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|
{-# LANGUAGE GADTs #-}
module GHC.Tc.Errors.Types (
-- * Main types
TcRnMessage(..)
, TcRnMessageDetailed(..)
, ErrInfo(..)
, LevityCheckProvenance(..)
, ShadowedNameProvenance(..)
, RecordFieldPart(..)
, InjectivityErrReason(..)
, HasKinds(..)
, hasKinds
, SuggestUndecidableInstances(..)
, suggestUndecidableInstances
, NotClosedReason(..)
, SuggestPartialTypeSignatures(..)
, suggestPartialTypeSignatures
, DeriveInstanceErrReason(..)
, UsingGeneralizedNewtypeDeriving(..)
, usingGeneralizedNewtypeDeriving
, DeriveAnyClassEnabled(..)
, deriveAnyClassEnabled
, DeriveInstanceBadConstructor(..)
, HasWildcard(..)
, hasWildcard
, DeriveGenericsErrReason(..)
, HasAssociatedDataFamInsts(..)
, hasAssociatedDataFamInsts
, AssociatedTyLastVarInKind(..)
, associatedTyLastVarInKind
, AssociatedTyNotParamOverLastTyVar(..)
, associatedTyNotParamOverLastTyVar
) where
import GHC.Prelude
import GHC.Hs
import {-# SOURCE #-} GHC.Tc.Types (TcIdSigInfo)
import GHC.Tc.Types.Constraint
import GHC.Tc.Types.Rank (Rank)
import GHC.Tc.Utils.TcType (TcType)
import GHC.Types.Error
import GHC.Types.FieldLabel (FieldLabelString)
import GHC.Types.Name (Name, OccName)
import GHC.Types.Name.Reader
import GHC.Types.SrcLoc
import GHC.Types.TyThing (TyThing)
import GHC.Types.Var (Id)
import GHC.Types.Var.Set (TyVarSet, VarSet)
import GHC.Unit.Types (Module)
import GHC.Utils.Outputable
import GHC.Core.Class (Class)
import GHC.Core.Coercion.Axiom (CoAxBranch)
import GHC.Core.ConLike (ConLike)
import GHC.Core.DataCon (DataCon)
import GHC.Core.FamInstEnv (FamInst)
import GHC.Core.InstEnv (ClsInst)
import GHC.Core.TyCon (TyCon, TyConFlavour)
import GHC.Core.Type (Kind, Type, Var, ThetaType, PredType)
import GHC.Unit.State (UnitState)
import GHC.Unit.Module.Name (ModuleName)
import GHC.Types.Basic
import qualified GHC.LanguageExtensions as LangExt
import qualified Data.List.NonEmpty as NE
import Data.Typeable hiding (TyCon)
{-
Note [Migrating TcM Messages]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As part of #18516, we are slowly migrating the diagnostic messages emitted
and reported in the TcM from SDoc to TcRnMessage. Historically, GHC emitted
some diagnostics in 3 pieces, i.e. there were lots of error-reporting functions
that accepted 3 SDocs an input: one for the important part of the message,
one for the context and one for any supplementary information. Consider the following:
• Couldn't match expected type ‘Int’ with actual type ‘Char’
• In the expression: x4
In a stmt of a 'do' block: return (x2, x4)
In the expression:
Under the hood, the reporting functions in Tc.Utils.Monad were emitting "Couldn't match"
as the important part, "In the expression" as the context and "In a stmt..In the expression"
as the supplementary, with the context and supplementary usually smashed together so that
the final message would be composed only by two SDoc (which would then be bulletted like in
the example).
In order for us to smooth out the migration to the new diagnostic infrastructure, we
introduce the 'ErrInfo' and 'TcRnMessageDetailed' types, which serve exactly the purpose
of bridging the two worlds together without breaking the external API or the existing
format of messages reported by GHC.
Using 'ErrInfo' and 'TcRnMessageDetailed' also allows us to move away from the SDoc-ridden
diagnostic API inside Tc.Utils.Monad, enabling further refactorings.
In the future, once the conversion will be complete and we will successfully eradicate
any use of SDoc in the diagnostic reporting of GHC, we can surely revisit the usage and
existence of these two types, which for now remain a "necessary evil".
-}
-- The majority of TcRn messages come with extra context about the error,
-- and this newtype captures it. See Note [Migrating TcM messages].
data ErrInfo = ErrInfo {
errInfoContext :: !SDoc
-- ^ Extra context associated to the error.
, errInfoSupplementary :: !SDoc
-- ^ Extra supplementary info associated to the error.
}
-- | 'TcRnMessageDetailed' is an \"internal\" type (used only inside
-- 'GHC.Tc.Utils.Monad' that wraps a 'TcRnMessage' while also providing
-- any extra info needed to correctly pretty-print this diagnostic later on.
data TcRnMessageDetailed
= TcRnMessageDetailed !ErrInfo
-- ^ Extra info associated with the message
!TcRnMessage
-- | An error which might arise during typechecking/renaming.
data TcRnMessage where
{-| Simply wraps a generic 'Diagnostic' message @a@. It can be used by plugins
to provide custom diagnostic messages originated during typechecking/renaming.
-}
TcRnUnknownMessage :: (Diagnostic a, Typeable a) => a -> TcRnMessage
{-| TcRnMessageWithInfo is a constructor which is used when extra information is needed
to be provided in order to qualify a diagnostic and where it was originated (and why).
It carries an extra 'UnitState' which can be used to pretty-print some names
and it wraps a 'TcRnMessageDetailed', which includes any extra context associated
with this diagnostic.
-}
TcRnMessageWithInfo :: !UnitState
-- ^ The 'UnitState' will allow us to pretty-print
-- some diagnostics with more detail.
-> !TcRnMessageDetailed
-> TcRnMessage
{-| A levity polymorphism check happening during TcRn.
-}
TcLevityPolyInType :: !Type
-> !LevityCheckProvenance
-> !ErrInfo -- Extra info accumulated in the TcM monad
-> TcRnMessage
{-| TcRnImplicitLift is a warning (controlled with -Wimplicit-lift) that occurs when
a Template Haskell quote implicitly uses 'lift'.
Example:
warning1 :: Lift t => t -> Q Exp
warning1 x = [| x |]
Test cases: th/T17804
-}
TcRnImplicitLift :: Outputable var => var -> !ErrInfo -> TcRnMessage
{-| TcRnUnusedPatternBinds is a warning (controlled with -Wunused-pattern-binds)
that occurs if a pattern binding binds no variables at all, unless it is a
lone wild-card pattern, or a banged pattern.
