{-# LANGUAGE CPP                 #-}
{-# LANGUAGE FlexibleContexts    #-}
{-# LANGUAGE RankNTypes          #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies        #-}

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

-}

module GHC.Tc.Gen.Bind
   ( tcLocalBinds
   , tcTopBinds
   , tcValBinds
   , tcHsBootSigs
   , tcPolyCheck
   , chooseInferredQuantifiers
   , badBootDeclErr
   )
where

import GHC.Prelude

import {-# SOURCE #-} GHC.Tc.Gen.Match ( tcGRHSsPat, tcMatchesFun )
import {-# SOURCE #-} GHC.Tc.Gen.Expr  ( tcCheckMonoExpr )
import {-# SOURCE #-} GHC.Tc.TyCl.PatSyn ( tcPatSynDecl, tcPatSynBuilderBind )

import GHC.Core (Tickish (..))
import GHC.Types.CostCentre (mkUserCC, CCFlavour(DeclCC))
import GHC.Driver.Session
import GHC.Data.FastString
import GHC.Hs
import GHC.Tc.Gen.Sig
import GHC.Tc.Utils.Monad
import GHC.Tc.Types.Origin
import GHC.Tc.Utils.Env
import GHC.Tc.Utils.Unify
import GHC.Tc.Solver
import GHC.Tc.Types.Evidence
import GHC.Tc.Gen.HsType
import GHC.Tc.Gen.Pat
import GHC.Tc.Utils.TcMType
import GHC.Core.Multiplicity
import GHC.Core.FamInstEnv( normaliseType )
import GHC.Tc.Instance.Family( tcGetFamInstEnvs )
import GHC.Tc.Utils.TcType
import GHC.Core.Type (mkStrLitTy, tidyOpenType, mkCastTy)
import GHC.Builtin.Types.Prim
import GHC.Builtin.Types( mkBoxedTupleTy )
import GHC.Types.SourceText
import GHC.Types.Id
import GHC.Types.Var as Var
import GHC.Types.Var.Set
import GHC.Types.Var.Env( TidyEnv )
import GHC.Unit.Module
import GHC.Types.Name
import GHC.Types.Name.Set
import GHC.Types.Name.Env
import GHC.Types.SrcLoc
import GHC.Data.Bag
import GHC.Utils.Error
import GHC.Data.Graph.Directed
import GHC.Data.Maybe
import GHC.Utils.Misc
import GHC.Types.Basic
import GHC.Utils.Outputable as Outputable
import GHC.Utils.Panic
import GHC.Builtin.Names( ipClassName )
import GHC.Tc.Validity (checkValidType)
import GHC.Types.Unique.FM
import GHC.Types.Unique.DSet
import GHC.Types.Unique.Set
import qualified GHC.LanguageExtensions as LangExt

import Control.Monad
import Data.Foldable (find)

#include "GhclibHsVersions.h"

{-
************************************************************************
*                                                                      *
\subsection{Type-checking bindings}
*                                                                      *
************************************************************************

@tcBindsAndThen@ typechecks a @HsBinds@.  The "and then" part is because
it needs to know something about the {\em usage} of the things bound,
so that it can create specialisations of them.  So @tcBindsAndThen@
takes a function which, given an extended environment, E, typechecks
the scope of the bindings returning a typechecked thing and (most
important) an LIE.  It is this LIE which is then used as the basis for
specialising the things bound.

@tcBindsAndThen@ also takes a "combiner" which glues together the
bindings and the "thing" to make a new "thing".

The real work is done by @tcBindWithSigsAndThen@.

Recursive and non-recursive binds are handled in essentially the same
way: because of uniques there are no scoping issues left.  The only
difference is that non-recursive bindings can bind primitive values.

Even for non-recursive binding groups we add typings for each binder
to the LVE for the following reason.  When each individual binding is
checked the type of its LHS is unified with that of its RHS; and
type-checking the LHS of course requires that the binder is in scope.

At the top-level the LIE is sure to contain nothing but constant
dictionaries, which we resolve at the module level.

Note [Polymorphic recursion]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The game plan for polymorphic recursion in the code above is

        * Bind any variable for which we have a type signature
          to an Id with a polymorphic type.  Then when type-checking
          the RHSs we'll make a full polymorphic call.

This fine, but if you aren't a bit careful you end up with a horrendous
amount of partial application and (worse) a huge space leak. For example:

        f :: Eq a => [a] -> [a]
        f xs = ...f...

If we don't take care, after typechecking we get

        f = /\a -> \d::Eq a -> let f' = f a d
                               in
                               \ys:[a] -> ...f'...

Notice the stupid construction of (f a d), which is of course
identical to the function we're executing.  In this case, the
polymorphic recursion isn't being used (but that's a very common case).
This can lead to a massive space leak, from the following top-level defn
(post-typechecking)

        ff :: [Int] -> [Int]
        ff = f Int dEqInt

Now (f dEqInt) evaluates to a lambda that has f' as a free variable; but
f' is another thunk which evaluates to the same thing... and you end
up with a chain of identical values all hung onto by the CAF ff.

        ff = f Int dEqInt

           = let f' = f Int dEqInt in \ys. ...f'...

           = let f' = let f' = f Int dEqInt in \ys. ...f'...
                      in \ys. ...f'...

Etc.

NOTE: a bit of arity analysis would push the (f a d) inside the (\ys...),
which would make the space leak go away in this case

Solution: when typechecking the RHSs we always have in hand the
*monomorphic* Ids for each binding.  So we just need to make sure that
if (Method f a d) shows up in the constraints emerging from (...f...)
we just use the monomorphic Id.  We achieve this by adding monomorphic Ids
to the "givens" when simplifying constraints.  That's what the "lies_avail"
is doing.

Then we get

        f = /\a -> \d::Eq a -> letrec
                                 fm = \ys:[a] -> ...fm...
                               in
                               fm
-}

tcTopBinds :: [(RecFlag, LHsBinds GhcRn)] -> [LSig GhcRn]
           -> TcM (TcGblEnv, TcLclEnv)
-- The TcGblEnv contains the new tcg_binds and tcg_spects
-- The TcLclEnv has an extended type envt for the new bindings
tcTopBinds :: [(RecFlag, LHsBinds GhcRn)]
-> [LSig GhcRn] -> TcM (TcGblEnv, TcLclEnv)
tcTopBinds [(RecFlag, LHsBinds GhcRn)]
binds [LSig GhcRn]
sigs
  = do  { -- Pattern synonym bindings populate the global environment
          ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
binds', (TcGblEnv
tcg_env, TcLclEnv
tcl_env)) <- TopLevelFlag
-> [(RecFlag, LHsBinds GhcRn)]
-> [LSig GhcRn]
-> TcM (TcGblEnv, TcLclEnv)
-> TcM ([(RecFlag, LHsBinds GhcTc)], (TcGblEnv, TcLclEnv))
forall thing.
TopLevelFlag
-> [(RecFlag, LHsBinds GhcRn)]
-> [LSig GhcRn]
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
tcValBinds TopLevelFlag
TopLevel [(RecFlag, LHsBinds GhcRn)]
binds [LSig GhcRn]
sigs (TcM (TcGblEnv, TcLclEnv)
 -> TcM ([(RecFlag, LHsBinds GhcTc)], (TcGblEnv, TcLclEnv)))
-> TcM (TcGblEnv, TcLclEnv)
-> TcM ([(RecFlag, LHsBinds GhcTc)], (TcGblEnv, TcLclEnv))
forall a b. (a -> b) -> a -> b
$
            do { TcGblEnv
gbl <- TcRnIf TcGblEnv TcLclEnv TcGblEnv
forall gbl lcl. TcRnIf gbl lcl gbl
getGblEnv
               ; TcLclEnv
lcl <- TcRnIf TcGblEnv TcLclEnv TcLclEnv
forall gbl lcl. TcRnIf gbl lcl lcl
getLclEnv
               ; (TcGblEnv, TcLclEnv) -> TcM (TcGblEnv, TcLclEnv)
forall (m :: * -> *) a. Monad m => a -> m a
return (TcGblEnv
gbl, TcLclEnv
lcl) }
        ; [LTcSpecPrag]
specs <- [LSig GhcRn] -> TcM [LTcSpecPrag]
tcImpPrags [LSig GhcRn]
sigs   -- SPECIALISE prags for imported Ids

        ; [CompleteMatch]
complete_matches <- (TcGblEnv, TcLclEnv)
-> TcRnIf TcGblEnv TcLclEnv [CompleteMatch]
-> TcRnIf TcGblEnv TcLclEnv [CompleteMatch]
forall gbl' lcl' a gbl lcl.
(gbl', lcl') -> TcRnIf gbl' lcl' a -> TcRnIf gbl lcl a
setEnvs (TcGblEnv
tcg_env, TcLclEnv
tcl_env) (TcRnIf TcGblEnv TcLclEnv [CompleteMatch]
 -> TcRnIf TcGblEnv TcLclEnv [CompleteMatch])
-> TcRnIf TcGblEnv TcLclEnv [CompleteMatch]
-> TcRnIf TcGblEnv TcLclEnv [CompleteMatch]
forall a b. (a -> b) -> a -> b
$ [LSig GhcRn] -> TcRnIf TcGblEnv TcLclEnv [CompleteMatch]
tcCompleteSigs [LSig GhcRn]
sigs
        ; String -> SDoc -> TcRn ()
traceTc String
"complete_matches" ([(RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))]
[(RecFlag, LHsBinds GhcRn)]
binds SDoc -> SDoc -> SDoc
$$ [Located (Sig GhcRn)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Located (Sig GhcRn)]
[LSig GhcRn]
sigs)
        ; String -> SDoc -> TcRn ()
traceTc String
"complete_matches" ([CompleteMatch] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [CompleteMatch]
complete_matches)

        ; let { tcg_env' :: TcGblEnv
tcg_env' = TcGblEnv
tcg_env { tcg_imp_specs :: [LTcSpecPrag]
tcg_imp_specs
                                      = [LTcSpecPrag]
specs [LTcSpecPrag] -> [LTcSpecPrag] -> [LTcSpecPrag]
forall a. [a] -> [a] -> [a]
++ TcGblEnv -> [LTcSpecPrag]
tcg_imp_specs TcGblEnv
tcg_env
                                   , tcg_complete_matches :: [CompleteMatch]
tcg_complete_matches
                                      = [CompleteMatch]
complete_matches
                                          [CompleteMatch] -> [CompleteMatch] -> [CompleteMatch]
forall a. [a] -> [a] -> [a]
++ TcGblEnv -> [CompleteMatch]
tcg_complete_matches TcGblEnv
tcg_env }
                           TcGblEnv -> [LHsBinds GhcTc] -> TcGblEnv
`addTypecheckedBinds` ((RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))
 -> Bag (Located (HsBindLR GhcTc GhcTc)))
-> [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
-> [Bag (Located (HsBindLR GhcTc GhcTc))]
forall a b. (a -> b) -> [a] -> [b]
map (RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a b. (a, b) -> b
snd [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
binds' }

        ; (TcGblEnv, TcLclEnv) -> TcM (TcGblEnv, TcLclEnv)
forall (m :: * -> *) a. Monad m => a -> m a
return (TcGblEnv
tcg_env', TcLclEnv
tcl_env) }
        -- The top level bindings are flattened into a giant
        -- implicitly-mutually-recursive LHsBinds

tcCompleteSigs  :: [LSig GhcRn] -> TcM [CompleteMatch]
tcCompleteSigs :: [LSig GhcRn] -> TcRnIf TcGblEnv TcLclEnv [CompleteMatch]
tcCompleteSigs [LSig GhcRn]
sigs =
  let
      doOne :: LSig GhcRn -> TcM (Maybe CompleteMatch)
      -- We don't need to "type-check" COMPLETE signatures anymore; if their
      -- combinations are invalid it will be found so at match sites. Hence we
      -- keep '_mtc' only for backwards compatibility.
      doOne :: LSig GhcRn -> TcM (Maybe CompleteMatch)
doOne (L loc c@(CompleteMatchSig _ext _src_txt (L _ ns) _mtc))
        = (CompleteMatch -> Maybe CompleteMatch)
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
-> TcM (Maybe CompleteMatch)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap CompleteMatch -> Maybe CompleteMatch
forall a. a -> Maybe a
Just (IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
 -> TcM (Maybe CompleteMatch))
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
-> TcM (Maybe CompleteMatch)
forall a b. (a -> b) -> a -> b
$ SrcSpan
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc (IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
 -> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch)
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
forall a b. (a -> b) -> a -> b
$ SDoc
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (String -> SDoc
text String
"In" SDoc -> SDoc -> SDoc
<+> Sig GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr Sig GhcRn
c) (IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
 -> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch)
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
forall a b. (a -> b) -> a -> b
$
            [ConLike] -> CompleteMatch
forall a. Uniquable a => [a] -> UniqDSet a
mkUniqDSet ([ConLike] -> CompleteMatch)
-> IOEnv (Env TcGblEnv TcLclEnv) [ConLike]
-> IOEnv (Env TcGblEnv TcLclEnv) CompleteMatch
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> (Located Name -> IOEnv (Env TcGblEnv TcLclEnv) ConLike)
-> [Located Name] -> IOEnv (Env TcGblEnv TcLclEnv) [ConLike]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((Name -> IOEnv (Env TcGblEnv TcLclEnv) ConLike)
-> Located Name -> IOEnv (Env TcGblEnv TcLclEnv) ConLike
forall a b. (a -> TcM b) -> Located a -> TcM b
addLocM Name -> IOEnv (Env TcGblEnv TcLclEnv) ConLike
tcLookupConLike) [Located Name]
ns
      doOne LSig GhcRn
_ = Maybe CompleteMatch -> TcM (Maybe CompleteMatch)
forall (m :: * -> *) a. Monad m => a -> m a
return Maybe CompleteMatch
forall a. Maybe a
Nothing

  -- For some reason I haven't investigated further, the signatures come in
  -- backwards wrt. declaration order. So we reverse them here, because it makes
  -- a difference for incomplete match suggestions.
  in (Located (Sig GhcRn) -> TcM (Maybe CompleteMatch))
-> [Located (Sig GhcRn)]
-> TcRnIf TcGblEnv TcLclEnv [CompleteMatch]
forall (m :: * -> *) a b.
Applicative m =>
(a -> m (Maybe b)) -> [a] -> m [b]
mapMaybeM Located (Sig GhcRn) -> TcM (Maybe CompleteMatch)
LSig GhcRn -> TcM (Maybe CompleteMatch)
doOne ([Located (Sig GhcRn)] -> TcRnIf TcGblEnv TcLclEnv [CompleteMatch])
-> [Located (Sig GhcRn)]
-> TcRnIf TcGblEnv TcLclEnv [CompleteMatch]
forall a b. (a -> b) -> a -> b
$ [Located (Sig GhcRn)] -> [Located (Sig GhcRn)]
forall a. [a] -> [a]
reverse [Located (Sig GhcRn)]
[LSig GhcRn]
sigs

tcHsBootSigs :: [(RecFlag, LHsBinds GhcRn)] -> [LSig GhcRn] -> TcM [Id]
-- A hs-boot file has only one BindGroup, and it only has type
-- signatures in it.  The renamer checked all this
tcHsBootSigs :: [(RecFlag, LHsBinds GhcRn)] -> [LSig GhcRn] -> TcM [Id]
tcHsBootSigs [(RecFlag, LHsBinds GhcRn)]
binds [LSig GhcRn]
sigs
  = do  { Bool -> SDoc -> TcRn ()
checkTc ([(RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [(RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))]
[(RecFlag, LHsBinds GhcRn)]
binds) SDoc
badBootDeclErr
        ; (Located (Sig GhcRn) -> TcM [Id])
-> [Located (Sig GhcRn)] -> TcM [Id]
forall (m :: * -> *) a b. Monad m => (a -> m [b]) -> [a] -> m [b]
concatMapM ((Sig GhcRn -> TcM [Id]) -> Located (Sig GhcRn) -> TcM [Id]
forall a b. (a -> TcM b) -> Located a -> TcM b
addLocM Sig GhcRn -> TcM [Id]
tc_boot_sig) ((Located (Sig GhcRn) -> Bool)
-> [Located (Sig GhcRn)] -> [Located (Sig GhcRn)]
forall a. (a -> Bool) -> [a] -> [a]
filter Located (Sig GhcRn) -> Bool
forall p. UnXRec p => LSig p -> Bool
isTypeLSig [Located (Sig GhcRn)]
[LSig GhcRn]
sigs) }
  where
    tc_boot_sig :: Sig GhcRn -> TcM [Id]
tc_boot_sig (TypeSig XTypeSig GhcRn
_ [LIdP GhcRn]
lnames LHsSigWcType GhcRn
hs_ty) = (Located Name -> IOEnv (Env TcGblEnv TcLclEnv) Id)
-> [Located Name] -> TcM [Id]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Located Name -> IOEnv (Env TcGblEnv TcLclEnv) Id
f [Located Name]
[LIdP GhcRn]
lnames
      where
        f :: Located Name -> IOEnv (Env TcGblEnv TcLclEnv) Id
f (L SrcSpan
_ Name
name)
          = do { Type
sigma_ty <- UserTypeCtxt -> LHsSigWcType GhcRn -> TcM Type
tcHsSigWcType (Name -> Bool -> UserTypeCtxt
FunSigCtxt Name
name Bool
False) LHsSigWcType GhcRn
hs_ty
               ; Id -> IOEnv (Env TcGblEnv TcLclEnv) Id
forall (m :: * -> *) a. Monad m => a -> m a
return (Name -> Type -> Id
mkVanillaGlobal Name
name Type
sigma_ty) }
        -- Notice that we make GlobalIds, not LocalIds
    tc_boot_sig Sig GhcRn
s = String -> SDoc -> TcM [Id]
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tcHsBootSigs/tc_boot_sig" (Sig GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr Sig GhcRn
s)

badBootDeclErr :: MsgDoc
badBootDeclErr :: SDoc
badBootDeclErr = String -> SDoc
text String
"Illegal declarations in an hs-boot file"

------------------------
tcLocalBinds :: HsLocalBinds GhcRn -> TcM thing
             -> TcM (HsLocalBinds GhcTc, thing)

tcLocalBinds :: HsLocalBinds GhcRn -> TcM thing -> TcM (HsLocalBinds GhcTc, thing)
tcLocalBinds (EmptyLocalBinds XEmptyLocalBinds GhcRn GhcRn
x) TcM thing
thing_inside
  = do  { thing
thing <- TcM thing
thing_inside
        ; (HsLocalBinds GhcTc, thing) -> TcM (HsLocalBinds GhcTc, thing)
forall (m :: * -> *) a. Monad m => a -> m a
return (XEmptyLocalBinds GhcTc GhcTc -> HsLocalBinds GhcTc
forall idL idR. XEmptyLocalBinds idL idR -> HsLocalBindsLR idL idR
EmptyLocalBinds XEmptyLocalBinds GhcRn GhcRn
XEmptyLocalBinds GhcTc GhcTc
x, thing
thing) }

tcLocalBinds (HsValBinds XHsValBinds GhcRn GhcRn
x (XValBindsLR (NValBinds binds sigs))) TcM thing
thing_inside
  = do  { ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
binds', thing
thing) <- TopLevelFlag
-> [(RecFlag, LHsBinds GhcRn)]
-> [LSig GhcRn]
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
forall thing.
TopLevelFlag
-> [(RecFlag, LHsBinds GhcRn)]
-> [LSig GhcRn]
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
tcValBinds TopLevelFlag
NotTopLevel [(RecFlag, LHsBinds GhcRn)]
binds [LSig GhcRn]
sigs TcM thing
thing_inside
        ; (HsLocalBinds GhcTc, thing) -> TcM (HsLocalBinds GhcTc, thing)
forall (m :: * -> *) a. Monad m => a -> m a
return (XHsValBinds GhcTc GhcTc
-> HsValBindsLR GhcTc GhcTc -> HsLocalBinds GhcTc
forall idL idR.
XHsValBinds idL idR
-> HsValBindsLR idL idR -> HsLocalBindsLR idL idR
HsValBinds XHsValBinds GhcRn GhcRn
XHsValBinds GhcTc GhcTc
x (XXValBindsLR GhcTc GhcTc -> HsValBindsLR GhcTc GhcTc
forall idL idR. XXValBindsLR idL idR -> HsValBindsLR idL idR
XValBindsLR ([(RecFlag, LHsBinds GhcTc)] -> [LSig GhcRn] -> NHsValBindsLR GhcTc
forall idL.
[(RecFlag, LHsBinds idL)] -> [LSig GhcRn] -> NHsValBindsLR idL
NValBinds [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
[(RecFlag, LHsBinds GhcTc)]
binds' [LSig GhcRn]
sigs)), thing
thing) }
tcLocalBinds (HsValBinds XHsValBinds GhcRn GhcRn
_ (ValBinds {})) TcM thing
_ = String -> TcM (HsLocalBinds GhcTc, thing)
forall a. String -> a
panic String
"tcLocalBinds"

tcLocalBinds (HsIPBinds XHsIPBinds GhcRn GhcRn
x (IPBinds XIPBinds GhcRn
_ [LIPBind GhcRn]
ip_binds)) TcM thing
thing_inside
  = do  { Class
ipClass <- Name -> TcM Class
tcLookupClass Name
ipClassName
        ; ([Id]
given_ips, [Located (IPBind GhcTc)]
ip_binds') <-
            (Located (IPBind GhcRn)
 -> IOEnv (Env TcGblEnv TcLclEnv) (Id, Located (IPBind GhcTc)))
-> [Located (IPBind GhcRn)]
-> IOEnv (Env TcGblEnv TcLclEnv) ([Id], [Located (IPBind GhcTc)])
forall (m :: * -> *) a b c.
Applicative m =>
(a -> m (b, c)) -> [a] -> m ([b], [c])
mapAndUnzipM ((IPBind GhcRn -> TcM (Id, IPBind GhcTc))
-> Located (IPBind GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) (Id, Located (IPBind GhcTc))
forall a b c. (a -> TcM (b, c)) -> Located a -> TcM (b, Located c)
wrapLocSndM (Class -> IPBind GhcRn -> TcM (Id, IPBind GhcTc)
tc_ip_bind Class
ipClass)) [Located (IPBind GhcRn)]
[LIPBind GhcRn]
ip_binds

        -- If the binding binds ?x = E, we  must now
        -- discharge any ?x constraints in expr_lie
        -- See Note [Implicit parameter untouchables]
        ; (TcEvBinds
ev_binds, thing
result) <- SkolemInfo -> [Id] -> [Id] -> TcM thing -> TcM (TcEvBinds, thing)
forall result.
SkolemInfo -> [Id] -> [Id] -> TcM result -> TcM (TcEvBinds, result)
checkConstraints ([HsIPName] -> SkolemInfo
IPSkol [HsIPName]
ips)
                                  [] [Id]
given_ips TcM thing
thing_inside

        ; (HsLocalBinds GhcTc, thing) -> TcM (HsLocalBinds GhcTc, thing)
forall (m :: * -> *) a. Monad m => a -> m a
return (XHsIPBinds GhcTc GhcTc -> HsIPBinds GhcTc -> HsLocalBinds GhcTc
forall idL idR.
XHsIPBinds idL idR -> HsIPBinds idR -> HsLocalBindsLR idL idR
HsIPBinds XHsIPBinds GhcRn GhcRn
XHsIPBinds GhcTc GhcTc
x (XIPBinds GhcTc -> [LIPBind GhcTc] -> HsIPBinds GhcTc
forall id. XIPBinds id -> [LIPBind id] -> HsIPBinds id
IPBinds TcEvBinds
XIPBinds GhcTc
ev_binds [Located (IPBind GhcTc)]
[LIPBind GhcTc]
ip_binds') , thing
result) }
  where
    ips :: [HsIPName]
ips = [HsIPName
ip | (L SrcSpan
_ (IPBind XCIPBind GhcRn
_ (Left (L _ ip)) LHsExpr GhcRn
_)) <- [Located (IPBind GhcRn)]
[LIPBind GhcRn]
ip_binds]

