    {-# LANGUAGE DataKinds #-}
    {-# LANGUAGE FlexibleContexts #-}
    {-# LANGUAGE GADTs #-}
    {-# LANGUAGE PolyKinds #-}
    {-# LANGUAGE StandaloneKindSignatures #-}
    {-# LANGUAGE TypeFamilies #-}

    -- | Describes the provenance of types as they flow through the type-checker.
    -- The datatypes here are mainly used for error message generation.
    module GHC.Tc.Types.Origin (
      -- * UserTypeCtxt
      UserTypeCtxt(..), pprUserTypeCtxt, isSigMaybe,
      ReportRedundantConstraints(..), reportRedundantConstraints,
      redundantConstraintsSpan,

      -- * SkolemInfo
      SkolemInfo(..), SkolemInfoAnon(..), mkSkolemInfo, getSkolemInfo, pprSigSkolInfo, pprSkolInfo,
      unkSkol, unkSkolAnon, mkClsInstSkol,

      -- * CtOrigin
      CtOrigin(..), exprCtOrigin, lexprCtOrigin, matchesCtOrigin, grhssCtOrigin,
      isVisibleOrigin, toInvisibleOrigin,
      pprCtOrigin, isGivenOrigin, isWantedWantedFunDepOrigin,
      isWantedSuperclassOrigin,
      ClsInstOrQC(..), NakedScFlag(..), NonLinearPatternReason(..),

      TypedThing(..), TyVarBndrs(..),

      -- * CallStack
      isPushCallStackOrigin, callStackOriginFS,

      -- * FixedRuntimeRep origin
      FixedRuntimeRepOrigin(..),
      FixedRuntimeRepContext(..),
      pprFixedRuntimeRepContext,
      StmtOrigin(..), ArgPos(..),
      mkFRRUnboxedTuple, mkFRRUnboxedSum,

      -- ** FixedRuntimeRep origin for rep-poly 'Id's
      RepPolyId(..), Polarity(..), Position(..),

      -- ** Arrow command FixedRuntimeRep origin
      FRRArrowContext(..), pprFRRArrowContext,

      -- ** ExpectedFunTy FixedRuntimeRepOrigin
      ExpectedFunTyOrigin(..), pprExpectedFunTyOrigin, pprExpectedFunTyHerald,

      -- * InstanceWhat
      InstanceWhat(..), SafeOverlapping
      ) where

    import GHC.Prelude

    import GHC.Tc.Utils.TcType

    import GHC.Hs

    import GHC.Core.DataCon
    import GHC.Core.ConLike
    import GHC.Core.TyCon
    import GHC.Core.Class
    import GHC.Core.InstEnv
    import GHC.Core.PatSyn
    import GHC.Core.Multiplicity ( scaledThing )

    import GHC.Unit.Module
    import GHC.Unit.Module.Warnings
    import GHC.Types.Id
    import GHC.Types.Name
    import GHC.Types.Name.Reader
    import GHC.Types.Basic
    import GHC.Types.SrcLoc

    import GHC.Data.FastString

    import GHC.Utils.Outputable
    import GHC.Utils.Panic
    import GHC.Stack
    import GHC.Utils.Monad
    import GHC.Utils.Misc( HasDebugCallStack )
    import GHC.Types.Unique
    import GHC.Types.Unique.Supply

    import Language.Haskell.Syntax.Basic (FieldLabelString(..))

    import qualified Data.Kind as Hs

    {- *********************************************************************
    *                                                                      *
              UserTypeCtxt
    *                                                                      *
    ********************************************************************* -}

    -------------------------------------
    -- | UserTypeCtxt describes the origin of the polymorphic type
    -- in the places where we need an expression to have that type
    data UserTypeCtxt
      = FunSigCtxt      -- Function type signature, when checking the type
                        -- Also used for types in SPECIALISE pragmas
           Name              -- Name of the function
           ReportRedundantConstraints
             -- See Note [Tracking redundant constraints] in GHC.Tc.Solver
             -- This field is usually 'WantRCC', but 'NoRCC' for
             --   * Record selectors (not important here)
             --   * Class and instance methods.  Here the code may legitimately
             --     be more polymorphic than the signature generated from the
             --     class declaration
             --   * Functions whose type signature has hidden the constraints
             --     behind a type synonym.  E.g.
             --          type Foo = forall a. Eq a => a -> a
             --          id :: Foo
             --          id x = x
             --     Here we can't give a good location for the redundant constraints
             --     (see lhsSigWcTypeContextSpan), so we don't report redundant
             --     constraints at all. It's not clear that this a good choice;
             --     perhaps we should report, just with a less informative SrcSpan.
             --     c.f. #16154

      | InfSigCtxt Name     -- Inferred type for function
      | ExprSigCtxt         -- Expression type signature
          ReportRedundantConstraints
      | KindSigCtxt         -- Kind signature
      | StandaloneKindSigCtxt  -- Standalone kind signature
           Name                -- Name of the type/class
      | TypeAppCtxt         -- Visible type application
      | ConArgCtxt Name     -- Data constructor argument
      | TySynCtxt Name      -- RHS of a type synonym decl
      | PatSynCtxt Name     -- Type sig for a pattern synonym
      | PatSigCtxt          -- Type sig in pattern
                            --   eg  f (x::t) = ...
                            --   or  (x::t, y) = e
      | RuleSigCtxt FastString Name    -- LHS of a RULE forall
                            --    RULE "foo" forall (x :: a -> a). f (Just x) = ...
      | ForSigCtxt Name     -- Foreign import or export signature
      | DefaultDeclCtxt     -- Class or types in a default declaration
      | InstDeclCtxt Bool   -- An instance declaration
                            --    True:  stand-alone deriving
                            --    False: vanilla instance declaration
      | SpecInstCtxt        -- SPECIALISE instance pragma
      | GenSigCtxt          -- Higher-rank or impredicative situations
                            -- e.g. (f e) where f has a higher-rank type
                            -- We might want to elaborate this
      | GhciCtxt Bool       -- GHCi command :kind <type>
                            -- The Bool indicates if we are checking the outermost
                            -- type application.
                            -- See Note [Unsaturated type synonyms in GHCi] in
                            -- GHC.Tc.Validity.

      | ClassSCCtxt Name    -- Superclasses of a class
      | SigmaCtxt           -- Theta part of a normal for-all type
                            --      f :: <S> => a -> a
      | DataTyCtxt Name     -- The "stupid theta" part of a data decl
                            --      data <S> => T a = MkT a
      | DerivClauseCtxt     -- A 'deriving' clause
      | TyVarBndrKindCtxt Name  -- The kind of a type variable being bound
      | DataKindCtxt Name   -- The kind of a data/newtype (instance)
      | TySynKindCtxt Name  -- The kind of the RHS of a type synonym
      | TyFamResKindCtxt Name   -- The result kind of a type family
      deriving( UserTypeCtxt -> UserTypeCtxt -> Bool
    (UserTypeCtxt -> UserTypeCtxt -> Bool)
    -> (UserTypeCtxt -> UserTypeCtxt -> Bool) -> Eq UserTypeCtxt
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    $c== :: UserTypeCtxt -> UserTypeCtxt -> Bool
    == :: UserTypeCtxt -> UserTypeCtxt -> Bool
    $c/= :: UserTypeCtxt -> UserTypeCtxt -> Bool
    /= :: UserTypeCtxt -> UserTypeCtxt -> Bool
    Eq ) -- Just for checkSkolInfoAnon

    -- | Report Redundant Constraints.
    data ReportRedundantConstraints
      = NoRRC            -- ^ Don't report redundant constraints

      | WantRRC SrcSpan  -- ^ Report redundant constraints
          -- The SrcSpan is for the constraints
          -- E.g. f :: (Eq a, Ord b) => blah
          --      The span is for the (Eq a, Ord b)
          -- We need to record the span here because we have
          -- long since discarded the HsType in favour of a Type

      deriving( ReportRedundantConstraints -> ReportRedundantConstraints -> Bool
    (ReportRedundantConstraints -> ReportRedundantConstraints -> Bool)
    -> (ReportRedundantConstraints
        -> ReportRedundantConstraints -> Bool)
    -> Eq ReportRedundantConstraints
    forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
    $c== :: ReportRedundantConstraints -> ReportRedundantConstraints -> Bool
    == :: ReportRedundantConstraints -> ReportRedundantConstraints -> Bool
    $c/= :: ReportRedundantConstraints -> ReportRedundantConstraints -> Bool
    /= :: ReportRedundantConstraints -> ReportRedundantConstraints -> Bool
    Eq )  -- Just for checkSkolInfoAnon

    reportRedundantConstraints :: ReportRedundantConstraints -> Bool
    reportRedundantConstraints :: ReportRedundantConstraints -> Bool
    reportRedundantConstraints ReportRedundantConstraints
    NoRRC        = Bool
    False
    reportRedundantConstraints (WantRRC {}) = Bool
    True

    redundantConstraintsSpan :: UserTypeCtxt -> SrcSpan
    redundantConstraintsSpan :: UserTypeCtxt -> SrcSpan
    redundantConstraintsSpan (FunSigCtxt Name
    _ (WantRRC SrcSpan
    span)) = SrcSpan
    span
    redundantConstraintsSpan (ExprSigCtxt (WantRRC SrcSpan
    span))  = SrcSpan
    span
    redundantConstraintsSpan UserTypeCtxt
    _ = SrcSpan
    noSrcSpan

    {-
    -- Notes re TySynCtxt
    -- We allow type synonyms that aren't types; e.g.  type List = []
    --
    -- If the RHS mentions tyvars that aren't in scope, we'll
    -- quantify over them:
    --      e.g.    type T = a->a
    -- will become  type T = forall a. a->a
    --
    -- With gla-exts that's right, but for H98 we should complain.
    -}

    pprUserTypeCtxt :: UserTypeCtxt -> SDoc
    pprUserTypeCtxt :: UserTypeCtxt -> SDoc
    pprUserTypeCtxt (FunSigCtxt Name
    n ReportRedundantConstraints
    _)  = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the type signature for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
    pprUserTypeCtxt (InfSigCtxt Name
    n)    = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the inferred type for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
    pprUserTypeCtxt (RuleSigCtxt FastString
    _ Name
    n) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the type signature for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
    pprUserTypeCtxt (ExprSigCtxt ReportRedundantConstraints
    _)   = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an expression type signature"
    pprUserTypeCtxt UserTypeCtxt
    KindSigCtxt       = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a kind signature"
    pprUserTypeCtxt (StandaloneKindSigCtxt Name
    n) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a standalone kind signature for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
    pprUserTypeCtxt UserTypeCtxt
    TypeAppCtxt       = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a type argument"
    pprUserTypeCtxt (ConArgCtxt Name
    c)    = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the type of the constructor" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    c)
    pprUserTypeCtxt (TySynCtxt Name
    c)     = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the RHS of the type synonym" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    c)
    pprUserTypeCtxt UserTypeCtxt
    PatSigCtxt        = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a pattern type signature"
    pprUserTypeCtxt (ForSigCtxt Name
    n)    = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the foreign declaration for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
    pprUserTypeCtxt UserTypeCtxt
    DefaultDeclCtxt   = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a `default' declaration"
    pprUserTypeCtxt (InstDeclCtxt Bool
    False) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an instance declaration"
    pprUserTypeCtxt (InstDeclCtxt Bool
    True)  = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a stand-alone deriving instance declaration"
    pprUserTypeCtxt UserTypeCtxt
    SpecInstCtxt      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a SPECIALISE instance pragma"
    pprUserTypeCtxt UserTypeCtxt
    GenSigCtxt        = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a type expected by the context"
    pprUserTypeCtxt (GhciCtxt {})     = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a type in a GHCi command"
    pprUserTypeCtxt (ClassSCCtxt Name
    c)   = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the super-classes of class" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    c)
    pprUserTypeCtxt UserTypeCtxt
    SigmaCtxt         = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the context of a polymorphic type"
    pprUserTypeCtxt (DataTyCtxt Name
    tc)   = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the context of the data type declaration for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    tc)
    pprUserTypeCtxt (PatSynCtxt Name
    n)    = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the signature for pattern synonym" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
    pprUserTypeCtxt (UserTypeCtxt
    DerivClauseCtxt) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a `deriving' clause"
    pprUserTypeCtxt (TyVarBndrKindCtxt Name
    n) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the kind annotation on the type variable" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
    pprUserTypeCtxt (DataKindCtxt Name
    n)  = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the kind annotation on the declaration for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
    pprUserTypeCtxt (TySynKindCtxt Name
    n) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the kind annotation on the declaration for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
    pprUserTypeCtxt (TyFamResKindCtxt Name
    n) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the result kind for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)

    isSigMaybe :: UserTypeCtxt -> Maybe Name
    isSigMaybe :: UserTypeCtxt -> Maybe Name
    isSigMaybe (FunSigCtxt Name
    n ReportRedundantConstraints
    _) = Name -> Maybe Name
    forall a. a -> Maybe a
    Just Name
    n
    isSigMaybe (ConArgCtxt Name
    n)   = Name -> Maybe Name
    forall a. a -> Maybe a
    Just Name
    n
    isSigMaybe (ForSigCtxt Name
    n)   = Name -> Maybe Name
    forall a. a -> Maybe a
    Just Name
    n
    isSigMaybe (PatSynCtxt Name
    n)   = Name -> Maybe Name
    forall a. a -> Maybe a
    Just Name
    n
    isSigMaybe UserTypeCtxt
    _                = Maybe Name
    forall a. Maybe a
    Nothing