Example:
Just _ = rhs3 -- Warning: unused pattern binding
(_, _) = rhs4 -- Warning: unused pattern binding
_ = rhs3 -- No warning: lone wild-card pattern
!() = rhs4 -- No warning: banged pattern; behaves like seq
Test cases: rename/{T13646,T17c,T17e,T7085}
-}
TcRnUnusedPatternBinds :: HsBind GhcRn -> TcRnMessage
{-| TcRnDodgyImports is a warning (controlled with -Wdodgy-imports) that occurs when
a datatype 'T' is imported with all constructors, i.e. 'T(..)', but has been exported
abstractly, i.e. 'T'.
Test cases: rename/should_compile/T7167
-}
TcRnDodgyImports :: RdrName -> TcRnMessage
{-| TcRnDodgyExports is a warning (controlled by -Wdodgy-exports) that occurs when a datatype
'T' is exported with all constructors, i.e. 'T(..)', but is it just a type synonym or a
type/data family.
Example:
module Foo (
T(..) -- Warning: T is a type synonym
, A(..) -- Warning: A is a type family
, C(..) -- Warning: C is a data family
) where
type T = Int
type family A :: * -> *
data family C :: * -> *
Test cases: warnings/should_compile/DodgyExports01
-}
TcRnDodgyExports :: Name -> TcRnMessage
{-| TcRnMissingImportList is a warning (controlled by -Wmissing-import-lists) that occurs when
an import declaration does not explicitly list all the names brought into scope.
Test cases: rename/should_compile/T4489
-}
TcRnMissingImportList :: IE GhcPs -> TcRnMessage
{-| When a module marked trustworthy or unsafe (using -XTrustworthy or -XUnsafe) is compiled
with a plugin, the TcRnUnsafeDueToPlugin warning (controlled by -Wunsafe) is used as the
reason the module was inferred to be unsafe. This warning is not raised if the
-fplugin-trustworthy flag is passed.
Test cases: plugins/T19926
-}
TcRnUnsafeDueToPlugin :: TcRnMessage
{-| TcRnModMissingRealSrcSpan is an error that occurrs when compiling a module that lacks
an associated 'RealSrcSpan'.
Test cases: None
-}
TcRnModMissingRealSrcSpan :: Module -> TcRnMessage
{-| TcRnIdNotExportedFromModuleSig is an error pertaining to backpack that occurs
when an identifier required by a signature is not exported by the module
or signature that is being used as a substitution for that signature.
Example(s): None
Test cases: backpack/should_fail/bkpfail36
-}
TcRnIdNotExportedFromModuleSig :: Name -> Module -> TcRnMessage
{-| TcRnIdNotExportedFromLocalSig is an error pertaining to backpack that
occurs when an identifier which is necessary for implementing a module
signature is not exported from that signature.
Example(s): None
Test cases: backpack/should_fail/bkpfail30
backpack/should_fail/bkpfail31
backpack/should_fail/bkpfail34
-}
TcRnIdNotExportedFromLocalSig :: Name -> TcRnMessage
{-| TcRnShadowedName is a warning (controlled by -Wname-shadowing) that occurs whenever
an inner-scope value has the same name as an outer-scope value, i.e. the inner
value shadows the outer one. This can catch typographical errors that turn into
hard-to-find bugs. The warning is suppressed for names beginning with an underscore.
Examples(s):
f = ... let f = id in ... f ... -- NOT OK, 'f' is shadowed
f x = do { _ignore <- this; _ignore <- that; return (the other) } -- suppressed via underscore
Test cases: typecheck/should_compile/T10971a
rename/should_compile/rn039
rename/should_compile/rn064
rename/should_compile/T1972
rename/should_fail/T2723
rename/should_compile/T3262
driver/werror
-}
TcRnShadowedName :: OccName -> ShadowedNameProvenance -> TcRnMessage
{-| TcRnDuplicateWarningDecls is an error that occurs whenever
a warning is declared twice.
Examples(s):
None.
Test cases:
None.
-}
TcRnDuplicateWarningDecls :: !(LocatedN RdrName) -> !RdrName -> TcRnMessage
{-| TcRnDuplicateWarningDecls is an error that occurs whenever
the constraint solver in the simplifier hits the iterations' limit.
Examples(s):
None.
Test cases:
None.
-}
TcRnSimplifierTooManyIterations :: Cts
-> !IntWithInf
-- ^ The limit.
-> WantedConstraints
-> TcRnMessage
{-| TcRnIllegalPatSynDecl is an error that occurs whenever
there is an illegal pattern synonym declaration.
Examples(s):
varWithLocalPatSyn x = case x of
P -> ()
where
pattern P = () -- not valid, it can't be local, it must be defined at top-level.
Test cases: patsyn/should_fail/local
-}
TcRnIllegalPatSynDecl :: !(LIdP GhcPs) -> TcRnMessage
{-| TcRnLinearPatSyn is an error that occurs whenever a pattern
synonym signature uses a field that is not unrestricted.
Example(s): None
Test cases: linear/should_fail/LinearPatSyn2
-}
TcRnLinearPatSyn :: !Type -> TcRnMessage
{-| TcRnEmptyRecordUpdate is an error that occurs whenever
a record is updated without specifying any field.
Examples(s):
$(deriveJSON defaultOptions{} ''Bad) -- not ok, no fields selected for update of defaultOptions
Test cases: th/T12788
-}
TcRnEmptyRecordUpdate :: TcRnMessage
{-| TcRnIllegalFieldPunning is an error that occurs whenever
field punning is used without the 'NamedFieldPuns' extension enabled.
Examples(s):
data Foo = Foo { a :: Int }
foo :: Foo -> Int
foo Foo{a} = a -- Not ok, punning used without extension.
Test cases: parser/should_fail/RecordDotSyntaxFail12
-}
TcRnIllegalFieldPunning :: !(Located RdrName) -> TcRnMessage
{-| TcRnIllegalWildcardsInRecord is an error that occurs whenever
wildcards (..) are used in a record without the relevant
extension being enabled.
Examples(s):
data Foo = Foo { a :: Int }
foo :: Foo -> Int
foo Foo{..} = a -- Not ok, wildcards used without extension.
Test cases: parser/should_fail/RecordWildCardsFail
-}
TcRnIllegalWildcardsInRecord :: !RecordFieldPart -> TcRnMessage
{-| TcRnDuplicateFieldName is an error that occurs whenever
there are duplicate field names in a record.
Examples(s): None.
Test cases: None.
-}
TcRnDuplicateFieldName :: !RecordFieldPart -> NE.NonEmpty RdrName -> TcRnMessage
{-| TcRnIllegalViewPattern is an error that occurs whenever
the ViewPatterns syntax is used but the ViewPatterns language extension
is not enabled.
Examples(s):
data Foo = Foo { a :: Int }
foo :: Foo -> Int
foo (a -> l) = l -- not OK, the 'ViewPattern' extension is not enabled.
Test cases: parser/should_fail/ViewPatternsFail
-}
TcRnIllegalViewPattern :: !(Pat GhcPs) -> TcRnMessage
{-| TcRnCharLiteralOutOfRange is an error that occurs whenever
a character is out of range.