        -- I wonder if we should do these one at a time
        -- Consider     ?x = 4
        --              ?y = ?x + 1
    tc_ip_bind :: Class -> IPBind GhcRn -> TcM (Id, IPBind GhcTc)
tc_ip_bind Class
ipClass (IPBind XCIPBind GhcRn
_ (Left (L _ ip)) LHsExpr GhcRn
expr)
       = do { Type
ty <- TcM Type
newOpenFlexiTyVarTy
            ; let p :: Type
p = FastString -> Type
mkStrLitTy (FastString -> Type) -> FastString -> Type
forall a b. (a -> b) -> a -> b
$ HsIPName -> FastString
hsIPNameFS HsIPName
ip
            ; Id
ip_id <- Class -> [Type] -> IOEnv (Env TcGblEnv TcLclEnv) Id
newDict Class
ipClass [ Type
p, Type
ty ]
            ; GenLocated SrcSpan (HsExpr GhcTc)
expr' <- LHsExpr GhcRn -> Type -> TcM (LHsExpr GhcTc)
tcCheckMonoExpr LHsExpr GhcRn
expr Type
ty
            ; let d :: GenLocated SrcSpan (HsExpr GhcTc)
d = Class -> Type -> Type -> HsExpr GhcTc -> HsExpr GhcTc
toDict Class
ipClass Type
p Type
ty (HsExpr GhcTc -> HsExpr GhcTc)
-> GenLocated SrcSpan (HsExpr GhcTc)
-> GenLocated SrcSpan (HsExpr GhcTc)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
`fmap` GenLocated SrcSpan (HsExpr GhcTc)
expr'
            ; (Id, IPBind GhcTc) -> TcM (Id, IPBind GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (Id
ip_id, (XCIPBind GhcTc
-> Either (XRec GhcTc HsIPName) (IdP GhcTc)
-> LHsExpr GhcTc
-> IPBind GhcTc
forall id.
XCIPBind id
-> Either (XRec id HsIPName) (IdP id) -> LHsExpr id -> IPBind id
IPBind NoExtField
XCIPBind GhcTc
noExtField (Id -> Either (Located HsIPName) Id
forall a b. b -> Either a b
Right Id
ip_id) GenLocated SrcSpan (HsExpr GhcTc)
LHsExpr GhcTc
d)) }
    tc_ip_bind Class
_ (IPBind XCIPBind GhcRn
_ (Right {}) LHsExpr GhcRn
_) = String -> TcM (Id, IPBind GhcTc)
forall a. String -> a
panic String
"tc_ip_bind"

    -- Coerces a `t` into a dictionary for `IP "x" t`.
    -- co : t -> IP "x" t
    toDict :: Class -> Type -> Type -> HsExpr GhcTc -> HsExpr GhcTc
toDict Class
ipClass Type
x Type
ty = HsWrapper -> HsExpr GhcTc -> HsExpr GhcTc
mkHsWrap (HsWrapper -> HsExpr GhcTc -> HsExpr GhcTc)
-> HsWrapper -> HsExpr GhcTc -> HsExpr GhcTc
forall a b. (a -> b) -> a -> b
$ TcCoercionR -> HsWrapper
mkWpCastR (TcCoercionR -> HsWrapper) -> TcCoercionR -> HsWrapper
forall a b. (a -> b) -> a -> b
$
                          Type -> TcCoercionR
wrapIP (Type -> TcCoercionR) -> Type -> TcCoercionR
forall a b. (a -> b) -> a -> b
$ Class -> [Type] -> Type
mkClassPred Class
ipClass [Type
x,Type
ty]

{- Note [Implicit parameter untouchables]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We add the type variables in the types of the implicit parameters
as untouchables, not so much because we really must not unify them,
but rather because we otherwise end up with constraints like this
    Num alpha, Implic { wanted = alpha ~ Int }
The constraint solver solves alpha~Int by unification, but then
doesn't float that solved constraint out (it's not an unsolved
wanted).  Result disaster: the (Num alpha) is again solved, this
time by defaulting.  No no no.

However [Oct 10] this is all handled automatically by the
untouchable-range idea.
-}

tcValBinds :: TopLevelFlag
           -> [(RecFlag, LHsBinds GhcRn)] -> [LSig GhcRn]
           -> TcM thing
           -> TcM ([(RecFlag, LHsBinds GhcTc)], thing)

tcValBinds :: TopLevelFlag
-> [(RecFlag, LHsBinds GhcRn)]
-> [LSig GhcRn]
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
tcValBinds TopLevelFlag
top_lvl [(RecFlag, LHsBinds GhcRn)]
binds [LSig GhcRn]
sigs TcM thing
thing_inside
  = do  {   -- Typecheck the signatures
            -- It's easier to do so now, once for all the SCCs together
            -- because a single signature  f,g :: <type>
            -- might relate to more than one SCC
          ([Id]
poly_ids, TcSigFun
sig_fn) <- [PatSynBind GhcRn GhcRn]
-> TcM ([Id], TcSigFun) -> TcM ([Id], TcSigFun)
forall a. [PatSynBind GhcRn GhcRn] -> TcM a -> TcM a
tcAddPatSynPlaceholders [PatSynBind GhcRn GhcRn]
patsyns (TcM ([Id], TcSigFun) -> TcM ([Id], TcSigFun))
-> TcM ([Id], TcSigFun) -> TcM ([Id], TcSigFun)
forall a b. (a -> b) -> a -> b
$
                                [LSig GhcRn] -> TcM ([Id], TcSigFun)
tcTySigs [LSig GhcRn]
sigs

        -- Extend the envt right away with all the Ids
        --   declared with complete type signatures
        -- Do not extend the TcBinderStack; instead
        --   we extend it on a per-rhs basis in tcExtendForRhs
        --   See Note [Relevant bindings and the binder stack]
        --
        -- For the moment, let bindings and top-level bindings introduce
        -- only unrestricted variables.
        ; TopLevelFlag
-> [Id]
-> TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
forall a. TopLevelFlag -> [Id] -> TcM a -> TcM a
tcExtendSigIds TopLevelFlag
top_lvl [Id]
poly_ids (TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
 -> TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing))
-> TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
forall a b. (a -> b) -> a -> b
$
     do { ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
binds', ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
extra_binds', thing
thing))
              <- TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> [(RecFlag, LHsBinds GhcRn)]
-> TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> TcM
     ([(RecFlag, LHsBinds GhcTc)],
      ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing))
forall thing.
TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> [(RecFlag, LHsBinds GhcRn)]
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
tcBindGroups TopLevelFlag
top_lvl TcSigFun
sig_fn TcPragEnv
prag_fn [(RecFlag, LHsBinds GhcRn)]
binds (TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
 -> TcM
      ([(RecFlag, LHsBinds GhcTc)],
       ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)))
-> TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> TcM
     ([(RecFlag, LHsBinds GhcTc)],
      ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing))
forall a b. (a -> b) -> a -> b
$
                 do { thing
thing <- TcM thing
thing_inside
                       -- See Note [Pattern synonym builders don't yield dependencies]
                       --     in GHC.Rename.Bind
                    ; [Bag (Located (HsBindLR GhcTc GhcTc))]
patsyn_builders <- (PatSynBind GhcRn GhcRn
 -> IOEnv
      (Env TcGblEnv TcLclEnv) (Bag (Located (HsBindLR GhcTc GhcTc))))
-> [PatSynBind GhcRn GhcRn]
-> IOEnv
     (Env TcGblEnv TcLclEnv) [Bag (Located (HsBindLR GhcTc GhcTc))]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM PatSynBind GhcRn GhcRn
-> IOEnv
     (Env TcGblEnv TcLclEnv) (Bag (Located (HsBindLR GhcTc GhcTc)))
PatSynBind GhcRn GhcRn -> TcM (LHsBinds GhcTc)
tcPatSynBuilderBind [PatSynBind GhcRn GhcRn]
patsyns
                    ; let extra_binds :: [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
extra_binds = [ (RecFlag
NonRecursive, Bag (Located (HsBindLR GhcTc GhcTc))
builder)
                                        | Bag (Located (HsBindLR GhcTc GhcTc))
builder <- [Bag (Located (HsBindLR GhcTc GhcTc))]
patsyn_builders ]
                    ; ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
forall (m :: * -> *) a. Monad m => a -> m a
return ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
extra_binds, thing
thing) }
        ; ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> TcM ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
forall (m :: * -> *) a. Monad m => a -> m a
return ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
binds' [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
-> [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
-> [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
forall a. [a] -> [a] -> [a]
++ [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
extra_binds', thing
thing) }}
  where
    patsyns :: [PatSynBind GhcRn GhcRn]
patsyns = [(RecFlag, LHsBinds GhcRn)] -> [PatSynBind GhcRn GhcRn]
forall id.
UnXRec id =>
[(RecFlag, LHsBinds id)] -> [PatSynBind id id]
getPatSynBinds [(RecFlag, LHsBinds GhcRn)]
binds
    prag_fn :: TcPragEnv
prag_fn = [LSig GhcRn] -> LHsBinds GhcRn -> TcPragEnv
mkPragEnv [LSig GhcRn]
sigs (((RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))
 -> Bag (Located (HsBindLR GhcRn GhcRn))
 -> Bag (Located (HsBindLR GhcRn GhcRn)))
-> Bag (Located (HsBindLR GhcRn GhcRn))
-> [(RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))]
-> Bag (Located (HsBindLR GhcRn GhcRn))
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (Bag (Located (HsBindLR GhcRn GhcRn))
-> Bag (Located (HsBindLR GhcRn GhcRn))
-> Bag (Located (HsBindLR GhcRn GhcRn))
forall a. Bag a -> Bag a -> Bag a
unionBags (Bag (Located (HsBindLR GhcRn GhcRn))
 -> Bag (Located (HsBindLR GhcRn GhcRn))
 -> Bag (Located (HsBindLR GhcRn GhcRn)))
-> ((RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))
    -> Bag (Located (HsBindLR GhcRn GhcRn)))
-> (RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))
-> Bag (Located (HsBindLR GhcRn GhcRn))
-> Bag (Located (HsBindLR GhcRn GhcRn))
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))
-> Bag (Located (HsBindLR GhcRn GhcRn))
forall a b. (a, b) -> b
snd) Bag (Located (HsBindLR GhcRn GhcRn))
forall a. Bag a
emptyBag [(RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))]
[(RecFlag, LHsBinds GhcRn)]
binds)

------------------------
tcBindGroups :: TopLevelFlag -> TcSigFun -> TcPragEnv
             -> [(RecFlag, LHsBinds GhcRn)] -> TcM thing
             -> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
-- Typecheck a whole lot of value bindings,
-- one strongly-connected component at a time
-- Here a "strongly connected component" has the straightforward
-- meaning of a group of bindings that mention each other,
-- ignoring type signatures (that part comes later)

tcBindGroups :: TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> [(RecFlag, LHsBinds GhcRn)]
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
tcBindGroups TopLevelFlag
_ TcSigFun
_ TcPragEnv
_ [] TcM thing
thing_inside
  = do  { thing
thing <- TcM thing
thing_inside
        ; ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
forall (m :: * -> *) a. Monad m => a -> m a
return ([], thing
thing) }

tcBindGroups TopLevelFlag
top_lvl TcSigFun
sig_fn TcPragEnv
prag_fn ((RecFlag, LHsBinds GhcRn)
group : [(RecFlag, LHsBinds GhcRn)]
groups) TcM thing
thing_inside
  = do  { -- See Note [Closed binder groups]
          TcTypeEnv
type_env <- TcM TcTypeEnv
getLclTypeEnv
        ; let closed :: IsGroupClosed
closed = TcTypeEnv -> LHsBinds GhcRn -> IsGroupClosed
isClosedBndrGroup TcTypeEnv
type_env ((RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))
-> Bag (Located (HsBindLR GhcRn GhcRn))
forall a b. (a, b) -> b
snd (RecFlag, Bag (Located (HsBindLR GhcRn GhcRn)))
(RecFlag, LHsBinds GhcRn)
group)
        ; ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
group', ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
groups', thing
thing))
                <- TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> (RecFlag, LHsBinds GhcRn)
-> IsGroupClosed
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> TcM
     ([(RecFlag, LHsBinds GhcTc)],
      ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing))
forall thing.
TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> (RecFlag, LHsBinds GhcRn)
-> IsGroupClosed
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
tc_group TopLevelFlag
top_lvl TcSigFun
sig_fn TcPragEnv
prag_fn (RecFlag, LHsBinds GhcRn)
group IsGroupClosed
closed (IOEnv
   (Env TcGblEnv TcLclEnv)
   ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
 -> TcM
      ([(RecFlag, LHsBinds GhcTc)],
       ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> TcM
     ([(RecFlag, LHsBinds GhcTc)],
      ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing))
forall a b. (a -> b) -> a -> b
$
                   TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> [(RecFlag, LHsBinds GhcRn)]
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
forall thing.
TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> [(RecFlag, LHsBinds GhcRn)]
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
tcBindGroups TopLevelFlag
top_lvl TcSigFun
sig_fn TcPragEnv
prag_fn [(RecFlag, LHsBinds GhcRn)]
groups TcM thing
thing_inside
        ; ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
forall (m :: * -> *) a. Monad m => a -> m a
return ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
group' [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
-> [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
-> [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
forall a. [a] -> [a] -> [a]
++ [(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))]
groups', thing
thing) }

-- Note [Closed binder groups]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
--  A mutually recursive group is "closed" if all of the free variables of
--  the bindings are closed. For example
--
-- >  h = \x -> let f = ...g...
-- >                g = ....f...x...
-- >             in ...
--
-- Here @g@ is not closed because it mentions @x@; and hence neither is @f@
-- closed.
--
-- So we need to compute closed-ness on each strongly connected components,
-- before we sub-divide it based on what type signatures it has.
--

------------------------
tc_group :: forall thing.
            TopLevelFlag -> TcSigFun -> TcPragEnv
         -> (RecFlag, LHsBinds GhcRn) -> IsGroupClosed -> TcM thing
         -> TcM ([(RecFlag, LHsBinds GhcTc)], thing)

-- Typecheck one strongly-connected component of the original program.
-- We get a list of groups back, because there may
-- be specialisations etc as well

tc_group :: TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> (RecFlag, LHsBinds GhcRn)
-> IsGroupClosed
-> TcM thing
-> TcM ([(RecFlag, LHsBinds GhcTc)], thing)
tc_group TopLevelFlag
top_lvl TcSigFun
sig_fn TcPragEnv
prag_fn (RecFlag
NonRecursive, LHsBinds GhcRn
binds) IsGroupClosed
closed TcM thing
thing_inside
        -- A single non-recursive binding
        -- We want to keep non-recursive things non-recursive
        -- so that we desugar unlifted bindings correctly
  = do { let bind :: Located (HsBindLR GhcRn GhcRn)
bind = case Bag (Located (HsBindLR GhcRn GhcRn))
-> [Located (HsBindLR GhcRn GhcRn)]
forall a. Bag a -> [a]
bagToList Bag (Located (HsBindLR GhcRn GhcRn))
LHsBinds GhcRn
binds of
                 [Located (HsBindLR GhcRn GhcRn)
bind] -> Located (HsBindLR GhcRn GhcRn)
bind
                 []     -> String -> Located (HsBindLR GhcRn GhcRn)
forall a. String -> a
panic String
"tc_group: empty list of binds"
                 [Located (HsBindLR GhcRn GhcRn)]
_      -> String -> Located (HsBindLR GhcRn GhcRn)
forall a. String -> a
panic String
"tc_group: NonRecursive binds is not a singleton bag"
       ; (Bag (Located (HsBindLR GhcTc GhcTc))
bind', thing
thing) <- TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> LHsBind GhcRn
-> IsGroupClosed
-> TcM thing
-> TcM (LHsBinds GhcTc, thing)
forall thing.
TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> LHsBind GhcRn
-> IsGroupClosed
-> TcM thing
-> TcM (LHsBinds GhcTc, thing)
tc_single TopLevelFlag
top_lvl TcSigFun
sig_fn TcPragEnv
prag_fn Located (HsBindLR GhcRn GhcRn)
LHsBind GhcRn
bind IsGroupClosed
closed
                                     TcM thing
thing_inside
       ; ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
forall (m :: * -> *) a. Monad m => a -> m a
return ( [(RecFlag
NonRecursive, Bag (Located (HsBindLR GhcTc GhcTc))
bind')], thing
thing) }

tc_group TopLevelFlag
top_lvl TcSigFun
sig_fn TcPragEnv
prag_fn (RecFlag
Recursive, LHsBinds GhcRn
binds) IsGroupClosed
closed TcM thing
thing_inside
  =     -- To maximise polymorphism, we do a new
        -- strongly-connected-component analysis, this time omitting
        -- any references to variables with type signatures.
        -- (This used to be optional, but isn't now.)
        -- See Note [Polymorphic recursion] in "GHC.Hs.Binds".
    do  { String -> SDoc -> TcRn ()
traceTc String
"tc_group rec" (LHsBinds GhcRn -> SDoc
forall (idL :: Pass) (idR :: Pass).
(OutputableBndrId idL, OutputableBndrId idR) =>
LHsBindsLR (GhcPass idL) (GhcPass idR) -> SDoc
pprLHsBinds LHsBinds GhcRn
binds)
        ; Maybe (Located (HsBindLR GhcRn GhcRn))
-> (Located (HsBindLR GhcRn GhcRn) -> TcRn ()) -> TcRn ()
forall (m :: * -> *) a. Monad m => Maybe a -> (a -> m ()) -> m ()
whenIsJust Maybe (Located (HsBindLR GhcRn GhcRn))
mbFirstPatSyn ((Located (HsBindLR GhcRn GhcRn) -> TcRn ()) -> TcRn ())
-> (Located (HsBindLR GhcRn GhcRn) -> TcRn ()) -> TcRn ()
forall a b. (a -> b) -> a -> b
$ \Located (HsBindLR GhcRn GhcRn)
lpat_syn ->
            SrcSpan -> LHsBinds GhcRn -> TcRn ()
forall (p :: Pass) a.
(OutputableBndrId p, CollectPass (GhcPass p)) =>
SrcSpan -> LHsBinds (GhcPass p) -> TcM a
recursivePatSynErr (Located (HsBindLR GhcRn GhcRn) -> SrcSpan
forall l e. GenLocated l e -> l
getLoc Located (HsBindLR GhcRn GhcRn)
lpat_syn) LHsBinds GhcRn
binds
        ; (Bag (Located (HsBindLR GhcTc GhcTc))
binds1, thing
thing) <- [SCC (LHsBind GhcRn)] -> TcM (LHsBinds GhcTc, thing)
go [SCC (LHsBind GhcRn)]
sccs
        ; ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     ([(RecFlag, Bag (Located (HsBindLR GhcTc GhcTc)))], thing)
forall (m :: * -> *) a. Monad m => a -> m a
return ([(RecFlag
Recursive, Bag (Located (HsBindLR GhcTc GhcTc))
binds1)], thing
thing) }
                -- Rec them all together
  where
    mbFirstPatSyn :: Maybe (Located (HsBindLR GhcRn GhcRn))
mbFirstPatSyn = (Located (HsBindLR GhcRn GhcRn) -> Bool)
-> Bag (Located (HsBindLR GhcRn GhcRn))
-> Maybe (Located (HsBindLR GhcRn GhcRn))
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Maybe a
find (HsBindLR GhcRn GhcRn -> Bool
forall idL idR. HsBindLR idL idR -> Bool
isPatSyn (HsBindLR GhcRn GhcRn -> Bool)
-> (Located (HsBindLR GhcRn GhcRn) -> HsBindLR GhcRn GhcRn)
-> Located (HsBindLR GhcRn GhcRn)
-> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Located (HsBindLR GhcRn GhcRn) -> HsBindLR GhcRn GhcRn
forall l e. GenLocated l e -> e
unLoc) Bag (Located (HsBindLR GhcRn GhcRn))
LHsBinds GhcRn
binds
    isPatSyn :: HsBindLR idL idR -> Bool
isPatSyn PatSynBind{} = Bool
True
    isPatSyn HsBindLR idL idR
_ = Bool
False

    sccs :: [SCC (LHsBind GhcRn)]
    sccs :: [SCC (LHsBind GhcRn)]
sccs = [Node BKey (Located (HsBindLR GhcRn GhcRn))]
-> [SCC (Located (HsBindLR GhcRn GhcRn))]
forall key payload.
Uniquable key =>
[Node key payload] -> [SCC payload]
stronglyConnCompFromEdgedVerticesUniq (TcSigFun -> LHsBinds GhcRn -> [Node BKey (LHsBind GhcRn)]
mkEdges TcSigFun
sig_fn LHsBinds GhcRn
binds)

    go :: [SCC (LHsBind GhcRn)] -> TcM (LHsBinds GhcTc, thing)
    go :: [SCC (LHsBind GhcRn)] -> TcM (LHsBinds GhcTc, thing)
go (SCC (LHsBind GhcRn)
scc:[SCC (LHsBind GhcRn)]
sccs) = do  { (Bag (Located (HsBindLR GhcTc GhcTc))
binds1, [Id]
ids1) <- SCC (Located (HsBindLR GhcRn GhcRn))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
tc_scc SCC (Located (HsBindLR GhcRn GhcRn))
SCC (LHsBind GhcRn)
scc
                         -- recursive bindings must be unrestricted
                         -- (the ids added to the environment here are the name of the recursive definitions).
                        ; (Bag (Located (HsBindLR GhcTc GhcTc))
binds2, thing
thing) <- TopLevelFlag
-> TcSigFun
-> IsGroupClosed
-> [Id]
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
forall a.
TopLevelFlag -> TcSigFun -> IsGroupClosed -> [Id] -> TcM a -> TcM a
tcExtendLetEnv TopLevelFlag
top_lvl TcSigFun
sig_fn IsGroupClosed
closed [Id]
ids1
                                                            ([SCC (LHsBind GhcRn)] -> TcM (LHsBinds GhcTc, thing)
go [SCC (LHsBind GhcRn)]
sccs)
                        ; (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
forall (m :: * -> *) a. Monad m => a -> m a
return (Bag (Located (HsBindLR GhcTc GhcTc))
binds1 Bag (Located (HsBindLR GhcTc GhcTc))
-> Bag (Located (HsBindLR GhcTc GhcTc))
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a. Bag a -> Bag a -> Bag a
`unionBags` Bag (Located (HsBindLR GhcTc GhcTc))
binds2, thing
thing) }
    go []         = do  { thing
thing <- TcM thing
thing_inside; (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
forall (m :: * -> *) a. Monad m => a -> m a
return (Bag (Located (HsBindLR GhcTc GhcTc))
forall a. Bag a
emptyBag, thing
thing) }

    tc_scc :: SCC (Located (HsBindLR GhcRn GhcRn))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
tc_scc (AcyclicSCC Located (HsBindLR GhcRn GhcRn)
bind) = RecFlag
-> [Located (HsBindLR GhcRn GhcRn)] -> TcM (LHsBinds GhcTc, [Id])
tc_sub_group RecFlag
NonRecursive [Located (HsBindLR GhcRn GhcRn)
bind]
    tc_scc (CyclicSCC [Located (HsBindLR GhcRn GhcRn)]
binds) = RecFlag
-> [Located (HsBindLR GhcRn GhcRn)] -> TcM (LHsBinds GhcTc, [Id])
tc_sub_group RecFlag
Recursive    [Located (HsBindLR GhcRn GhcRn)]
binds