    {-
    ************************************************************************
    *                                                                      *
                    SkolemInfo
    *                                                                      *
    ************************************************************************
    -}

    -- | 'SkolemInfo' stores the origin of a skolem type variable,
    -- so that we can display this information to the user in case of a type error.
    --
    -- The 'Unique' field allows us to report all skolem type variables bound in the
    -- same place in a single report.
    data SkolemInfo
      = SkolemInfo
          Unique         -- ^ The Unique is used to common up skolem variables bound
                         --   at the same location (only used in pprSkols)
          SkolemInfoAnon -- ^ The information about the origin of the skolem type variable

    instance Uniquable SkolemInfo where
      getUnique :: SkolemInfo -> Unique
    getUnique (SkolemInfo Unique
    u SkolemInfoAnon
    _) = Unique
    u

    -- | 'SkolemInfoAnon' stores the origin of a skolem type variable (e.g. bound by
    -- a user-written forall, the header of a data declaration, a deriving clause, ...).
    --
    -- This information is displayed when reporting an error message, such as
    --
    --  @"Couldn't match 'k' with 'l'"@
    --
    -- This allows us to explain where the type variable came from.
    --
    -- When several skolem type variables are bound at once, prefer using 'SkolemInfo',
    -- which stores a 'Unique' which allows these type variables to be reported
    data SkolemInfoAnon
      = SigSkol -- A skolem that is created by instantiating
                -- a programmer-supplied type signature
                -- Location of the binding site is on the TyVar
                -- See Note [SigSkol SkolemInfo]
           UserTypeCtxt        -- What sort of signature
           TcType              -- Original type signature (before skolemisation)
           [(Name,TcTyVar)]    -- Maps the original name of the skolemised tyvar
                               -- to its instantiated version

      | SigTypeSkol UserTypeCtxt
                     -- like SigSkol, but when we're kind-checking the *type*
                     -- hence, we have less info

      | ForAllSkol  -- Bound by a user-written "forall".
          TyVarBndrs   -- Shows just the binders, used when reporting a bad telescope
                        -- See Note [Checking telescopes] in GHC.Tc.Types.Constraint

      | DerivSkol Type      -- Bound by a 'deriving' clause;
                            -- the type is the instance we are trying to derive

      | InstSkol            -- Bound at an instance decl, or quantified constraint
           ClsInstOrQC      -- Whether class instance or quantified constraint
           PatersonSize     -- Head has the given PatersonSize

      | FamInstSkol         -- Bound at a family instance decl
      | PatSkol             -- An existential type variable bound by a pattern for
          ConLike           -- a data constructor with an existential type.
          HsMatchContextRn
                 -- e.g.   data T = forall a. Eq a => MkT a
                 --        f (MkT x) = ...
                 -- The pattern MkT x will allocate an existential type
                 -- variable for 'a'.

      | IPSkol [HsIPName]   -- Binding site of an implicit parameter

      | RuleSkol RuleName   -- The LHS of a RULE

      | InferSkol [(Name,TcType)]
                            -- We have inferred a type for these (mutually recursive)
                            -- polymorphic Ids, and are now checking that their RHS
                            -- constraints are satisfied.

      | BracketSkol         -- Template Haskell bracket

      | UnifyForAllSkol     -- We are unifying two for-all types
           TcType           -- The instantiated type *inside* the forall

      | TyConSkol (TyConFlavour TyCon) Name -- bound in a type declaration of the given flavour

      | DataConSkol Name    -- bound as an existential in a Haskell98 datacon decl or
                            -- as any variable in a GADT datacon decl

      | ReifySkol           -- Bound during Template Haskell reification

      | RuntimeUnkSkol      -- Runtime skolem from the GHCi debugger      #14628

      | ArrowReboundIfSkol  -- Bound by the expected type of the rebound arrow ifThenElse command.

      | UnkSkol CallStack

    -- | Use this when you can't specify a helpful origin for
    -- some skolem type variable.
    --
    -- We're hoping to be able to get rid of this entirely, but for the moment
    -- it's still needed.
    unkSkol :: HasDebugCallStack => SkolemInfo
    unkSkol :: HasDebugCallStack => SkolemInfo
    unkSkol = Unique -> SkolemInfoAnon -> SkolemInfo
    SkolemInfo (Word64 -> Unique
    mkUniqueGrimily Word64
    0) SkolemInfoAnon
    HasDebugCallStack => SkolemInfoAnon
    unkSkolAnon

    unkSkolAnon :: HasDebugCallStack => SkolemInfoAnon
    unkSkolAnon :: HasDebugCallStack => SkolemInfoAnon
    unkSkolAnon = CallStack -> SkolemInfoAnon
    UnkSkol CallStack
    HasCallStack => CallStack
    callStack

    -- | Wrap up the origin of a skolem type variable with a new 'Unique',
    -- so that we can common up skolem type variables whose 'SkolemInfo'
    -- shares a certain 'Unique'.
    mkSkolemInfo :: MonadIO m => SkolemInfoAnon -> m SkolemInfo
    mkSkolemInfo :: forall (m :: * -> *). MonadIO m => SkolemInfoAnon -> m SkolemInfo
    mkSkolemInfo SkolemInfoAnon
    sk_anon = do
      u <- IO Unique -> m Unique
    forall a. IO a -> m a
    forall (m :: * -> *) a. MonadIO m => IO a -> m a
    liftIO (IO Unique -> m Unique) -> IO Unique -> m Unique
    forall a b. (a -> b) -> a -> b
    $! Char -> IO Unique
    uniqFromTag Char
    's'
      return (SkolemInfo u sk_anon)

    getSkolemInfo :: SkolemInfo -> SkolemInfoAnon
    getSkolemInfo :: SkolemInfo -> SkolemInfoAnon
    getSkolemInfo (SkolemInfo Unique
    _ SkolemInfoAnon
    skol_anon) = SkolemInfoAnon
    skol_anon

    mkClsInstSkol :: Class -> [Type] -> SkolemInfoAnon
    mkClsInstSkol :: Class -> [TcType] -> SkolemInfoAnon
    mkClsInstSkol Class
    cls [TcType]
    tys = ClsInstOrQC -> PatersonSize -> SkolemInfoAnon
    InstSkol ClsInstOrQC
    IsClsInst (Class -> [TcType] -> PatersonSize
    pSizeClassPred Class
    cls [TcType]
    tys)

    instance Outputable SkolemInfo where
      ppr :: SkolemInfo -> SDoc
    ppr (SkolemInfo Unique
    _ SkolemInfoAnon
    sk_info ) = SkolemInfoAnon -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr SkolemInfoAnon
    sk_info

    instance Outputable SkolemInfoAnon where
      ppr :: SkolemInfoAnon -> SDoc
    ppr = SkolemInfoAnon -> SDoc
    pprSkolInfo

    pprSkolInfo :: SkolemInfoAnon -> SDoc
    -- Complete the sentence "is a rigid type variable bound by..."
    pprSkolInfo :: SkolemInfoAnon -> SDoc
    pprSkolInfo (SigSkol UserTypeCtxt
    cx TcType
    ty [(Name, Id)]
    _) = UserTypeCtxt -> TcType -> SDoc
    pprSigSkolInfo UserTypeCtxt
    cx TcType
    ty
    pprSkolInfo (SigTypeSkol UserTypeCtxt
    cx)  = UserTypeCtxt -> SDoc
    pprUserTypeCtxt UserTypeCtxt
    cx
    pprSkolInfo (ForAllSkol TyVarBndrs
    tvs)  = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an explicit forall" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> TyVarBndrs -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TyVarBndrs
    tvs
    pprSkolInfo (IPSkol [HsIPName]
    ips)      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the implicit-parameter binding" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> [HsIPName] -> SDoc
    forall a. [a] -> SDoc
    plural [HsIPName]
    ips SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "for"
                                     SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> (HsIPName -> SDoc) -> [HsIPName] -> SDoc
    forall a. (a -> SDoc) -> [a] -> SDoc
    pprWithCommas HsIPName -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr [HsIPName]
    ips
    pprSkolInfo (DerivSkol TcType
    pred)  = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the deriving clause for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    pred)
    pprSkolInfo (InstSkol ClsInstOrQC
    IsClsInst PatersonSize
    sz) = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the instance declaration"
                                               , SDoc -> SDoc
    forall doc. IsOutput doc => doc -> doc
    whenPprDebug (SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    braces (PatersonSize -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr PatersonSize
    sz)) ]
    pprSkolInfo (InstSkol (IsQC {}) PatersonSize
    sz) = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a quantified context"
                                               , SDoc -> SDoc
    forall doc. IsOutput doc => doc -> doc
    whenPprDebug (SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    braces (PatersonSize -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr PatersonSize
    sz)) ]
    pprSkolInfo SkolemInfoAnon
    FamInstSkol       = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a family instance declaration"
    pprSkolInfo SkolemInfoAnon
    BracketSkol       = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a Template Haskell bracket"
    pprSkolInfo (RuleSkol FastString
    name)   = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the RULE" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> FastString -> SDoc
    pprRuleName FastString
    name
    pprSkolInfo (PatSkol ConLike
    cl HsMatchContextRn
    mc)   = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ ConLike -> SDoc
    pprPatSkolInfo ConLike
    cl
                                        , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "in" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> HsMatchContext (GenLocated SrcSpanAnnN Name) -> SDoc
    forall fn. Outputable fn => HsMatchContext fn -> SDoc
    pprMatchContext HsMatchContextRn
    HsMatchContext (GenLocated SrcSpanAnnN Name)
    mc ]
    pprSkolInfo (InferSkol [(Name, TcType)]
    ids)   = SDoc -> ScDepth -> SDoc -> SDoc
    hang (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the inferred type" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> [(Name, TcType)] -> SDoc
    forall a. [a] -> SDoc
    plural [(Name, TcType)]
    ids SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "of")
                                       ScDepth
    2 ([SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    name SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc
    dcolon SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    ty
                                               | (Name
    name,TcType
    ty) <- [(Name, TcType)]
    ids ])
    pprSkolInfo (UnifyForAllSkol TcType
    ty)  = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the type" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    ty
    pprSkolInfo (TyConSkol TyConFlavour TyCon
    flav Name
    name) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> TyConFlavour TyCon -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TyConFlavour TyCon
    flav SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "declaration for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    name)
    pprSkolInfo (DataConSkol Name
    name)    = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the type signature for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    name)
    pprSkolInfo SkolemInfoAnon
    ReifySkol             = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the type being reified"

    pprSkolInfo SkolemInfoAnon
    RuntimeUnkSkol     = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "Unknown type from GHCi runtime"
    pprSkolInfo SkolemInfoAnon
    ArrowReboundIfSkol = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the expected type of a rebound if-then-else command"

    -- unkSkol
    -- For type variables the others are dealt with by pprSkolTvBinding.
    -- For Insts, these cases should not happen
    pprSkolInfo (UnkSkol CallStack
    cs) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "UnkSkol (please report this as a bug)" SDoc -> SDoc -> SDoc
    forall doc. IsDoc doc => doc -> doc -> doc
    $$ CallStack -> SDoc
    prettyCallStackDoc CallStack
    cs

    pprSigSkolInfo :: UserTypeCtxt -> TcType -> SDoc
    -- The type is already tidied
    pprSigSkolInfo :: UserTypeCtxt -> TcType -> SDoc
    pprSigSkolInfo UserTypeCtxt
    ctxt TcType
    ty
      = case UserTypeCtxt
    ctxt of
           FunSigCtxt Name
    f ReportRedundantConstraints
    _ -> [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the type signature for:"
                                  , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (Name -> SDoc
    forall a. OutputableBndr a => a -> SDoc
    pprPrefixOcc Name
    f SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc
    dcolon SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    ty) ]
           PatSynCtxt {}  -> UserTypeCtxt -> SDoc
    pprUserTypeCtxt UserTypeCtxt
    ctxt  -- See Note [Skolem info for pattern synonyms]
           UserTypeCtxt
    _              -> [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ UserTypeCtxt -> SDoc
    pprUserTypeCtxt UserTypeCtxt
    ctxt SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    colon
                                  , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    ty) ]

    pprPatSkolInfo :: ConLike -> SDoc
    pprPatSkolInfo :: ConLike -> SDoc
    pprPatSkolInfo (RealDataCon DataCon
    dc)
      = (SDocContext -> Bool) -> (Bool -> SDoc) -> SDoc
    forall a. (SDocContext -> a) -> (a -> SDoc) -> SDoc
    sdocOption SDocContext -> Bool
    sdocLinearTypes (\Bool
    show_linear_types ->
          [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a pattern with constructor:"
              , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (SDoc -> SDoc) -> SDoc -> SDoc
    forall a b. (a -> b) -> a -> b
    $ DataCon -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr DataCon
    dc SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc
    dcolon
                SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> TcType -> SDoc
    pprType (Bool -> DataCon -> TcType
    dataConDisplayType Bool
    show_linear_types DataCon
    dc) SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma ])
                -- pprType prints forall's regardless of -fprint-explicit-foralls
                -- which is what we want here, since we might be saying
                -- type variable 't' is bound by ...

    pprPatSkolInfo (PatSynCon PatSyn
    ps)
      = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a pattern with pattern synonym:"
            , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (SDoc -> SDoc) -> SDoc -> SDoc
    forall a b. (a -> b) -> a -> b
    $ PatSyn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr PatSyn
    ps SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc
    dcolon
                       SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> PatSyn -> SDoc
    pprPatSynType PatSyn
    ps SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma ]

    {- Note [Skolem info for pattern synonyms]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    For pattern synonym SkolemInfo we have
       SigSkol (PatSynCtxt p) ty _
    but the type 'ty' is not very helpful.  The full pattern-synonym type
    has the provided and required pieces, which it is inconvenient to
    record and display here. So we simply don't display the type at all,
    contenting ourselves with just the name of the pattern synonym, which
    is fine.  We could do more, but it doesn't seem worth it.