Examples(s): None
Test cases: None
-}
TcRnCharLiteralOutOfRange :: !Char -> TcRnMessage
{-| TcRnIllegalWildcardsInConstructor is an error that occurs whenever
the record wildcards '..' are used inside a constructor without labeled fields.
Examples(s): None
Test cases: None
-}
TcRnIllegalWildcardsInConstructor :: !Name -> TcRnMessage
{-| TcRnIgnoringAnnotations is a warning that occurs when the source code
contains annotation pragmas but the platform in use does not support an
external interpreter such as GHCi and therefore the annotations are ignored.
Example(s): None
Test cases: None
-}
TcRnIgnoringAnnotations :: [LAnnDecl GhcRn] -> TcRnMessage
{-| TcRnAnnotationInSafeHaskell is an error that occurs if annotation pragmas
are used in conjunction with Safe Haskell.
Example(s): None
Test cases: annotations/should_fail/T10826
-}
TcRnAnnotationInSafeHaskell :: TcRnMessage
{-| TcRnInvalidTypeApplication is an error that occurs when a visible type application
is used with an expression that does not accept "specified" type arguments.
Example(s):
foo :: forall {a}. a -> a
foo x = x
bar :: ()
bar = let x = foo @Int 42
in ()
Test cases: overloadedrecflds/should_fail/overloadedlabelsfail03
typecheck/should_fail/ExplicitSpecificity1
typecheck/should_fail/ExplicitSpecificity10
typecheck/should_fail/ExplicitSpecificity2
typecheck/should_fail/T17173
typecheck/should_fail/VtaFail
-}
TcRnInvalidTypeApplication :: Type -> LHsWcType GhcRn -> TcRnMessage
{-| TcRnTagToEnumMissingValArg is an error that occurs when the 'tagToEnum#'
function is not applied to a single value argument.
Example(s):
tagToEnum# 1 2
Test cases: None
-}
TcRnTagToEnumMissingValArg :: TcRnMessage
{-| TcRnTagToEnumUnspecifiedResTy is an error that occurs when the 'tagToEnum#'
function is not given a concrete result type.
Example(s):
foo :: forall a. a
foo = tagToEnum# 0#
Test cases: typecheck/should_fail/tcfail164
-}
TcRnTagToEnumUnspecifiedResTy :: Type -> TcRnMessage
{-| TcRnTagToEnumResTyNotAnEnum is an error that occurs when the 'tagToEnum#'
function is given a result type that is not an enumeration type.
Example(s):
foo :: Int -- not an enumeration TyCon
foo = tagToEnum# 0#
Test cases: typecheck/should_fail/tcfail164
-}
TcRnTagToEnumResTyNotAnEnum :: Type -> TcRnMessage
{-| TcRnArrowIfThenElsePredDependsOnResultTy is an error that occurs when the
predicate type of an ifThenElse expression in arrow notation depends on
the type of the result.
Example(s): None
Test cases: None
-}
TcRnArrowIfThenElsePredDependsOnResultTy :: TcRnMessage
{-| TcRnArrowCommandExpected is an error that occurs if a non-arrow command
is used where an arrow command is expected.
Example(s): None
Test cases: None
-}
TcRnArrowCommandExpected :: HsCmd GhcRn -> TcRnMessage
{-| TcRnIllegalHsBootFileDecl is an error that occurs when an hs-boot file
contains declarations that are not allowed, such as bindings.
Example(s): None
Test cases: None
-}
TcRnIllegalHsBootFileDecl :: TcRnMessage
{-| TcRnRecursivePatternSynonym is an error that occurs when a pattern synonym
is defined in terms of itself, either directly or indirectly.
Example(s):
pattern A = B
pattern B = A
Test cases: patsyn/should_fail/T16900
-}
TcRnRecursivePatternSynonym :: LHsBinds GhcRn -> TcRnMessage
{-| TcRnPartialTypeSigTyVarMismatch is an error that occurs when a partial type signature
attempts to unify two different types.
Example(s):
f :: a -> b -> _
f x y = [x, y]
Test cases: partial-sigs/should_fail/T14449
-}
TcRnPartialTypeSigTyVarMismatch
:: Name -- ^ first type variable
-> Name -- ^ second type variable
-> Name -- ^ function name
-> LHsSigWcType GhcRn -> TcRnMessage
{-| TcRnPartialTypeSigBadQuantifier is an error that occurs when a type variable
being quantified over in the partial type signature of a function gets unified
with a type that is free in that function's context.
Example(s):
foo :: Num a => a -> a
foo xxx = g xxx
where
g :: forall b. Num b => _ -> b
g y = xxx + y
Test cases: partial-sig/should_fail/T14479
-}
TcRnPartialTypeSigBadQuantifier
:: Name -- ^ type variable being quantified
-> Name -- ^ function name
-> LHsSigWcType GhcRn -> TcRnMessage
{-| TcRnPolymorphicBinderMissingSig is a warning controlled by -Wmissing-local-signatures
that occurs when a local polymorphic binding lacks a type signature.
Example(s):
id a = a
Test cases: warnings/should_compile/T12574
-}
TcRnPolymorphicBinderMissingSig :: Name -> Type -> TcRnMessage
{-| TcRnOverloadedSig is an error that occurs when a binding group conflicts
with the monomorphism restriction.
Example(s):
data T a = T a
mono = ... where
x :: Applicative f => f a
T x = ...
Test cases: typecheck/should_compile/T11339
-}
TcRnOverloadedSig :: TcIdSigInfo -> TcRnMessage
{-| TcRnTupleConstraintInst is an error that occurs whenever an instance
for a tuple constraint is specified.
Examples(s):
class C m a
class D m a
f :: (forall a. Eq a => (C m a, D m a)) => m a
f = undefined
Test cases: quantified-constraints/T15334
-}
TcRnTupleConstraintInst :: !Class -> TcRnMessage
{-| TcRnAbstractClassInst is an error that occurs whenever an instance
of an abstract class is specified.
Examples(s):
-- A.hs-boot
module A where
class C a
-- B.hs
module B where
import {-# SOURCE #-} A
instance C Int where
-- A.hs
module A where
import B
class C a where
f :: a
-- Main.hs
import A
main = print (f :: Int)
Test cases: typecheck/should_fail/T13068
-}
TcRnAbstractClassInst :: !Class -> TcRnMessage
{-| TcRnNoClassInstHead is an error that occurs whenever an instance
head is not headed by a class.
Examples(s):
instance c
Test cases: typecheck/rename/T5513
typecheck/rename/T16385
-}
TcRnNoClassInstHead :: !Type -> TcRnMessage
{-| TcRnUserTypeError is an error that occurs due to a user's custom type error,
which can be triggered by adding a `TypeError` constraint in a type signature
or typeclass instance.