    tc_sub_group :: RecFlag
-> [Located (HsBindLR GhcRn GhcRn)] -> TcM (LHsBinds GhcTc, [Id])
tc_sub_group RecFlag
rec_tc [Located (HsBindLR GhcRn GhcRn)]
binds =
      TcSigFun
-> TcPragEnv
-> RecFlag
-> RecFlag
-> IsGroupClosed
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [Id])
tcPolyBinds TcSigFun
sig_fn TcPragEnv
prag_fn RecFlag
Recursive RecFlag
rec_tc IsGroupClosed
closed [Located (HsBindLR GhcRn GhcRn)]
[LHsBind GhcRn]
binds

recursivePatSynErr ::
     (OutputableBndrId p, CollectPass (GhcPass p))
  => SrcSpan -- ^ The location of the first pattern synonym binding
             --   (for error reporting)
  -> LHsBinds (GhcPass p)
  -> TcM a
recursivePatSynErr :: SrcSpan -> LHsBinds (GhcPass p) -> TcM a
recursivePatSynErr SrcSpan
loc LHsBinds (GhcPass p)
binds
  = SrcSpan -> SDoc -> TcM a
forall a. SrcSpan -> SDoc -> TcRn a
failAt SrcSpan
loc (SDoc -> TcM a) -> SDoc -> TcM a
forall a b. (a -> b) -> a -> b
$
    SDoc -> BKey -> SDoc -> SDoc
hang (String -> SDoc
text String
"Recursive pattern synonym definition with following bindings:")
       BKey
2 ([SDoc] -> SDoc
vcat ([SDoc] -> SDoc) -> [SDoc] -> SDoc
forall a b. (a -> b) -> a -> b
$ (GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p)) -> SDoc)
-> [GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p))]
-> [SDoc]
forall a b. (a -> b) -> [a] -> [b]
map GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p)) -> SDoc
forall p a idR.
(CollectPass p, Outputable (IdP p), Outputable a) =>
GenLocated a (HsBindLR p idR) -> SDoc
pprLBind ([GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p))] -> [SDoc])
-> (Bag (GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p)))
    -> [GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p))])
-> Bag (GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p)))
-> [SDoc]
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Bag (GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p)))
-> [GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p))]
forall a. Bag a -> [a]
bagToList (Bag (GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p)))
 -> [SDoc])
-> Bag (GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p)))
-> [SDoc]
forall a b. (a -> b) -> a -> b
$ Bag (GenLocated SrcSpan (HsBindLR (GhcPass p) (GhcPass p)))
LHsBinds (GhcPass p)
binds)
  where
    pprLoc :: a -> SDoc
pprLoc a
loc  = SDoc -> SDoc
parens (String -> SDoc
text String
"defined at" SDoc -> SDoc -> SDoc
<+> a -> SDoc
forall a. Outputable a => a -> SDoc
ppr a
loc)
    pprLBind :: GenLocated a (HsBindLR p idR) -> SDoc
pprLBind (L a
loc HsBindLR p idR
bind) = (IdP p -> SDoc) -> [IdP p] -> SDoc
forall a. (a -> SDoc) -> [a] -> SDoc
pprWithCommas IdP p -> SDoc
forall a. Outputable a => a -> SDoc
ppr (HsBindLR p idR -> [IdP p]
forall p idR. CollectPass p => HsBindLR p idR -> [IdP p]
collectHsBindBinders HsBindLR p idR
bind)
                                SDoc -> SDoc -> SDoc
<+> a -> SDoc
forall a. Outputable a => a -> SDoc
pprLoc a
loc

tc_single :: forall thing.
            TopLevelFlag -> TcSigFun -> TcPragEnv
          -> LHsBind GhcRn -> IsGroupClosed -> TcM thing
          -> TcM (LHsBinds GhcTc, thing)
tc_single :: TopLevelFlag
-> TcSigFun
-> TcPragEnv
-> LHsBind GhcRn
-> IsGroupClosed
-> TcM thing
-> TcM (LHsBinds GhcTc, thing)
tc_single TopLevelFlag
_top_lvl TcSigFun
sig_fn TcPragEnv
_prag_fn
          (L _ (PatSynBind _ psb@PSB{ psb_id = L _ name }))
          IsGroupClosed
_ TcM thing
thing_inside
  = do { (Bag (Located (HsBindLR GhcTc GhcTc))
aux_binds, TcGblEnv
tcg_env) <- PatSynBind GhcRn GhcRn
-> Maybe TcSigInfo -> TcM (LHsBinds GhcTc, TcGblEnv)
tcPatSynDecl PatSynBind GhcRn GhcRn
psb (TcSigFun
sig_fn Name
name)
       ; thing
thing <- TcGblEnv -> TcM thing -> TcM thing
forall gbl lcl a. gbl -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
setGblEnv TcGblEnv
tcg_env TcM thing
thing_inside
       ; (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
forall (m :: * -> *) a. Monad m => a -> m a
return (Bag (Located (HsBindLR GhcTc GhcTc))
aux_binds, thing
thing)
       }

tc_single TopLevelFlag
top_lvl TcSigFun
sig_fn TcPragEnv
prag_fn LHsBind GhcRn
lbind IsGroupClosed
closed TcM thing
thing_inside
  = do { (Bag (Located (HsBindLR GhcTc GhcTc))
binds1, [Id]
ids) <- TcSigFun
-> TcPragEnv
-> RecFlag
-> RecFlag
-> IsGroupClosed
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [Id])
tcPolyBinds TcSigFun
sig_fn TcPragEnv
prag_fn
                                      RecFlag
NonRecursive RecFlag
NonRecursive
                                      IsGroupClosed
closed
                                      [LHsBind GhcRn
lbind]
         -- since we are defining a non-recursive binding, it is not necessary here
         -- to define an unrestricted binding. But we do so until toplevel linear bindings are supported.
       ; thing
thing <- TopLevelFlag
-> TcSigFun -> IsGroupClosed -> [Id] -> TcM thing -> TcM thing
forall a.
TopLevelFlag -> TcSigFun -> IsGroupClosed -> [Id] -> TcM a -> TcM a
tcExtendLetEnv TopLevelFlag
top_lvl TcSigFun
sig_fn IsGroupClosed
closed [Id]
ids TcM thing
thing_inside
       ; (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), thing)
forall (m :: * -> *) a. Monad m => a -> m a
return (Bag (Located (HsBindLR GhcTc GhcTc))
binds1, thing
thing) }

------------------------
type BKey = Int -- Just number off the bindings

mkEdges :: TcSigFun -> LHsBinds GhcRn -> [Node BKey (LHsBind GhcRn)]
-- See Note [Polymorphic recursion] in "GHC.Hs.Binds".
mkEdges :: TcSigFun -> LHsBinds GhcRn -> [Node BKey (LHsBind GhcRn)]
mkEdges TcSigFun
sig_fn LHsBinds GhcRn
binds
  = [ Located (HsBindLR GhcRn GhcRn)
-> BKey -> [BKey] -> Node BKey (Located (HsBindLR GhcRn GhcRn))
forall key payload. payload -> key -> [key] -> Node key payload
DigraphNode Located (HsBindLR GhcRn GhcRn)
bind BKey
key [BKey
key | Name
n <- UniqSet Name -> [Name]
forall elt. UniqSet elt -> [elt]
nonDetEltsUniqSet (HsBindLR GhcRn GhcRn -> UniqSet Name
forall idL idR.
(XFunBind idL idR ~ UniqSet Name,
 XPatBind idL idR ~ UniqSet Name) =>
HsBindLR idL idR -> UniqSet Name
bind_fvs (Located (HsBindLR GhcRn GhcRn) -> HsBindLR GhcRn GhcRn
forall l e. GenLocated l e -> e
unLoc Located (HsBindLR GhcRn GhcRn)
bind)),
                         Just BKey
key <- [NameEnv BKey -> Name -> Maybe BKey
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv NameEnv BKey
key_map Name
n], Name -> Bool
no_sig Name
n ]
    | (Located (HsBindLR GhcRn GhcRn)
bind, BKey
key) <- [(Located (HsBindLR GhcRn GhcRn), BKey)]
keyd_binds
    ]
    -- It's OK to use nonDetEltsUFM here as stronglyConnCompFromEdgedVertices
    -- is still deterministic even if the edges are in nondeterministic order
    -- as explained in Note [Deterministic SCC] in GHC.Data.Graph.Directed.
  where
    bind_fvs :: HsBindLR idL idR -> UniqSet Name
bind_fvs (FunBind { fun_ext :: forall idL idR. HsBindLR idL idR -> XFunBind idL idR
fun_ext = XFunBind idL idR
fvs }) = UniqSet Name
XFunBind idL idR
fvs
    bind_fvs (PatBind { pat_ext :: forall idL idR. HsBindLR idL idR -> XPatBind idL idR
pat_ext = XPatBind idL idR
fvs }) = UniqSet Name
XPatBind idL idR
fvs
    bind_fvs HsBindLR idL idR
_                           = UniqSet Name
emptyNameSet

    no_sig :: Name -> Bool
    no_sig :: Name -> Bool
no_sig Name
n = Bool -> Bool
not (TcSigFun -> Name -> Bool
hasCompleteSig TcSigFun
sig_fn Name
n)

    keyd_binds :: [(Located (HsBindLR GhcRn GhcRn), BKey)]
keyd_binds = Bag (Located (HsBindLR GhcRn GhcRn))
-> [Located (HsBindLR GhcRn GhcRn)]
forall a. Bag a -> [a]
bagToList Bag (Located (HsBindLR GhcRn GhcRn))
LHsBinds GhcRn
binds [Located (HsBindLR GhcRn GhcRn)]
-> [BKey] -> [(Located (HsBindLR GhcRn GhcRn), BKey)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [BKey
0::BKey ..]

    key_map :: NameEnv BKey     -- Which binding it comes from
    key_map :: NameEnv BKey
key_map = [(Name, BKey)] -> NameEnv BKey
forall a. [(Name, a)] -> NameEnv a
mkNameEnv [(Name
bndr, BKey
key) | (L SrcSpan
_ HsBindLR GhcRn GhcRn
bind, BKey
key) <- [(Located (HsBindLR GhcRn GhcRn), BKey)]
keyd_binds
                                     , Name
bndr <- HsBindLR GhcRn GhcRn -> [IdP GhcRn]
forall p idR. CollectPass p => HsBindLR p idR -> [IdP p]
collectHsBindBinders HsBindLR GhcRn GhcRn
bind ]

------------------------
tcPolyBinds :: TcSigFun -> TcPragEnv
            -> RecFlag         -- Whether the group is really recursive
            -> RecFlag         -- Whether it's recursive after breaking
                               -- dependencies based on type signatures
            -> IsGroupClosed   -- Whether the group is closed
            -> [LHsBind GhcRn]  -- None are PatSynBind
            -> TcM (LHsBinds GhcTc, [TcId])

-- Typechecks a single bunch of values bindings all together,
-- and generalises them.  The bunch may be only part of a recursive
-- group, because we use type signatures to maximise polymorphism
--
-- Returns a list because the input may be a single non-recursive binding,
-- in which case the dependency order of the resulting bindings is
-- important.
--
-- Knows nothing about the scope of the bindings
-- None of the bindings are pattern synonyms

tcPolyBinds :: TcSigFun
-> TcPragEnv
-> RecFlag
-> RecFlag
-> IsGroupClosed
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [Id])
tcPolyBinds TcSigFun
sig_fn TcPragEnv
prag_fn RecFlag
rec_group RecFlag
rec_tc IsGroupClosed
closed [LHsBind GhcRn]
bind_list
  = SrcSpan
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
loc                              (IOEnv
   (Env TcGblEnv TcLclEnv)
   (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      (Bag (Located (HsBindLR GhcTc GhcTc)), [Id]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall a b. (a -> b) -> a -> b
$
    IOEnv
  (Env TcGblEnv TcLclEnv)
  (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall r. TcRn r -> TcRn r -> TcRn r
recoverM ([Name] -> TcSigFun -> TcM (LHsBinds GhcTc, [Id])
recoveryCode [Name]
[IdP GhcRn]
binder_names TcSigFun
sig_fn) (IOEnv
   (Env TcGblEnv TcLclEnv)
   (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      (Bag (Located (HsBindLR GhcTc GhcTc)), [Id]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall a b. (a -> b) -> a -> b
$ do
        -- Set up main recover; take advantage of any type sigs

    { String -> SDoc -> TcRn ()
traceTc String
"------------------------------------------------" SDoc
Outputable.empty
    ; String -> SDoc -> TcRn ()
traceTc String
"Bindings for {" ([Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Name]
[IdP GhcRn]
binder_names)
    ; DynFlags
dflags   <- IOEnv (Env TcGblEnv TcLclEnv) DynFlags
forall (m :: * -> *). HasDynFlags m => m DynFlags
getDynFlags
    ; let plan :: GeneralisationPlan
plan = DynFlags
-> [LHsBind GhcRn]
-> IsGroupClosed
-> TcSigFun
-> GeneralisationPlan
decideGeneralisationPlan DynFlags
dflags [LHsBind GhcRn]
bind_list IsGroupClosed
closed TcSigFun
sig_fn
    ; String -> SDoc -> TcRn ()
traceTc String
"Generalisation plan" (GeneralisationPlan -> SDoc
forall a. Outputable a => a -> SDoc
ppr GeneralisationPlan
plan)
    ; result :: (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
result@(Bag (Located (HsBindLR GhcTc GhcTc))
_, [Id]
poly_ids) <- case GeneralisationPlan
plan of
         GeneralisationPlan
NoGen              -> RecFlag
-> TcPragEnv
-> TcSigFun
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [Id])
tcPolyNoGen RecFlag
rec_tc TcPragEnv
prag_fn TcSigFun
sig_fn [LHsBind GhcRn]
bind_list
         InferGen Bool
mn        -> RecFlag
-> TcPragEnv
-> TcSigFun
-> Bool
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [Id])
tcPolyInfer RecFlag
rec_tc TcPragEnv
prag_fn TcSigFun
sig_fn Bool
mn [LHsBind GhcRn]
bind_list
         CheckGen LHsBind GhcRn
lbind TcIdSigInfo
sig -> TcPragEnv
-> TcIdSigInfo -> LHsBind GhcRn -> TcM (LHsBinds GhcTc, [Id])
tcPolyCheck TcPragEnv
prag_fn TcIdSigInfo
sig LHsBind GhcRn
lbind

    ; String -> SDoc -> TcRn ()
traceTc String
"} End of bindings for" ([SDoc] -> SDoc
vcat [ [Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Name]
[IdP GhcRn]
binder_names, RecFlag -> SDoc
forall a. Outputable a => a -> SDoc
ppr RecFlag
rec_group
                                            , [SDoc] -> SDoc
vcat [Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr Id
id SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Id -> Type
idType Id
id) | Id
id <- [Id]
poly_ids]
                                          ])

    ; (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall (m :: * -> *) a. Monad m => a -> m a
return (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
result }
  where
    binder_names :: [IdP GhcRn]
binder_names = [LHsBind GhcRn] -> [IdP GhcRn]
forall p idR. CollectPass p => [LHsBindLR p idR] -> [IdP p]
collectHsBindListBinders [LHsBind GhcRn]
bind_list
    loc :: SrcSpan
loc = (SrcSpan -> SrcSpan -> SrcSpan) -> [SrcSpan] -> SrcSpan
forall (t :: * -> *) a. Foldable t => (a -> a -> a) -> t a -> a
foldr1 SrcSpan -> SrcSpan -> SrcSpan
combineSrcSpans ((Located (HsBindLR GhcRn GhcRn) -> SrcSpan)
-> [Located (HsBindLR GhcRn GhcRn)] -> [SrcSpan]
forall a b. (a -> b) -> [a] -> [b]
map Located (HsBindLR GhcRn GhcRn) -> SrcSpan
forall l e. GenLocated l e -> l
getLoc [Located (HsBindLR GhcRn GhcRn)]
[LHsBind GhcRn]
bind_list)
         -- The mbinds have been dependency analysed and
         -- may no longer be adjacent; so find the narrowest
         -- span that includes them all

--------------
-- If typechecking the binds fails, then return with each
-- signature-less binder given type (forall a.a), to minimise
-- subsequent error messages
recoveryCode :: [Name] -> TcSigFun -> TcM (LHsBinds GhcTc, [Id])
recoveryCode :: [Name] -> TcSigFun -> TcM (LHsBinds GhcTc, [Id])
recoveryCode [Name]
binder_names TcSigFun
sig_fn
  = do  { String -> SDoc -> TcRn ()
traceTc String
"tcBindsWithSigs: error recovery" ([Name] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Name]
binder_names)
        ; let poly_ids :: [Id]
poly_ids = (Name -> Id) -> [Name] -> [Id]
forall a b. (a -> b) -> [a] -> [b]
map Name -> Id
mk_dummy [Name]
binder_names
        ; (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall (m :: * -> *) a. Monad m => a -> m a
return (Bag (Located (HsBindLR GhcTc GhcTc))
forall a. Bag a
emptyBag, [Id]
poly_ids) }
  where
    mk_dummy :: Name -> Id
mk_dummy Name
name
      | Just TcSigInfo
sig <- TcSigFun
sig_fn Name
name
      , Just Id
poly_id <- TcSigInfo -> Maybe Id
completeSigPolyId_maybe TcSigInfo
sig
      = Id
poly_id
      | Bool
otherwise
      = HasDebugCallStack => Name -> Type -> Type -> Id
Name -> Type -> Type -> Id
mkLocalId Name
name Type
Many Type
forall_a_a

forall_a_a :: TcType
-- At one point I had (forall r (a :: TYPE r). a), but of course
-- that type is ill-formed: its mentions 'r' which escapes r's scope.
-- Another alternative would be (forall (a :: TYPE kappa). a), where
-- kappa is a unification variable. But I don't think we need that
-- complication here. I'm going to just use (forall (a::*). a).
-- See #15276
forall_a_a :: Type
forall_a_a = [Id] -> Type -> Type
mkSpecForAllTys [Id
alphaTyVar] Type
alphaTy

{- *********************************************************************
*                                                                      *
                         tcPolyNoGen
*                                                                      *
********************************************************************* -}

tcPolyNoGen     -- No generalisation whatsoever
  :: RecFlag       -- Whether it's recursive after breaking
                   -- dependencies based on type signatures
  -> TcPragEnv -> TcSigFun
  -> [LHsBind GhcRn]
  -> TcM (LHsBinds GhcTc, [TcId])

tcPolyNoGen :: RecFlag
-> TcPragEnv
-> TcSigFun
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [Id])
tcPolyNoGen RecFlag
rec_tc TcPragEnv
prag_fn TcSigFun
tc_sig_fn [LHsBind GhcRn]
bind_list
  = do { (Bag (Located (HsBindLR GhcTc GhcTc))
binds', [MonoBindInfo]
mono_infos) <- RecFlag
-> TcSigFun
-> LetBndrSpec
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [MonoBindInfo])
tcMonoBinds RecFlag
rec_tc TcSigFun
tc_sig_fn
                                             (TcPragEnv -> LetBndrSpec
LetGblBndr TcPragEnv
prag_fn)
                                             [LHsBind GhcRn]
bind_list
       ; [Id]
mono_ids' <- (MonoBindInfo -> IOEnv (Env TcGblEnv TcLclEnv) Id)
-> [MonoBindInfo] -> TcM [Id]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM MonoBindInfo -> IOEnv (Env TcGblEnv TcLclEnv) Id
tc_mono_info [MonoBindInfo]
mono_infos
       ; (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall (m :: * -> *) a. Monad m => a -> m a
return (Bag (Located (HsBindLR GhcTc GhcTc))
binds', [Id]
mono_ids') }
  where
    tc_mono_info :: MonoBindInfo -> IOEnv (Env TcGblEnv TcLclEnv) Id
tc_mono_info (MBI { mbi_poly_name :: MonoBindInfo -> Name
mbi_poly_name = Name
name, mbi_mono_id :: MonoBindInfo -> Id
mbi_mono_id = Id
mono_id })
      = do { [LTcSpecPrag]
_specs <- Id -> [LSig GhcRn] -> TcM [LTcSpecPrag]
tcSpecPrags Id
mono_id (TcPragEnv -> Name -> [LSig GhcRn]
lookupPragEnv TcPragEnv
prag_fn Name
name)
           ; Id -> IOEnv (Env TcGblEnv TcLclEnv) Id
forall (m :: * -> *) a. Monad m => a -> m a
return Id
mono_id }
           -- NB: tcPrags generates error messages for
           --     specialisation pragmas for non-overloaded sigs
           -- Indeed that is why we call it here!
           -- So we can safely ignore _specs


{- *********************************************************************
*                                                                      *
                         tcPolyCheck
*                                                                      *
********************************************************************* -}

tcPolyCheck :: TcPragEnv
            -> TcIdSigInfo     -- Must be a complete signature
            -> LHsBind GhcRn   -- Must be a FunBind
            -> TcM (LHsBinds GhcTc, [TcId])
-- There is just one binding,
--   it is a FunBind
--   it has a complete type signature,
tcPolyCheck :: TcPragEnv
-> TcIdSigInfo -> LHsBind GhcRn -> TcM (LHsBinds GhcTc, [Id])
tcPolyCheck TcPragEnv
prag_fn
            (CompleteSig { sig_bndr :: TcIdSigInfo -> Id
sig_bndr  = Id
poly_id
                         , sig_ctxt :: TcIdSigInfo -> UserTypeCtxt
sig_ctxt  = UserTypeCtxt
ctxt
                         , sig_loc :: TcIdSigInfo -> SrcSpan
sig_loc   = SrcSpan
sig_loc })
            (L bind_loc (FunBind { fun_id = L nm_loc name
                                 , fun_matches = matches }))
  = do { String -> SDoc -> TcRn ()
traceTc String
"tcPolyCheck" (Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr Id
poly_id SDoc -> SDoc -> SDoc
$$ SrcSpan -> SDoc
forall a. Outputable a => a -> SDoc
ppr SrcSpan
sig_loc)

       ; Name
mono_name <- OccName -> SrcSpan -> TcM Name
newNameAt (Name -> OccName
nameOccName Name
name) SrcSpan
nm_loc
       ; (HsWrapper
wrap_gen, (HsWrapper
wrap_res, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
matches'))
             <- SrcSpan
-> TcRn
     (HsWrapper,
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcRn
     (HsWrapper,
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
sig_loc (TcRn
   (HsWrapper,
    (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
 -> TcRn
      (HsWrapper,
       (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))))
-> TcRn
     (HsWrapper,
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcRn
     (HsWrapper,
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
forall a b. (a -> b) -> a -> b
$ -- Sets the binding location for the skolems
                UserTypeCtxt
-> Type
-> (Type
    -> TcM
         (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcRn
     (HsWrapper,
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
forall result.
UserTypeCtxt
-> Type -> (Type -> TcM result) -> TcM (HsWrapper, result)
tcSkolemiseScoped UserTypeCtxt
ctxt (Id -> Type
idType Id
poly_id) ((Type
  -> TcM
       (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
 -> TcRn
      (HsWrapper,
       (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))))
-> (Type
    -> TcM
         (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcRn
     (HsWrapper,
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
forall a b. (a -> b) -> a -> b
$ \Type
rho_ty ->
                -- Unwraps multiple layers; e.g
                --    f :: forall a. Eq a => forall b. Ord b => blah
                -- NB: tcSkolemise makes fresh type variables
                -- See Note [Instantiate sig with fresh variables]

                let mono_id :: Id
mono_id = HasDebugCallStack => Name -> Type -> Type -> Id
Name -> Type -> Type -> Id
mkLocalId Name
mono_name (Id -> Type
varMult Id
poly_id) Type
rho_ty in
                [TcBinder]
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
forall a. [TcBinder] -> TcM a -> TcM a
tcExtendBinderStack [Id -> TopLevelFlag -> TcBinder
TcIdBndr Id
mono_id TopLevelFlag
NotTopLevel] (TcM
   (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
 -> TcM
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
forall a b. (a -> b) -> a -> b
$
                -- Why mono_id in the BinderStack?
                --    See Note [Relevant bindings and the binder stack]