    Note [SigSkol SkolemInfo]
    ~~~~~~~~~~~~~~~~~~~~~~~~~
    Suppose we skolemise a type
       f :: forall a. Eq a => forall b. b -> a
    Then we'll instantiate [a :-> a', b :-> b'], and with the instantiated
          a' -> b' -> a.
    But when, in an error message, we report that "b is a rigid type
    variable bound by the type signature for f", we want to show the foralls
    in the right place.  So we proceed as follows:

    * In SigSkol we record
        - the original signature forall a. a -> forall b. b -> a
        - the instantiation mapping [a :-> a', b :-> b']

    * Then when tidying in GHC.Tc.Utils.TcMType.tidySkolemInfo, we first tidy a' to
      whatever it tidies to, say a''; and then we walk over the type
      replacing the binder a by the tidied version a'', to give
           forall a''. Eq a'' => forall b''. b'' -> a''
      We need to do this under (=>) arrows and (->), to match what skolemisation
      does.

    * Typically a'' will have a nice pretty name like "a", but the point is
      that the foral-bound variables of the signature we report line up with
      the instantiated skolems lying  around in other types.
    -}

    {- *********************************************************************
    *                                                                      *
                CtOrigin
    *                                                                      *
    ************************************************************************
    -}

    -- | Some thing which has a type.
    --
    -- This datatype is used when we want to report to the user
    -- that something has an unexpected type.
    data TypedThing
      = HsTypeRnThing (HsType GhcRn)
      | TypeThing Type
      | HsExprRnThing (HsExpr GhcRn)
      | HsExprTcThing (HsExpr GhcTc)
      | NameThing Name

    -- | Some kind of type variable binder.
    --
    -- Used for reporting errors, in 'SkolemInfo' and 'TcSolverReportMsg'.
    data TyVarBndrs
      = forall flag. OutputableBndrFlag flag 'Renamed =>
          HsTyVarBndrsRn [HsTyVarBndr flag GhcRn]

    instance Outputable TypedThing where
      ppr :: TypedThing -> SDoc
    ppr (HsTypeRnThing HsType GhcRn
    ty) = HsType GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsType GhcRn
    ty
      ppr (TypeThing TcType
    ty) = TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    ty
      ppr (HsExprRnThing HsExpr GhcRn
    expr) = HsExpr GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr GhcRn
    expr
      ppr (HsExprTcThing HsExpr GhcTc
    expr) = HsExpr GhcTc -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr GhcTc
    expr
      ppr (NameThing Name
    name) = Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    name

    instance Outputable TyVarBndrs where
      ppr :: TyVarBndrs -> SDoc
    ppr (HsTyVarBndrsRn [HsTyVarBndr flag GhcRn]
    bndrs) = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    fsep ((HsTyVarBndr flag GhcRn -> SDoc)
    -> [HsTyVarBndr flag GhcRn] -> [SDoc]
    forall a b. (a -> b) -> [a] -> [b]
    map HsTyVarBndr flag GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr [HsTyVarBndr flag GhcRn]
    bndrs)

    data CtOrigin
      = -- | A given constraint from a user-written type signature. The
        -- 'SkolemInfo' inside gives more information.
        GivenOrigin SkolemInfoAnon

      -- | 'GivenSCOrigin' is used for a Given constraint obtained by superclass selection
      -- from the context of an instance declaration.  E.g.
      --       instance @(Foo a, Bar a) => C [a]@ where ...
      -- When typechecking the instance decl itself, including producing evidence
      -- for the superclasses of @C@, the superclasses of @(Foo a)@ and @(Bar a)@ will
      -- have 'GivenSCOrigin' origin.
      | GivenSCOrigin
            SkolemInfoAnon  -- ^ Just like GivenOrigin

            ScDepth         -- ^ The number of superclass selections necessary to
                            -- get this constraint; see Note [Replacement vs keeping]
                            -- in GHC.Tc.Solver.Dict

            Bool   -- ^ True => "blocked": cannot use this to solve naked superclass Wanteds
                   --                      i.e. ones with (ScOrigin _ NakedSc)
                   --   False => can use this to solve all Wanted constraints
                   -- See Note [Solving superclass constraints] in GHC.Tc.TyCl.Instance

      ----------- Below here, all are Origins for Wanted constraints ------------

      | OccurrenceOf Name              -- Occurrence of an overloaded identifier
      | OccurrenceOfRecSel RdrName     -- Occurrence of a record selector
      | AppOrigin                      -- An application of some kind

      | SpecPragOrigin UserTypeCtxt    -- Specialisation pragma for
                                       -- function or instance

      | TypeEqOrigin { CtOrigin -> TcType
    uo_actual   :: TcType
                     , CtOrigin -> TcType
    uo_expected :: TcType
                     , CtOrigin -> Maybe TypedThing
    uo_thing    :: Maybe TypedThing
                           -- ^ The thing that has type "actual"
                     , CtOrigin -> Bool
    uo_visible  :: Bool
                           -- ^ Is at least one of the three elements above visible?
                           -- (Errors from the polymorphic subsumption check are considered
                           -- visible.) Only used for prioritizing error messages.
                     }

      | KindEqOrigin
          TcType TcType             -- A kind equality arising from unifying these two types
          CtOrigin                  -- originally arising from this
          (Maybe TypeOrKind)        -- the level of the eq this arises from

      | IPOccOrigin  HsIPName       -- Occurrence of an implicit parameter
      | OverLabelOrigin FastString  -- Occurrence of an overloaded label

      | LiteralOrigin (HsOverLit GhcRn)     -- Occurrence of a literal
      | NegateOrigin                        -- Occurrence of syntactic negation

      | ArithSeqOrigin (ArithSeqInfo GhcRn) -- [x..], [x..y] etc
      | AssocFamPatOrigin   -- When matching the patterns of an associated
                            -- family instance with that of its parent class
                            -- IMPORTANT: These constraints will never cause errors;
                            -- See Note [Constraints to ignore] in GHC.Tc.Errors
      | SectionOrigin
      | HasFieldOrigin FastString
      | TupleOrigin         -- (..,..)
      | ExprSigOrigin       -- e :: ty
      | PatSigOrigin        -- p :: ty
      | PatOrigin           -- Instantiating a polytyped pattern at a constructor
      | ProvCtxtOrigin      -- The "provided" context of a pattern synonym signature
            (PatSynBind GhcRn GhcRn) -- Information about the pattern synonym, in
                                     -- particular the name and the right-hand side
      | RecordUpdOrigin
      | ViewPatOrigin

      -- | 'ScOrigin' is used only for the Wanted constraints for the
      --   superclasses of an instance declaration.
      | ScOrigin
          ClsInstOrQC   -- Whether class instance or quantified constraint
          NakedScFlag

      | DerivClauseOrigin   -- Typechecking a deriving clause (as opposed to
                            -- standalone deriving).
      | DerivOriginDC DataCon Int Bool
          -- Checking constraints arising from this data con and field index. The
          -- Bool argument in DerivOriginDC and DerivOriginCoerce is True if
          -- standalong deriving (with a wildcard constraint) is being used. This
          -- is used to inform error messages on how to recommended fixes (e.g., if
          -- the argument is True, then don't recommend "use standalone deriving",
          -- but rather "fill in the wildcard constraint yourself").
          -- See Note [Inferring the instance context] in GHC.Tc.Deriv.Infer
      | DerivOriginCoerce Id Type Type Bool
                            -- DerivOriginCoerce id ty1 ty2: Trying to coerce class method `id` from
                            -- `ty1` to `ty2`.
      | StandAloneDerivOrigin -- Typechecking stand-alone deriving. Useful for
                              -- constraints coming from a wildcard constraint,
                              -- e.g., deriving instance _ => Eq (Foo a)
                              -- See Note [Inferring the instance context]
                              -- in GHC.Tc.Deriv.Infer
      | DefaultOrigin       -- Typechecking a default decl
      | DoOrigin            -- Arising from a do expression
      | DoPatOrigin (LPat GhcRn) -- Arising from a failable pattern in
                                 -- a do expression
      | MCompOrigin         -- Arising from a monad comprehension
      | MCompPatOrigin (LPat GhcRn) -- Arising from a failable pattern in a
                                    -- monad comprehension
      | ProcOrigin          -- Arising from a proc expression
      | ArrowCmdOrigin      -- Arising from an arrow command
      | AnnOrigin           -- An annotation

      | FunDepOrigin1       -- A functional dependency from combining
            PredType CtOrigin RealSrcSpan      -- This constraint arising from ...
            PredType CtOrigin RealSrcSpan      -- and this constraint arising from ...

      | FunDepOrigin2       -- A functional dependency from combining
            PredType CtOrigin   -- This constraint arising from ...
            PredType SrcSpan    -- and this top-level instance
            -- We only need a CtOrigin on the first, because the location
            -- is pinned on the entire error message

      | InjTFOrigin1    -- injective type family equation combining
          PredType CtOrigin RealSrcSpan    -- This constraint arising from ...
          PredType CtOrigin RealSrcSpan    -- and this constraint arising from ...

      | ExprHoleOrigin (Maybe RdrName)   -- from an expression hole
      | TypeHoleOrigin OccName   -- from a type hole (partial type signature)
      | PatCheckOrigin      -- normalisation of a type during pattern-match checking
      | ListOrigin          -- An overloaded list
      | IfThenElseOrigin    -- An if-then-else expression
      | BracketOrigin       -- An overloaded quotation bracket
      | StaticOrigin        -- A static form
      | ImpedanceMatching Id   -- See Note [Impedance matching] in GHC.Tc.Gen.Bind
      | Shouldn'tHappenOrigin String  -- The user should never see this one

      -- | Testing whether the constraint associated with an instance declaration
      -- in a signature file is satisfied upon instantiation.
      --
      -- Test cases: backpack/should_fail/bkpfail{11,43}.bkp
      | InstProvidedOrigin
          Module  -- ^ Module in which the instance was declared
          ClsInst -- ^ The declared typeclass instance

      | NonLinearPatternOrigin NonLinearPatternReason (LPat GhcRn)
      | OmittedFieldOrigin (Maybe FieldLabel)
      | UsageEnvironmentOf Name

      | CycleBreakerOrigin
          CtOrigin   -- origin of the original constraint

          -- See Detail (7) of Note [Type equality cycles] in GHC.Tc.Solver.Equality
      | FRROrigin
          FixedRuntimeRepOrigin

      | WantedSuperclassOrigin PredType CtOrigin
            -- From expanding out the superclasses of a Wanted; the PredType
            -- is the subclass predicate, and the origin
            -- of the original Wanted is the CtOrigin

      | InstanceSigOrigin   -- from the sub-type check of an InstanceSig
          Name   -- the method name
          Type   -- the instance-sig type
          Type   -- the instantiated type of the method
      | AmbiguityCheckOrigin UserTypeCtxt

    data NonLinearPatternReason
      = LazyPatternReason
      | GeneralisedPatternReason
      | PatternSynonymReason
      | ViewPatternReason
      | OtherPatternReason