Examples(s):
f :: TypeError (Text "This is a type error")
f = undefined
Test cases: typecheck/should_fail/CustomTypeErrors02
typecheck/should_fail/CustomTypeErrors03
-}
TcRnUserTypeError :: !Type -> TcRnMessage
{-| TcRnConstraintInKind is an error that occurs whenever a constraint is specified
in a kind.
Examples(s):
data Q :: Eq a => Type where {}
Test cases: dependent/should_fail/T13895
polykinds/T16263
saks/should_fail/saks_fail004
typecheck/should_fail/T16059a
typecheck/should_fail/T18714
-}
TcRnConstraintInKind :: !Type -> TcRnMessage
{-| TcRnUnboxedTupleTypeFuncArg is an error that occurs whenever an unboxed tuple type
is specified as a function argument.
Examples(s):
-- T15073.hs
import T15073a
newtype Foo a = MkFoo a
deriving P
-- T15073a.hs
class P a where
p :: a -> (# a #)
Test cases: deriving/should_fail/T15073.hs
deriving/should_fail/T15073a.hs
typecheck/should_fail/T16059d
-}
TcRnUnboxedTupleTypeFuncArg :: !Type -> TcRnMessage
{-| TcRnLinearFuncInKind is an error that occurs whenever a linear function is
specified in a kind.
Examples(s):
data A :: * %1 -> *
Test cases: linear/should_fail/LinearKind
linear/should_fail/LinearKind2
linear/should_fail/LinearKind3
-}
TcRnLinearFuncInKind :: !Type -> TcRnMessage
{-| TcRnForAllEscapeError is an error that occurs whenever a quantified type's kind
mentions quantified type variable.
Examples(s):
type T :: TYPE (BoxedRep l)
data T = MkT
Test cases: unlifted-datatypes/should_fail/UnlDataNullaryPoly
-}
TcRnForAllEscapeError :: !Type -> !Kind -> TcRnMessage
{-| TcRnVDQInTermType is an error that occurs whenever a visible dependent quantification
is specified in the type of a term.
Examples(s):
a = (undefined :: forall k -> k -> Type) @Int
Test cases: dependent/should_fail/T15859
dependent/should_fail/T16326_Fail1
dependent/should_fail/T16326_Fail2
dependent/should_fail/T16326_Fail3
dependent/should_fail/T16326_Fail4
dependent/should_fail/T16326_Fail5
dependent/should_fail/T16326_Fail6
dependent/should_fail/T16326_Fail7
dependent/should_fail/T16326_Fail8
dependent/should_fail/T16326_Fail9
dependent/should_fail/T16326_Fail10
dependent/should_fail/T16326_Fail11
dependent/should_fail/T16326_Fail12
dependent/should_fail/T17687
dependent/should_fail/T18271
-}
TcRnVDQInTermType :: !Type -> TcRnMessage
{-| TcRnIllegalEqualConstraints is an error that occurs whenever an illegal equational
constraint is specified.
Examples(s):
blah :: (forall a. a b ~ a c) => b -> c
blah = undefined
Test cases: typecheck/should_fail/T17563
-}
TcRnIllegalEqualConstraints :: !Type -> TcRnMessage
{-| TcRnBadQuantPredHead is an error that occurs whenever a quantified predicate
lacks a class or type variable head.
Examples(s):
class (forall a. A t a => A t [a]) => B t where
type A t a :: Constraint
Test cases: quantified-constraints/T16474
-}
TcRnBadQuantPredHead :: !Type -> TcRnMessage
{-| TcRnIllegalTupleConstraint is an error that occurs whenever an illegal tuple
constraint is specified.
Examples(s):
g :: ((Show a, Num a), Eq a) => a -> a
g = undefined
Test cases: typecheck/should_fail/tcfail209a
-}
TcRnIllegalTupleConstraint :: !Type -> TcRnMessage
{-| TcRnNonTypeVarArgInConstraint is an error that occurs whenever a non type-variable
argument is specified in a constraint.
Examples(s):
data T
instance Eq Int => Eq T
Test cases: ghci/scripts/T13202
ghci/scripts/T13202a
polykinds/T12055a
typecheck/should_fail/T10351
typecheck/should_fail/T19187
typecheck/should_fail/T6022
typecheck/should_fail/T8883
-}
TcRnNonTypeVarArgInConstraint :: !Type -> TcRnMessage
{-| TcRnIllegalImplicitParam is an error that occurs whenever an illegal implicit
parameter is specified.
Examples(s):
type Bla = ?x::Int
data T = T
instance Bla => Eq T
Test cases: polykinds/T11466
typecheck/should_fail/T8912
typecheck/should_fail/tcfail041
typecheck/should_fail/tcfail211
typecheck/should_fail/tcrun045
-}
TcRnIllegalImplicitParam :: !Type -> TcRnMessage
{-| TcRnIllegalConstraintSynonymOfKind is an error that occurs whenever an illegal constraint
synonym of kind is specified.
Examples(s):
type Showish = Show
f :: (Showish a) => a -> a
f = undefined
Test cases: typecheck/should_fail/tcfail209
-}
TcRnIllegalConstraintSynonymOfKind :: !Type -> TcRnMessage
{-| TcRnIllegalClassInst is an error that occurs whenever a class instance is specified
for a non-class.
Examples(s):
type C1 a = (Show (a -> Bool))
instance C1 Int where
Test cases: polykinds/T13267
-}
TcRnIllegalClassInst :: !TyConFlavour -> TcRnMessage
{-| TcRnOversaturatedVisibleKindArg is an error that occurs whenever an illegal oversaturated
visible kind argument is specified.
Examples(s):
type family
F2 :: forall (a :: Type). Type where
F2 @a = Maybe a
Test cases: typecheck/should_fail/T15793
typecheck/should_fail/T16255
-}
TcRnOversaturatedVisibleKindArg :: !Type -> TcRnMessage
{-| TcRnBadAssociatedType is an error that occurs whenever a class doesn't have an
associated type.
Examples(s):
$(do d <- instanceD (cxt []) (conT ''Eq `appT` conT ''Foo)
[tySynInstD $ tySynEqn Nothing (conT ''Rep `appT` conT ''Foo) (conT ''Maybe)]
return [d])
======>
instance Eq Foo where
type Rep Foo = Maybe
Test cases: th/T12387a
-}
TcRnBadAssociatedType :: {-Class-} !Name -> {-TyCon-} !Name -> TcRnMessage
{-| TcRnForAllRankErr is an error that occurs whenever an illegal ranked type
is specified.
