- Type -> Maybe (Type, Type)
tcSplitAppTy_maybe Type
rhs_ty
  = do { Bool
warn_unused <- WarningFlag -> TcRnIf DsGblEnv DsLclEnv Bool
forall gbl lcl. WarningFlag -> TcRnIf gbl lcl Bool
woptM WarningFlag
Opt_WarnUnusedDoBind
       ; Bool
warn_wrong <- WarningFlag -> TcRnIf DsGblEnv DsLclEnv Bool
forall gbl lcl. WarningFlag -> TcRnIf gbl lcl Bool
woptM WarningFlag
Opt_WarnWrongDoBind
       ; Bool
-> IOEnv (Env DsGblEnv DsLclEnv) ()
-> IOEnv (Env DsGblEnv DsLclEnv) ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when (Bool
warn_unused Bool -> Bool -> Bool
|| Bool
warn_wrong) (IOEnv (Env DsGblEnv DsLclEnv) ()
 -> IOEnv (Env DsGblEnv DsLclEnv) ())
-> IOEnv (Env DsGblEnv DsLclEnv) ()
-> IOEnv (Env DsGblEnv DsLclEnv) ()
forall a b. (a -> b) -> a -> b
$
    do { FamInstEnvs
fam_inst_envs <- DsM FamInstEnvs
dsGetFamInstEnvs
       ; let norm_elt_ty :: Type
norm_elt_ty = FamInstEnvs -> Type -> Type
topNormaliseType FamInstEnvs
fam_inst_envs Type
elt_ty

           -- Warn about discarding non-() things in 'monadic' binding
       ; if Bool
warn_unused Bool -> Bool -> Bool
&& Bool -> Bool
not (Type -> Bool
isUnitTy Type
norm_elt_ty)
         then WarnReason -> SDoc -> IOEnv (Env DsGblEnv DsLclEnv) ()
warnDs (WarningFlag -> WarnReason
Reason WarningFlag
Opt_WarnUnusedDoBind)
                     (LHsExpr GhcTc -> Type -> SDoc
badMonadBind LHsExpr GhcTc
rhs Type
elt_ty)
         else

           -- Warn about discarding m a things in 'monadic' binding of the same type,
           -- but only if we didn't already warn due to Opt_WarnUnusedDoBind
           Bool
-> IOEnv (Env DsGblEnv DsLclEnv) ()
-> IOEnv (Env DsGblEnv DsLclEnv) ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when Bool
warn_wrong (IOEnv (Env DsGblEnv DsLclEnv) ()
 -> IOEnv (Env DsGblEnv DsLclEnv) ())
-> IOEnv (Env DsGblEnv DsLclEnv) ()
-> IOEnv (Env DsGblEnv DsLclEnv) ()
forall a b. (a -> b) -> a -> b
$
                case Type -> Maybe (Type, Type)
tcSplitAppTy_maybe Type
norm_elt_ty of
                      Just (Type
elt_m_ty, Type
_)
                         | Type
m_ty Type -> Type -> Bool
`eqType` FamInstEnvs -> Type -> Type
topNormaliseType FamInstEnvs
fam_inst_envs Type
elt_m_ty
                         -> WarnReason -> SDoc -> IOEnv (Env DsGblEnv DsLclEnv) ()
warnDs (WarningFlag -> WarnReason
Reason WarningFlag
Opt_WarnWrongDoBind)
                                   (LHsExpr GhcTc -> Type -> SDoc
badMonadBind LHsExpr GhcTc
rhs Type
elt_ty)
                      Maybe (Type, Type)
_ -> () -> IOEnv (Env DsGblEnv DsLclEnv) ()
forall (m :: * -> *) a. Monad m => a -> m a
return () } }

  | Bool
otherwise   -- RHS does have type of form (m ty), which is weird
  = () -> IOEnv (Env DsGblEnv DsLclEnv) ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()   -- but at least this warning is irrelevant

badMonadBind :: LHsExpr GhcTc -> Type -> SDoc
badMonadBind :: LHsExpr GhcTc -> Type -> SDoc
badMonadBind LHsExpr GhcTc
rhs Type
elt_ty
  = [SDoc] -> SDoc
vcat [ SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"A do-notation statement discarded a result of type")
              Int
2 (SDoc -> SDoc
quotes (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
elt_ty))
         , SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Suppress this warning by saying")
              Int
2 (SDoc -> SDoc
quotes (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ String -> SDoc
text String
"_ <-" SDoc -> SDoc -> SDoc
<+> Located (HsExpr GhcTc) -> SDoc
forall a. Outputable a => a -> SDoc
ppr Located (HsExpr GhcTc)
LHsExpr GhcTc
rhs)
         ]

{-
************************************************************************
*                                                                      *
   Forced eta expansion and levity polymorphism
*                                                                      *
************************************************************************

Note [Detecting forced eta expansion]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We cannot have levity polymorphic function arguments. See
Note [Levity polymorphism invariants] in GHC.Core. But we *can* have
functions that take levity polymorphic arguments, as long as these
functions are eta-reduced. (See #12708 for an example.)

However, we absolutely cannot do this for functions that have no
binding (i.e., say True to Id.hasNoBinding), like primops and unboxed
tuple constructors. These get eta-expanded in CorePrep.maybeSaturate.