    -- | The number of superclass selections needed to get this Given.
    -- If @d :: C ty@   has @ScDepth=2@, then the evidence @d@ will look
    -- like @sc_sel (sc_sel dg)@, where @dg@ is a Given.
    type ScDepth = Int

    data ClsInstOrQC = IsClsInst
                     | IsQC CtOrigin

    data NakedScFlag = NakedSc | NotNakedSc
          --   The NakedScFlag affects only GHC.Tc.Solver.InertSet.prohibitedSuperClassSolve
          --   * For the original superclass constraints we use (ScOrigin _ NakedSc)
          --   * But after using an instance declaration we use (ScOrigin _ NotNakedSc)
          --   See Note [Solving superclass constraints] in GHC.Tc.TyCl.Instance

    instance Outputable NakedScFlag where
      ppr :: NakedScFlag -> SDoc
    ppr NakedScFlag
    NakedSc    = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "NakedSc"
      ppr NakedScFlag
    NotNakedSc = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "NotNakedSc"

    -- An origin is visible if the place where the constraint arises is manifest
    -- in user code. Currently, all origins are visible except for invisible
    -- TypeEqOrigins. This is used when choosing which error of
    -- several to report
    isVisibleOrigin :: CtOrigin -> Bool
    isVisibleOrigin :: CtOrigin -> Bool
    isVisibleOrigin (TypeEqOrigin { uo_visible :: CtOrigin -> Bool
    uo_visible = Bool
    vis }) = Bool
    vis
    isVisibleOrigin (KindEqOrigin TcType
    _ TcType
    _ CtOrigin
    sub_orig Maybe TypeOrKind
    _)       = CtOrigin -> Bool
    isVisibleOrigin CtOrigin
    sub_orig
    isVisibleOrigin CtOrigin
    _                                   = Bool
    True

    -- Converts a visible origin to an invisible one, if possible. Currently,
    -- this works only for TypeEqOrigin
    toInvisibleOrigin :: CtOrigin -> CtOrigin
    toInvisibleOrigin :: CtOrigin -> CtOrigin
    toInvisibleOrigin orig :: CtOrigin
    orig@(TypeEqOrigin {}) = CtOrigin
    orig { uo_visible = False }
    toInvisibleOrigin CtOrigin
    orig                   = CtOrigin
    orig

    isGivenOrigin :: CtOrigin -> Bool
    isGivenOrigin :: CtOrigin -> Bool
    isGivenOrigin (GivenOrigin {})       = Bool
    True
    isGivenOrigin (GivenSCOrigin {})     = Bool
    True
    isGivenOrigin (CycleBreakerOrigin CtOrigin
    o) = CtOrigin -> Bool
    isGivenOrigin CtOrigin
    o
    isGivenOrigin CtOrigin
    _                      = Bool
    False

    -- See Note [Suppressing confusing errors] in GHC.Tc.Errors
    isWantedWantedFunDepOrigin :: CtOrigin -> Bool
    isWantedWantedFunDepOrigin :: CtOrigin -> Bool
    isWantedWantedFunDepOrigin (FunDepOrigin1 TcType
    _ CtOrigin
    orig1 RealSrcSpan
    _ TcType
    _ CtOrigin
    orig2 RealSrcSpan
    _)
      = Bool -> Bool
    not (CtOrigin -> Bool
    isGivenOrigin CtOrigin
    orig1) Bool -> Bool -> Bool
    && Bool -> Bool
    not (CtOrigin -> Bool
    isGivenOrigin CtOrigin
    orig2)
    isWantedWantedFunDepOrigin (InjTFOrigin1 TcType
    _ CtOrigin
    orig1 RealSrcSpan
    _ TcType
    _ CtOrigin
    orig2 RealSrcSpan
    _)
      = Bool -> Bool
    not (CtOrigin -> Bool
    isGivenOrigin CtOrigin
    orig1) Bool -> Bool -> Bool
    && Bool -> Bool
    not (CtOrigin -> Bool
    isGivenOrigin CtOrigin
    orig2)
    isWantedWantedFunDepOrigin CtOrigin
    _ = Bool
    False

    -- | Did a constraint arise from expanding a Wanted constraint
    -- to look at superclasses?
    isWantedSuperclassOrigin :: CtOrigin -> Bool
    isWantedSuperclassOrigin :: CtOrigin -> Bool
    isWantedSuperclassOrigin (WantedSuperclassOrigin {}) = Bool
    True
    isWantedSuperclassOrigin CtOrigin
    _                           = Bool
    False

    instance Outputable CtOrigin where
      ppr :: CtOrigin -> SDoc
    ppr = CtOrigin -> SDoc
    pprCtOrigin

    ctoHerald :: SDoc
    ctoHerald :: SDoc
    ctoHerald = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "arising from"

    -- | Extract a suitable CtOrigin from a HsExpr
    lexprCtOrigin :: LHsExpr GhcRn -> CtOrigin
    lexprCtOrigin :: LHsExpr GhcRn -> CtOrigin
    lexprCtOrigin (L SrcSpanAnnA
    _ HsExpr GhcRn
    e) = HsExpr GhcRn -> CtOrigin
    exprCtOrigin HsExpr GhcRn
    e

    exprCtOrigin :: HsExpr GhcRn -> CtOrigin
    exprCtOrigin :: HsExpr GhcRn -> CtOrigin
    exprCtOrigin (HsVar XVar GhcRn
    _ (L SrcSpanAnnN
    _ Name
    name)) = Name -> CtOrigin
    OccurrenceOf Name
    name
    exprCtOrigin (HsGetField XGetField GhcRn
    _ LHsExpr GhcRn
    _ (L EpAnnCO
    _ DotFieldOcc GhcRn
    f)) = FastString -> CtOrigin
    HasFieldOrigin (FieldLabelString -> FastString
    field_label (FieldLabelString -> FastString) -> FieldLabelString -> FastString
    forall a b. (a -> b) -> a -> b
    $ GenLocated SrcSpanAnnN FieldLabelString -> FieldLabelString
    forall l e. GenLocated l e -> e
    unLoc (GenLocated SrcSpanAnnN FieldLabelString -> FieldLabelString)
    -> GenLocated SrcSpanAnnN FieldLabelString -> FieldLabelString
    forall a b. (a -> b) -> a -> b
    $ DotFieldOcc GhcRn -> XRec GhcRn FieldLabelString
    forall p. DotFieldOcc p -> XRec p FieldLabelString
    dfoLabel DotFieldOcc GhcRn
    f)
    exprCtOrigin (HsUnboundVar {})    = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "unbound variable"
    exprCtOrigin (HsOverLabel XOverLabel GhcRn
    _ FastString
    l)  = FastString -> CtOrigin
    OverLabelOrigin FastString
    l
    exprCtOrigin (ExplicitList {})    = CtOrigin
    ListOrigin
    exprCtOrigin (HsIPVar XIPVar GhcRn
    _ HsIPName
    ip)       = HsIPName -> CtOrigin
    IPOccOrigin HsIPName
    ip
    exprCtOrigin (HsOverLit XOverLitE GhcRn
    _ HsOverLit GhcRn
    lit)    = HsOverLit GhcRn -> CtOrigin
    LiteralOrigin HsOverLit GhcRn
    lit
    exprCtOrigin (HsLit {})           = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "concrete literal"
    exprCtOrigin (HsLam XLam GhcRn
    _ HsLamVariant
    _ MatchGroup GhcRn (LHsExpr GhcRn)
    ms)       = MatchGroup GhcRn (LHsExpr GhcRn) -> CtOrigin
    matchesCtOrigin MatchGroup GhcRn (LHsExpr GhcRn)
    ms
    exprCtOrigin (HsApp XApp GhcRn
    _ LHsExpr GhcRn
    e1 LHsExpr GhcRn
    _)       = LHsExpr GhcRn -> CtOrigin
    lexprCtOrigin LHsExpr GhcRn
    e1
    exprCtOrigin (HsAppType XAppTypeE GhcRn
    _ LHsExpr GhcRn
    e1 LHsWcType (NoGhcTc GhcRn)
    _)   = LHsExpr GhcRn -> CtOrigin
    lexprCtOrigin LHsExpr GhcRn
    e1
    exprCtOrigin (OpApp XOpApp GhcRn
    _ LHsExpr GhcRn
    _ LHsExpr GhcRn
    op LHsExpr GhcRn
    _)     = LHsExpr GhcRn -> CtOrigin
    lexprCtOrigin LHsExpr GhcRn
    op
    exprCtOrigin (NegApp XNegApp GhcRn
    _ LHsExpr GhcRn
    e SyntaxExpr GhcRn
    _)       = LHsExpr GhcRn -> CtOrigin
    lexprCtOrigin LHsExpr GhcRn
    e
    exprCtOrigin (HsPar XPar GhcRn
    _ LHsExpr GhcRn
    e)          = LHsExpr GhcRn -> CtOrigin
    lexprCtOrigin LHsExpr GhcRn
    e
    exprCtOrigin (HsProjection XProjection GhcRn
    _ NonEmpty (DotFieldOcc GhcRn)
    _)   = CtOrigin
    SectionOrigin
    exprCtOrigin (SectionL XSectionL GhcRn
    _ LHsExpr GhcRn
    _ LHsExpr GhcRn
    _)     = CtOrigin
    SectionOrigin
    exprCtOrigin (SectionR XSectionR GhcRn
    _ LHsExpr GhcRn
    _ LHsExpr GhcRn
    _)     = CtOrigin
    SectionOrigin
    exprCtOrigin (ExplicitTuple {})   = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "explicit tuple"
    exprCtOrigin ExplicitSum{}        = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "explicit sum"
    exprCtOrigin (HsCase XCase GhcRn
    _ LHsExpr GhcRn
    _ MatchGroup GhcRn (LHsExpr GhcRn)
    matches) = MatchGroup GhcRn (LHsExpr GhcRn) -> CtOrigin
    matchesCtOrigin MatchGroup GhcRn (LHsExpr GhcRn)
    matches
    exprCtOrigin (HsIf {})           = CtOrigin
    IfThenElseOrigin
    exprCtOrigin (HsMultiIf XMultiIf GhcRn
    _ [LGRHS GhcRn (LHsExpr GhcRn)]
    rhs)   = [LGRHS GhcRn (LHsExpr GhcRn)] -> CtOrigin
    lGRHSCtOrigin [LGRHS GhcRn (LHsExpr GhcRn)]
    rhs
    exprCtOrigin (HsLet XLet GhcRn
    _ HsLocalBinds GhcRn
    _ LHsExpr GhcRn
    e)       = LHsExpr GhcRn -> CtOrigin
    lexprCtOrigin LHsExpr GhcRn
    e
    exprCtOrigin (HsDo {})           = CtOrigin
    DoOrigin
    exprCtOrigin (RecordCon {})      = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "record construction"
    exprCtOrigin (RecordUpd {})      = CtOrigin
    RecordUpdOrigin
    exprCtOrigin (ExprWithTySig {})  = CtOrigin
    ExprSigOrigin
    exprCtOrigin (ArithSeq {})       = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "arithmetic sequence"
    exprCtOrigin (HsPragE XPragE GhcRn
    _ HsPragE GhcRn
    _ LHsExpr GhcRn
    e)     = LHsExpr GhcRn -> CtOrigin
    lexprCtOrigin LHsExpr GhcRn
    e
    exprCtOrigin (HsTypedBracket {}) = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "TH typed bracket"
    exprCtOrigin (HsUntypedBracket {}) = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "TH untyped bracket"
    exprCtOrigin (HsTypedSplice {})    = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "TH typed splice"
    exprCtOrigin (HsUntypedSplice {})  = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "TH untyped splice"
    exprCtOrigin (HsProc {})         = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "proc"
    exprCtOrigin (HsStatic {})       = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "static expression"
    exprCtOrigin (HsEmbTy {})        = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "type expression"
    exprCtOrigin (HsForAll {})       = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "forall telescope"    -- See Note [Types in terms]
    exprCtOrigin (HsQual {})         = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "constraint context"  -- See Note [Types in terms]
    exprCtOrigin (HsFunArr {})       = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "function arrow"      -- See Note [Types in terms]
    exprCtOrigin (XExpr (ExpandedThingRn HsThingRn
    thing HsExpr GhcRn
    _)) | OrigExpr HsExpr GhcRn
    a <- HsThingRn
    thing = HsExpr GhcRn -> CtOrigin
    exprCtOrigin HsExpr GhcRn
    a
                                                   | OrigStmt ExprLStmt GhcRn
    _ <- HsThingRn
    thing = CtOrigin
    DoOrigin
                                                   | OrigPat LPat GhcRn
    p  <- HsThingRn
    thing = LPat GhcRn -> CtOrigin
    DoPatOrigin LPat GhcRn
    p
    exprCtOrigin (XExpr (PopErrCtxt {})) = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "PopErrCtxt"
    exprCtOrigin (XExpr (HsRecSelRn FieldOcc GhcRn
    f))  = RdrName -> CtOrigin
    OccurrenceOfRecSel (FieldOcc GhcRn -> XCFieldOcc GhcRn
    forall pass. FieldOcc pass -> XCFieldOcc pass
    foExt FieldOcc GhcRn
    f)