Examples(s):
foo :: (a,b) -> (a~b => t) -> (a,b)
foo p x = p
Test cases:
- ghci/should_run/T15806
- indexed-types/should_fail/SimpleFail15
- typecheck/should_fail/T11355
- typecheck/should_fail/T12083a
- typecheck/should_fail/T12083b
- typecheck/should_fail/T16059c
- typecheck/should_fail/T16059e
- typecheck/should_fail/T17213
- typecheck/should_fail/T18939_Fail
- typecheck/should_fail/T2538
- typecheck/should_fail/T5957
- typecheck/should_fail/T7019
- typecheck/should_fail/T7019a
- typecheck/should_fail/T7809
- typecheck/should_fail/T9196
- typecheck/should_fail/tcfail127
- typecheck/should_fail/tcfail184
- typecheck/should_fail/tcfail196
- typecheck/should_fail/tcfail197
-}
TcRnForAllRankErr :: !Rank -> !Type -> TcRnMessage
{-| TcRnMonomorphicBindings is a warning (controlled by -Wmonomorphism-restriction)
that arise when the monomorphism restriction applies to the given bindings.
Examples(s):
{-# OPTIONS_GHC -Wmonomorphism-restriction #-}
bar = 10
foo :: Int
foo = bar
main :: IO ()
main = print foo
The example above emits the warning (for 'bar'), because without monomorphism
restriction the inferred type for 'bar' is 'bar :: Num p => p'. This warning tells us
that /if/ we were to enable '-XMonomorphismRestriction' we would make 'bar'
less polymorphic, as its type would become 'bar :: Int', so GHC warns us about that.
Test cases: typecheck/should_compile/T13785
-}
TcRnMonomorphicBindings :: [Name] -> TcRnMessage
{-| TcRnOrphanInstance is a warning (controlled by -Wwarn-orphans)
that arises when a typeclass instance is an \"orphan\", i.e. if it appears
in a module in which neither the class nor the type being instanced are
declared in the same module.
Examples(s): None
Test cases: warnings/should_compile/T9178
typecheck/should_compile/T4912
-}
TcRnOrphanInstance :: ClsInst -> TcRnMessage
{-| TcRnFunDepConflict is an error that occurs when there are functional dependencies
conflicts between instance declarations.
Examples(s): None
Test cases: typecheck/should_fail/T2307
typecheck/should_fail/tcfail096
typecheck/should_fail/tcfail202
-}
TcRnFunDepConflict :: !UnitState -> NE.NonEmpty ClsInst -> TcRnMessage
{-| TcRnDupInstanceDecls is an error that occurs when there are duplicate instance
declarations.
Examples(s):
class Foo a where
foo :: a -> Int
instance Foo Int where
foo = id
instance Foo Int where
foo = const 42
Test cases: cabal/T12733/T12733
typecheck/should_fail/tcfail035
typecheck/should_fail/tcfail023
backpack/should_fail/bkpfail18
typecheck/should_fail/TcNullaryTCFail
typecheck/should_fail/tcfail036
typecheck/should_fail/tcfail073
module/mod51
module/mod52
module/mod44
-}
TcRnDupInstanceDecls :: !UnitState -> NE.NonEmpty ClsInst -> TcRnMessage
{-| TcRnConflictingFamInstDecls is an error that occurs when there are conflicting
family instance declarations.
Examples(s): None.
Test cases: indexed-types/should_fail/ExplicitForAllFams4b
indexed-types/should_fail/NoGood
indexed-types/should_fail/Over
indexed-types/should_fail/OverDirectThisMod
indexed-types/should_fail/OverIndirectThisMod
indexed-types/should_fail/SimpleFail11a
indexed-types/should_fail/SimpleFail11b
indexed-types/should_fail/SimpleFail11c
indexed-types/should_fail/SimpleFail11d
indexed-types/should_fail/SimpleFail2a
indexed-types/should_fail/SimpleFail2b
indexed-types/should_fail/T13092/T13092
indexed-types/should_fail/T13092c/T13092c
indexed-types/should_fail/T14179
indexed-types/should_fail/T2334A
indexed-types/should_fail/T2677
indexed-types/should_fail/T3330b
indexed-types/should_fail/T4246
indexed-types/should_fail/T7102a
indexed-types/should_fail/T9371
polykinds/T7524
typecheck/should_fail/UnliftedNewtypesOverlap
-}
TcRnConflictingFamInstDecls :: NE.NonEmpty FamInst -> TcRnMessage
TcRnFamInstNotInjective :: InjectivityErrReason -> TyCon -> NE.NonEmpty CoAxBranch -> TcRnMessage
{-| TcRnBangOnUnliftedType is a warning (controlled by -Wredundant-strictness-flags) that
occurs when a strictness annotation is applied to an unlifted type.
Example(s):
data T = MkT !Int# -- Strictness flag has no effect on unlifted types
Test cases: typecheck/should_compile/T20187a
typecheck/should_compile/T20187b
-}
TcRnBangOnUnliftedType :: !Type -> TcRnMessage
{-| TcRnMultipleDefaultDeclarations is an error that occurs when a module has
more than one default declaration.
Example:
default (Integer, Int)
default (Double, Float) -- 2nd default declaration not allowed
Text cases: module/mod58
-}
TcRnMultipleDefaultDeclarations :: [LDefaultDecl GhcRn] -> TcRnMessage
{-| TcRnBadDefaultType is an error that occurs when a type used in a default
declaration does not have an instance for any of the applicable classes.
Example(s):
data Foo
default (Foo)
Test cases: typecheck/should_fail/T11974b
-}
TcRnBadDefaultType :: Type -> [Class] -> TcRnMessage
{-| TcRnPatSynBundledWithNonDataCon is an error that occurs when a module's
export list bundles a pattern synonym with a type that is not a proper
`data` or `newtype` construction.
Example(s):
module Foo (MyClass(.., P)) where
pattern P = Nothing
class MyClass a where
foo :: a -> Int
Test cases: patsyn/should_fail/export-class
-}
TcRnPatSynBundledWithNonDataCon :: TcRnMessage
{-| TcRnPatSynBundledWithWrongType is an error that occurs when the export list
of a module has a pattern synonym bundled with a type that does not match
the type of the pattern synonym.
Example(s):
module Foo (R(P,x)) where
data Q = Q Int
data R = R
pattern P{x} = Q x
Text cases: patsyn/should_fail/export-ps-rec-sel
patsyn/should_fail/export-type-synonym
patsyn/should_fail/export-type
-}
TcRnPatSynBundledWithWrongType :: Type -> Type -> TcRnMessage
{-| TcRnDupeModuleExport is a warning controlled by @-Wduplicate-exports@ that
occurs when a module appears more than once in an export list.
Example(s):
module Foo (module Bar, module Bar)
import Bar
Text cases: None
-}
TcRnDupeModuleExport :: ModuleName -> TcRnMessage
{-| TcRnExportedModNotImported is an error that occurs when an export list
contains a module that is not imported.