                SrcSpan
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
bind_loc (TcM
   (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
 -> TcM
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
forall a b. (a -> b) -> a -> b
$
                Located Name
-> MatchGroup GhcRn (LHsExpr GhcRn)
-> ExpSigmaType
-> TcM (HsWrapper, MatchGroup GhcTc (LHsExpr GhcTc))
tcMatchesFun (SrcSpan -> Name -> Located Name
forall l e. l -> e -> GenLocated l e
L SrcSpan
nm_loc Name
mono_name) MatchGroup GhcRn (LHsExpr GhcRn)
matches
                             (Type -> ExpSigmaType
mkCheckExpType Type
rho_ty)

       -- We make a funny AbsBinds, abstracting over nothing,
       -- just so we haev somewhere to put the SpecPrags.
       -- Otherwise we could just use the FunBind
       -- Hence poly_id2 is just a clone of poly_id;
       -- We re-use mono-name, but we could equally well use a fresh one

       ; let prag_sigs :: [LSig GhcRn]
prag_sigs = TcPragEnv -> Name -> [LSig GhcRn]
lookupPragEnv TcPragEnv
prag_fn Name
name
             poly_id2 :: Id
poly_id2  = HasDebugCallStack => Name -> Type -> Type -> Id
Name -> Type -> Type -> Id
mkLocalId Name
mono_name (Id -> Type
idMult Id
poly_id) (Id -> Type
idType Id
poly_id)
       ; [LTcSpecPrag]
spec_prags <- Id -> [LSig GhcRn] -> TcM [LTcSpecPrag]
tcSpecPrags    Id
poly_id [LSig GhcRn]
prag_sigs
       ; Id
poly_id    <- Id -> [LSig GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) Id
addInlinePrags Id
poly_id [LSig GhcRn]
prag_sigs

       ; Module
mod <- IOEnv (Env TcGblEnv TcLclEnv) Module
forall (m :: * -> *). HasModule m => m Module
getModule
       ; [Tickish Id]
tick <- SrcSpan -> Id -> Module -> [LSig GhcRn] -> TcM [Tickish Id]
funBindTicks SrcSpan
nm_loc Id
poly_id Module
mod [LSig GhcRn]
prag_sigs

       ; let bind' :: HsBindLR GhcTc GhcTc
bind' = FunBind :: forall idL idR.
XFunBind idL idR
-> LIdP idL
-> MatchGroup idR (LHsExpr idR)
-> [Tickish Id]
-> HsBindLR idL idR
FunBind { fun_id :: LIdP GhcTc
fun_id      = SrcSpan -> Id -> GenLocated SrcSpan Id
forall l e. l -> e -> GenLocated l e
L SrcSpan
nm_loc Id
poly_id2
                             , fun_matches :: MatchGroup GhcTc (LHsExpr GhcTc)
fun_matches = MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
MatchGroup GhcTc (LHsExpr GhcTc)
matches'
                             , fun_ext :: XFunBind GhcTc GhcTc
fun_ext     = HsWrapper
wrap_gen HsWrapper -> HsWrapper -> HsWrapper
<.> HsWrapper
wrap_res
                             , fun_tick :: [Tickish Id]
fun_tick    = [Tickish Id]
tick }

             export :: ABExport GhcTc
export = ABE :: forall p.
XABE p -> IdP p -> IdP p -> HsWrapper -> TcSpecPrags -> ABExport p
ABE { abe_ext :: XABE GhcTc
abe_ext   = NoExtField
XABE GhcTc
noExtField
                          , abe_wrap :: HsWrapper
abe_wrap  = HsWrapper
idHsWrapper
                          , abe_poly :: IdP GhcTc
abe_poly  = Id
IdP GhcTc
poly_id
                          , abe_mono :: IdP GhcTc
abe_mono  = Id
IdP GhcTc
poly_id2
                          , abe_prags :: TcSpecPrags
abe_prags = [LTcSpecPrag] -> TcSpecPrags
SpecPrags [LTcSpecPrag]
spec_prags }

             abs_bind :: Located (HsBindLR GhcTc GhcTc)
abs_bind = SrcSpan -> HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcSpan
bind_loc (HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc))
-> HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc)
forall a b. (a -> b) -> a -> b
$
                        AbsBinds :: forall idL idR.
XAbsBinds idL idR
-> [Id]
-> [Id]
-> [ABExport idL]
-> [TcEvBinds]
-> LHsBinds idL
-> Bool
-> HsBindLR idL idR
AbsBinds { abs_ext :: XAbsBinds GhcTc GhcTc
abs_ext      = NoExtField
XAbsBinds GhcTc GhcTc
noExtField
                                 , abs_tvs :: [Id]
abs_tvs      = []
                                 , abs_ev_vars :: [Id]
abs_ev_vars  = []
                                 , abs_ev_binds :: [TcEvBinds]
abs_ev_binds = []
                                 , abs_exports :: [ABExport GhcTc]
abs_exports  = [ABExport GhcTc
export]
                                 , abs_binds :: LHsBinds GhcTc
abs_binds    = Located (HsBindLR GhcTc GhcTc)
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a. a -> Bag a
unitBag (SrcSpan -> HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcSpan
bind_loc HsBindLR GhcTc GhcTc
bind')
                                 , abs_sig :: Bool
abs_sig      = Bool
True }

       ; (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall (m :: * -> *) a. Monad m => a -> m a
return (Located (HsBindLR GhcTc GhcTc)
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a. a -> Bag a
unitBag Located (HsBindLR GhcTc GhcTc)
abs_bind, [Id
poly_id]) }

tcPolyCheck TcPragEnv
_prag_fn TcIdSigInfo
sig LHsBind GhcRn
bind
  = String
-> SDoc
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tcPolyCheck" (TcIdSigInfo -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcIdSigInfo
sig SDoc -> SDoc -> SDoc
$$ Located (HsBindLR GhcRn GhcRn) -> SDoc
forall a. Outputable a => a -> SDoc
ppr Located (HsBindLR GhcRn GhcRn)
LHsBind GhcRn
bind)

funBindTicks :: SrcSpan -> TcId -> Module -> [LSig GhcRn]
             -> TcM [Tickish TcId]
funBindTicks :: SrcSpan -> Id -> Module -> [LSig GhcRn] -> TcM [Tickish Id]
funBindTicks SrcSpan
loc Id
fun_id Module
mod [LSig GhcRn]
sigs
  | (Maybe (GenLocated SrcSpan StringLiteral)
mb_cc_str : [Maybe (GenLocated SrcSpan StringLiteral)]
_) <- [ Maybe (GenLocated SrcSpan StringLiteral)
Maybe (XRec GhcRn StringLiteral)
cc_name | L SrcSpan
_ (SCCFunSig XSCCFunSig GhcRn
_ SourceText
_ LIdP GhcRn
_ Maybe (XRec GhcRn StringLiteral)
cc_name) <- [Located (Sig GhcRn)]
[LSig GhcRn]
sigs ]
      -- this can only be a singleton list, as duplicate pragmas are rejected
      -- by the renamer
  , let cc_str :: FastString
cc_str
          | Just GenLocated SrcSpan StringLiteral
cc_str <- Maybe (GenLocated SrcSpan StringLiteral)
mb_cc_str
          = StringLiteral -> FastString
sl_fs (StringLiteral -> FastString) -> StringLiteral -> FastString
forall a b. (a -> b) -> a -> b
$ GenLocated SrcSpan StringLiteral -> StringLiteral
forall l e. GenLocated l e -> e
unLoc GenLocated SrcSpan StringLiteral
cc_str
          | Bool
otherwise
          = Name -> FastString
forall a. NamedThing a => a -> FastString
getOccFS (Id -> Name
Var.varName Id
fun_id)
        cc_name :: FastString
cc_name = ModuleName -> FastString
moduleNameFS (Module -> ModuleName
forall unit. GenModule unit -> ModuleName
moduleName Module
mod) FastString -> FastString -> FastString
`appendFS` Char -> FastString -> FastString
consFS Char
'.' FastString
cc_str
  = do
      CCFlavour
flavour <- CostCentreIndex -> CCFlavour
DeclCC (CostCentreIndex -> CCFlavour)
-> IOEnv (Env TcGblEnv TcLclEnv) CostCentreIndex
-> IOEnv (Env TcGblEnv TcLclEnv) CCFlavour
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> FastString -> IOEnv (Env TcGblEnv TcLclEnv) CostCentreIndex
getCCIndexTcM FastString
cc_name
      let cc :: CostCentre
cc = FastString -> Module -> SrcSpan -> CCFlavour -> CostCentre
mkUserCC FastString
cc_name Module
mod SrcSpan
loc CCFlavour
flavour
      [Tickish Id] -> TcM [Tickish Id]
forall (m :: * -> *) a. Monad m => a -> m a
return [CostCentre -> Bool -> Bool -> Tickish Id
forall id. CostCentre -> Bool -> Bool -> Tickish id
ProfNote CostCentre
cc Bool
True Bool
True]
  | Bool
otherwise
  = [Tickish Id] -> TcM [Tickish Id]
forall (m :: * -> *) a. Monad m => a -> m a
return []

{- Note [Instantiate sig with fresh variables]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It's vital to instantiate a type signature with fresh variables.
For example:
      type T = forall a. [a] -> [a]
      f :: T;
      f = g where { g :: T; g = <rhs> }

 We must not use the same 'a' from the defn of T at both places!!
(Instantiation is only necessary because of type synonyms.  Otherwise,
it's all cool; each signature has distinct type variables from the renamer.)
-}


{- *********************************************************************
*                                                                      *
                         tcPolyInfer
*                                                                      *
********************************************************************* -}

tcPolyInfer
  :: RecFlag       -- Whether it's recursive after breaking
                   -- dependencies based on type signatures
  -> TcPragEnv -> TcSigFun
  -> Bool         -- True <=> apply the monomorphism restriction
  -> [LHsBind GhcRn]
  -> TcM (LHsBinds GhcTc, [TcId])
tcPolyInfer :: RecFlag
-> TcPragEnv
-> TcSigFun
-> Bool
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [Id])
tcPolyInfer RecFlag
rec_tc TcPragEnv
prag_fn TcSigFun
tc_sig_fn Bool
mono [LHsBind GhcRn]
bind_list
  = do { (TcLevel
tclvl, WantedConstraints
wanted, (Bag (Located (HsBindLR GhcTc GhcTc))
binds', [MonoBindInfo]
mono_infos))
             <- IOEnv
  (Env TcGblEnv TcLclEnv)
  (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
-> TcM
     (TcLevel, WantedConstraints,
      (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo]))
forall a. TcM a -> TcM (TcLevel, WantedConstraints, a)
pushLevelAndCaptureConstraints  (IOEnv
   (Env TcGblEnv TcLclEnv)
   (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
 -> TcM
      (TcLevel, WantedConstraints,
       (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
-> TcM
     (TcLevel, WantedConstraints,
      (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo]))
forall a b. (a -> b) -> a -> b
$
                RecFlag
-> TcSigFun
-> LetBndrSpec
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [MonoBindInfo])
tcMonoBinds RecFlag
rec_tc TcSigFun
tc_sig_fn LetBndrSpec
LetLclBndr [LHsBind GhcRn]
bind_list

       ; let name_taus :: [(Name, Type)]
name_taus  = [ (MonoBindInfo -> Name
mbi_poly_name MonoBindInfo
info, Id -> Type
idType (MonoBindInfo -> Id
mbi_mono_id MonoBindInfo
info))
                          | MonoBindInfo
info <- [MonoBindInfo]
mono_infos ]
             sigs :: [TcIdSigInst]
sigs       = [ TcIdSigInst
sig | MBI { mbi_sig :: MonoBindInfo -> Maybe TcIdSigInst
mbi_sig = Just TcIdSigInst
sig } <- [MonoBindInfo]
mono_infos ]
             infer_mode :: InferMode
infer_mode = if Bool
mono then InferMode
ApplyMR else InferMode
NoRestrictions

       ; (TcIdSigInst -> TcRn ()) -> [TcIdSigInst] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (Bool -> TcIdSigInst -> TcRn ()
checkOverloadedSig Bool
mono) [TcIdSigInst]
sigs

       ; String -> SDoc -> TcRn ()
traceTc String
"simplifyInfer call" (TcLevel -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcLevel
tclvl SDoc -> SDoc -> SDoc
$$ [(Name, Type)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [(Name, Type)]
name_taus SDoc -> SDoc -> SDoc
$$ WantedConstraints -> SDoc
forall a. Outputable a => a -> SDoc
ppr WantedConstraints
wanted)
       ; ([Id]
qtvs, [Id]
givens, TcEvBinds
ev_binds, WantedConstraints
residual, Bool
insoluble)
                 <- TcLevel
-> InferMode
-> [TcIdSigInst]
-> [(Name, Type)]
-> WantedConstraints
-> TcM ([Id], [Id], TcEvBinds, WantedConstraints, Bool)
simplifyInfer TcLevel
tclvl InferMode
infer_mode [TcIdSigInst]
sigs [(Name, Type)]
name_taus WantedConstraints
wanted
       ; WantedConstraints -> TcRn ()
emitConstraints WantedConstraints
residual

       ; let inferred_theta :: [Type]
inferred_theta = (Id -> Type) -> [Id] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map Id -> Type
evVarPred [Id]
givens
       ; [ABExport GhcTc]
exports <- TcM [ABExport GhcTc] -> TcM [ABExport GhcTc]
forall r. TcM r -> TcM r
checkNoErrs (TcM [ABExport GhcTc] -> TcM [ABExport GhcTc])
-> TcM [ABExport GhcTc] -> TcM [ABExport GhcTc]
forall a b. (a -> b) -> a -> b
$
                    (MonoBindInfo -> IOEnv (Env TcGblEnv TcLclEnv) (ABExport GhcTc))
-> [MonoBindInfo] -> TcM [ABExport GhcTc]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (TcPragEnv
-> Bool
-> [Id]
-> [Type]
-> MonoBindInfo
-> IOEnv (Env TcGblEnv TcLclEnv) (ABExport GhcTc)
mkExport TcPragEnv
prag_fn Bool
insoluble [Id]
qtvs [Type]
inferred_theta) [MonoBindInfo]
mono_infos

       ; SrcSpan
loc <- TcRn SrcSpan
getSrcSpanM
       ; let poly_ids :: [Id]
poly_ids = (ABExport GhcTc -> Id) -> [ABExport GhcTc] -> [Id]
forall a b. (a -> b) -> [a] -> [b]
map ABExport GhcTc -> Id
forall p. ABExport p -> IdP p
abe_poly [ABExport GhcTc]
exports
             abs_bind :: Located (HsBindLR GhcTc GhcTc)
abs_bind = SrcSpan -> HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc (HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc))
-> HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc)
forall a b. (a -> b) -> a -> b
$
                        AbsBinds :: forall idL idR.
XAbsBinds idL idR
-> [Id]
-> [Id]
-> [ABExport idL]
-> [TcEvBinds]
-> LHsBinds idL
-> Bool
-> HsBindLR idL idR
AbsBinds { abs_ext :: XAbsBinds GhcTc GhcTc
abs_ext = NoExtField
XAbsBinds GhcTc GhcTc
noExtField
                                 , abs_tvs :: [Id]
abs_tvs = [Id]
qtvs
                                 , abs_ev_vars :: [Id]
abs_ev_vars = [Id]
givens, abs_ev_binds :: [TcEvBinds]
abs_ev_binds = [TcEvBinds
ev_binds]
                                 , abs_exports :: [ABExport GhcTc]
abs_exports = [ABExport GhcTc]
exports, abs_binds :: LHsBinds GhcTc
abs_binds = Bag (Located (HsBindLR GhcTc GhcTc))
LHsBinds GhcTc
binds'
                                 , abs_sig :: Bool
abs_sig = Bool
False }

       ; String -> SDoc -> TcRn ()
traceTc String
"Binding:" ([(Id, Type)] -> SDoc
forall a. Outputable a => a -> SDoc
ppr ([Id]
poly_ids [Id] -> [Type] -> [(Id, Type)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` (Id -> Type) -> [Id] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map Id -> Type
idType [Id]
poly_ids))
       ; (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [Id])
forall (m :: * -> *) a. Monad m => a -> m a
return (Located (HsBindLR GhcTc GhcTc)
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a. a -> Bag a
unitBag Located (HsBindLR GhcTc GhcTc)
abs_bind, [Id]
poly_ids) }
         -- poly_ids are guaranteed zonked by mkExport

--------------
mkExport :: TcPragEnv
         -> Bool                        -- True <=> there was an insoluble type error
                                        --          when typechecking the bindings
         -> [TyVar] -> TcThetaType      -- Both already zonked
         -> MonoBindInfo
         -> TcM (ABExport GhcTc)
-- Only called for generalisation plan InferGen, not by CheckGen or NoGen
--
-- mkExport generates exports with
--      zonked type variables,
--      zonked poly_ids
-- The former is just because no further unifications will change
-- the quantified type variables, so we can fix their final form
-- right now.
-- The latter is needed because the poly_ids are used to extend the
-- type environment; see the invariant on GHC.Tc.Utils.Env.tcExtendIdEnv

-- Pre-condition: the qtvs and theta are already zonked

mkExport :: TcPragEnv
-> Bool
-> [Id]
-> [Type]
-> MonoBindInfo
-> IOEnv (Env TcGblEnv TcLclEnv) (ABExport GhcTc)
mkExport TcPragEnv
prag_fn Bool
insoluble [Id]
qtvs [Type]
theta
         mono_info :: MonoBindInfo
mono_info@(MBI { mbi_poly_name :: MonoBindInfo -> Name
mbi_poly_name = Name
poly_name
                        , mbi_sig :: MonoBindInfo -> Maybe TcIdSigInst
mbi_sig       = Maybe TcIdSigInst
mb_sig
                        , mbi_mono_id :: MonoBindInfo -> Id
mbi_mono_id   = Id
mono_id })
  = do  { Type
mono_ty <- Type -> TcM Type
zonkTcType (Id -> Type
idType Id
mono_id)
        ; Id
poly_id <- Bool
-> [Id]
-> [Type]
-> Name
-> Maybe TcIdSigInst
-> Type
-> IOEnv (Env TcGblEnv TcLclEnv) Id
mkInferredPolyId Bool
insoluble [Id]
qtvs [Type]
theta Name
poly_name Maybe TcIdSigInst
mb_sig Type
mono_ty

        -- NB: poly_id has a zonked type
        ; Id
poly_id <- Id -> [LSig GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) Id
addInlinePrags Id
poly_id [LSig GhcRn]
prag_sigs
        ; [LTcSpecPrag]
spec_prags <- Id -> [LSig GhcRn] -> TcM [LTcSpecPrag]
tcSpecPrags Id
poly_id [LSig GhcRn]
prag_sigs
                -- tcPrags requires a zonked poly_id

        -- See Note [Impedance matching]
        -- NB: we have already done checkValidType, including an ambiguity check,
        --     on the type; either when we checked the sig or in mkInferredPolyId
        ; let poly_ty :: Type
poly_ty     = Id -> Type
idType Id
poly_id
              sel_poly_ty :: Type
sel_poly_ty = [Id] -> [Type] -> Type -> Type
mkInfSigmaTy [Id]
qtvs [Type]
theta Type
mono_ty
                -- This type is just going into tcSubType,
                -- so Inferred vs. Specified doesn't matter

        ; HsWrapper
wrap <- if Type
sel_poly_ty Type -> Type -> Bool
`eqType` Type
poly_ty  -- NB: eqType ignores visibility
                  then HsWrapper -> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
forall (m :: * -> *) a. Monad m => a -> m a
return HsWrapper
idHsWrapper  -- Fast path; also avoids complaint when we infer
                                           -- an ambiguous type and have AllowAmbiguousType
                                           -- e..g infer  x :: forall a. F a -> Int
                  else (TidyEnv -> TcM (TidyEnv, SDoc))
-> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
-> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
forall a. (TidyEnv -> TcM (TidyEnv, SDoc)) -> TcM a -> TcM a
addErrCtxtM (MonoBindInfo -> Type -> Type -> TidyEnv -> TcM (TidyEnv, SDoc)
mk_impedance_match_msg MonoBindInfo
mono_info Type
sel_poly_ty Type
poly_ty) (IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
 -> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper)
-> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
-> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
forall a b. (a -> b) -> a -> b
$
                       UserTypeCtxt
-> Type -> Type -> IOEnv (Env TcGblEnv TcLclEnv) HsWrapper
tcSubTypeSigma UserTypeCtxt
sig_ctxt Type
sel_poly_ty Type
poly_ty

        ; Bool
warn_missing_sigs <- WarningFlag -> TcRnIf TcGblEnv TcLclEnv Bool
forall gbl lcl. WarningFlag -> TcRnIf gbl lcl Bool
woptM WarningFlag
Opt_WarnMissingLocalSignatures
        ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
when Bool
warn_missing_sigs (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
              WarningFlag -> Id -> Maybe TcIdSigInst -> TcRn ()
localSigWarn WarningFlag
Opt_WarnMissingLocalSignatures Id
poly_id Maybe TcIdSigInst
mb_sig

        ; ABExport GhcTc -> IOEnv (Env TcGblEnv TcLclEnv) (ABExport GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return (ABE :: forall p.
XABE p -> IdP p -> IdP p -> HsWrapper -> TcSpecPrags -> ABExport p
ABE { abe_ext :: XABE GhcTc
abe_ext = NoExtField
XABE GhcTc
noExtField
                      , abe_wrap :: HsWrapper
abe_wrap = HsWrapper
wrap
                        -- abe_wrap :: idType poly_id ~ (forall qtvs. theta => mono_ty)
                      , abe_poly :: IdP GhcTc
abe_poly  = Id
IdP GhcTc
poly_id
                      , abe_mono :: IdP GhcTc
abe_mono  = Id
IdP GhcTc
mono_id
                      , abe_prags :: TcSpecPrags
abe_prags = [LTcSpecPrag] -> TcSpecPrags
SpecPrags [LTcSpecPrag]
spec_prags }) }
  where
    prag_sigs :: [LSig GhcRn]
prag_sigs = TcPragEnv -> Name -> [LSig GhcRn]
lookupPragEnv TcPragEnv
prag_fn Name
poly_name
    sig_ctxt :: UserTypeCtxt
sig_ctxt  = Name -> UserTypeCtxt
InfSigCtxt Name
poly_name

mkInferredPolyId :: Bool  -- True <=> there was an insoluble error when
                          --          checking the binding group for this Id
                 -> [TyVar] -> TcThetaType
                 -> Name -> Maybe TcIdSigInst -> TcType
                 -> TcM TcId
mkInferredPolyId :: Bool
-> [Id]
-> [Type]
-> Name
-> Maybe TcIdSigInst
-> Type
-> IOEnv (Env TcGblEnv TcLclEnv) Id
mkInferredPolyId Bool
insoluble [Id]
qtvs [Type]
inferred_theta Name
poly_name Maybe TcIdSigInst
mb_sig_inst Type
mono_ty
  | Just (TISI { sig_inst_sig :: TcIdSigInst -> TcIdSigInfo
sig_inst_sig = TcIdSigInfo
sig })  <- Maybe TcIdSigInst
mb_sig_inst
  , CompleteSig { sig_bndr :: TcIdSigInfo -> Id
sig_bndr = Id
poly_id } <- TcIdSigInfo
sig
  = Id -> IOEnv (Env TcGblEnv TcLclEnv) Id
forall (m :: * -> *) a. Monad m => a -> m a
return Id
poly_id

  | Bool
otherwise  -- Either no type sig or partial type sig
  = IOEnv (Env TcGblEnv TcLclEnv) Id
-> IOEnv (Env TcGblEnv TcLclEnv) Id
forall r. TcM r -> TcM r
checkNoErrs (IOEnv (Env TcGblEnv TcLclEnv) Id
 -> IOEnv (Env TcGblEnv TcLclEnv) Id)
-> IOEnv (Env TcGblEnv TcLclEnv) Id
-> IOEnv (Env TcGblEnv TcLclEnv) Id
forall a b. (a -> b) -> a -> b
$  -- The checkNoErrs ensures that if the type is ambiguous
                   -- we don't carry on to the impedance matching, and generate
                   -- a duplicate ambiguity error.  There is a similar
                   -- checkNoErrs for complete type signatures too.
    do { FamInstEnvs
fam_envs <- TcM FamInstEnvs
tcGetFamInstEnvs
       ; let (TcCoercionR
_co, Type
mono_ty') = FamInstEnvs -> Role -> Type -> (TcCoercionR, Type)
normaliseType FamInstEnvs
fam_envs Role
Nominal Type
mono_ty
               -- Unification may not have normalised the type,
               -- (see Note [Lazy flattening] in GHC.Tc.Solver.Flatten) so do it
               -- here to make it as uncomplicated as possible.
               -- Example: f :: [F Int] -> Bool
               -- should be rewritten to f :: [Char] -> Bool, if possible
               --
               -- We can discard the coercion _co, because we'll reconstruct
               -- it in the call to tcSubType below

       ; ([InvisTVBinder]
binders, [Type]
theta') <- [Type]
-> TcTyVarSet
-> [Id]
-> Maybe TcIdSigInst
-> TcM ([InvisTVBinder], [Type])
chooseInferredQuantifiers [Type]
inferred_theta
                                (Type -> TcTyVarSet
tyCoVarsOfType Type
mono_ty') [Id]
qtvs Maybe TcIdSigInst
mb_sig_inst

       ; let inferred_poly_ty :: Type
inferred_poly_ty = [InvisTVBinder] -> Type -> Type
mkInvisForAllTys [InvisTVBinder]
binders ([Type] -> Type -> Type
mkPhiTy [Type]
theta' Type
mono_ty')

       ; String -> SDoc -> TcRn ()
traceTc String
"mkInferredPolyId" ([SDoc] -> SDoc
vcat [Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
poly_name, [Id] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Id]
qtvs, [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
theta'
                                          , Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
inferred_poly_ty])
       ; Bool -> TcRn () -> TcRn ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless Bool
insoluble (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         (TidyEnv -> TcM (TidyEnv, SDoc)) -> TcRn () -> TcRn ()
forall a. (TidyEnv -> TcM (TidyEnv, SDoc)) -> TcM a -> TcM a
addErrCtxtM (Name -> Type -> TidyEnv -> TcM (TidyEnv, SDoc)
mk_inf_msg Name
poly_name Type
inferred_poly_ty) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
         UserTypeCtxt -> Type -> TcRn ()
checkValidType (Name -> UserTypeCtxt
InfSigCtxt Name
poly_name) Type
inferred_poly_ty
         -- See Note [Validity of inferred types]
         -- If we found an insoluble error in the function definition, don't
         -- do this check; otherwise (#14000) we may report an ambiguity
         -- error for a rather bogus type.