    -- | Extract a suitable CtOrigin from a MatchGroup
    matchesCtOrigin :: MatchGroup GhcRn (LHsExpr GhcRn) -> CtOrigin
    matchesCtOrigin :: MatchGroup GhcRn (LHsExpr GhcRn) -> CtOrigin
    matchesCtOrigin (MG { mg_alts :: forall p body. MatchGroup p body -> XRec p [LMatch p body]
    mg_alts = XRec GhcRn [LMatch GhcRn (LHsExpr GhcRn)]
    alts })
      | L SrcSpanAnnLW
    _ [L SrcSpanAnnA
    _ Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn))
    match] <- XRec GhcRn [LMatch GhcRn (LHsExpr GhcRn)]
    alts
      , Match { m_grhss :: forall p body. Match p body -> GRHSs p body
    m_grhss = GRHSs GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn))
    grhss } <- Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn))
    match
      = GRHSs GhcRn (LHsExpr GhcRn) -> CtOrigin
    grhssCtOrigin GRHSs GhcRn (LHsExpr GhcRn)
    GRHSs GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn))
    grhss

      | Bool
    otherwise
      = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "multi-way match"

    -- | Extract a suitable CtOrigin from guarded RHSs
    grhssCtOrigin :: GRHSs GhcRn (LHsExpr GhcRn) -> CtOrigin
    grhssCtOrigin :: GRHSs GhcRn (LHsExpr GhcRn) -> CtOrigin
    grhssCtOrigin (GRHSs { grhssGRHSs :: forall p body. GRHSs p body -> [LGRHS p body]
    grhssGRHSs = [LGRHS GhcRn (LHsExpr GhcRn)]
    lgrhss }) = [LGRHS GhcRn (LHsExpr GhcRn)] -> CtOrigin
    lGRHSCtOrigin [LGRHS GhcRn (LHsExpr GhcRn)]
    lgrhss

    -- | Extract a suitable CtOrigin from a list of guarded RHSs
    lGRHSCtOrigin :: [LGRHS GhcRn (LHsExpr GhcRn)] -> CtOrigin
    lGRHSCtOrigin :: [LGRHS GhcRn (LHsExpr GhcRn)] -> CtOrigin
    lGRHSCtOrigin [L EpAnnCO
    _ (GRHS XCGRHS GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn))
    _ [ExprLStmt GhcRn]
    _ (L SrcSpanAnnA
    _ HsExpr GhcRn
    e))] = HsExpr GhcRn -> CtOrigin
    exprCtOrigin HsExpr GhcRn
    e
    lGRHSCtOrigin [LGRHS GhcRn (LHsExpr GhcRn)]
    _ = String -> CtOrigin
    Shouldn'tHappenOrigin String
    "multi-way GRHS"

    pprCtOrigin :: CtOrigin -> SDoc
    -- "arising from ..."
    pprCtOrigin :: CtOrigin -> SDoc
    pprCtOrigin (GivenOrigin SkolemInfoAnon
    sk)
      = SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SkolemInfoAnon -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr SkolemInfoAnon
    sk

    pprCtOrigin (GivenSCOrigin SkolemInfoAnon
    sk ScDepth
    d Bool
    blk)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SkolemInfoAnon -> SDoc
    pprSkolInfo SkolemInfoAnon
    sk
             , SDoc -> SDoc
    forall doc. IsOutput doc => doc -> doc
    whenPprDebug (SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    braces (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "given-sc:" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr ScDepth
    d SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> Bool -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Bool
    blk)) ]

    pprCtOrigin (SpecPragOrigin UserTypeCtxt
    ctxt)
      = case UserTypeCtxt
    ctxt of
           FunSigCtxt Name
    n ReportRedundantConstraints
    _ -> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    n)
           UserTypeCtxt
    SpecInstCtxt   -> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a SPECIALISE INSTANCE pragma"
           UserTypeCtxt
    _              -> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a SPECIALISE pragma"  -- Never happens I think

    pprCtOrigin (FunDepOrigin1 TcType
    pred1 CtOrigin
    orig1 RealSrcSpan
    loc1 TcType
    pred2 CtOrigin
    orig2 RealSrcSpan
    loc2)
      = SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a functional dependency between constraints:")
           ScDepth
    2 ([SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    pred1)) ScDepth
    2 (CtOrigin -> SDoc
    pprCtOrigin CtOrigin
    orig1 SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "at" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> RealSrcSpan -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr RealSrcSpan
    loc1)
                   , SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    pred2)) ScDepth
    2 (CtOrigin -> SDoc
    pprCtOrigin CtOrigin
    orig2 SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "at" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> RealSrcSpan -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr RealSrcSpan
    loc2) ])

    pprCtOrigin (FunDepOrigin2 TcType
    pred1 CtOrigin
    orig1 TcType
    pred2 SrcSpan
    loc2)
      = SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a functional dependency between:")
           ScDepth
    2 ([SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ SDoc -> ScDepth -> SDoc -> SDoc
    hang (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "constraint" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    pred1))
                        ScDepth
    2 (CtOrigin -> SDoc
    pprCtOrigin CtOrigin
    orig1 )
                   , SDoc -> ScDepth -> SDoc -> SDoc
    hang (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "instance" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    pred2))
                        ScDepth
    2 (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "at" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SrcSpan -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr SrcSpan
    loc2) ])

    pprCtOrigin (InjTFOrigin1 TcType
    pred1 CtOrigin
    orig1 RealSrcSpan
    loc1 TcType
    pred2 CtOrigin
    orig2 RealSrcSpan
    loc2)
      = SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "reasoning about an injective type family using constraints:")
           ScDepth
    2 ([SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    pred1)) ScDepth
    2 (CtOrigin -> SDoc
    pprCtOrigin CtOrigin
    orig1 SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "at" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> RealSrcSpan -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr RealSrcSpan
    loc1)
                   , SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    pred2)) ScDepth
    2 (CtOrigin -> SDoc
    pprCtOrigin CtOrigin
    orig2 SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "at" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> RealSrcSpan -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr RealSrcSpan
    loc2) ])

    pprCtOrigin CtOrigin
    AssocFamPatOrigin
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "when matching a family LHS with its class instance head"

    pprCtOrigin (TypeEqOrigin { uo_actual :: CtOrigin -> TcType
    uo_actual = TcType
    t1, uo_expected :: CtOrigin -> TcType
    uo_expected =  TcType
    t2, uo_visible :: CtOrigin -> Bool
    uo_visible = Bool
    vis })
      = SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a type equality" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc -> SDoc
    forall doc. IsOutput doc => doc -> doc
    whenPprDebug (SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    brackets (Bool -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Bool
    vis)))
           ScDepth
    2 ([SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    t1, Char -> SDoc
    forall doc. IsLine doc => Char -> doc
    char Char
    '~', TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    t2])

    pprCtOrigin (KindEqOrigin TcType
    t1 TcType
    t2 CtOrigin
    _ Maybe TypeOrKind
    _)
      = SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a kind equality arising from")
           ScDepth
    2 ([SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    t1, Char -> SDoc
    forall doc. IsLine doc => Char -> doc
    char Char
    '~', TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    t2])

    pprCtOrigin (DerivOriginDC DataCon
    dc ScDepth
    n Bool
    _)
      = SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    speakNth ScDepth
    n
              SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "field of" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (DataCon -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr DataCon
    dc))
           ScDepth
    2 (SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    parens (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "type" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr (Scaled TcType -> TcType
    forall a. Scaled a -> a
    scaledThing Scaled TcType
    ty))))
      where
        ty :: Scaled TcType
    ty = DataCon -> [Scaled TcType]
    dataConOrigArgTys DataCon
    dc [Scaled TcType] -> ScDepth -> Scaled TcType
    forall a. HasCallStack => [a] -> ScDepth -> a
    !! (ScDepth
    nScDepth -> ScDepth -> ScDepth
    forall a. Num a => a -> a -> a
    -ScDepth
    1)

    pprCtOrigin (DerivOriginCoerce Id
    meth TcType
    ty1 TcType
    ty2 Bool
    _)
      = SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the coercion of the method" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Id -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Id
    meth))
           ScDepth
    2 ([SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "from type" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    ty1)
                  , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (SDoc -> SDoc) -> SDoc -> SDoc
    forall a b. (a -> b) -> a -> b
    $ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "to type" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    ty2) ])

    pprCtOrigin (DoPatOrigin LPat GhcRn
    pat)
        = SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a do statement"
          SDoc -> SDoc -> SDoc
    forall doc. IsDoc doc => doc -> doc -> doc
    $$
          String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "with the failable pattern" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (GenLocated SrcSpanAnnA (Pat GhcRn) -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr LPat GhcRn
    GenLocated SrcSpanAnnA (Pat GhcRn)
    pat)

    pprCtOrigin (MCompPatOrigin LPat GhcRn
    pat)
        = SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the failable pattern"
               , SDoc -> SDoc
    quotes (GenLocated SrcSpanAnnA (Pat GhcRn) -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr LPat GhcRn
    GenLocated SrcSpanAnnA (Pat GhcRn)
    pat)
               , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "in a statement in a monad comprehension" ]

    pprCtOrigin (Shouldn'tHappenOrigin String
    note)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "<< This should not appear in error messages. If you see this"
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "in an error message, please report a bug mentioning"
                 SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    note) SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "at"
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "https://gitlab.haskell.org/ghc/ghc/wikis/report-a-bug >>"
             ]

    pprCtOrigin (ProvCtxtOrigin PSB{ psb_id :: forall idL idR. PatSynBind idL idR -> LIdP idL
    psb_id = (L SrcSpanAnnN
    _ Name
    name) })
      = SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the \"provided\" constraints claimed by")
           ScDepth
    2 (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the signature of" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    name))

    pprCtOrigin (InstProvidedOrigin Module
    mod ClsInst
    cls_inst)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "arising when attempting to show that"
             , ClsInst -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr ClsInst
    cls_inst
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "is provided by" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Module -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Module
    mod)]

    pprCtOrigin (ImpedanceMatching Id
    x)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "arising when matching required constraints"
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "in a group involving" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Id -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Id
    x)]

    pprCtOrigin (CycleBreakerOrigin CtOrigin
    orig)
      = CtOrigin -> SDoc
    pprCtOrigin CtOrigin
    orig

    pprCtOrigin (WantedSuperclassOrigin TcType
    subclass_pred CtOrigin
    subclass_orig)
      = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a superclass required to satisfy" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    subclass_pred) SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma
            , CtOrigin -> SDoc
    pprCtOrigin CtOrigin
    subclass_orig ]

    pprCtOrigin (InstanceSigOrigin Name
    method_name TcType
    sig_type TcType
    orig_method_type)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the check that an instance signature is more general"
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "than the type of the method (instantiated for this instance)"
             , SDoc -> ScDepth -> SDoc -> SDoc
    hang (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "instance signature:")
                  ScDepth
    2 (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    method_name SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc
    dcolon SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    sig_type)
             , SDoc -> ScDepth -> SDoc -> SDoc
    hang (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "instantiated method type:")
                  ScDepth
    2 (TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    orig_method_type) ]

    pprCtOrigin (AmbiguityCheckOrigin UserTypeCtxt
    ctxt)
      = SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a type ambiguity check for" SDoc -> SDoc -> SDoc
    forall doc. IsDoc doc => doc -> doc -> doc
    $$
        UserTypeCtxt -> SDoc
    pprUserTypeCtxt UserTypeCtxt
    ctxt

    pprCtOrigin (ScOrigin ClsInstOrQC
    IsClsInst NakedScFlag
    nkd)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the superclasses of an instance declaration"
             , SDoc -> SDoc
    forall doc. IsOutput doc => doc -> doc
    whenPprDebug (SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    braces (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "sc-origin:" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> NakedScFlag -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr NakedScFlag
    nkd)) ]

    pprCtOrigin (ScOrigin (IsQC CtOrigin
    orig) NakedScFlag
    nkd)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the head of a quantified constraint"
             , SDoc -> SDoc
    forall doc. IsOutput doc => doc -> doc
    whenPprDebug (SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    braces (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "sc-origin:" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> NakedScFlag -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr NakedScFlag
    nkd))
             , CtOrigin -> SDoc
    pprCtOrigin CtOrigin
    orig ]

    pprCtOrigin (NonLinearPatternOrigin NonLinearPatternReason
    reason LPat GhcRn
    pat)
      = SDoc -> ScDepth -> SDoc -> SDoc
    hang (SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a non-linear pattern" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (GenLocated SrcSpanAnnA (Pat GhcRn) -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr LPat GhcRn
    GenLocated SrcSpanAnnA (Pat GhcRn)
    pat))
           ScDepth
    2 (HasDebugCallStack => NonLinearPatternReason -> SDoc
    NonLinearPatternReason -> SDoc
    pprNonLinearPatternReason NonLinearPatternReason
    reason)

    pprCtOrigin CtOrigin
    simple_origin
      = SDoc
    ctoHerald SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> HasDebugCallStack => CtOrigin -> SDoc
    CtOrigin -> SDoc
    pprCtO CtOrigin
    simple_origin