Detecting when this is about to happen is a bit tricky, though. When
the desugarer is looking at the Id itself (let's be concrete and
suppose we have (#,#)), we don't know whether it will be levity
polymorphic. So the right spot seems to be to look after the Id has
been applied to its type arguments. To make the algorithm efficient,
it's important to be able to spot ((#,#) @a @b @c @d) without looking
past all the type arguments. We thus require that
  * The body of an HsWrap is not an HsWrap, nor an HsPar.
This invariant is checked in dsExpr.
With that representation invariant, we simply look inside every HsWrap
to see if its body is an HsVar whose Id hasNoBinding. Then, we look
at the wrapped type. If it has any levity polymorphic arguments, reject.
Because we might have an HsVar without a wrapper, we check in dsHsVar
as well. typecheck/should_fail/T17021 triggers this case.

Interestingly, this approach does not look to see whether the Id in
question will be eta expanded. The logic is this:
  * Either the Id in question is saturated or not.
  * If it is, then it surely can't have levity polymorphic arguments.
    If its wrapped type contains levity polymorphic arguments, reject.
  * If it's not, then it can't be eta expanded with levity polymorphic
    argument. If its wrapped type contains levity polymorphic arguments, reject.
So, either way, we're good to reject.

-}

-- | Takes an expression and its instantiated type. If the expression is an
-- HsVar with a hasNoBinding primop and the type has levity-polymorphic arguments,
-- issue an error. See Note [Detecting forced eta expansion]
checkForcedEtaExpansion :: HsExpr GhcTc -> SDoc -> Type -> DsM ()
checkForcedEtaExpansion :: HsExpr GhcTc -> SDoc -> Type -> IOEnv (Env DsGblEnv DsLclEnv) ()
checkForcedEtaExpansion HsExpr GhcTc
expr SDoc
expr_doc Type
ty
  | Just CoreBndr
var <- case HsExpr GhcTc
expr of
                  HsVar XVar GhcTc
_ (L _ var)               -> CoreBndr -> Maybe CoreBndr
forall a. a -> Maybe a
Just CoreBndr
var
                  HsConLikeOut XConLikeOut GhcTc
_ (RealDataCon DataCon
dc) -> CoreBndr -> Maybe CoreBndr
forall a. a -> Maybe a
Just (DataCon -> CoreBndr
dataConWrapId DataCon
dc)
                  HsExpr GhcTc
_                               -> Maybe CoreBndr
forall a. Maybe a
Nothing
  , let bad_tys :: [Type]
bad_tys = CoreBndr -> Type -> [Type]
badUseOfLevPolyPrimop CoreBndr
var Type
ty
  , Bool -> Bool
not ([Type] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Type]
bad_tys)
  = SDoc -> Type -> [Type] -> IOEnv (Env DsGblEnv DsLclEnv) ()
levPolyPrimopErr SDoc
expr_doc Type
ty [Type]
bad_tys
checkForcedEtaExpansion HsExpr GhcTc
_ SDoc
_ Type
_ = () -> IOEnv (Env DsGblEnv DsLclEnv) ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()

-- | Is this a hasNoBinding Id with a levity-polymorphic type?
-- Returns the arguments that are levity polymorphic if they are bad;
-- or an empty list otherwise
-- See Note [Detecting forced eta expansion]
badUseOfLevPolyPrimop :: Id -> Type -> [Type]
badUseOfLevPolyPrimop :: CoreBndr -> Type -> [Type]
badUseOfLevPolyPrimop CoreBndr
id Type
ty
  | CoreBndr -> Bool
hasNoBinding CoreBndr
id
  = (Type -> Bool) -> [Type] -> [Type]
forall a. (a -> Bool) -> [a] -> [a]
filter Type -> Bool
isTypeLevPoly [Type]
arg_tys
  | Bool
otherwise
  = []
  where
    ([TyCoBinder]
binders, Type
_) = Type -> ([TyCoBinder], Type)
splitPiTys Type
ty
    arg_tys :: [Type]
arg_tys      = (TyCoBinder -> Maybe Type) -> [TyCoBinder] -> [Type]
forall a b. (a -> Maybe b) -> [a] -> [b]
mapMaybe TyCoBinder -> Maybe Type
binderRelevantType_maybe [TyCoBinder]
binders

levPolyPrimopErr :: SDoc -> Type -> [Type] -> DsM ()
levPolyPrimopErr :: SDoc -> Type -> [Type] -> IOEnv (Env DsGblEnv DsLclEnv) ()
levPolyPrimopErr SDoc
expr_doc Type
ty [Type]
bad_tys
  = SDoc -> IOEnv (Env DsGblEnv DsLclEnv) ()
errDs (SDoc -> IOEnv (Env DsGblEnv DsLclEnv) ())
-> SDoc -> IOEnv (Env DsGblEnv DsLclEnv) ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
vcat
    [ SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Cannot use function with levity-polymorphic arguments:")
         Int
2 (SDoc
expr_doc SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
pprWithTYPE Type
ty)
    , (SDocContext -> Bool) -> SDoc -> SDoc
ppUnlessOption SDocContext -> Bool
sdocPrintTypecheckerElaboration (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
vcat
        [ String -> SDoc
text String
"(Note that levity-polymorphic primops such as 'coerce' and unboxed tuples"
        , String -> SDoc
text String
"are eta-expanded internally because they must occur fully saturated."
        , String -> SDoc
text String
"Use -fprint-typechecker-elaboration to display the full expression.)"
        ]
    , SDoc -> Int -> SDoc -> SDoc
hang (String -> SDoc
text String
"Levity-polymorphic arguments:")
         Int
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
vcat ([SDoc] -> SDoc) -> [SDoc] -> SDoc
forall a b. (a -> b) -> a -> b
$ (Type -> SDoc) -> [Type] -> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map
           (\Type
t -> Type -> SDoc
pprWithTYPE Type
t SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
pprWithTYPE (HasDebugCallStack => Type -> Type
Type -> Type
typeKind Type
t))
           [Type]
bad_tys
    ]