       ; Id -> IOEnv (Env TcGblEnv TcLclEnv) Id
forall (m :: * -> *) a. Monad m => a -> m a
return (HasDebugCallStack => Name -> Type -> Type -> Id
Name -> Type -> Type -> Id
mkLocalId Name
poly_name Type
Many Type
inferred_poly_ty) }


chooseInferredQuantifiers :: TcThetaType   -- inferred
                          -> TcTyVarSet    -- tvs free in tau type
                          -> [TcTyVar]     -- inferred quantified tvs
                          -> Maybe TcIdSigInst
                          -> TcM ([InvisTVBinder], TcThetaType)
chooseInferredQuantifiers :: [Type]
-> TcTyVarSet
-> [Id]
-> Maybe TcIdSigInst
-> TcM ([InvisTVBinder], [Type])
chooseInferredQuantifiers [Type]
inferred_theta TcTyVarSet
tau_tvs [Id]
qtvs Maybe TcIdSigInst
Nothing
  = -- No type signature (partial or complete) for this binder,
    do { let free_tvs :: TcTyVarSet
free_tvs = TcTyVarSet -> TcTyVarSet
closeOverKinds ([Type] -> TcTyVarSet -> TcTyVarSet
growThetaTyVars [Type]
inferred_theta TcTyVarSet
tau_tvs)
                        -- Include kind variables!  #7916
             my_theta :: [Type]
my_theta = TcTyVarSet -> [Type] -> [Type]
pickCapturedPreds TcTyVarSet
free_tvs [Type]
inferred_theta
             binders :: [InvisTVBinder]
binders  = [ Specificity -> Id -> InvisTVBinder
forall vis. vis -> Id -> VarBndr Id vis
mkTyVarBinder Specificity
InferredSpec Id
tv
                        | Id
tv <- [Id]
qtvs
                        , Id
tv Id -> TcTyVarSet -> Bool
`elemVarSet` TcTyVarSet
free_tvs ]
       ; ([InvisTVBinder], [Type]) -> TcM ([InvisTVBinder], [Type])
forall (m :: * -> *) a. Monad m => a -> m a
return ([InvisTVBinder]
binders, [Type]
my_theta) }

chooseInferredQuantifiers [Type]
inferred_theta TcTyVarSet
tau_tvs [Id]
qtvs
                          (Just (TISI { sig_inst_sig :: TcIdSigInst -> TcIdSigInfo
sig_inst_sig   = TcIdSigInfo
sig  -- Always PartialSig
                                      , sig_inst_wcx :: TcIdSigInst -> Maybe Type
sig_inst_wcx   = Maybe Type
wcx
                                      , sig_inst_theta :: TcIdSigInst -> [Type]
sig_inst_theta = [Type]
annotated_theta
                                      , sig_inst_skols :: TcIdSigInst -> [(Name, InvisTVBinder)]
sig_inst_skols = [(Name, InvisTVBinder)]
annotated_tvs }))
  = -- Choose quantifiers for a partial type signature
    do { let ([Name]
psig_qtv_nms, [InvisTVBinder]
psig_qtv_bndrs) = [(Name, InvisTVBinder)] -> ([Name], [InvisTVBinder])
forall a b. [(a, b)] -> ([a], [b])
unzip [(Name, InvisTVBinder)]
annotated_tvs
       ; [InvisTVBinder]
psig_qtv_bndrs <- (InvisTVBinder -> IOEnv (Env TcGblEnv TcLclEnv) InvisTVBinder)
-> [InvisTVBinder] -> IOEnv (Env TcGblEnv TcLclEnv) [InvisTVBinder]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM InvisTVBinder -> IOEnv (Env TcGblEnv TcLclEnv) InvisTVBinder
forall spec. VarBndr Id spec -> TcM (VarBndr Id spec)
zonkInvisTVBinder [InvisTVBinder]
psig_qtv_bndrs
       ; let psig_qtvs :: [Id]
psig_qtvs    = (InvisTVBinder -> Id) -> [InvisTVBinder] -> [Id]
forall a b. (a -> b) -> [a] -> [b]
map InvisTVBinder -> Id
forall tv argf. VarBndr tv argf -> tv
binderVar [InvisTVBinder]
psig_qtv_bndrs
             psig_qtv_set :: TcTyVarSet
psig_qtv_set = [Id] -> TcTyVarSet
mkVarSet [Id]
psig_qtvs
             psig_qtv_prs :: [(Name, Id)]
psig_qtv_prs = [Name]
psig_qtv_nms [Name] -> [Id] -> [(Name, Id)]
forall a b. [a] -> [b] -> [(a, b)]
`zip` [Id]
psig_qtvs


            -- Check whether the quantified variables of the
            -- partial signature have been unified together
            -- See Note [Quantified variables in partial type signatures]
       ; ((Name, Name) -> TcRn ()) -> [(Name, Name)] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (Name, Name) -> TcRn ()
report_dup_tyvar_tv_err  ([(Name, Id)] -> [(Name, Name)]
findDupTyVarTvs [(Name, Id)]
psig_qtv_prs)

            -- Check whether a quantified variable of the partial type
            -- signature is not actually quantified.  How can that happen?
            -- See Note [Quantification and partial signatures] Wrinkle 4
            --     in GHC.Tc.Solver
       ; (Name -> TcRn ()) -> [Name] -> TcRn ()
forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ Name -> TcRn ()
report_mono_sig_tv_err [ Name
n | (Name
n,Id
tv) <- [(Name, Id)]
psig_qtv_prs
                                          , Bool -> Bool
not (Id
tv Id -> [Id] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [Id]
qtvs) ]

       ; [Type]
annotated_theta      <- [Type] -> TcM [Type]
zonkTcTypes [Type]
annotated_theta
       ; (TcTyVarSet
free_tvs, [Type]
my_theta) <- TcTyVarSet -> [Type] -> Maybe Type -> TcM (TcTyVarSet, [Type])
choose_psig_context TcTyVarSet
psig_qtv_set [Type]
annotated_theta Maybe Type
wcx

       ; let keep_me :: TcTyVarSet
keep_me    = TcTyVarSet
free_tvs TcTyVarSet -> TcTyVarSet -> TcTyVarSet
`unionVarSet` TcTyVarSet
psig_qtv_set
             final_qtvs :: [InvisTVBinder]
final_qtvs = [ Specificity -> Id -> InvisTVBinder
forall vis. vis -> Id -> VarBndr Id vis
mkTyVarBinder Specificity
vis Id
tv
                          | Id
tv <- [Id]
qtvs -- Pulling from qtvs maintains original order
                          , Id
tv Id -> TcTyVarSet -> Bool
`elemVarSet` TcTyVarSet
keep_me
                          , let vis :: Specificity
vis = case Id -> [InvisTVBinder] -> Maybe Specificity
forall var flag. Eq var => var -> [VarBndr var flag] -> Maybe flag
lookupVarBndr Id
tv [InvisTVBinder]
psig_qtv_bndrs of
                                  Just Specificity
spec -> Specificity
spec
                                  Maybe Specificity
Nothing   -> Specificity
InferredSpec ]

       ; ([InvisTVBinder], [Type]) -> TcM ([InvisTVBinder], [Type])
forall (m :: * -> *) a. Monad m => a -> m a
return ([InvisTVBinder]
final_qtvs, [Type]
my_theta) }
  where
    report_dup_tyvar_tv_err :: (Name, Name) -> TcRn ()
report_dup_tyvar_tv_err (Name
n1,Name
n2)
      | PartialSig { psig_name :: TcIdSigInfo -> Name
psig_name = Name
fn_name, psig_hs_ty :: TcIdSigInfo -> LHsSigWcType GhcRn
psig_hs_ty = LHsSigWcType GhcRn
hs_ty } <- TcIdSigInfo
sig
      = SDoc -> TcRn ()
addErrTc (SDoc -> BKey -> SDoc -> SDoc
hang (String -> SDoc
text String
"Couldn't match" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
n1)
                        SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"with" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
n2))
                     BKey
2 (SDoc -> BKey -> SDoc -> SDoc
hang (String -> SDoc
text String
"both bound by the partial type signature:")
                           BKey
2 (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
fn_name SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> HsWildCardBndrs
  GhcRn (HsImplicitBndrs GhcRn (Located (HsType GhcRn)))
-> SDoc
forall a. Outputable a => a -> SDoc
ppr HsWildCardBndrs
  GhcRn (HsImplicitBndrs GhcRn (Located (HsType GhcRn)))
LHsSigWcType GhcRn
hs_ty)))

      | Bool
otherwise -- Can't happen; by now we know it's a partial sig
      = String -> SDoc -> TcRn ()
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"report_tyvar_tv_err" (TcIdSigInfo -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcIdSigInfo
sig)

    report_mono_sig_tv_err :: Name -> TcRn ()
report_mono_sig_tv_err Name
n
      | PartialSig { psig_name :: TcIdSigInfo -> Name
psig_name = Name
fn_name, psig_hs_ty :: TcIdSigInfo -> LHsSigWcType GhcRn
psig_hs_ty = LHsSigWcType GhcRn
hs_ty } <- TcIdSigInfo
sig
      = SDoc -> TcRn ()
addErrTc (SDoc -> BKey -> SDoc -> SDoc
hang (String -> SDoc
text String
"Can't quantify over" SDoc -> SDoc -> SDoc
<+> SDoc -> SDoc
quotes (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
n))
                     BKey
2 (SDoc -> BKey -> SDoc -> SDoc
hang (String -> SDoc
text String
"bound by the partial type signature:")
                           BKey
2 (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
fn_name SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> HsWildCardBndrs
  GhcRn (HsImplicitBndrs GhcRn (Located (HsType GhcRn)))
-> SDoc
forall a. Outputable a => a -> SDoc
ppr HsWildCardBndrs
  GhcRn (HsImplicitBndrs GhcRn (Located (HsType GhcRn)))
LHsSigWcType GhcRn
hs_ty)))
      | Bool
otherwise -- Can't happen; by now we know it's a partial sig
      = String -> SDoc -> TcRn ()
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"report_mono_sig_tv_err" (TcIdSigInfo -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcIdSigInfo
sig)

    choose_psig_context :: VarSet -> TcThetaType -> Maybe TcType
                        -> TcM (VarSet, TcThetaType)
    choose_psig_context :: TcTyVarSet -> [Type] -> Maybe Type -> TcM (TcTyVarSet, [Type])
choose_psig_context TcTyVarSet
_ [Type]
annotated_theta Maybe Type
Nothing
      = do { let free_tvs :: TcTyVarSet
free_tvs = TcTyVarSet -> TcTyVarSet
closeOverKinds ([Type] -> TcTyVarSet
tyCoVarsOfTypes [Type]
annotated_theta
                                            TcTyVarSet -> TcTyVarSet -> TcTyVarSet
`unionVarSet` TcTyVarSet
tau_tvs)
           ; (TcTyVarSet, [Type]) -> TcM (TcTyVarSet, [Type])
forall (m :: * -> *) a. Monad m => a -> m a
return (TcTyVarSet
free_tvs, [Type]
annotated_theta) }

    choose_psig_context TcTyVarSet
psig_qtvs [Type]
annotated_theta (Just Type
wc_var_ty)
      = do { let free_tvs :: TcTyVarSet
free_tvs = TcTyVarSet -> TcTyVarSet
closeOverKinds ([Type] -> TcTyVarSet -> TcTyVarSet
growThetaTyVars [Type]
inferred_theta TcTyVarSet
seed_tvs)
                            -- growThetaVars just like the no-type-sig case
                            -- Omitting this caused #12844
                 seed_tvs :: TcTyVarSet
seed_tvs = [Type] -> TcTyVarSet
tyCoVarsOfTypes [Type]
annotated_theta  -- These are put there
                            TcTyVarSet -> TcTyVarSet -> TcTyVarSet
`unionVarSet` TcTyVarSet
tau_tvs            --       by the user

           ; let keep_me :: TcTyVarSet
keep_me  = TcTyVarSet
psig_qtvs TcTyVarSet -> TcTyVarSet -> TcTyVarSet
`unionVarSet` TcTyVarSet
free_tvs
                 my_theta :: [Type]
my_theta = TcTyVarSet -> [Type] -> [Type]
pickCapturedPreds TcTyVarSet
keep_me [Type]
inferred_theta

           -- Fill in the extra-constraints wildcard hole with inferred_theta,
           -- so that the Hole constraint we have already emitted
           -- (in tcHsPartialSigType) can report what filled it in.
           -- NB: my_theta already includes all the annotated constraints
           ; let inferred_diff :: [Type]
inferred_diff = [ Type
pred
                                 | Type
pred <- [Type]
my_theta
                                 , (Type -> Bool) -> [Type] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all (Bool -> Bool
not (Bool -> Bool) -> (Type -> Bool) -> Type -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Type -> Type -> Bool
`eqType` Type
pred)) [Type]
annotated_theta ]
           ; Type
ctuple <- [Type] -> TcM Type
forall (m :: * -> *). Monad m => [Type] -> m Type
mk_ctuple [Type]
inferred_diff

           ; case Type -> Maybe (Id, TcCoercionR)
tcGetCastedTyVar_maybe Type
wc_var_ty of
               -- We know that wc_co must have type kind(wc_var) ~ Constraint, as it
               -- comes from the checkExpectedKind in GHC.Tc.Gen.HsType.tcAnonWildCardOcc. So, to
               -- make the kinds work out, we reverse the cast here.
               Just (Id
wc_var, TcCoercionR
wc_co) -> Id -> Type -> TcRn ()
writeMetaTyVar Id
wc_var (Type
ctuple Type -> TcCoercionR -> Type
`mkCastTy` TcCoercionR -> TcCoercionR
mkTcSymCo TcCoercionR
wc_co)
               Maybe (Id, TcCoercionR)
Nothing              -> String -> SDoc -> TcRn ()
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"chooseInferredQuantifiers 1" (Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
wc_var_ty)

           ; String -> SDoc -> TcRn ()
traceTc String
"completeTheta" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
                [SDoc] -> SDoc
vcat [ TcIdSigInfo -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcIdSigInfo
sig
                     , [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
annotated_theta, [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
inferred_theta
                     , [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
inferred_diff ]
           ; (TcTyVarSet, [Type]) -> TcM (TcTyVarSet, [Type])
forall (m :: * -> *) a. Monad m => a -> m a
return (TcTyVarSet
free_tvs, [Type]
my_theta) }

    mk_ctuple :: [Type] -> m Type
mk_ctuple [Type]
preds = Type -> m Type
forall (m :: * -> *) a. Monad m => a -> m a
return ([Type] -> Type
mkBoxedTupleTy [Type]
preds)
       -- Hack alert!  See GHC.Tc.Gen.HsType:
       -- Note [Extra-constraint holes in partial type signatures]


mk_impedance_match_msg :: MonoBindInfo
                       -> TcType -> TcType
                       -> TidyEnv -> TcM (TidyEnv, SDoc)
-- This is a rare but rather awkward error messages
mk_impedance_match_msg :: MonoBindInfo -> Type -> Type -> TidyEnv -> TcM (TidyEnv, SDoc)
mk_impedance_match_msg (MBI { mbi_poly_name :: MonoBindInfo -> Name
mbi_poly_name = Name
name, mbi_sig :: MonoBindInfo -> Maybe TcIdSigInst
mbi_sig = Maybe TcIdSigInst
mb_sig })
                       Type
inf_ty Type
sig_ty TidyEnv
tidy_env
 = do { (TidyEnv
tidy_env1, Type
inf_ty) <- TidyEnv -> Type -> TcM (TidyEnv, Type)
zonkTidyTcType TidyEnv
tidy_env  Type
inf_ty
      ; (TidyEnv
tidy_env2, Type
sig_ty) <- TidyEnv -> Type -> TcM (TidyEnv, Type)
zonkTidyTcType TidyEnv
tidy_env1 Type
sig_ty
      ; let msg :: SDoc
msg = [SDoc] -> SDoc
vcat [ String -> SDoc
text String
"When checking that the inferred type"
                       , BKey -> SDoc -> SDoc
nest BKey
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
inf_ty
                       , String -> SDoc
text String
"is as general as its" SDoc -> SDoc -> SDoc
<+> SDoc
what SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"signature"
                       , BKey -> SDoc -> SDoc
nest BKey
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
sig_ty ]
      ; (TidyEnv, SDoc) -> TcM (TidyEnv, SDoc)
forall (m :: * -> *) a. Monad m => a -> m a
return (TidyEnv
tidy_env2, SDoc
msg) }
  where
    what :: SDoc
what = case Maybe TcIdSigInst
mb_sig of
             Maybe TcIdSigInst
Nothing                     -> String -> SDoc
text String
"inferred"
             Just TcIdSigInst
sig | TcIdSigInst -> Bool
isPartialSig TcIdSigInst
sig -> String -> SDoc
text String
"(partial)"
                      | Bool
otherwise        -> SDoc
empty


mk_inf_msg :: Name -> TcType -> TidyEnv -> TcM (TidyEnv, SDoc)
mk_inf_msg :: Name -> Type -> TidyEnv -> TcM (TidyEnv, SDoc)
mk_inf_msg Name
poly_name Type
poly_ty TidyEnv
tidy_env
 = do { (TidyEnv
tidy_env1, Type
poly_ty) <- TidyEnv -> Type -> TcM (TidyEnv, Type)
zonkTidyTcType TidyEnv
tidy_env Type
poly_ty
      ; let msg :: SDoc
msg = [SDoc] -> SDoc
vcat [ String -> SDoc
text String
"When checking the inferred type"
                       , BKey -> SDoc -> SDoc
nest BKey
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
poly_name SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
poly_ty ]
      ; (TidyEnv, SDoc) -> TcM (TidyEnv, SDoc)
forall (m :: * -> *) a. Monad m => a -> m a
return (TidyEnv
tidy_env1, SDoc
msg) }


-- | Warn the user about polymorphic local binders that lack type signatures.
localSigWarn :: WarningFlag -> Id -> Maybe TcIdSigInst -> TcM ()
localSigWarn :: WarningFlag -> Id -> Maybe TcIdSigInst -> TcRn ()
localSigWarn WarningFlag
flag Id
id Maybe TcIdSigInst
mb_sig
  | Just TcIdSigInst
_ <- Maybe TcIdSigInst
mb_sig               = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  | Bool -> Bool
not (Type -> Bool
isSigmaTy (Id -> Type
idType Id
id))    = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()
  | Bool
otherwise                      = WarningFlag -> SDoc -> Id -> TcRn ()
warnMissingSignatures WarningFlag
flag SDoc
msg Id
id
  where
    msg :: SDoc
msg = String -> SDoc
text String
"Polymorphic local binding with no type signature:"

warnMissingSignatures :: WarningFlag -> SDoc -> Id -> TcM ()
warnMissingSignatures :: WarningFlag -> SDoc -> Id -> TcRn ()
warnMissingSignatures WarningFlag
flag SDoc
msg Id
id
  = do  { TidyEnv
env0 <- TcM TidyEnv
tcInitTidyEnv
        ; let (TidyEnv
env1, Type
tidy_ty) = TidyEnv -> Type -> (TidyEnv, Type)
tidyOpenType TidyEnv
env0 (Id -> Type
idType Id
id)
        ; WarnReason -> (TidyEnv, SDoc) -> TcRn ()
addWarnTcM (WarningFlag -> WarnReason
Reason WarningFlag
flag) (TidyEnv
env1, Type -> SDoc
mk_msg Type
tidy_ty) }
  where
    mk_msg :: Type -> SDoc
mk_msg Type
ty = [SDoc] -> SDoc
sep [ SDoc
msg, BKey -> SDoc -> SDoc
nest BKey
2 (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ Name -> SDoc
forall a. NamedThing a => a -> SDoc
pprPrefixName (Id -> Name
idName Id
id) SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty ]

checkOverloadedSig :: Bool -> TcIdSigInst -> TcM ()
-- Example:
--   f :: Eq a => a -> a
--   K f = e
-- The MR applies, but the signature is overloaded, and it's
-- best to complain about this directly
-- c.f #11339
checkOverloadedSig :: Bool -> TcIdSigInst -> TcRn ()
checkOverloadedSig Bool
monomorphism_restriction_applies TcIdSigInst
sig
  | Bool -> Bool
not ([Type] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null (TcIdSigInst -> [Type]
sig_inst_theta TcIdSigInst
sig))
  , Bool
monomorphism_restriction_applies
  , let orig_sig :: TcIdSigInfo
orig_sig = TcIdSigInst -> TcIdSigInfo
sig_inst_sig TcIdSigInst
sig
  = SrcSpan -> TcRn () -> TcRn ()
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan (TcIdSigInfo -> SrcSpan
sig_loc TcIdSigInfo
orig_sig) (TcRn () -> TcRn ()) -> TcRn () -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    SDoc -> TcRn ()
forall a. SDoc -> TcRn a
failWith (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$
    SDoc -> BKey -> SDoc -> SDoc
hang (String -> SDoc
text String
"Overloaded signature conflicts with monomorphism restriction")
       BKey
2 (TcIdSigInfo -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcIdSigInfo
orig_sig)
  | Bool
otherwise
  = () -> TcRn ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()

{- Note [Partial type signatures and generalisation]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If /any/ of the signatures in the group is a partial type signature
   f :: _ -> Int
then we *always* use the InferGen plan, and hence tcPolyInfer.
We do this even for a local binding with -XMonoLocalBinds, when
we normally use NoGen.