    -- | Short one-liners
    pprCtO :: HasDebugCallStack => CtOrigin -> SDoc
    pprCtO :: HasDebugCallStack => CtOrigin -> SDoc
    pprCtO (OccurrenceOf Name
    name)   = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a use of", SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    name)]
    pprCtO (OccurrenceOfRecSel RdrName
    name) = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a use of", SDoc -> SDoc
    quotes (RdrName -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr RdrName
    name)]
    pprCtO CtOrigin
    AppOrigin             = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an application"
    pprCtO (IPOccOrigin HsIPName
    name)    = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a use of implicit parameter", SDoc -> SDoc
    quotes (HsIPName -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsIPName
    name)]
    pprCtO (OverLabelOrigin FastString
    l)   = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the overloaded label"
                                        ,SDoc -> SDoc
    quotes (Char -> SDoc
    forall doc. IsLine doc => Char -> doc
    char Char
    '#' SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> FastString -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr FastString
    l)]
    pprCtO CtOrigin
    RecordUpdOrigin       = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a record update"
    pprCtO CtOrigin
    ExprSigOrigin         = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an expression type signature"
    pprCtO CtOrigin
    PatSigOrigin          = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a pattern type signature"
    pprCtO CtOrigin
    PatOrigin             = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a pattern"
    pprCtO CtOrigin
    ViewPatOrigin         = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a view pattern"
    pprCtO (LiteralOrigin HsOverLit GhcRn
    lit)   = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the literal", SDoc -> SDoc
    quotes (HsOverLit GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsOverLit GhcRn
    lit)]
    pprCtO (ArithSeqOrigin ArithSeqInfo GhcRn
    seq)  = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the arithmetic sequence", SDoc -> SDoc
    quotes (ArithSeqInfo GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr ArithSeqInfo GhcRn
    seq)]
    pprCtO CtOrigin
    SectionOrigin         = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an operator section"
    pprCtO (HasFieldOrigin FastString
    f)    = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "selecting the field", SDoc -> SDoc
    quotes (FastString -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr FastString
    f)]
    pprCtO CtOrigin
    AssocFamPatOrigin     = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the LHS of a family instance"
    pprCtO CtOrigin
    TupleOrigin           = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a tuple"
    pprCtO CtOrigin
    NegateOrigin          = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a use of syntactic negation"
    pprCtO (ScOrigin ClsInstOrQC
    IsClsInst NakedScFlag
    _) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the superclasses of an instance declaration"
    pprCtO (ScOrigin (IsQC {}) NakedScFlag
    _) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the head of a quantified constraint"
    pprCtO CtOrigin
    DerivClauseOrigin     = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the 'deriving' clause of a data type declaration"
    pprCtO CtOrigin
    StandAloneDerivOrigin = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a 'deriving' declaration"
    pprCtO CtOrigin
    DefaultOrigin         = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a 'default' declaration"
    pprCtO CtOrigin
    DoOrigin              = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a do statement"
    pprCtO CtOrigin
    MCompOrigin           = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a statement in a monad comprehension"
    pprCtO CtOrigin
    ProcOrigin            = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a proc expression"
    pprCtO CtOrigin
    ArrowCmdOrigin        = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an arrow command"
    pprCtO CtOrigin
    AnnOrigin             = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an annotation"
    pprCtO (ExprHoleOrigin Maybe RdrName
    Nothing)    = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an expression hole"
    pprCtO (ExprHoleOrigin (Just RdrName
    occ)) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a use of" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (RdrName -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr RdrName
    occ)
    pprCtO (TypeHoleOrigin OccName
    occ)  = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a use of wildcard" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (OccName -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr OccName
    occ)
    pprCtO CtOrigin
    PatCheckOrigin        = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a pattern-match completeness check"
    pprCtO CtOrigin
    ListOrigin            = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an overloaded list"
    pprCtO CtOrigin
    IfThenElseOrigin      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an if-then-else expression"
    pprCtO CtOrigin
    StaticOrigin          = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a static form"
    pprCtO (UsageEnvironmentOf Name
    x) = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "multiplicity of", SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    x)]
    pprCtO (OmittedFieldOrigin Maybe FieldLabel
    Nothing) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an omitted anonymous field"
    pprCtO (OmittedFieldOrigin (Just FieldLabel
    fl)) = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "omitted field" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (FieldLabel -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr FieldLabel
    fl)]
    pprCtO CtOrigin
    BracketOrigin         = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a quotation bracket"

    -- These ones are handled by pprCtOrigin, but we nevertheless sometimes
    -- get here via callStackOriginFS, when doing ambiguity checks
    -- A bit silly, but no great harm
    pprCtO (GivenOrigin {})             = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a given constraint"
    pprCtO (GivenSCOrigin {})           = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the superclass of a given constraint"
    pprCtO (SpecPragOrigin {})          = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a SPECIALISE pragma"
    pprCtO (FunDepOrigin1 {})           = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a functional dependency"
    pprCtO (FunDepOrigin2 {})           = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a functional dependency"
    pprCtO (InjTFOrigin1 {})            = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "an injective type family"
    pprCtO (TypeEqOrigin {})            = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a type equality"
    pprCtO (KindEqOrigin {})            = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a kind equality"
    pprCtO (DerivOriginDC {})           = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a deriving clause"
    pprCtO (DerivOriginCoerce {})       = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a derived method"
    pprCtO (DoPatOrigin {})             = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a do statement"
    pprCtO (MCompPatOrigin {})          = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a monad comprehension pattern"
    pprCtO (Shouldn'tHappenOrigin String
    note) = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    note
    pprCtO (ProvCtxtOrigin {})          = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a provided constraint"
    pprCtO (InstProvidedOrigin {})      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a provided constraint"
    pprCtO (CycleBreakerOrigin CtOrigin
    orig)    = HasDebugCallStack => CtOrigin -> SDoc
    CtOrigin -> SDoc
    pprCtO CtOrigin
    orig
    pprCtO (FRROrigin {})               = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a representation-polymorphism check"
    pprCtO (WantedSuperclassOrigin {})  = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a superclass constraint"
    pprCtO (InstanceSigOrigin {})       = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a type signature in an instance"
    pprCtO (AmbiguityCheckOrigin {})    = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a type ambiguity check"
    pprCtO (ImpedanceMatching {})       = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "combining required constraints"
    pprCtO (NonLinearPatternOrigin NonLinearPatternReason
    _ LPat GhcRn
    pat) = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    hsep [String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a non-linear pattern" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (GenLocated SrcSpanAnnA (Pat GhcRn) -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr LPat GhcRn
    GenLocated SrcSpanAnnA (Pat GhcRn)
    pat)]

    pprNonLinearPatternReason :: HasDebugCallStack => NonLinearPatternReason -> SDoc
    pprNonLinearPatternReason :: HasDebugCallStack => NonLinearPatternReason -> SDoc
    pprNonLinearPatternReason NonLinearPatternReason
    LazyPatternReason = SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    parens (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "non-variable lazy pattern aren't linear")
    pprNonLinearPatternReason NonLinearPatternReason
    GeneralisedPatternReason = SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    parens (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "non-variable pattern bindings that have been generalised aren't linear")
    pprNonLinearPatternReason NonLinearPatternReason
    PatternSynonymReason = SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    parens (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "pattern synonyms aren't linear")
    pprNonLinearPatternReason NonLinearPatternReason
    ViewPatternReason = SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    parens (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "view patterns aren't linear")
    pprNonLinearPatternReason NonLinearPatternReason
    OtherPatternReason = SDoc
    forall doc. IsOutput doc => doc
    empty

    {- *********************************************************************
    *                                                                      *
                 CallStacks and CtOrigin

        See Note [Overview of implicit CallStacks] in GHC.Tc.Types.Evidence
    *                                                                      *
    ********************************************************************* -}

    isPushCallStackOrigin :: CtOrigin -> Bool
    -- Do we want to solve this IP constraint directly (return False)
    -- or push the call site (return True)
    -- See Note [Overview of implicit CallStacks] in GHc.Tc.Types.Evidence
    isPushCallStackOrigin :: CtOrigin -> Bool
    isPushCallStackOrigin (IPOccOrigin {}) = Bool
    False
    isPushCallStackOrigin CtOrigin
    _                = Bool
    True

    callStackOriginFS :: CtOrigin -> FastString
    -- This is the string that appears in the CallStack
    callStackOriginFS :: CtOrigin -> FastString
    callStackOriginFS (OccurrenceOf Name
    fun) = OccName -> FastString
    occNameFS (Name -> OccName
    forall a. NamedThing a => a -> OccName
    getOccName Name
    fun)
    callStackOriginFS CtOrigin
    orig               = String -> FastString
    mkFastString (SDoc -> String
    showSDocUnsafe (HasDebugCallStack => CtOrigin -> SDoc
    CtOrigin -> SDoc
    pprCtO CtOrigin
    orig))

    {-
    ************************************************************************
    *                                                                      *
                Checking for representation polymorphism
    *                                                                      *
    ************************************************************************

    Note [Reporting representation-polymorphism errors]
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    As explained in Note [The Concrete mechanism] in GHC.Tc.Utils.Concrete,
    to check that (ty :: ki) has a fixed runtime representation, we emit
    an equality constraint of the form

      ki ~# concrete_tv

    where concrete_tv is a concrete metavariable. In this situation, we attach
    a 'FixedRuntimeRepOrigin' to both the equality and the concrete type variable.
    The 'FixedRuntimeRepOrigin' consists of two pieces of information:

      - the type 'ty' on which we performed the representation-polymorphism check,
      - a 'FixedRuntimeRepContext' which explains why we needed to perform a check
        (e.g. because 'ty' was the kind of a function argument, or of a bound variable
        in a lambda abstraction, ...).

    This information gets passed along as we make progress on solving the constraint,
    and if we end up with an unsolved constraint we can report an informative error
    message to the user using the 'FixedRuntimeRepOrigin'.

    The error reporting goes through two different paths:

      - constraints whose 'CtOrigin' contains a 'FixedRuntimeRepOrigin' are reported
        using 'mkFRRErr' in 'reportWanteds',
      - equality constraints in which one side is a concrete metavariable and the
        other side is not concrete are reported using 'mkTyVarEqErr'. In this case,
        we pass on the type variable and the non-concrete type for error reporting,
        using the 'frr_info_not_concrete' field.

    This is why we have the 'FixedRuntimeRepErrorInfo' datatype: so that we can optionally
    include this extra message about an unsolved equality between a concrete type variable
    and a non-concrete type.
    -}

    -- | The context for a representation-polymorphism check.
    --
    -- For example, when typechecking @ \ (a :: k) -> ...@,
    -- we are checking the type @a@ because it's the type of
    -- a term variable bound in a lambda, so we use 'FRRBinder'.
    data FixedRuntimeRepOrigin
      = FixedRuntimeRepOrigin
        { FixedRuntimeRepOrigin -> TcType
    frr_type    :: Type
           -- ^ What type are we checking?
           -- For example, @a[tau]@ in @a[tau] :: TYPE rr[tau]@.