Example(s): None
Text cases: module/mod135
module/mod8
rename/should_fail/rnfail028
backpack/should_fail/bkpfail48
-}
TcRnExportedModNotImported :: ModuleName -> TcRnMessage
{-| TcRnNullExportedModule is a warning controlled by -Wdodgy-exports that occurs
when an export list contains a module that has no exports.
Example(s):
module Foo (module Bar) where
import Bar ()
Test cases: None
-}
TcRnNullExportedModule :: ModuleName -> TcRnMessage
{-| TcRnMissingExportList is a warning controlled by -Wmissing-export-lists that
occurs when a module does not have an explicit export list.
Example(s): None
Test cases: typecheck/should_fail/MissingExportList03
-}
TcRnMissingExportList :: ModuleName -> TcRnMessage
{-| TcRnExportHiddenComponents is an error that occurs when an export contains
constructor or class methods that are not visible.
Example(s): None
Test cases: None
-}
TcRnExportHiddenComponents :: IE GhcPs -> TcRnMessage
{-| TcRnDuplicateExport is a warning (controlled by -Wduplicate-exports) that occurs
when an identifier appears in an export list more than once.
Example(s): None
Test cases: module/MultiExport
module/mod128
module/mod14
module/mod5
overloadedrecflds/should_fail/DuplicateExports
patsyn/should_compile/T11959
-}
TcRnDuplicateExport :: GreName -> IE GhcPs -> IE GhcPs -> TcRnMessage
{-| TcRnExportedParentChildMismatch is an error that occurs when an export is
bundled with a parent that it does not belong to
Example(s):
module Foo (T(a)) where
data T
a = True
Test cases: module/T11970
module/T11970B
module/mod17
module/mod3
overloadedrecflds/should_fail/NoParent
-}
TcRnExportedParentChildMismatch :: Name -> TyThing -> GreName -> [Name] -> TcRnMessage
{-| TcRnConflictingExports is an error that occurs when different identifiers that
have the same name are being exported by a module.
Example(s):
module Foo (Bar.f, module Baz) where
import qualified Bar (f)
import Baz (f)
Test cases: module/mod131
module/mod142
module/mod143
module/mod144
module/mod145
module/mod146
module/mod150
module/mod155
overloadedrecflds/should_fail/T14953
overloadedrecflds/should_fail/overloadedrecfldsfail10
rename/should_fail/rnfail029
rename/should_fail/rnfail040
typecheck/should_fail/T16453E2
typecheck/should_fail/tcfail025
typecheck/should_fail/tcfail026
-}
TcRnConflictingExports
:: OccName -- ^ Occurrence name shared by both exports
-> GreName -- ^ Name of first export
-> GlobalRdrElt -- ^ Provenance for definition site of first export
-> IE GhcPs -- ^ Export decl of first export
-> GreName -- ^ Name of second export
-> GlobalRdrElt -- ^ Provenance for definition site of second export
-> IE GhcPs -- ^ Export decl of second export
-> TcRnMessage
{-| TcRnAmbiguousField is a warning controlled by -Wambiguous-fields occurring
when a record update's type cannot be precisely determined. This will not
be supported by -XDuplicateRecordFields in future releases.
Example(s):
data Person = MkPerson { personId :: Int, name :: String }
data Address = MkAddress { personId :: Int, address :: String }
bad1 x = x { personId = 4 } :: Person -- ambiguous
bad2 (x :: Person) = x { personId = 4 } -- ambiguous
good x = (x :: Person) { personId = 4 } -- not ambiguous
Test cases: overloadedrecflds/should_fail/overloadedrecfldsfail06
-}
TcRnAmbiguousField
:: HsExpr GhcRn -- ^ Field update
-> TyCon -- ^ Record type
-> TcRnMessage
{-| TcRnMissingFields is a warning controlled by -Wmissing-fields occurring
when the intialisation of a record is missing one or more (lazy) fields.
Example(s):
data Rec = Rec { a :: Int, b :: String, c :: Bool }
x = Rec { a = 1, b = "two" } -- missing field 'c'
Test cases: deSugar/should_compile/T13870
deSugar/should_compile/ds041
patsyn/should_compile/T11283
rename/should_compile/T5334
rename/should_compile/T12229
rename/should_compile/T5892a
warnings/should_fail/WerrorFail2
-}
TcRnMissingFields :: ConLike -> [(FieldLabelString, TcType)] -> TcRnMessage
{-| TcRnFieldUpdateInvalidType is an error occurring when an updated field's
type mentions something that is outside the universally quantified variables
of the data constructor, such as an existentially quantified type.
Example(s):
data X = forall a. MkX { f :: a }
x = (MkX ()) { f = False }
Test cases: patsyn/should_fail/records-exquant
typecheck/should_fail/T3323
-}
TcRnFieldUpdateInvalidType :: [(FieldLabelString,TcType)] -> TcRnMessage
{-| TcRnNoConstructorHasAllFields is an error that occurs when a record update
has fields that no single constructor encompasses.
Example(s):
data Foo = A { x :: Bool }
| B { y :: Int }
foo = (A False) { x = True, y = 5 }
Test cases: overloadedrecflds/should_fail/overloadedrecfldsfail08
patsyn/should_fail/mixed-pat-syn-record-sels
typecheck/should_fail/T7989
-}
TcRnNoConstructorHasAllFields :: [FieldLabelString] -> TcRnMessage
{- TcRnMixedSelectors is an error for when a mixture of pattern synonym and
record selectors are used in the same record update block.
Example(s):
data Rec = Rec { foo :: Int, bar :: String }
pattern Pat { f1, f2 } = Rec { foo = f1, bar = f2 }
illegal :: Rec -> Rec
illegal r = r { f1 = 1, bar = "two" }
Test cases: patsyn/should_fail/records-mixing-fields
-}
TcRnMixedSelectors
:: Name -- ^ Record
-> [Id] -- ^ Record selectors
-> Name -- ^ Pattern synonym
-> [Id] -- ^ Pattern selectors
-> TcRnMessage
{- TcRnMissingStrictFields is an error occurring when a record field marked
as strict is omitted when constructing said record.
Example(s):
data R = R { strictField :: !Bool, nonStrict :: Int }
x = R { nonStrict = 1 }
Test cases: typecheck/should_fail/T18869
typecheck/should_fail/tcfail085
typecheck/should_fail/tcfail112
-}
TcRnMissingStrictFields :: ConLike -> [(FieldLabelString, TcType)] -> TcRnMessage
{- TcRnNoPossibleParentForFields is an error thrown when the fields used in a
record update block do not all belong to any one type.
Example(s):
data R1 = R1 { x :: Int, y :: Int }
data R2 = R2 { y :: Int, z :: Int }
update r = r { x = 1, y = 2, z = 3 }
Test cases: overloadedrecflds/should_fail/overloadedrecfldsfail01
overloadedrecflds/should_fail/overloadedrecfldsfail14
-}
TcRnNoPossibleParentForFields :: [LHsRecUpdField GhcRn] -> TcRnMessage
{- TcRnBadOverloadedRecordUpdate is an error for a record update that cannot
be pinned down to any one constructor and thus must be given a type signature.