Reasons:
  * The TcSigInfo for 'f' has a unification variable for the '_',
    whose TcLevel is one level deeper than the current level.
    (See pushTcLevelM in tcTySig.)  But NoGen doesn't increase
    the TcLevel like InferGen, so we lose the level invariant.

  * The signature might be   f :: forall a. _ -> a
    so it really is polymorphic.  It's not clear what it would
    mean to use NoGen on this, and indeed the ASSERT in tcLhs,
    in the (Just sig) case, checks that if there is a signature
    then we are using LetLclBndr, and hence a nested AbsBinds with
    increased TcLevel

It might be possible to fix these difficulties somehow, but there
doesn't seem much point.  Indeed, adding a partial type signature is a
way to get per-binding inferred generalisation.

We apply the MR if /all/ of the partial signatures lack a context.
In particular (#11016):
   f2 :: (?loc :: Int) => _
   f2 = ?loc
It's stupid to apply the MR here.  This test includes an extra-constraints
wildcard; that is, we don't apply the MR if you write
   f3 :: _ => blah

Note [Quantified variables in partial type signatures]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
  f :: forall a. a -> a -> _
  f x y = g x y
  g :: forall b. b -> b -> _
  g x y = [x, y]

Here, 'f' and 'g' are mutually recursive, and we end up unifying 'a' and 'b'
together, which is fine.  So we bind 'a' and 'b' to TyVarTvs, which can then
unify with each other.

But now consider:
  f :: forall a b. a -> b -> _
  f x y = [x, y]

We want to get an error from this, because 'a' and 'b' get unified.
So we make a test, one per partial signature, to check that the
explicitly-quantified type variables have not been unified together.
#14449 showed this up.


Note [Validity of inferred types]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We need to check inferred type for validity, in case it uses language
extensions that are not turned on.  The principle is that if the user
simply adds the inferred type to the program source, it'll compile fine.
See #8883.

Examples that might fail:
 - the type might be ambiguous

 - an inferred theta that requires type equalities e.g. (F a ~ G b)
                                or multi-parameter type classes
 - an inferred type that includes unboxed tuples


Note [Impedance matching]
~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
   f 0 x = x
   f n x = g [] (not x)

   g [] y = f 10 y
   g _  y = f 9  y

After typechecking we'll get
  f_mono_ty :: a -> Bool -> Bool
  g_mono_ty :: [b] -> Bool -> Bool
with constraints
  (Eq a, Num a)

Note that f is polymorphic in 'a' and g in 'b'; and these are not linked.
The types we really want for f and g are
   f :: forall a. (Eq a, Num a) => a -> Bool -> Bool
   g :: forall b. [b] -> Bool -> Bool

We can get these by "impedance matching":
   tuple :: forall a b. (Eq a, Num a) => (a -> Bool -> Bool, [b] -> Bool -> Bool)
   tuple a b d1 d1 = let ...bind f_mono, g_mono in (f_mono, g_mono)

   f a d1 d2 = case tuple a Any d1 d2 of (f, g) -> f
   g b = case tuple Integer b dEqInteger dNumInteger of (f,g) -> g

Suppose the shared quantified tyvars are qtvs and constraints theta.
Then we want to check that
     forall qtvs. theta => f_mono_ty   is more polymorphic than   f's polytype
and the proof is the impedance matcher.

Notice that the impedance matcher may do defaulting.  See #7173.

It also cleverly does an ambiguity check; for example, rejecting
   f :: F a -> F a
where F is a non-injective type function.
-}