        , FixedRuntimeRepOrigin -> FixedRuntimeRepContext
    frr_context :: FixedRuntimeRepContext
          -- ^ What context requires a fixed runtime representation?
        }

    instance Outputable FixedRuntimeRepOrigin where
      ppr :: FixedRuntimeRepOrigin -> SDoc
    ppr (FixedRuntimeRepOrigin { frr_type :: FixedRuntimeRepOrigin -> TcType
    frr_type = TcType
    ty, frr_context :: FixedRuntimeRepOrigin -> FixedRuntimeRepContext
    frr_context = FixedRuntimeRepContext
    cxt })
        = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "FrOrigin" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc
    braces ([SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "frr_type:" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> TcType -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TcType
    ty
                                          , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "frr_context:" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> FixedRuntimeRepContext -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr FixedRuntimeRepContext
    cxt ])

    -- | The context in which a representation-polymorphism check was performed.
    --
    -- Does not include the type on which the check was performed; see
    -- 'FixedRuntimeRepOrigin' for that.
    data FixedRuntimeRepContext

      -- | Record fields in record construction must have a fixed runtime
      -- representation.
      = FRRRecordCon !RdrName !(HsExpr GhcTc)

      -- | Record fields in record updates must have a fixed runtime representation.
      --
      -- Test case: RepPolyRecordUpdate.
      | FRRRecordUpdate !Name !(HsExpr GhcRn)

      -- | Variable binders must have a fixed runtime representation.
      --
      -- Test cases: LevPolyLet, RepPolyPatBind.
      | FRRBinder !Name

      -- | Types appearing in negative position in the type of a
      -- representation-polymorphic 'Id' must have a fixed runtime representation.
      --
      -- This includes:
      --
      --  - arguments,
      --
      --    Test cases: RepPolyMagic, RepPolyRightSection, RepPolyWrappedVar,
      --                T14561b, T17817.
      --
      --  - continuation result types, such as in 'catch#', 'keepAlive#'
      --    and 'control0#'.
      --
      --    Test case: T21906.
      | FRRRepPolyId
          !Name
          !RepPolyId
          !(Position Neg)

      -- | A partial application of the constructor of a representation-polymorphic
      -- unlifted newtype in which the argument type does not have a fixed
      -- runtime representation.
      --
      -- Test cases: UnliftedNewtypesLevityBinder, UnliftedNewtypesCoerceFail.
      | FRRRepPolyUnliftedNewtype !DataCon

      -- | Pattern binds must have a fixed runtime representation.
      --
      -- Test case: RepPolyInferPatBind.
      | FRRPatBind

      -- | Pattern synonym arguments must have a fixed runtime representation.
      --
      -- Test case: RepPolyInferPatSyn.
      | FRRPatSynArg

      -- | The type of the scrutinee in a case statement must have a
      -- fixed runtime representation.
      --
      -- Test cases: RepPolyCase{1,2}.
      | FRRCase

      -- | An instantiation of a newtype/data constructor pattern in which
      -- an argument type does not have a fixed runtime representation.
      --
      -- Test case: T20363.
      | FRRDataConPatArg !DataCon !Int

      -- | The 'RuntimeRep' arguments to unboxed tuples must be concrete 'RuntimeRep's.
      --
      -- Test case: RepPolyTuple.
      | FRRUnboxedTuple !Int

      -- | Tuple sections must have a fixed runtime representation.
      --
      -- Test case: RepPolyTupleSection.
      | FRRUnboxedTupleSection !Int

      -- | The 'RuntimeRep' arguments to unboxed sums must be concrete 'RuntimeRep's.
      --
      -- Test cases: RepPolySum.
      | FRRUnboxedSum !(Maybe Int)

      -- | The body of a @do@ expression or a monad comprehension must
      -- have a fixed runtime representation.
      --
      -- Test cases: RepPolyDoBody{1,2}, RepPolyMcBody.
      | FRRBodyStmt !StmtOrigin !Int

      -- | Arguments to a guard in a monad comprehension must have
      -- a fixed runtime representation.
      --
      -- Test case: RepPolyMcGuard.
      | FRRBodyStmtGuard

      -- | Arguments to `(>>=)` arising from a @do@ expression
      -- or a monad comprehension must have a fixed runtime representation.
      --
      -- Test cases: RepPolyDoBind, RepPolyMcBind.
      | FRRBindStmt !StmtOrigin

      -- | A value bound by a pattern guard must have a fixed runtime representation.
      --
      -- Test cases: none.
      | FRRBindStmtGuard

      -- | A representation-polymorphism check arising from arrow notation.
      --
      -- See 'FRRArrowContext' for more details.
      | FRRArrow !FRRArrowContext

      -- | A representation-polymorphic check arising from a call
      -- to 'matchExpectedFunTys' or 'matchActualFunTy'.
      --
      -- See 'ExpectedFunTyOrigin' for more details.
      | FRRExpectedFunTy
          !ExpectedFunTyOrigin
          !Int
            -- ^ argument position (1-indexed)

    -- | The description of a representation-polymorphic 'Id'.
    data RepPolyId
      -- | A representation-polymorphic 'PrimOp'.
      = RepPolyPrimOp
      -- | An unboxed tuple constructor.
      | RepPolyTuple
      -- | An unboxed sum constructor.
      | RepPolySum
      -- | An unspecified representation-polymorphic function,
      -- e.g. a pseudo-op such as 'coerce'.
      | RepPolyFunction

    -- | A synonym for 'FRRUnboxedTuple' exposed in the hs-boot file
    -- for "GHC.Tc.Types.Origin".
    mkFRRUnboxedTuple :: Int -> FixedRuntimeRepContext
    mkFRRUnboxedTuple :: ScDepth -> FixedRuntimeRepContext
    mkFRRUnboxedTuple = ScDepth -> FixedRuntimeRepContext
    FRRUnboxedTuple

    -- | A synonym for 'FRRUnboxedSum' exposed in the hs-boot file
    -- for "GHC.Tc.Types.Origin".
    mkFRRUnboxedSum :: Maybe Int -> FixedRuntimeRepContext
    mkFRRUnboxedSum :: Maybe ScDepth -> FixedRuntimeRepContext
    mkFRRUnboxedSum = Maybe ScDepth -> FixedRuntimeRepContext
    FRRUnboxedSum

    -- | Print the context for a @FixedRuntimeRep@ representation-polymorphism check.
    --
    -- Note that this function does not include the specific 'RuntimeRep'
    -- which is not fixed. That information is stored in 'FixedRuntimeRepOrigin'
    -- and is reported separately.
    pprFixedRuntimeRepContext :: FixedRuntimeRepContext -> SDoc
    pprFixedRuntimeRepContext :: FixedRuntimeRepContext -> SDoc
    pprFixedRuntimeRepContext (FRRRecordCon RdrName
    lbl HsExpr GhcTc
    _arg)
      = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The field", SDoc -> SDoc
    quotes (RdrName -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr RdrName
    lbl)
            , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "of the record constructor" ]
    pprFixedRuntimeRepContext (FRRRecordUpdate Name
    lbl HsExpr GhcRn
    _arg)
      = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The record update at field"
            , SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    lbl) ]
    pprFixedRuntimeRepContext (FRRBinder Name
    binder)
      = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The binder"
            , SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    binder) ]
    pprFixedRuntimeRepContext (FRRRepPolyId Name
    nm RepPolyId
    id Position 'Neg
    what)
      = RepPolyId -> Name -> Position 'Neg -> SDoc
    pprFRRRepPolyId RepPolyId
    id Name
    nm Position 'Neg
    what
    pprFixedRuntimeRepContext FixedRuntimeRepContext
    FRRPatBind
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The pattern binding"
    pprFixedRuntimeRepContext FixedRuntimeRepContext
    FRRPatSynArg
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The pattern synonym argument pattern"
    pprFixedRuntimeRepContext FixedRuntimeRepContext
    FRRCase
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The scrutinee of the case statement"
    pprFixedRuntimeRepContext (FRRDataConPatArg DataCon
    con ScDepth
    i)
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc
    what
      where
        what :: SDoc
        what :: SDoc
    what
          | DataCon -> Bool
    isNewDataCon DataCon
    con
          = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "newtype constructor pattern"
          | Bool
    otherwise
          = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "data constructor pattern in" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    speakNth ScDepth
    i SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "position"
    pprFixedRuntimeRepContext (FRRRepPolyUnliftedNewtype DataCon
    dc)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "Unsaturated use of a representation-polymorphic unlifted newtype."
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The argument of the newtype constructor" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (DataCon -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr DataCon
    dc) ]
    pprFixedRuntimeRepContext (FRRUnboxedTuple ScDepth
    i)
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    speakNth ScDepth
    i SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "component of the unboxed tuple"
    pprFixedRuntimeRepContext (FRRUnboxedTupleSection ScDepth
    i)
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    speakNth ScDepth
    i SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "component of the unboxed tuple section"
    pprFixedRuntimeRepContext (FRRUnboxedSum Maybe ScDepth
    Nothing)
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The unboxed sum"
    pprFixedRuntimeRepContext (FRRUnboxedSum (Just ScDepth
    i))
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    speakNth ScDepth
    i SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "component of the unboxed sum"
    pprFixedRuntimeRepContext (FRRBodyStmt StmtOrigin
    stmtOrig ScDepth
    i)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    speakNth ScDepth
    i SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "argument to (>>)" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "arising from the" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> StmtOrigin -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr StmtOrigin
    stmtOrig SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma ]
    pprFixedRuntimeRepContext FixedRuntimeRepContext
    FRRBodyStmtGuard
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The argument to" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "guard") SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "arising from the" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> StmtOrigin -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr StmtOrigin
    MonadComprehension SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma ]
    pprFixedRuntimeRepContext (FRRBindStmt StmtOrigin
    stmtOrig)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The first argument to (>>=)" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "arising from the" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> StmtOrigin -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr StmtOrigin
    stmtOrig SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> SDoc
    forall doc. IsLine doc => doc
    comma ]
    pprFixedRuntimeRepContext FixedRuntimeRepContext
    FRRBindStmtGuard
      = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The body of the bind statement" ]
    pprFixedRuntimeRepContext (FRRArrow FRRArrowContext
    arrowContext)
      = FRRArrowContext -> SDoc
    pprFRRArrowContext FRRArrowContext
    arrowContext
    pprFixedRuntimeRepContext (FRRExpectedFunTy ExpectedFunTyOrigin
    funTyOrig ScDepth
    arg_pos)
      = ExpectedFunTyOrigin -> ScDepth -> SDoc
    pprExpectedFunTyOrigin ExpectedFunTyOrigin
    funTyOrig ScDepth
    arg_pos

    instance Outputable FixedRuntimeRepContext where
      ppr :: FixedRuntimeRepContext -> SDoc
    ppr = FixedRuntimeRepContext -> SDoc
    pprFixedRuntimeRepContext

    -- | Are we in a @do@ expression or a monad comprehension?
    --
    -- This datatype is only used to report this context to the user in error messages.
    data StmtOrigin
      = MonadComprehension
      | DoNotation

    instance Outputable StmtOrigin where
      ppr :: StmtOrigin -> SDoc
    ppr StmtOrigin
    MonadComprehension = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "monad comprehension"
      ppr StmtOrigin
    DoNotation         = SDoc -> SDoc
    quotes ( String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "do" ) SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "statement"

    -- | The position of an argument (to be reported in an error message).
    data ArgPos
      = ArgPosInvis
        -- ^ Invisible argument: don't report its position to the user.
      | ArgPosVis !Int
        -- ^ Visible argument in i-th position.

    {- *********************************************************************
    *                                                                      *
                FixedRuntimeRep: representation-polymorphic Ids
    *                                                                      *
    ********************************************************************* -}

    data Polarity = Pos | Neg

    type FlipPolarity :: Polarity -> Polarity
    type family FlipPolarity p where
      FlipPolarity Pos = Neg
      FlipPolarity Neg = Pos

    -- | A position in which a type variable appears in a type;
    -- in particular, whether it appears in a positive or a negative position.
    type Position :: Polarity -> Hs.Type
    data Position p where
      -- | In the @i@-th argument of a function arrow
      Argument :: Int -> Position (FlipPolarity p) -> Position p
      -- | In the result of a function arrow
      Result   :: Position p -> Position p
      -- | At the top level of a type
      Top      :: Position Pos

    pprFRRRepPolyId :: RepPolyId -> Name -> Position Neg -> SDoc
    pprFRRRepPolyId :: RepPolyId -> Name -> Position 'Neg -> SDoc
    pprFRRRepPolyId RepPolyId
    id Name
    nm (Argument ScDepth
    i Position (FlipPolarity 'Neg)
    pos) =
      String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc
    what SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    speakNth ScDepth
    i SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "argument of" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> RepPolyId -> Name -> SDoc
    pprRepPolyId RepPolyId
    id Name
    nm
      where
        what :: SDoc
    what = case Position (FlipPolarity 'Neg)
    pos of
          Position (FlipPolarity 'Neg)
    Top       -> SDoc
    forall doc. IsOutput doc => doc
    empty
          Result {} -> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "return type of the"
          Position (FlipPolarity 'Neg)
    _         -> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "nested return type inside the"
    pprFRRRepPolyId RepPolyId
    id Name
    nm (Result {}) =
      String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The result of" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> RepPolyId -> Name -> SDoc
    pprRepPolyId RepPolyId
    id Name
    nm

    pprRepPolyId :: RepPolyId -> Name -> SDoc
    pprRepPolyId :: RepPolyId -> Name -> SDoc
    pprRepPolyId RepPolyId
    id Name
    nm = SDoc
    id_desc SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Name -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr Name
    nm)
      where
        id_desc :: SDoc
    id_desc = case RepPolyId
    id of
          RepPolyPrimOp   {} -> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the primop"
          RepPolySum      {} -> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the unboxed sum constructor"
          RepPolyTuple    {} -> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the unboxed tuple constructor"
          RepPolyFunction {} -> SDoc
    forall doc. IsOutput doc => doc
    empty

    {- *********************************************************************
    *                                                                      *
                           FixedRuntimeRep: arrows
    *                                                                      *
    ********************************************************************* -}

    -- | While typechecking arrow notation, in which context
    -- did a representation polymorphism check arise?
    --
    -- See 'FixedRuntimeRepContext' for more general origins of
    -- representation polymorphism checks.
    data FRRArrowContext

      -- | The result of an arrow command does not have a fixed runtime representation.
      --
      -- Test case: RepPolyArrowCmd.
      = ArrowCmdResTy !(HsCmd GhcRn)

      -- | The argument to an arrow in an arrow command application does not have
      -- a fixed runtime representation.
      --
      -- Test cases: none.
      | ArrowCmdApp !(HsCmd GhcRn) !(HsExpr GhcRn)