Example(s):
data R1 = R1 { x :: Int }
data R2 = R2 { x :: Int }
update r = r { x = 1 } -- needs a type signature
Test cases: overloadedrecflds/should_fail/overloadedrecfldsfail01
-}
TcRnBadOverloadedRecordUpdate :: [LHsRecUpdField GhcRn] -> TcRnMessage
{- TcRnStaticFormNotClosed is an error pertaining to terms that are marked static
using the -XStaticPointers extension but which are not closed terms.
Example(s):
f x = static x
Test cases: rename/should_fail/RnStaticPointersFail01
rename/should_fail/RnStaticPointersFail03
-}
TcRnStaticFormNotClosed :: Name -> NotClosedReason -> TcRnMessage
{-| TcRnUselessTypeable is a warning (controlled by -Wderiving-typeable) that
occurs when trying to derive an instance of the 'Typeable' class. Deriving
'Typeable' is no longer necessary (hence the \"useless\") as all types
automatically derive 'Typeable' in modern GHC versions.
Example(s): None.
Test cases: warnings/should_compile/DerivingTypeable
-}
TcRnUselessTypeable :: TcRnMessage
{-| TcRnDerivingDefaults is a warning (controlled by -Wderiving-defaults) that
occurs when both 'DeriveAnyClass' and 'GeneralizedNewtypeDeriving' are
enabled, and therefore GHC defaults to 'DeriveAnyClass', which might not
be what the user wants.
Example(s): None.
Test cases: typecheck/should_compile/T15839a
deriving/should_compile/T16179
-}
TcRnDerivingDefaults :: !Class -> TcRnMessage
{-| TcRnNonUnaryTypeclassConstraint is an error that occurs when GHC
encounters a non-unary constraint when trying to derive a typeclass.
Example(s):
class A
deriving instance A
data B deriving A -- We cannot derive A, is not unary (i.e. 'class A a').
Test cases: deriving/should_fail/T7959
deriving/should_fail/drvfail005
deriving/should_fail/drvfail009
deriving/should_fail/drvfail006
-}
TcRnNonUnaryTypeclassConstraint :: !(LHsSigType GhcRn) -> TcRnMessage
{-| TcRnPartialTypeSignatures is a warning (controlled by -Wpartial-type-signatures)
that occurs when a wildcard '_' is found in place of a type in a signature or a
type class derivation
Example(s):
foo :: _ -> Int
foo = ...
deriving instance _ => Eq (Foo a)
Test cases: dependent/should_compile/T11241
dependent/should_compile/T15076
dependent/should_compile/T14880-2
typecheck/should_compile/T17024
typecheck/should_compile/T10072
partial-sigs/should_fail/TidyClash2
partial-sigs/should_fail/Defaulting1MROff
partial-sigs/should_fail/WildcardsInPatternAndExprSig
partial-sigs/should_fail/T10615
partial-sigs/should_fail/T14584a
partial-sigs/should_fail/TidyClash
partial-sigs/should_fail/T11122
partial-sigs/should_fail/T14584
partial-sigs/should_fail/T10045
partial-sigs/should_fail/PartialTypeSignaturesDisabled
partial-sigs/should_fail/T10999
partial-sigs/should_fail/ExtraConstraintsWildcardInExpressionSignature
partial-sigs/should_fail/ExtraConstraintsWildcardInPatternSplice
partial-sigs/should_fail/WildcardInstantiations
partial-sigs/should_run/T15415
partial-sigs/should_compile/T10463
partial-sigs/should_compile/T15039a
partial-sigs/should_compile/T16728b
partial-sigs/should_compile/T15039c
partial-sigs/should_compile/T10438
partial-sigs/should_compile/SplicesUsed
partial-sigs/should_compile/T18008
partial-sigs/should_compile/ExprSigLocal
partial-sigs/should_compile/T11339a
partial-sigs/should_compile/T11670
partial-sigs/should_compile/WarningWildcardInstantiations
partial-sigs/should_compile/T16728
partial-sigs/should_compile/T12033
partial-sigs/should_compile/T15039b
partial-sigs/should_compile/T10403
partial-sigs/should_compile/T11192
partial-sigs/should_compile/T16728a
partial-sigs/should_compile/TypedSplice
partial-sigs/should_compile/T15039d
partial-sigs/should_compile/T11016
partial-sigs/should_compile/T13324_compile2
linear/should_fail/LinearPartialSig
polykinds/T14265
polykinds/T14172
-}
TcRnPartialTypeSignatures :: !SuggestPartialTypeSignatures -> !ThetaType -> TcRnMessage
{-| TcRnCannotDeriveInstance is an error that occurs every time a typeclass instance
can't be derived. The 'DeriveInstanceErrReason' will contain the specific reason
this error arose.
Example(s): None.
Test cases: generics/T10604/T10604_no_PolyKinds
deriving/should_fail/drvfail009
deriving/should_fail/drvfail-functor2
deriving/should_fail/T10598_fail3
deriving/should_fail/deriving-via-fail2
deriving/should_fail/deriving-via-fail
deriving/should_fail/T16181
-}
TcRnCannotDeriveInstance :: !Class
-- ^ The typeclass we are trying to derive
-- an instance for
-> [Type]
-- ^ The typeclass arguments, if any.
-> !(Maybe (DerivStrategy GhcTc))
-- ^ The derivation strategy, if any.
-> !UsingGeneralizedNewtypeDeriving
-- ^ Is '-XGeneralizedNewtypeDeriving' enabled?
-> !DeriveInstanceErrReason
-- ^ The specific reason why we couldn't derive
-- an instance for the class.
-> TcRnMessage
-- | Which parts of a record field are affected by a particular error or warning.
data RecordFieldPart
= RecordFieldConstructor !Name
| RecordFieldPattern !Name
| RecordFieldUpdate
-- | Where a shadowed name comes from
data ShadowedNameProvenance
= ShadowedNameProvenanceLocal !SrcLoc
-- ^ The shadowed name is local to the module
| ShadowedNameProvenanceGlobal [GlobalRdrElt]
-- ^ The shadowed name is global, typically imported from elsewhere.