{-
Note [SPECIALISE pragmas]
~~~~~~~~~~~~~~~~~~~~~~~~~
There is no point in a SPECIALISE pragma for a non-overloaded function:
   reverse :: [a] -> [a]
   {-# SPECIALISE reverse :: [Int] -> [Int] #-}

But SPECIALISE INLINE *can* make sense for GADTS:
   data Arr e where
     ArrInt :: !Int -> ByteArray# -> Arr Int
     ArrPair :: !Int -> Arr e1 -> Arr e2 -> Arr (e1, e2)

   (!:) :: Arr e -> Int -> e
   {-# SPECIALISE INLINE (!:) :: Arr Int -> Int -> Int #-}
   {-# SPECIALISE INLINE (!:) :: Arr (a, b) -> Int -> (a, b) #-}
   (ArrInt _ ba)     !: (I# i) = I# (indexIntArray# ba i)
   (ArrPair _ a1 a2) !: i      = (a1 !: i, a2 !: i)

When (!:) is specialised it becomes non-recursive, and can usefully
be inlined.  Scary!  So we only warn for SPECIALISE *without* INLINE
for a non-overloaded function.

************************************************************************
*                                                                      *
                         tcMonoBinds
*                                                                      *
************************************************************************

@tcMonoBinds@ deals with a perhaps-recursive group of HsBinds.
The signatures have been dealt with already.
-}

data MonoBindInfo = MBI { MonoBindInfo -> Name
mbi_poly_name :: Name
                        , MonoBindInfo -> Maybe TcIdSigInst
mbi_sig       :: Maybe TcIdSigInst
                        , MonoBindInfo -> Id
mbi_mono_id   :: TcId }

tcMonoBinds :: RecFlag  -- Whether the binding is recursive for typechecking purposes
                        -- i.e. the binders are mentioned in their RHSs, and
                        --      we are not rescued by a type signature
            -> TcSigFun -> LetBndrSpec
            -> [LHsBind GhcRn]
            -> TcM (LHsBinds GhcTc, [MonoBindInfo])

-- SPECIAL CASE 1: see Note [Inference for non-recursive function bindings]
tcMonoBinds :: RecFlag
-> TcSigFun
-> LetBndrSpec
-> [LHsBind GhcRn]
-> TcM (LHsBinds GhcTc, [MonoBindInfo])
tcMonoBinds RecFlag
is_rec TcSigFun
sig_fn LetBndrSpec
no_gen
           [ L b_loc (FunBind { fun_id = L nm_loc name
                              , fun_matches = matches })]
                             -- Single function binding,
  | RecFlag
NonRecursive <- RecFlag
is_rec   -- ...binder isn't mentioned in RHS
  , Maybe TcSigInfo
Nothing <- TcSigFun
sig_fn Name
name   -- ...with no type signature
  = SrcSpan
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
forall a. SrcSpan -> TcRn a -> TcRn a
setSrcSpan SrcSpan
b_loc    (IOEnv
   (Env TcGblEnv TcLclEnv)
   (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
forall a b. (a -> b) -> a -> b
$
    do  { ((HsWrapper
co_fn, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
matches'), Type
rhs_ty)
            <- (ExpSigmaType
 -> TcM
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcM
     ((HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))),
      Type)
forall a. (ExpSigmaType -> TcM a) -> TcM (a, Type)
tcInfer ((ExpSigmaType
  -> TcM
       (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
 -> TcM
      ((HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))),
       Type))
-> (ExpSigmaType
    -> TcM
         (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcM
     ((HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))),
      Type)
forall a b. (a -> b) -> a -> b
$ \ ExpSigmaType
exp_ty ->
               [TcBinder]
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
forall a. [TcBinder] -> TcM a -> TcM a
tcExtendBinderStack [Name -> ExpSigmaType -> TopLevelFlag -> TcBinder
TcIdBndr_ExpType Name
name ExpSigmaType
exp_ty TopLevelFlag
NotTopLevel] (TcM
   (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
 -> TcM
      (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
-> TcM
     (HsWrapper, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
forall a b. (a -> b) -> a -> b
$
                  -- We extend the error context even for a non-recursive
                  -- function so that in type error messages we show the
                  -- type of the thing whose rhs we are type checking
               Located Name
-> MatchGroup GhcRn (LHsExpr GhcRn)
-> ExpSigmaType
-> TcM (HsWrapper, MatchGroup GhcTc (LHsExpr GhcTc))
tcMatchesFun (SrcSpan -> Name -> Located Name
forall l e. l -> e -> GenLocated l e
L SrcSpan
nm_loc Name
name) MatchGroup GhcRn (LHsExpr GhcRn)
matches ExpSigmaType
exp_ty

        ; Id
mono_id <- LetBndrSpec
-> Name -> Type -> Type -> IOEnv (Env TcGblEnv TcLclEnv) Id
newLetBndr LetBndrSpec
no_gen Name
name Type
Many Type
rhs_ty
        ; (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return (Located (HsBindLR GhcTc GhcTc)
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a. a -> Bag a
unitBag (Located (HsBindLR GhcTc GhcTc)
 -> Bag (Located (HsBindLR GhcTc GhcTc)))
-> Located (HsBindLR GhcTc GhcTc)
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a b. (a -> b) -> a -> b
$ SrcSpan -> HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcSpan
b_loc (HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc))
-> HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc)
forall a b. (a -> b) -> a -> b
$
                     FunBind :: forall idL idR.
XFunBind idL idR
-> LIdP idL
-> MatchGroup idR (LHsExpr idR)
-> [Tickish Id]
-> HsBindLR idL idR
FunBind { fun_id :: LIdP GhcTc
fun_id = SrcSpan -> Id -> GenLocated SrcSpan Id
forall l e. l -> e -> GenLocated l e
L SrcSpan
nm_loc Id
mono_id,
                               fun_matches :: MatchGroup GhcTc (LHsExpr GhcTc)
fun_matches = MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
MatchGroup GhcTc (LHsExpr GhcTc)
matches',
                               fun_ext :: XFunBind GhcTc GhcTc
fun_ext = HsWrapper
XFunBind GhcTc GhcTc
co_fn, fun_tick :: [Tickish Id]
fun_tick = [] },
                  [MBI :: Name -> Maybe TcIdSigInst -> Id -> MonoBindInfo
MBI { mbi_poly_name :: Name
mbi_poly_name = Name
name
                       , mbi_sig :: Maybe TcIdSigInst
mbi_sig       = Maybe TcIdSigInst
forall a. Maybe a
Nothing
                       , mbi_mono_id :: Id
mbi_mono_id   = Id
mono_id }]) }

-- SPECIAL CASE 2: see Note [Inference for non-recursive pattern bindings]
tcMonoBinds RecFlag
is_rec TcSigFun
sig_fn LetBndrSpec
no_gen
           [L b_loc (PatBind { pat_lhs = pat, pat_rhs = grhss })]
  | RecFlag
NonRecursive <- RecFlag
is_rec   -- ...binder isn't mentioned in RHS
  , (Name -> Bool) -> [Name] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all (Maybe TcSigInfo -> Bool
forall a. Maybe a -> Bool
isNothing (Maybe TcSigInfo -> Bool) -> TcSigFun -> Name -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. TcSigFun
sig_fn) [Name]
[IdP GhcRn]
bndrs
  = SDoc
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (LPat GhcRn -> GRHSs GhcRn (Located (HsExpr GhcRn)) -> SDoc
forall (p :: Pass) body.
(OutputableBndrId p, Outputable body) =>
LPat (GhcPass p) -> GRHSs GhcRn body -> SDoc
patMonoBindsCtxt LPat GhcRn
pat GRHSs GhcRn (Located (HsExpr GhcRn))
GRHSs GhcRn (LHsExpr GhcRn)
grhss) (IOEnv
   (Env TcGblEnv TcLclEnv)
   (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
 -> IOEnv
      (Env TcGblEnv TcLclEnv)
      (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo]))
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
forall a b. (a -> b) -> a -> b
$
    do { (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
grhss', Type
pat_ty) <- (ExpSigmaType
 -> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc)), Type)
forall a. (ExpSigmaType -> TcM a) -> TcM (a, Type)
tcInfer ((ExpSigmaType
  -> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
 -> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc)), Type))
-> (ExpSigmaType
    -> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc)), Type)
forall a b. (a -> b) -> a -> b
$ \ ExpSigmaType
exp_ty ->
                             GRHSs GhcRn (LHsExpr GhcRn)
-> ExpSigmaType -> TcM (GRHSs GhcTc (LHsExpr GhcTc))
tcGRHSsPat GRHSs GhcRn (LHsExpr GhcRn)
grhss ExpSigmaType
exp_ty

       ; let exp_pat_ty :: Scaled ExpSigmaType
             exp_pat_ty :: Scaled ExpSigmaType
exp_pat_ty = ExpSigmaType -> Scaled ExpSigmaType
forall a. a -> Scaled a
unrestricted (Type -> ExpSigmaType
mkCheckExpType Type
pat_ty)
       ; (Located (Pat GhcTc)
pat', [MonoBindInfo]
mbis) <- (Name -> Maybe Id)
-> LetBndrSpec
-> LPat GhcRn
-> Scaled ExpSigmaType
-> TcM [MonoBindInfo]
-> TcM (LPat GhcTc, [MonoBindInfo])
forall a.
(Name -> Maybe Id)
-> LetBndrSpec
-> LPat GhcRn
-> Scaled ExpSigmaType
-> TcM a
-> TcM (LPat GhcTc, a)
tcLetPat (Maybe Id -> Name -> Maybe Id
forall a b. a -> b -> a
const Maybe Id
forall a. Maybe a
Nothing) LetBndrSpec
no_gen LPat GhcRn
pat Scaled ExpSigmaType
exp_pat_ty (TcM [MonoBindInfo] -> TcM (LPat GhcTc, [MonoBindInfo]))
-> TcM [MonoBindInfo] -> TcM (LPat GhcTc, [MonoBindInfo])
forall a b. (a -> b) -> a -> b
$
                         (Name -> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo)
-> [Name] -> TcM [MonoBindInfo]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Name -> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo
lookupMBI [Name]
[IdP GhcRn]
bndrs

       ; (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return ( Located (HsBindLR GhcTc GhcTc)
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a. a -> Bag a
unitBag (Located (HsBindLR GhcTc GhcTc)
 -> Bag (Located (HsBindLR GhcTc GhcTc)))
-> Located (HsBindLR GhcTc GhcTc)
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a b. (a -> b) -> a -> b
$ SrcSpan -> HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc)
forall l e. l -> e -> GenLocated l e
L SrcSpan
b_loc (HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc))
-> HsBindLR GhcTc GhcTc -> Located (HsBindLR GhcTc GhcTc)
forall a b. (a -> b) -> a -> b
$
                     PatBind :: forall idL idR.
XPatBind idL idR
-> LPat idL
-> GRHSs idR (LHsExpr idR)
-> ([Tickish Id], [[Tickish Id]])
-> HsBindLR idL idR
PatBind { pat_lhs :: LPat GhcTc
pat_lhs = Located (Pat GhcTc)
LPat GhcTc
pat', pat_rhs :: GRHSs GhcTc (LHsExpr GhcTc)
pat_rhs = GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
GRHSs GhcTc (LHsExpr GhcTc)
grhss'
                             , pat_ext :: XPatBind GhcTc GhcTc
pat_ext = Type
XPatBind GhcTc GhcTc
pat_ty, pat_ticks :: ([Tickish Id], [[Tickish Id]])
pat_ticks = ([],[]) }

                , [MonoBindInfo]
mbis ) }
  where
    bndrs :: [IdP GhcRn]
bndrs = LPat GhcRn -> [IdP GhcRn]
forall p. CollectPass p => LPat p -> [IdP p]
collectPatBinders LPat GhcRn
pat

-- GENERAL CASE
tcMonoBinds RecFlag
_ TcSigFun
sig_fn LetBndrSpec
no_gen [LHsBind GhcRn]
binds
  = do  { [Located TcMonoBind]
tc_binds <- (Located (HsBindLR GhcRn GhcRn)
 -> IOEnv (Env TcGblEnv TcLclEnv) (Located TcMonoBind))
-> [Located (HsBindLR GhcRn GhcRn)]
-> IOEnv (Env TcGblEnv TcLclEnv) [Located TcMonoBind]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((HsBindLR GhcRn GhcRn -> TcM TcMonoBind)
-> Located (HsBindLR GhcRn GhcRn)
-> IOEnv (Env TcGblEnv TcLclEnv) (Located TcMonoBind)
forall a b. (a -> TcM b) -> Located a -> TcM (Located b)
wrapLocM (TcSigFun -> LetBndrSpec -> HsBindLR GhcRn GhcRn -> TcM TcMonoBind
tcLhs TcSigFun
sig_fn LetBndrSpec
no_gen)) [Located (HsBindLR GhcRn GhcRn)]
[LHsBind GhcRn]
binds

        -- Bring the monomorphic Ids, into scope for the RHSs
        ; let mono_infos :: [MonoBindInfo]
mono_infos = [Located TcMonoBind] -> [MonoBindInfo]
getMonoBindInfo [Located TcMonoBind]
tc_binds
              rhs_id_env :: [(Name, Id)]
rhs_id_env = [ (Name
name, Id
mono_id)
                           | MBI { mbi_poly_name :: MonoBindInfo -> Name
mbi_poly_name = Name
name
                                 , mbi_sig :: MonoBindInfo -> Maybe TcIdSigInst
mbi_sig       = Maybe TcIdSigInst
mb_sig
                                 , mbi_mono_id :: MonoBindInfo -> Id
mbi_mono_id   = Id
mono_id } <- [MonoBindInfo]
mono_infos
                           , case Maybe TcIdSigInst
mb_sig of
                               Just TcIdSigInst
sig -> TcIdSigInst -> Bool
isPartialSig TcIdSigInst
sig
                               Maybe TcIdSigInst
Nothing  -> Bool
True ]
                -- A monomorphic binding for each term variable that lacks
                -- a complete type sig.  (Ones with a sig are already in scope.)

        ; String -> SDoc -> TcRn ()
traceTc String
"tcMonoBinds" (SDoc -> TcRn ()) -> SDoc -> TcRn ()
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
vcat [ Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
n SDoc -> SDoc -> SDoc
<+> Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr Id
id SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Id -> Type
idType Id
id)
                                       | (Name
n,Id
id) <- [(Name, Id)]
rhs_id_env]
        ; [Located (HsBindLR GhcTc GhcTc)]
binds' <- [(Name, Id)]
-> TcM [Located (HsBindLR GhcTc GhcTc)]
-> TcM [Located (HsBindLR GhcTc GhcTc)]
forall a. [(Name, Id)] -> TcM a -> TcM a
tcExtendRecIds [(Name, Id)]
rhs_id_env (TcM [Located (HsBindLR GhcTc GhcTc)]
 -> TcM [Located (HsBindLR GhcTc GhcTc)])
-> TcM [Located (HsBindLR GhcTc GhcTc)]
-> TcM [Located (HsBindLR GhcTc GhcTc)]
forall a b. (a -> b) -> a -> b
$
                    (Located TcMonoBind
 -> IOEnv (Env TcGblEnv TcLclEnv) (Located (HsBindLR GhcTc GhcTc)))
-> [Located TcMonoBind] -> TcM [Located (HsBindLR GhcTc GhcTc)]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM ((TcMonoBind -> TcM (HsBindLR GhcTc GhcTc))
-> Located TcMonoBind
-> IOEnv (Env TcGblEnv TcLclEnv) (Located (HsBindLR GhcTc GhcTc))
forall a b. (a -> TcM b) -> Located a -> TcM (Located b)
wrapLocM TcMonoBind -> TcM (HsBindLR GhcTc GhcTc)
tcRhs) [Located TcMonoBind]
tc_binds

        ; (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
-> IOEnv
     (Env TcGblEnv TcLclEnv)
     (Bag (Located (HsBindLR GhcTc GhcTc)), [MonoBindInfo])
forall (m :: * -> *) a. Monad m => a -> m a
return ([Located (HsBindLR GhcTc GhcTc)]
-> Bag (Located (HsBindLR GhcTc GhcTc))
forall a. [a] -> Bag a
listToBag [Located (HsBindLR GhcTc GhcTc)]
binds', [MonoBindInfo]
mono_infos) }

{- Note [Special case for non-recursive function bindings]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the special case of
* A non-recursive FunBind
* With no type signature
we infer the type of the right hand side first (it may have a
higher-rank type) and *then* make the monomorphic Id for the LHS e.g.
   f = \(x::forall a. a->a) -> <body>

We want to infer a higher-rank type for f

Note [Special case for non-recursive pattern bindings]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the special case of
* A pattern binding
* With no type signature for any of the binders
we can /infer/ the type of the RHS, and /check/ the pattern
against that type.  For example (#18323)

  ids :: [forall a. a -> a]
  combine :: (forall a . [a] -> a) -> [forall a. a -> a]
          -> ((forall a . [a] -> a), [forall a. a -> a])

  (x,y) = combine head ids

with -XImpredicativeTypes we can infer a good type for
(combine head ids), and use that to tell us the polymorphic
types of x and y.

We don't need to check -XImpredicativeTypes beucase without it
these types like [forall a. a->a] are illegal anyway, so this
special case code only really has an effect if -XImpredicativeTypes
is on.  Small exception:
  (x) = e
is currently treated as a pattern binding so, even absent
-XImpredicativeTypes, we will get a small improvement in behaviour.
But I don't think it's worth an extension flag.

Why do we require no type signatures on /any/ of the binders?
Consider
   x :: forall a. a->a
   y :: forall a. a->a
   (x,y) = (id,id)

Here we should /check/ the RHS with expected type
  (forall a. a->a, forall a. a->a).

If we have no signatures, we can the approach of this Note
to /infer/ the type of the RHS.

But what if we have some signatures, but not all? Say this:
  p :: forall a. a->a
  (p,q) = (id,  (\(x::forall b. b->b). x True))

Here we want to push p's signature inwards, i.e. /checking/, to
correctly elaborate 'id'. But we want to /infer/ q's higher rank
type.  There seems to be no way to do this.  So currently we only
switch to inference when we have no signature for any of the binders.
-}


------------------------
-- tcLhs typechecks the LHS of the bindings, to construct the environment in which
-- we typecheck the RHSs.  Basically what we are doing is this: for each binder:
--      if there's a signature for it, use the instantiated signature type
--      otherwise invent a type variable
-- You see that quite directly in the FunBind case.
--
-- But there's a complication for pattern bindings:
--      data T = MkT (forall a. a->a)
--      MkT f = e
-- Here we can guess a type variable for the entire LHS (which will be refined to T)
-- but we want to get (f::forall a. a->a) as the RHS environment.
-- The simplest way to do this is to typecheck the pattern, and then look up the
-- bound mono-ids.  Then we want to retain the typechecked pattern to avoid re-doing
-- it; hence the TcMonoBind data type in which the LHS is done but the RHS isn't

data TcMonoBind         -- Half completed; LHS done, RHS not done
  = TcFunBind  MonoBindInfo  SrcSpan (MatchGroup GhcRn (LHsExpr GhcRn))
  | TcPatBind [MonoBindInfo] (LPat GhcTc) (GRHSs GhcRn (LHsExpr GhcRn))
              TcSigmaType

tcLhs :: TcSigFun -> LetBndrSpec -> HsBind GhcRn -> TcM TcMonoBind
-- Only called with plan InferGen (LetBndrSpec = LetLclBndr)
--                    or NoGen    (LetBndrSpec = LetGblBndr)
-- CheckGen is used only for functions with a complete type signature,
--          and tcPolyCheck doesn't use tcMonoBinds at all

tcLhs :: TcSigFun -> LetBndrSpec -> HsBindLR GhcRn GhcRn -> TcM TcMonoBind
tcLhs TcSigFun
sig_fn LetBndrSpec
no_gen (FunBind { fun_id :: forall idL idR. HsBindLR idL idR -> LIdP idL
fun_id = L nm_loc name
                             , fun_matches :: forall idL idR. HsBindLR idL idR -> MatchGroup idR (LHsExpr idR)
fun_matches = MatchGroup GhcRn (LHsExpr GhcRn)
matches })
  | Just (TcIdSig TcIdSigInfo
sig) <- TcSigFun
sig_fn Name
name
  = -- There is a type signature.
    -- It must be partial; if complete we'd be in tcPolyCheck!
    --    e.g.   f :: _ -> _
    --           f x = ...g...
    --           Just g = ...f...
    -- Hence always typechecked with InferGen
    do { MonoBindInfo
mono_info <- LetBndrSpec
-> (Name, TcIdSigInfo)
-> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo
tcLhsSigId LetBndrSpec
no_gen (Name
name, TcIdSigInfo
sig)
       ; TcMonoBind -> TcM TcMonoBind
forall (m :: * -> *) a. Monad m => a -> m a
return (MonoBindInfo
-> SrcSpan -> MatchGroup GhcRn (LHsExpr GhcRn) -> TcMonoBind
TcFunBind MonoBindInfo
mono_info SrcSpan
nm_loc MatchGroup GhcRn (LHsExpr GhcRn)
matches) }

  | Bool
otherwise  -- No type signature
  = do { Type
mono_ty <- TcM Type
newOpenFlexiTyVarTy
       ; Id
mono_id <- LetBndrSpec
-> Name -> Type -> Type -> IOEnv (Env TcGblEnv TcLclEnv) Id
newLetBndr LetBndrSpec
no_gen Name
name Type
Many Type
mono_ty
          -- This ^ generates a binder with Many multiplicity because all
          -- let/where-binders are unrestricted. When we introduce linear let
          -- binders, we will need to retrieve the multiplicity information.
       ; let mono_info :: MonoBindInfo
mono_info = MBI :: Name -> Maybe TcIdSigInst -> Id -> MonoBindInfo
MBI { mbi_poly_name :: Name
mbi_poly_name = Name
name
                             , mbi_sig :: Maybe TcIdSigInst
mbi_sig       = Maybe TcIdSigInst
forall a. Maybe a
Nothing
                             , mbi_mono_id :: Id
mbi_mono_id   = Id
mono_id }
       ; TcMonoBind -> TcM TcMonoBind
forall (m :: * -> *) a. Monad m => a -> m a
return (MonoBindInfo
-> SrcSpan -> MatchGroup GhcRn (LHsExpr GhcRn) -> TcMonoBind
TcFunBind MonoBindInfo
mono_info SrcSpan
nm_loc MatchGroup GhcRn (LHsExpr GhcRn)
matches) }

tcLhs TcSigFun
sig_fn LetBndrSpec
no_gen (PatBind { pat_lhs :: forall idL idR. HsBindLR idL idR -> LPat idL
pat_lhs = LPat GhcRn
pat, pat_rhs :: forall idL idR. HsBindLR idL idR -> GRHSs idR (LHsExpr idR)
pat_rhs = GRHSs GhcRn (LHsExpr GhcRn)
grhss })
  = -- See Note [Typechecking pattern bindings]
    do  { [MonoBindInfo]
sig_mbis <- ((Name, TcIdSigInfo) -> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo)
-> [(Name, TcIdSigInfo)] -> TcM [MonoBindInfo]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM (LetBndrSpec
-> (Name, TcIdSigInfo)
-> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo
tcLhsSigId LetBndrSpec
no_gen) [(Name, TcIdSigInfo)]
sig_names

        ; let inst_sig_fun :: Name -> Maybe Id
inst_sig_fun = NameEnv Id -> Name -> Maybe Id
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv (NameEnv Id -> Name -> Maybe Id) -> NameEnv Id -> Name -> Maybe Id
forall a b. (a -> b) -> a -> b
$ [(Name, Id)] -> NameEnv Id
forall a. [(Name, a)] -> NameEnv a
mkNameEnv ([(Name, Id)] -> NameEnv Id) -> [(Name, Id)] -> NameEnv Id
forall a b. (a -> b) -> a -> b
$
                             [ (MonoBindInfo -> Name
mbi_poly_name MonoBindInfo
mbi, MonoBindInfo -> Id
mbi_mono_id MonoBindInfo
mbi)
                             | MonoBindInfo
mbi <- [MonoBindInfo]
sig_mbis ]

            -- See Note [Existentials in pattern bindings]
        ; ((Located (Pat GhcTc)
pat', [MonoBindInfo]
nosig_mbis), Type
pat_ty)
            <- SDoc
-> TcM ((Located (Pat GhcTc), [MonoBindInfo]), Type)
-> TcM ((Located (Pat GhcTc), [MonoBindInfo]), Type)
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (LPat GhcRn -> GRHSs GhcRn (Located (HsExpr GhcRn)) -> SDoc
forall (p :: Pass) body.
(OutputableBndrId p, Outputable body) =>
LPat (GhcPass p) -> GRHSs GhcRn body -> SDoc
patMonoBindsCtxt LPat GhcRn
pat GRHSs GhcRn (Located (HsExpr GhcRn))
GRHSs GhcRn (LHsExpr GhcRn)
grhss) (TcM ((Located (Pat GhcTc), [MonoBindInfo]), Type)
 -> TcM ((Located (Pat GhcTc), [MonoBindInfo]), Type))
-> TcM ((Located (Pat GhcTc), [MonoBindInfo]), Type)
-> TcM ((Located (Pat GhcTc), [MonoBindInfo]), Type)
forall a b. (a -> b) -> a -> b
$
               (ExpSigmaType
 -> IOEnv
      (Env TcGblEnv TcLclEnv) (Located (Pat GhcTc), [MonoBindInfo]))
-> TcM ((Located (Pat GhcTc), [MonoBindInfo]), Type)
forall a. (ExpSigmaType -> TcM a) -> TcM (a, Type)
tcInfer ((ExpSigmaType
  -> IOEnv
       (Env TcGblEnv TcLclEnv) (Located (Pat GhcTc), [MonoBindInfo]))
 -> TcM ((Located (Pat GhcTc), [MonoBindInfo]), Type))
-> (ExpSigmaType
    -> IOEnv
         (Env TcGblEnv TcLclEnv) (Located (Pat GhcTc), [MonoBindInfo]))
-> TcM ((Located (Pat GhcTc), [MonoBindInfo]), Type)
forall a b. (a -> b) -> a -> b
$ \ ExpSigmaType
exp_ty ->
               (Name -> Maybe Id)
-> LetBndrSpec
-> LPat GhcRn
-> Scaled ExpSigmaType
-> TcM [MonoBindInfo]
-> TcM (LPat GhcTc, [MonoBindInfo])
forall a.
(Name -> Maybe Id)
-> LetBndrSpec
-> LPat GhcRn
-> Scaled ExpSigmaType
-> TcM a
-> TcM (LPat GhcTc, a)
tcLetPat Name -> Maybe Id
inst_sig_fun LetBndrSpec
no_gen LPat GhcRn
pat (ExpSigmaType -> Scaled ExpSigmaType
forall a. a -> Scaled a
unrestricted ExpSigmaType
exp_ty) (TcM [MonoBindInfo] -> TcM (LPat GhcTc, [MonoBindInfo]))
-> TcM [MonoBindInfo] -> TcM (LPat GhcTc, [MonoBindInfo])
forall a b. (a -> b) -> a -> b
$
                 -- The above inferred type get an unrestricted multiplicity. It may be
                 -- worth it to try and find a finer-grained multiplicity here
                 -- if examples warrant it.
               (Name -> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo)
-> [Name] -> TcM [MonoBindInfo]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
(a -> m b) -> t a -> m (t b)
mapM Name -> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo
lookupMBI [Name]
nosig_names

        ; let mbis :: [MonoBindInfo]
mbis = [MonoBindInfo]
sig_mbis [MonoBindInfo] -> [MonoBindInfo] -> [MonoBindInfo]
forall a. [a] -> [a] -> [a]
++ [MonoBindInfo]
nosig_mbis

        ; String -> SDoc -> TcRn ()
traceTc String
"tcLhs" ([SDoc] -> SDoc
vcat [ Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr Id
id SDoc -> SDoc -> SDoc
<+> SDoc
dcolon SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Id -> Type
idType Id
id)
                                | MonoBindInfo
mbi <- [MonoBindInfo]
mbis, let id :: Id
id = MonoBindInfo -> Id
mbi_mono_id MonoBindInfo
mbi ]
                           SDoc -> SDoc -> SDoc
$$ LetBndrSpec -> SDoc
forall a. Outputable a => a -> SDoc
ppr LetBndrSpec
no_gen)

        ; TcMonoBind -> TcM TcMonoBind
forall (m :: * -> *) a. Monad m => a -> m a
return ([MonoBindInfo]
-> LPat GhcTc -> GRHSs GhcRn (LHsExpr GhcRn) -> Type -> TcMonoBind
TcPatBind [MonoBindInfo]
mbis Located (Pat GhcTc)
LPat GhcTc
pat' GRHSs GhcRn (LHsExpr GhcRn)
grhss Type
pat_ty) }
  where
    bndr_names :: [IdP GhcRn]
bndr_names = LPat GhcRn -> [IdP GhcRn]
forall p. CollectPass p => LPat p -> [IdP p]
collectPatBinders LPat GhcRn
pat
    ([Name]
nosig_names, [(Name, TcIdSigInfo)]
sig_names) = (Name -> Either Name (Name, TcIdSigInfo))
-> [Name] -> ([Name], [(Name, TcIdSigInfo)])
forall a b c. (a -> Either b c) -> [a] -> ([b], [c])
partitionWith Name -> Either Name (Name, TcIdSigInfo)
find_sig [Name]
[IdP GhcRn]
bndr_names

    find_sig :: Name -> Either Name (Name, TcIdSigInfo)
    find_sig :: Name -> Either Name (Name, TcIdSigInfo)
find_sig Name
name = case TcSigFun
sig_fn Name
name of
                      Just (TcIdSig TcIdSigInfo
sig) -> (Name, TcIdSigInfo) -> Either Name (Name, TcIdSigInfo)
forall a b. b -> Either a b
Right (Name
name, TcIdSigInfo
sig)
                      Maybe TcSigInfo
_                  -> Name -> Either Name (Name, TcIdSigInfo)
forall a b. a -> Either a b
Left Name
name

tcLhs TcSigFun
_ LetBndrSpec
_ HsBindLR GhcRn GhcRn
other_bind = String -> SDoc -> TcM TcMonoBind
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"tcLhs" (HsBindLR GhcRn GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsBindLR GhcRn GhcRn
other_bind)
        -- AbsBind, VarBind impossible

lookupMBI :: Name -> TcM MonoBindInfo
-- After typechecking the pattern, look up the binder
-- names that lack a signature, which the pattern has brought
-- into scope.
lookupMBI :: Name -> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo
lookupMBI Name
name
  = do { Id
mono_id <- Name -> IOEnv (Env TcGblEnv TcLclEnv) Id
tcLookupId Name
name
       ; MonoBindInfo -> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo
forall (m :: * -> *) a. Monad m => a -> m a
return (MBI :: Name -> Maybe TcIdSigInst -> Id -> MonoBindInfo
MBI { mbi_poly_name :: Name
mbi_poly_name = Name
name
                     , mbi_sig :: Maybe TcIdSigInst
mbi_sig       = Maybe TcIdSigInst
forall a. Maybe a
Nothing
                     , mbi_mono_id :: Id
mbi_mono_id   = Id
mono_id }) }

-------------------
tcLhsSigId :: LetBndrSpec -> (Name, TcIdSigInfo) -> TcM MonoBindInfo
tcLhsSigId :: LetBndrSpec
-> (Name, TcIdSigInfo)
-> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo
tcLhsSigId LetBndrSpec
no_gen (Name
name, TcIdSigInfo
sig)
  = do { TcIdSigInst
inst_sig <- TcIdSigInfo -> TcM TcIdSigInst
tcInstSig TcIdSigInfo
sig
       ; Id
mono_id <- LetBndrSpec
-> Name -> TcIdSigInst -> IOEnv (Env TcGblEnv TcLclEnv) Id
newSigLetBndr LetBndrSpec
no_gen Name
name TcIdSigInst
inst_sig
       ; MonoBindInfo -> IOEnv (Env TcGblEnv TcLclEnv) MonoBindInfo
forall (m :: * -> *) a. Monad m => a -> m a
return (MBI :: Name -> Maybe TcIdSigInst -> Id -> MonoBindInfo
MBI { mbi_poly_name :: Name
mbi_poly_name = Name
name
                     , mbi_sig :: Maybe TcIdSigInst
mbi_sig       = TcIdSigInst -> Maybe TcIdSigInst
forall a. a -> Maybe a
Just TcIdSigInst
inst_sig
                     , mbi_mono_id :: Id