      -- | A function in an arrow application does not have
      -- a fixed runtime representation.
      --
      -- Test cases: none.
      | ArrowCmdArrApp !(HsExpr GhcRn) !(HsExpr GhcRn) !HsArrAppType

      -- | The scrutinee type in an arrow command case statement does not have a
      -- fixed runtime representation.
      --
      -- Test cases: none.
      | ArrowCmdCase

      -- | The overall type of an arrow proc expression does not have
      -- a fixed runtime representation.
      --
      -- Test case: RepPolyArrowFun.
      | ArrowFun !(HsExpr GhcRn)

    pprFRRArrowContext :: FRRArrowContext -> SDoc
    pprFRRArrowContext :: FRRArrowContext -> SDoc
    pprFRRArrowContext (ArrowCmdResTy HsCmd GhcRn
    cmd)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ SDoc -> ScDepth -> SDoc -> SDoc
    hang (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The arrow command") ScDepth
    2 (SDoc -> SDoc
    quotes (HsCmd GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsCmd GhcRn
    cmd)) ]
    pprFRRArrowContext (ArrowCmdApp HsCmd GhcRn
    fun HsExpr GhcRn
    arg)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The argument in the arrow command application of"
             , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (SDoc -> SDoc
    quotes (HsCmd GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsCmd GhcRn
    fun))
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "to"
             , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (SDoc -> SDoc
    quotes (HsExpr GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr GhcRn
    arg)) ]
    pprFRRArrowContext (ArrowCmdArrApp HsExpr GhcRn
    fun HsExpr GhcRn
    arg HsArrAppType
    ho_app)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The function in the" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> HsArrAppType -> SDoc
    pprHsArrType HsArrAppType
    ho_app SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "of"
             , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (SDoc -> SDoc
    quotes (HsExpr GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr GhcRn
    fun))
             , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "to"
             , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (SDoc -> SDoc
    quotes (HsExpr GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr GhcRn
    arg)) ]
    pprFRRArrowContext FRRArrowContext
    ArrowCmdCase
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The scrutinee of the arrow case command"
    pprFRRArrowContext (ArrowFun HsExpr GhcRn
    fun)
      = [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The return type of the arrow function"
             , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (SDoc -> SDoc
    quotes (HsExpr GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr GhcRn
    fun)) ]

    instance Outputable FRRArrowContext where
      ppr :: FRRArrowContext -> SDoc
    ppr = FRRArrowContext -> SDoc
    pprFRRArrowContext

    {- *********************************************************************
    *                                                                      *
                  FixedRuntimeRep: ExpectedFunTy origin
    *                                                                      *
    ********************************************************************* -}

    -- | In what context are we calling 'matchExpectedFunTys'
    -- or 'matchActualFunTy'?
    --
    -- Used for two things:
    --
    --  1. Reporting error messages which explain that a function has been
    --     given an unexpected number of arguments.
    --     Uses 'pprExpectedFunTyHerald'.
    --     See Note [Herald for matchExpectedFunTys] in GHC.Tc.Utils.Unify.
    --
    --  2. Reporting representation-polymorphism errors when a function argument
    --     doesn't have a fixed RuntimeRep as per Note [Fixed RuntimeRep]
    --     in GHC.Tc.Utils.Concrete.
    --     Uses 'pprExpectedFunTyOrigin'.
    --     See 'FixedRuntimeRepContext' for the situations in which
    --     representation-polymorphism checks are performed.
    data ExpectedFunTyOrigin

      -- | A rebindable syntax operator is expected to have a function type.
      --
      -- Test cases for representation-polymorphism checks:
      --   RepPolyDoBind, RepPolyDoBody{1,2}, RepPolyMc{Bind,Body,Guard}, RepPolyNPlusK
      = forall (p :: Pass)
         . (OutputableBndrId p)
        => ExpectedFunTySyntaxOp !CtOrigin !(HsExpr (GhcPass p))
          -- ^ rebindable syntax operator

      -- | A view pattern must have a function type.
      --
      -- Test cases for representation-polymorphism checks:
      --   RepPolyBinder
      | ExpectedFunTyViewPat
        !(HsExpr GhcRn)
          -- ^ function used in the view pattern

      -- | Need to be able to extract an argument type from a function type.
      --
      -- Test cases for representation-polymorphism checks:
      --   RepPolyApp
      | forall (p :: Pass)
         . Outputable (HsExpr (GhcPass p)) => ExpectedFunTyArg
              !TypedThing
                -- ^ function
              !(HsExpr (GhcPass p))
                -- ^ argument

      -- | Ensure that a function defined by equations indeed has a function type
      -- with the appropriate number of arguments.
      --
      -- Test cases for representation-polymorphism checks:
      --   RepPolyBinder, RepPolyRecordPattern, RepPolyWildcardPattern
      | ExpectedFunTyMatches
          !TypedThing
            -- ^ name of the function
          !(MatchGroup GhcRn (LHsExpr GhcRn))
           -- ^ equations

      -- | Ensure that a lambda abstraction has a function type.
      --
      -- Test cases for representation-polymorphism checks:
      --   RepPolyLambda, RepPolyMatch
      | ExpectedFunTyLam HsLamVariant
          !(HsExpr GhcRn)
           -- ^ the entire lambda-case expression

    pprExpectedFunTyOrigin :: ExpectedFunTyOrigin
                           -> Int -- ^ argument position (starting at 1)
                           -> SDoc
    pprExpectedFunTyOrigin :: ExpectedFunTyOrigin -> ScDepth -> SDoc
    pprExpectedFunTyOrigin ExpectedFunTyOrigin
    funTy_origin ScDepth
    i =
      case ExpectedFunTyOrigin
    funTy_origin of
        ExpectedFunTySyntaxOp CtOrigin
    orig HsExpr (GhcPass p)
    op ->
          [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ SDoc
    the_arg_of
                     , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the rebindable syntax operator"
                     , SDoc -> SDoc
    quotes (HsExpr (GhcPass p) -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr (GhcPass p)
    op) ]
               , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (CtOrigin -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr CtOrigin
    orig) ]
        ExpectedFunTyViewPat HsExpr GhcRn
    expr ->
          [SDoc] -> SDoc
    forall doc. IsDoc doc => [doc] -> doc
    vcat [ SDoc
    the_arg_of SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "the view pattern"
               , ScDepth -> SDoc -> SDoc
    nest ScDepth
    2 (HsExpr GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr GhcRn
    expr) ]
        ExpectedFunTyArg TypedThing
    fun HsExpr (GhcPass p)
    arg ->
          [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The argument"
              , SDoc -> SDoc
    quotes (HsExpr (GhcPass p) -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr (GhcPass p)
    arg)
              , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "of"
              , SDoc -> SDoc
    quotes (TypedThing -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TypedThing
    fun) ]
        ExpectedFunTyMatches TypedThing
    fun (MG { mg_alts :: forall p body. MatchGroup p body -> XRec p [LMatch p body]
    mg_alts = L SrcSpanAnnLW
    _ [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    alts })
          | [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    -> Bool
    forall a. [a] -> Bool
    forall (t :: * -> *) a. Foldable t => t a -> Bool
    null [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    alts
          -> SDoc
    the_arg_of SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TypedThing -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TypedThing
    fun)
          | Bool
    otherwise
          -> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    speakNth ScDepth
    i SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "pattern in the equation" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    -> SDoc
    forall a. [a] -> SDoc
    plural [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    alts
         SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TypedThing -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TypedThing
    fun)
        ExpectedFunTyLam HsLamVariant
    lam_variant HsExpr GhcRn
    _ -> SDoc -> SDoc
    binder_of (SDoc -> SDoc) -> SDoc -> SDoc
    forall a b. (a -> b) -> a -> b
    $ HsLamVariant -> SDoc
    lamCaseKeyword HsLamVariant
    lam_variant
      where
        the_arg_of :: SDoc
        the_arg_of :: SDoc
    the_arg_of = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> ScDepth -> SDoc
    speakNth ScDepth
    i SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "argument of"

        binder_of :: SDoc -> SDoc
        binder_of :: SDoc -> SDoc
    binder_of SDoc
    what = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The binder of the" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc
    what SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "expression"

    pprExpectedFunTyHerald :: ExpectedFunTyOrigin -> SDoc
    pprExpectedFunTyHerald :: ExpectedFunTyOrigin -> SDoc
    pprExpectedFunTyHerald (ExpectedFunTySyntaxOp {})
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "This rebindable syntax expects a function with"
    pprExpectedFunTyHerald (ExpectedFunTyViewPat {})
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "A view pattern expression expects"
    pprExpectedFunTyHerald (ExpectedFunTyArg TypedThing
    fun HsExpr (GhcPass p)
    _)
      = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The function" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TypedThing -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TypedThing
    fun)
            , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "is applied to" ]
    pprExpectedFunTyHerald (ExpectedFunTyMatches TypedThing
    fun (MG { mg_alts :: forall p body. MatchGroup p body -> XRec p [LMatch p body]
    mg_alts = L SrcSpanAnnLW
    _ [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    alts }))
      = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The equation" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <> [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    -> SDoc
    forall a. [a] -> SDoc
    plural [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    alts SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "for" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (TypedThing -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr TypedThing
    fun) SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    -> SDoc
    forall a. [a] -> SDoc
    hasOrHave [GenLocated
       SrcSpanAnnA (Match GhcRn (GenLocated SrcSpanAnnA (HsExpr GhcRn)))]
    alts
    pprExpectedFunTyHerald (ExpectedFunTyLam HsLamVariant
    lam_variant HsExpr GhcRn
    expr)
      = [SDoc] -> SDoc
    forall doc. IsLine doc => [doc] -> doc
    sep [ String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "The" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> HsLamVariant -> SDoc
    lamCaseKeyword HsLamVariant
    lam_variant SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "expression"
                         SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> SDoc -> SDoc
    quotes (Depth -> SDoc -> SDoc
    pprSetDepth (ScDepth -> Depth
    PartWay ScDepth
    1) (HsExpr GhcRn -> SDoc
    forall a. Outputable a => a -> SDoc
    ppr HsExpr GhcRn
    expr))
                   -- The pprSetDepth makes the lambda abstraction print briefly
            , String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "has" ]

    {- *******************************************************************
    *                                                                    *
                           InstanceWhat
    *                                                                    *
    **********************************************************************-}

    -- | Indicates if Instance met the Safe Haskell overlapping instances safety
    -- check.
    --
    -- See Note [Safe Haskell Overlapping Instances] in GHC.Tc.Solver
    -- See Note [Safe Haskell Overlapping Instances Implementation] in GHC.Tc.Solver
    type SafeOverlapping = Bool

    data InstanceWhat  -- How did we solve this constraint?
      = BuiltinEqInstance    -- Built-in solver for (t1 ~ t2), (t1 ~~ t2), Coercible t1 t2
                             -- See GHC.Tc.Solver.InertSet Note [Solved dictionaries]

      | BuiltinTypeableInstance TyCon   -- Built-in solver for Typeable (T t1 .. tn)
                             -- See Note [Well-staged instance evidence]

      | BuiltinInstance      -- Built-in solver for (C t1 .. tn) where C is
                             --   KnownNat, .. etc (classes with no top-level evidence)

      | LocalInstance        -- Solved by a quantified constraint
                             -- See GHC.Tc.Solver.InertSet Note [Solved dictionaries]

      | TopLevInstance       -- Solved by a top-level instance decl
          { InstanceWhat -> Id
    iw_dfun_id   :: DFunId
          , InstanceWhat -> Bool
    iw_safe_over :: SafeOverlapping
          , InstanceWhat -> Maybe (WarningTxt GhcRn)
    iw_warn      :: Maybe (WarningTxt GhcRn) }
                -- See Note [Implementation of deprecated instances]
                -- in GHC.Tc.Solver.Dict

    instance Outputable InstanceWhat where
      ppr :: InstanceWhat -> SDoc
    ppr InstanceWhat
    BuiltinInstance   = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a built-in instance"
      ppr BuiltinTypeableInstance {} = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a built-in typeable instance"
      ppr InstanceWhat
    BuiltinEqInstance = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a built-in equality instance"
      ppr InstanceWhat
    LocalInstance     = String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "a locally-quantified instance"
      ppr (TopLevInstance { iw_dfun_id :: InstanceWhat -> Id
    iw_dfun_id = Id
    dfun })
          = SDoc -> ScDepth -> SDoc -> SDoc
    hang (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "instance" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> TcType -> SDoc
    pprSigmaType (Id -> TcType
    idType Id
    dfun))
               ScDepth
    2 (String -> SDoc
    forall doc. IsLine doc => String -> doc
    text String
    "--" SDoc -> SDoc -> SDoc
    forall doc. IsLine doc => doc -> doc -> doc
    <+> Name -> SDoc
    pprDefinedAt (Id -> Name
    idName Id
    dfun))