mbi_mono_id   = Id
mono_id }) }

------------
newSigLetBndr :: LetBndrSpec -> Name -> TcIdSigInst -> TcM TcId
newSigLetBndr :: LetBndrSpec
-> Name -> TcIdSigInst -> IOEnv (Env TcGblEnv TcLclEnv) Id
newSigLetBndr (LetGblBndr TcPragEnv
prags) Name
name (TISI { sig_inst_sig :: TcIdSigInst -> TcIdSigInfo
sig_inst_sig = TcIdSigInfo
id_sig })
  | CompleteSig { sig_bndr :: TcIdSigInfo -> Id
sig_bndr = Id
poly_id } <- TcIdSigInfo
id_sig
  = Id -> [LSig GhcRn] -> IOEnv (Env TcGblEnv TcLclEnv) Id
addInlinePrags Id
poly_id (TcPragEnv -> Name -> [LSig GhcRn]
lookupPragEnv TcPragEnv
prags Name
name)
newSigLetBndr LetBndrSpec
no_gen Name
name (TISI { sig_inst_tau :: TcIdSigInst -> Type
sig_inst_tau = Type
tau })
  = LetBndrSpec
-> Name -> Type -> Type -> IOEnv (Env TcGblEnv TcLclEnv) Id
newLetBndr LetBndrSpec
no_gen Name
name Type
Many Type
tau
    -- Binders with a signature are currently always of multiplicity
    -- Many. Because they come either from toplevel, let, or where
    -- declarations. Which are all unrestricted currently.

-------------------
tcRhs :: TcMonoBind -> TcM (HsBind GhcTc)
tcRhs :: TcMonoBind -> TcM (HsBindLR GhcTc GhcTc)
tcRhs (TcFunBind info :: MonoBindInfo
info@(MBI { mbi_sig :: MonoBindInfo -> Maybe TcIdSigInst
mbi_sig = Maybe TcIdSigInst
mb_sig, mbi_mono_id :: MonoBindInfo -> Id
mbi_mono_id = Id
mono_id })
                 SrcSpan
loc MatchGroup GhcRn (LHsExpr GhcRn)
matches)
  = [MonoBindInfo]
-> TcM (HsBindLR GhcTc GhcTc) -> TcM (HsBindLR GhcTc GhcTc)
forall a. [MonoBindInfo] -> TcM a -> TcM a
tcExtendIdBinderStackForRhs [MonoBindInfo
info]  (TcM (HsBindLR GhcTc GhcTc) -> TcM (HsBindLR GhcTc GhcTc))
-> TcM (HsBindLR GhcTc GhcTc) -> TcM (HsBindLR GhcTc GhcTc)
forall a b. (a -> b) -> a -> b
$
    Maybe TcIdSigInst
-> TcM (HsBindLR GhcTc GhcTc) -> TcM (HsBindLR GhcTc GhcTc)
forall a. Maybe TcIdSigInst -> TcM a -> TcM a
tcExtendTyVarEnvForRhs Maybe TcIdSigInst
mb_sig       (TcM (HsBindLR GhcTc GhcTc) -> TcM (HsBindLR GhcTc GhcTc))
-> TcM (HsBindLR GhcTc GhcTc) -> TcM (HsBindLR GhcTc GhcTc)
forall a b. (a -> b) -> a -> b
$
    do  { String -> SDoc -> TcRn ()
traceTc String
"tcRhs: fun bind" (Id -> SDoc
forall a. Outputable a => a -> SDoc
ppr Id
mono_id SDoc -> SDoc -> SDoc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr (Id -> Type
idType Id
mono_id))
        ; (HsWrapper
co_fn, MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
matches') <- Located Name
-> MatchGroup GhcRn (LHsExpr GhcRn)
-> ExpSigmaType
-> TcM (HsWrapper, MatchGroup GhcTc (LHsExpr GhcTc))
tcMatchesFun (SrcSpan -> Name -> Located Name
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc (Id -> Name
idName Id
mono_id))
                                 MatchGroup GhcRn (LHsExpr GhcRn)
matches (Type -> ExpSigmaType
mkCheckExpType (Type -> ExpSigmaType) -> Type -> ExpSigmaType
forall a b. (a -> b) -> a -> b
$ Id -> Type
idType Id
mono_id)
        ; HsBindLR GhcTc GhcTc -> TcM (HsBindLR GhcTc GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return ( FunBind :: forall idL idR.
XFunBind idL idR
-> LIdP idL
-> MatchGroup idR (LHsExpr idR)
-> [Tickish Id]
-> HsBindLR idL idR
FunBind { fun_id :: LIdP GhcTc
fun_id = SrcSpan -> Id -> GenLocated SrcSpan Id
forall l e. l -> e -> GenLocated l e
L SrcSpan
loc Id
mono_id
                           , fun_matches :: MatchGroup GhcTc (LHsExpr GhcTc)
fun_matches = MatchGroup GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
MatchGroup GhcTc (LHsExpr GhcTc)
matches'
                           , fun_ext :: XFunBind GhcTc GhcTc
fun_ext = HsWrapper
XFunBind GhcTc GhcTc
co_fn
                           , fun_tick :: [Tickish Id]
fun_tick = [] } ) }

tcRhs (TcPatBind [MonoBindInfo]
infos LPat GhcTc
pat' GRHSs GhcRn (LHsExpr GhcRn)
grhss Type
pat_ty)
  = -- When we are doing pattern bindings we *don't* bring any scoped
    -- type variables into scope unlike function bindings
    -- Wny not?  They are not completely rigid.
    -- That's why we have the special case for a single FunBind in tcMonoBinds
    [MonoBindInfo]
-> TcM (HsBindLR GhcTc GhcTc) -> TcM (HsBindLR GhcTc GhcTc)
forall a. [MonoBindInfo] -> TcM a -> TcM a
tcExtendIdBinderStackForRhs [MonoBindInfo]
infos        (TcM (HsBindLR GhcTc GhcTc) -> TcM (HsBindLR GhcTc GhcTc))
-> TcM (HsBindLR GhcTc GhcTc) -> TcM (HsBindLR GhcTc GhcTc)
forall a b. (a -> b) -> a -> b
$
    do  { String -> SDoc -> TcRn ()
traceTc String
"tcRhs: pat bind" (Located (Pat GhcTc) -> SDoc
forall a. Outputable a => a -> SDoc
ppr Located (Pat GhcTc)
LPat GhcTc
pat' SDoc -> SDoc -> SDoc
$$ Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
pat_ty)
        ; GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
grhss' <- SDoc
-> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
-> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
forall a. SDoc -> TcM a -> TcM a
addErrCtxt (LPat GhcTc -> GRHSs GhcRn (Located (HsExpr GhcRn)) -> SDoc
forall (p :: Pass) body.
(OutputableBndrId p, Outputable body) =>
LPat (GhcPass p) -> GRHSs GhcRn body -> SDoc
patMonoBindsCtxt LPat GhcTc
pat' GRHSs GhcRn (Located (HsExpr GhcRn))
GRHSs GhcRn (LHsExpr GhcRn)
grhss) (TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
 -> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc))))
-> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
-> TcM (GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc)))
forall a b. (a -> b) -> a -> b
$
                    GRHSs GhcRn (LHsExpr GhcRn)
-> ExpSigmaType -> TcM (GRHSs GhcTc (LHsExpr GhcTc))
tcGRHSsPat GRHSs GhcRn (LHsExpr GhcRn)
grhss (Type -> ExpSigmaType
mkCheckExpType Type
pat_ty)
        ; HsBindLR GhcTc GhcTc -> TcM (HsBindLR GhcTc GhcTc)
forall (m :: * -> *) a. Monad m => a -> m a
return ( PatBind :: forall idL idR.
XPatBind idL idR
-> LPat idL
-> GRHSs idR (LHsExpr idR)
-> ([Tickish Id], [[Tickish Id]])
-> HsBindLR idL idR
PatBind { pat_lhs :: LPat GhcTc
pat_lhs = LPat GhcTc
pat', pat_rhs :: GRHSs GhcTc (LHsExpr GhcTc)
pat_rhs = GRHSs GhcTc (GenLocated SrcSpan (HsExpr GhcTc))
GRHSs GhcTc (LHsExpr GhcTc)
grhss'
                           , pat_ext :: XPatBind GhcTc GhcTc
pat_ext = Type
XPatBind GhcTc GhcTc
pat_ty
                           , pat_ticks :: ([Tickish Id], [[Tickish Id]])
pat_ticks = ([],[]) } )}

tcExtendTyVarEnvForRhs :: Maybe TcIdSigInst -> TcM a -> TcM a
tcExtendTyVarEnvForRhs :: Maybe TcIdSigInst -> TcM a -> TcM a
tcExtendTyVarEnvForRhs Maybe TcIdSigInst
Nothing TcM a
thing_inside
  = TcM a
thing_inside
tcExtendTyVarEnvForRhs (Just TcIdSigInst
sig) TcM a
thing_inside
  = TcIdSigInst -> TcM a -> TcM a
forall a. TcIdSigInst -> TcM a -> TcM a
tcExtendTyVarEnvFromSig TcIdSigInst
sig TcM a
thing_inside

tcExtendTyVarEnvFromSig :: TcIdSigInst -> TcM a -> TcM a
tcExtendTyVarEnvFromSig :: TcIdSigInst -> TcM a -> TcM a
tcExtendTyVarEnvFromSig TcIdSigInst
sig_inst TcM a
thing_inside
  | TISI { sig_inst_skols :: TcIdSigInst -> [(Name, InvisTVBinder)]
sig_inst_skols = [(Name, InvisTVBinder)]
skol_prs, sig_inst_wcs :: TcIdSigInst -> [(Name, Id)]
sig_inst_wcs = [(Name, Id)]
wcs } <- TcIdSigInst
sig_inst
  = [(Name, Id)] -> TcM a -> TcM a
forall a. [(Name, Id)] -> TcM a -> TcM a
tcExtendNameTyVarEnv [(Name, Id)]
wcs (TcM a -> TcM a) -> TcM a -> TcM a
forall a b. (a -> b) -> a -> b
$
    [(Name, Id)] -> TcM a -> TcM a
forall a. [(Name, Id)] -> TcM a -> TcM a
tcExtendNameTyVarEnv ((InvisTVBinder -> Id) -> [(Name, InvisTVBinder)] -> [(Name, Id)]
forall b c a. (b -> c) -> [(a, b)] -> [(a, c)]
mapSnd InvisTVBinder -> Id
forall tv argf. VarBndr tv argf -> tv
binderVar [(Name, InvisTVBinder)]
skol_prs) (TcM a -> TcM a) -> TcM a -> TcM a
forall a b. (a -> b) -> a -> b
$
    TcM a
thing_inside

tcExtendIdBinderStackForRhs :: [MonoBindInfo] -> TcM a -> TcM a
-- See Note [Relevant bindings and the binder stack]
tcExtendIdBinderStackForRhs :: [MonoBindInfo] -> TcM a -> TcM a
tcExtendIdBinderStackForRhs [MonoBindInfo]
infos TcM a
thing_inside
  = [TcBinder] -> TcM a -> TcM a
forall a. [TcBinder] -> TcM a -> TcM a
tcExtendBinderStack [ Id -> TopLevelFlag -> TcBinder
TcIdBndr Id
mono_id TopLevelFlag
NotTopLevel
                        | MBI { mbi_mono_id :: MonoBindInfo -> Id
mbi_mono_id = Id
mono_id } <- [MonoBindInfo]
infos ]
                        TcM a
thing_inside
    -- NotTopLevel: it's a monomorphic binding

---------------------
getMonoBindInfo :: [Located TcMonoBind] -> [MonoBindInfo]
getMonoBindInfo :: [Located TcMonoBind] -> [MonoBindInfo]
getMonoBindInfo [Located TcMonoBind]
tc_binds
  = (Located TcMonoBind -> [MonoBindInfo] -> [MonoBindInfo])
-> [MonoBindInfo] -> [Located TcMonoBind] -> [MonoBindInfo]
forall (t :: * -> *) a b.
Foldable t =>
(a -> b -> b) -> b -> t a -> b
foldr (TcMonoBind -> [MonoBindInfo] -> [MonoBindInfo]
get_info (TcMonoBind -> [MonoBindInfo] -> [MonoBindInfo])
-> (Located TcMonoBind -> TcMonoBind)
-> Located TcMonoBind
-> [MonoBindInfo]
-> [MonoBindInfo]
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Located TcMonoBind -> TcMonoBind
forall l e. GenLocated l e -> e
unLoc) [] [Located TcMonoBind]
tc_binds
  where
    get_info :: TcMonoBind -> [MonoBindInfo] -> [MonoBindInfo]
get_info (TcFunBind MonoBindInfo
info SrcSpan
_ MatchGroup GhcRn (LHsExpr GhcRn)
_)    [MonoBindInfo]
rest = MonoBindInfo
info MonoBindInfo -> [MonoBindInfo] -> [MonoBindInfo]
forall a. a -> [a] -> [a]
: [MonoBindInfo]
rest
    get_info (TcPatBind [MonoBindInfo]
infos LPat GhcTc
_ GRHSs GhcRn (LHsExpr GhcRn)
_ Type
_) [MonoBindInfo]
rest = [MonoBindInfo]
infos [MonoBindInfo] -> [MonoBindInfo] -> [MonoBindInfo]
forall a. [a] -> [a] -> [a]
++ [MonoBindInfo]
rest


{- Note [Relevant bindings and the binder stack]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When typecking a binding we extend the TcBinderStack for the RHS of
the binding, with the /monomorphic/ Id.  That way, if we have, say
    f = \x -> blah
and something goes wrong in 'blah', we get a "relevant binding"
looking like  f :: alpha -> beta
This applies if 'f' has a type signature too:
   f :: forall a. [a] -> [a]
   f x = True
We can't unify True with [a], and a relevant binding is f :: [a] -> [a]
If we had the *polymorphic* version of f in the TcBinderStack, it
would not be reported as relevant, because its type is closed.
(See TcErrors.relevantBindings.)

Note [Typechecking pattern bindings]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Look at:
   - typecheck/should_compile/ExPat
   - #12427, typecheck/should_compile/T12427{a,b}

  data T where
    MkT :: Integral a => a -> Int -> T

and suppose t :: T.  Which of these pattern bindings are ok?

  E1. let { MkT p _ = t } in <body>

  E2. let { MkT _ q = t } in <body>

  E3. let { MkT (toInteger -> r) _ = t } in <body>

* (E1) is clearly wrong because the existential 'a' escapes.
  What type could 'p' possibly have?

* (E2) is fine, despite the existential pattern, because
  q::Int, and nothing escapes.

* Even (E3) is fine.  The existential pattern binds a dictionary
  for (Integral a) which the view pattern can use to convert the
  a-valued field to an Integer, so r :: Integer.

An easy way to see all three is to imagine the desugaring.
For (E2) it would look like
    let q = case t of MkT _ q' -> q'
    in <body>


We typecheck pattern bindings as follows.  First tcLhs does this:

  1. Take each type signature q :: ty, partial or complete, and
     instantiate it (with tcLhsSigId) to get a MonoBindInfo.  This
     gives us a fresh "mono_id" qm :: instantiate(ty), where qm has
     a fresh name.

     Any fresh unification variables in instantiate(ty) born here, not
     deep under implications as would happen if we allocated them when
     we encountered q during tcPat.

  2. Build a little environment mapping "q" -> "qm" for those Ids
     with signatures (inst_sig_fun)

  3. Invoke tcLetPat to typecheck the pattern.

     - We pass in the current TcLevel.  This is captured by
       GHC.Tc.Gen.Pat.tcLetPat, and put into the pc_lvl field of PatCtxt, in
       PatEnv.

     - When tcPat finds an existential constructor, it binds fresh
       type variables and dictionaries as usual, increments the TcLevel,
       and emits an implication constraint.

     - When we come to a binder (GHC.Tc.Gen.Pat.tcPatBndr), it looks it up
       in the little environment (the pc_sig_fn field of PatCtxt).

         Success => There was a type signature, so just use it,
                    checking compatibility with the expected type.

         Failure => No type signature.
             Infer case: (happens only outside any constructor pattern)
                         use a unification variable
                         at the outer level pc_lvl

             Check case: use promoteTcType to promote the type
                         to the outer level pc_lvl.  This is the
                         place where we emit a constraint that'll blow
                         up if existential capture takes place

       Result: the type of the binder is always at pc_lvl. This is
       crucial.

  4. Throughout, when we are making up an Id for the pattern-bound variables
     (newLetBndr), we have two cases:

     - If we are generalising (generalisation plan is InferGen or
       CheckGen), then the let_bndr_spec will be LetLclBndr.  In that case
       we want to bind a cloned, local version of the variable, with the
       type given by the pattern context, *not* by the signature (even if
       there is one; see #7268). The mkExport part of the
       generalisation step will do the checking and impedance matching
       against the signature.

     - If for some reason we are not generalising (plan = NoGen), the
       LetBndrSpec will be LetGblBndr.  In that case we must bind the
       global version of the Id, and do so with precisely the type given
       in the signature.  (Then we unify with the type from the pattern
       context type.)


And that's it!  The implication constraints check for the skolem
escape.  It's quite simple and neat, and more expressive than before
e.g. GHC 8.0 rejects (E2) and (E3).

Example for (E1), starting at level 1.  We generate
     p :: beta:1, with constraints (forall:3 a. Integral a => a ~ beta)
The (a~beta) can't float (because of the 'a'), nor be solved (because
beta is untouchable.)

Example for (E2), we generate
     q :: beta:1, with constraint (forall:3 a. Integral a => Int ~ beta)
The beta is untouchable, but floats out of the constraint and can
be solved absolutely fine.


************************************************************************
*                                                                      *
                Generalisation
*                                                                      *
********************************************************************* -}

data GeneralisationPlan
  = NoGen               -- No generalisation, no AbsBinds

  | InferGen            -- Implicit generalisation; there is an AbsBinds
       Bool             --   True <=> apply the MR; generalise only unconstrained type vars

  | CheckGen (LHsBind GhcRn) TcIdSigInfo
                        -- One FunBind with a signature
                        -- Explicit generalisation

-- A consequence of the no-AbsBinds choice (NoGen) is that there is
-- no "polymorphic Id" and "monmomorphic Id"; there is just the one

instance Outputable GeneralisationPlan where
  ppr :: GeneralisationPlan -> SDoc
ppr GeneralisationPlan
NoGen          = String -> SDoc
text String
"NoGen"
  ppr (InferGen Bool
b)   = String -> SDoc
text String
"InferGen" SDoc -> SDoc -> SDoc
<+> Bool -> SDoc
forall a. Outputable a => a -> SDoc
ppr Bool
b
  ppr (CheckGen LHsBind GhcRn
_ TcIdSigInfo
s) = String -> SDoc
text String
"CheckGen" SDoc -> SDoc -> SDoc
<+> TcIdSigInfo -> SDoc
forall a. Outputable a => a -> SDoc
ppr TcIdSigInfo
s

decideGeneralisationPlan
   :: DynFlags -> [LHsBind GhcRn] -> IsGroupClosed -> TcSigFun
   -> GeneralisationPlan
decideGeneralisationPlan :: DynFlags
-> [LHsBind GhcRn]
-> IsGroupClosed
-> TcSigFun
-> GeneralisationPlan
decideGeneralisationPlan DynFlags
dflags [LHsBind GhcRn]
lbinds IsGroupClosed
closed TcSigFun
sig_fn
  | Bool
has_partial_sigs                         = Bool -> GeneralisationPlan
InferGen ([Bool] -> Bool
forall (t :: * -> *). Foldable t => t Bool -> Bool
and [Bool]
partial_sig_mrs)
  | Just (Located (HsBindLR GhcRn GhcRn)
bind, TcIdSigInfo
sig) <- Maybe (Located (HsBindLR GhcRn GhcRn), TcIdSigInfo)
one_funbind_with_sig = LHsBind GhcRn -> TcIdSigInfo -> GeneralisationPlan
CheckGen Located (HsBindLR GhcRn GhcRn)
LHsBind GhcRn
bind TcIdSigInfo
sig
  | IsGroupClosed -> Bool
do_not_generalise IsGroupClosed
closed                 = GeneralisationPlan
NoGen
  | Bool
otherwise                                = Bool -> GeneralisationPlan
InferGen Bool
mono_restriction
  where
    binds :: [HsBindLR GhcRn GhcRn]
binds = (Located (HsBindLR GhcRn GhcRn) -> HsBindLR GhcRn GhcRn)
-> [Located (HsBindLR GhcRn GhcRn)] -> [HsBindLR GhcRn GhcRn]
forall a b. (a -> b) -> [a] -> [b]
map Located (HsBindLR GhcRn GhcRn) -> HsBindLR GhcRn GhcRn
forall l e. GenLocated l e -> e
unLoc [Located (HsBindLR GhcRn GhcRn)]
[LHsBind GhcRn]
lbinds

    partial_sig_mrs :: [Bool]
    -- One for each partial signature (so empty => no partial sigs)
    -- The Bool is True if the signature has no constraint context
    --      so we should apply the MR
    -- See Note [Partial type signatures and generalisation]
    partial_sig_mrs :: [Bool]
partial_sig_mrs
      = [ [Located (HsType GhcRn)] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Located (HsType GhcRn)]
theta
        | TcIdSig (PartialSig { psig_hs_ty :: TcIdSigInfo -> LHsSigWcType GhcRn
psig_hs_ty = LHsSigWcType GhcRn
hs_ty })
            <- TcSigFun -> [Name] -> [TcSigInfo]
forall a b. (a -> Maybe b) -> [a] -> [b]
mapMaybe TcSigFun
sig_fn ([LHsBind GhcRn] -> [IdP GhcRn]
forall p idR. CollectPass p => [LHsBindLR p idR] -> [IdP p]
collectHsBindListBinders [LHsBind GhcRn]
lbinds)
        , let ([Located (HsTyVarBndr Specificity GhcRn)]
_, L SrcSpan
_ [Located (HsType GhcRn)]
theta, Located (HsType GhcRn)
_) = LHsType GhcRn
-> ([LHsTyVarBndr Specificity GhcRn], LHsContext GhcRn,
    LHsType GhcRn)
forall (p :: Pass).
LHsType (GhcPass p)
-> ([LHsTyVarBndr Specificity (GhcPass p)], LHsContext (GhcPass p),
    LHsType (GhcPass p))
splitLHsSigmaTyInvis (LHsSigWcType GhcRn -> LHsType GhcRn
forall pass. LHsSigWcType pass -> LHsType pass
hsSigWcType LHsSigWcType GhcRn
hs_ty) ]

    has_partial_sigs :: Bool
has_partial_sigs   = Bool -> Bool
not ([Bool] -> Bool
forall (t :: * -> *) a. Foldable t => t a -> Bool
null [Bool]
partial_sig_mrs)

    mono_restriction :: Bool
mono_restriction  = Extension -> DynFlags -> Bool
xopt Extension
LangExt.MonomorphismRestriction DynFlags
dflags
                     Bool -> Bool -> Bool
&& (HsBindLR GhcRn GhcRn -> Bool) -> [HsBindLR GhcRn GhcRn] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
any HsBindLR GhcRn GhcRn -> Bool
restricted [HsBindLR GhcRn GhcRn]
binds

    do_not_generalise :: IsGroupClosed -> Bool
do_not_generalise (IsGroupClosed NameEnv (UniqSet Name)
_ Bool
True) = Bool
False
        -- The 'True' means that all of the group's
        -- free vars have ClosedTypeId=True; so we can ignore
        -- -XMonoLocalBinds, and generalise anyway
    do_not_generalise IsGroupClosed
_ = Extension -> DynFlags -> Bool
xopt Extension
LangExt.MonoLocalBinds DynFlags
dflags

    -- With OutsideIn, all nested bindings are monomorphic
    -- except a single function binding with a signature
    one_funbind_with_sig :: Maybe (Located (HsBindLR GhcRn GhcRn), TcIdSigInfo)
one_funbind_with_sig
      | [lbind :: LHsBind GhcRn
lbind@(L _ (FunBind { fun_id = v }))] <- [LHsBind GhcRn]
lbinds
      , Just (TcIdSig TcIdSigInfo
sig) <- TcSigFun
sig_fn (Located Name -> Name
forall l e. GenLocated l e -> e
unLoc Located Name
LIdP GhcRn
v)
      = (Located (HsBindLR GhcRn GhcRn), TcIdSigInfo)
-> Maybe (Located (HsBindLR GhcRn GhcRn), TcIdSigInfo)
forall a. a -> Maybe a
Just (Located (HsBindLR GhcRn GhcRn)
LHsBind GhcRn
lbind, TcIdSigInfo
sig)
      | Bool
otherwise
      = Maybe (Located (HsBindLR GhcRn GhcRn), TcIdSigInfo)
forall a. Maybe a
Nothing

    -- The Haskell 98 monomorphism restriction
    restricted :: HsBindLR GhcRn GhcRn -> Bool
restricted (PatBind {})                              = Bool
True
    restricted (VarBind { var_id :: forall idL idR. HsBindLR idL idR -> IdP idL
var_id = IdP GhcRn
v })                  = Name -> Bool
no_sig Name
IdP GhcRn
v
    restricted (FunBind { fun_id :: forall idL idR. HsBindLR idL idR -> LIdP idL
fun_id = LIdP GhcRn
v, fun_matches :: forall idL idR. HsBindLR idL idR -> MatchGroup idR (LHsExpr idR)
fun_matches = MatchGroup GhcRn (LHsExpr GhcRn)
m }) = MatchGroup GhcRn (Located (HsExpr GhcRn)) -> Bool
forall (id :: Pass) body. MatchGroup (GhcPass id) body -> Bool
restricted_match MatchGroup GhcRn (Located (HsExpr GhcRn))
MatchGroup GhcRn (LHsExpr GhcRn)
m
                                                           Bool -> Bool -> Bool
&& Name -> Bool
no_sig (Located Name -> Name
forall l e. GenLocated l e -> e
unLoc Located Name
LIdP GhcRn
v)
    restricted HsBindLR GhcRn GhcRn
b = String -> SDoc -> Bool
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"isRestrictedGroup/unrestricted" (HsBindLR GhcRn GhcRn -> SDoc
forall a. Outputable a => a -> SDoc
ppr HsBindLR GhcRn GhcRn
b)

    restricted_match :: MatchGroup (GhcPass id) body -> Bool
restricted_match MatchGroup (GhcPass id) body
mg = MatchGroup (GhcPass id) body -> BKey
forall (id :: Pass) body. MatchGroup (GhcPass id) body -> BKey
matchGroupArity MatchGroup (GhcPass id) body
mg BKey -> BKey -> Bool
forall a. Eq a => a -> a -> Bool
== BKey
0
        -- No args => like a pattern binding
        -- Some args => a function binding

    no_sig :: Name -> Bool
no_sig Name
n = Bool -> Bool
not (TcSigFun -> Name -> Bool
hasCompleteSig TcSigFun
sig_fn Name
n)

isClosedBndrGroup :: TcTypeEnv -> Bag (LHsBind GhcRn) -> IsGroupClosed
isClosedBndrGroup :: TcTypeEnv -> LHsBinds GhcRn -> IsGroupClosed
isClosedBndrGroup TcTypeEnv
type_env LHsBinds GhcRn
binds
  = NameEnv (UniqSet Name) -> Bool -> IsGroupClosed
IsGroupClosed NameEnv (UniqSet Name)
fv_env Bool
type_closed
  where
    type_closed :: Bool
type_closed = (UniqSet Name -> Bool) -> NameEnv (UniqSet Name) -> Bool
forall elt key. (elt -> Bool) -> UniqFM key elt -> Bool
allUFM ((Name -> Bool) -> UniqSet Name -> Bool
nameSetAll Name -> Bool
is_closed_type_id) NameEnv (UniqSet Name)
fv_env

    fv_env :: NameEnv NameSet
    fv_env :: NameEnv (UniqSet Name)
fv_env = [(Name, UniqSet Name)] -> NameEnv (UniqSet Name)
forall a. [(Name, a)] -> NameEnv a
mkNameEnv ([(Name, UniqSet Name)] -> NameEnv (UniqSet Name))
-> [(Name, UniqSet Name)] -> NameEnv (UniqSet Name)
forall a b. (a -> b) -> a -> b
$ (Located (HsBindLR GhcRn GhcRn) -> [(Name, UniqSet Name)])
-> Bag (Located (HsBindLR GhcRn GhcRn)) -> [(Name, UniqSet Name)]
forall (t :: * -> *) a b. Foldable t => (a -> [b]) -> t a -> [b]
concatMap (HsBindLR GhcRn GhcRn -> [(Name, UniqSet Name)]
bindFvs (HsBindLR GhcRn GhcRn -> [(Name, UniqSet Name)])
-> (Located (HsBindLR GhcRn GhcRn) -> HsBindLR GhcRn GhcRn)
-> Located (HsBindLR GhcRn GhcRn)
-> [(Name, UniqSet Name)]
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Located (HsBindLR GhcRn GhcRn) -> HsBindLR GhcRn GhcRn
forall l e. GenLocated l e -> e
unLoc) Bag (Located (HsBindLR GhcRn GhcRn))
LHsBinds GhcRn
binds

    bindFvs :: HsBindLR GhcRn GhcRn -> [(Name, NameSet)]
    bindFvs :: HsBindLR GhcRn GhcRn -> [(Name, UniqSet Name)]
bindFvs (FunBind { fun_id :: forall idL idR. HsBindLR idL idR -> LIdP idL
fun_id = L _ f
                     , fun_ext :: forall idL idR. HsBindLR idL idR -> XFunBind idL idR
fun_ext = XFunBind GhcRn GhcRn
fvs })
       = let open_fvs :: UniqSet Name
open_fvs = UniqSet Name -> UniqSet Name
get_open_fvs UniqSet Name
XFunBind GhcRn GhcRn
fvs
         in [(Name
f, UniqSet Name
open_fvs)]
    bindFvs (PatBind { pat_lhs :: forall idL idR. HsBindLR idL idR -> LPat idL
pat_lhs = LPat GhcRn
pat, pat_ext :: forall idL idR. HsBindLR idL idR -> XPatBind idL idR
pat_ext = XPatBind GhcRn GhcRn
fvs })
       = let open_fvs :: UniqSet Name
open_fvs = UniqSet Name -> UniqSet Name
get_open_fvs UniqSet Name
XPatBind GhcRn GhcRn
fvs
         in [(Name
b, UniqSet Name
open_fvs) | Name
b <- LPat GhcRn -> [IdP GhcRn]
forall p. CollectPass p => LPat p -> [IdP p]
collectPatBinders LPat GhcRn
pat]
    bindFvs HsBindLR GhcRn GhcRn
_
       = []

    get_open_fvs :: UniqSet Name -> UniqSet Name
get_open_fvs UniqSet Name
fvs = (Name -> Bool) -> UniqSet Name -> UniqSet Name
filterNameSet (Bool -> Bool
not (Bool -> Bool) -> (Name -> Bool) -> Name -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Name -> Bool
is_closed) UniqSet Name
fvs

    is_closed :: Name -> ClosedTypeId
    is_closed :: Name -> Bool
is_closed Name
name
      | Just TcTyThing
thing <- TcTypeEnv -> Name -> Maybe TcTyThing
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv TcTypeEnv
type_env Name
name
      = case TcTyThing
thing of
          AGlobal {}                     -> Bool
True
          ATcId { tct_info :: TcTyThing -> IdBindingInfo
tct_info = IdBindingInfo
ClosedLet } -> Bool
True
          TcTyThing
_                              -> Bool
False

      | Bool
otherwise
      = Bool
True  -- The free-var set for a top level binding mentions


    is_closed_type_id :: Name -> Bool
    -- We're already removed Global and ClosedLet Ids
    is_closed_type_id :: Name -> Bool
is_closed_type_id Name
name
      | Just TcTyThing
thing <- TcTypeEnv -> Name -> Maybe TcTyThing
forall a. NameEnv a -> Name -> Maybe a
lookupNameEnv TcTypeEnv
type_env Name
name
      = case TcTyThing
thing of
          ATcId { tct_info :: TcTyThing -> IdBindingInfo
tct_info = NonClosedLet UniqSet Name
_ Bool
cl } -> Bool
cl
          ATcId { tct_info :: TcTyThing -> IdBindingInfo
tct_info = IdBindingInfo
NotLetBound }       -> Bool
False
          ATyVar {}                              -> Bool
False
               -- In-scope type variables are not closed!
          TcTyThing
_ -> String -> SDoc -> Bool
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"is_closed_id" (Name -> SDoc
forall a. Outputable a => a -> SDoc
ppr Name
name)

      | Bool
otherwise
      = Bool
True   -- The free-var set for a top level binding mentions
               -- imported things too, so that we can report unused imports
               -- These won't be in the local type env.
               -- Ditto class method etc from the current module


{- *********************************************************************
*                                                                      *
               Error contexts and messages
*                                                                      *
********************************************************************* -}

-- This one is called on LHS, when pat and grhss are both Name
-- and on RHS, when pat is TcId and grhss is still Name
patMonoBindsCtxt :: (OutputableBndrId p, Outputable body)
                 => LPat (GhcPass p) -> GRHSs GhcRn body -> SDoc
patMonoBindsCtxt :: LPat (GhcPass p) -> GRHSs GhcRn body -> SDoc
patMonoBindsCtxt LPat (GhcPass p)
pat GRHSs GhcRn body
grhss
  = SDoc -> BKey -> SDoc -> SDoc
hang (String -> SDoc
text String
"In a pattern binding:") BKey
2 (LPat (GhcPass p) -> GRHSs GhcRn body -> SDoc
forall (bndr :: Pass) (p :: Pass) body.
(OutputableBndrId bndr, OutputableBndrId p, Outputable body) =>
LPat (GhcPass bndr) -> GRHSs (GhcPass p) body -> SDoc
pprPatBind LPat (GhcPass p)
pat GRHSs GhcRn body
grhss)