-- | Where the levity checking for the input type originated
data LevityCheckProvenance
= LevityCheckInVarType
| LevityCheckInBinder !Var
| LevityCheckInWildcardPattern
| LevityCheckInUnboxedTuplePattern !(Pat GhcTc)
| LevityCheckPatSynSig
| LevityCheckCmdStmt
| LevityCheckMkCmdEnv !Var
| LevityCheckDoCmd !(HsCmd GhcTc)
| LevityCheckDesugaringCmd !(LHsCmd GhcTc)
| LevityCheckInCmd !(LHsCmd GhcTc)
| LevityCheckInFunUse !(LHsExpr GhcTc)
| LevityCheckInValidDataCon
| LevityCheckInValidClass
-- | Why the particular injectivity error arose together with more information,
-- if any.
data InjectivityErrReason
= InjErrRhsBareTyVar [Type]
| InjErrRhsCannotBeATypeFam
| InjErrRhsOverlap
| InjErrCannotInferFromRhs !TyVarSet !HasKinds !SuggestUndecidableInstances
data HasKinds
= YesHasKinds
| NoHasKinds
deriving (Show, Eq)
hasKinds :: Bool -> HasKinds
hasKinds True = YesHasKinds
hasKinds False = NoHasKinds
data SuggestUndecidableInstances
= YesSuggestUndecidableInstaces
| NoSuggestUndecidableInstaces
deriving (Show, Eq)
suggestUndecidableInstances :: Bool -> SuggestUndecidableInstances
suggestUndecidableInstances True = YesSuggestUndecidableInstaces
suggestUndecidableInstances False = NoSuggestUndecidableInstaces
-- | A data type to describe why a variable is not closed.
-- See Note [Not-closed error messages] in GHC.Tc.Gen.Expr
data NotClosedReason = NotLetBoundReason
| NotTypeClosed VarSet
| NotClosed Name NotClosedReason
data SuggestPartialTypeSignatures
= YesSuggestPartialTypeSignatures
| NoSuggestPartialTypeSignatures
deriving (Show, Eq)
suggestPartialTypeSignatures :: Bool -> SuggestPartialTypeSignatures
suggestPartialTypeSignatures True = YesSuggestPartialTypeSignatures
suggestPartialTypeSignatures False = NoSuggestPartialTypeSignatures
data UsingGeneralizedNewtypeDeriving
= YesGeneralizedNewtypeDeriving
| NoGeneralizedNewtypeDeriving
deriving Eq
usingGeneralizedNewtypeDeriving :: Bool -> UsingGeneralizedNewtypeDeriving
usingGeneralizedNewtypeDeriving True = YesGeneralizedNewtypeDeriving
usingGeneralizedNewtypeDeriving False = NoGeneralizedNewtypeDeriving
data DeriveAnyClassEnabled
= YesDeriveAnyClassEnabled
| NoDeriveAnyClassEnabled
deriving Eq
deriveAnyClassEnabled :: Bool -> DeriveAnyClassEnabled
deriveAnyClassEnabled True = YesDeriveAnyClassEnabled
deriveAnyClassEnabled False = NoDeriveAnyClassEnabled
-- | Why a particular typeclass instance couldn't be derived.
data DeriveInstanceErrReason
=
-- | The typeclass instance is not well-kinded.
DerivErrNotWellKinded !TyCon
-- ^ The type constructor that occurs in
-- the typeclass instance declaration.
!Kind
-- ^ The typeclass kind.
!Int
-- ^ The number of typeclass arguments that GHC
-- kept. See Note [tc_args and tycon arity] in
-- GHC.Tc.Deriv.
-- | Generic instances can only be derived using the stock strategy
-- in Safe Haskell.
| DerivErrSafeHaskellGenericInst
| DerivErrDerivingViaWrongKind !Kind !Type !Kind
| DerivErrNoEtaReduce !Type
-- ^ The instance type
-- | We cannot derive instances in boot files
| DerivErrBootFileFound
| DerivErrDataConsNotAllInScope !TyCon
-- | We cannot use GND on non-newtype types
| DerivErrGNDUsedOnData
-- | We cannot derive instances of nullary classes
| DerivErrNullaryClasses
-- | Last arg must be newtype or data application
| DerivErrLastArgMustBeApp
| DerivErrNoFamilyInstance !TyCon [Type]
| DerivErrNotStockDeriveable !DeriveAnyClassEnabled
| DerivErrHasAssociatedDatatypes !HasAssociatedDataFamInsts
!AssociatedTyLastVarInKind
!AssociatedTyNotParamOverLastTyVar
| DerivErrNewtypeNonDeriveableClass
| DerivErrCannotEtaReduceEnough !Bool -- Is eta-reduction OK?
| DerivErrOnlyAnyClassDeriveable !TyCon
-- ^ Type constructor for which the instance
-- is requested
!DeriveAnyClassEnabled
-- ^ Whether or not -XDeriveAnyClass is enabled
-- already.
-- | Stock deriving won't work, but perhas DeriveAnyClass will.
| DerivErrNotDeriveable !DeriveAnyClassEnabled
-- | The given 'PredType' is not a class.
| DerivErrNotAClass !PredType
-- | The given (representation of the) 'TyCon' has no
-- data constructors.
| DerivErrNoConstructors !TyCon
| DerivErrLangExtRequired !LangExt.Extension
-- | GHC simply doesn't how to how derive the input 'Class' for the given
-- 'Type'.
| DerivErrDunnoHowToDeriveForType !Type
-- | The given 'TyCon' must be an enumeration.
-- See Note [Enumeration types] in GHC.Core.TyCon
| DerivErrMustBeEnumType !TyCon
-- | The given 'TyCon' must have /precisely/ one constructor.
| DerivErrMustHaveExactlyOneConstructor !TyCon
-- | The given data type must have some parameters.
| DerivErrMustHaveSomeParameters !TyCon
-- | The given data type must not have a class context.
| DerivErrMustNotHaveClassContext !TyCon !ThetaType
-- | We couldn't derive an instance for a particular data constructor
-- for a variety of reasons.
| DerivErrBadConstructor !(Maybe HasWildcard) [DeriveInstanceBadConstructor]
-- | We couldn't derive a 'Generic' instance for the given type for a
-- variety of reasons
| DerivErrGenerics [DeriveGenericsErrReason]
-- | We couldn't derive an instance either because the type was not an
-- enum type or because it did have more than one constructor.
| DerivErrEnumOrProduct !DeriveInstanceErrReason !DeriveInstanceErrReason
data DeriveInstanceBadConstructor
=
-- | The given 'DataCon' must be truly polymorphic in the
-- last argument of the data type.
DerivErrBadConExistential !DataCon
-- | The given 'DataCon' must not use the type variable in a function argument"
| DerivErrBadConCovariant !DataCon
-- | The given 'DataCon' must not contain function types
| DerivErrBadConFunTypes !DataCon
-- | The given 'DataCon' must use the type variable only
-- as the last argument of a data type
| DerivErrBadConWrongArg !DataCon
-- | The given 'DataCon' is a GADT so we cannot directly
-- derive an istance for it.
| DerivErrBadConIsGADT !DataCon
-- | The given 'DataCon' has existentials type vars in its type.
| DerivErrBadConHasExistentials !DataCon
-- | The given 'DataCon' has constraints in its type.
| DerivErrBadConHasConstraints !DataCon
-- | The given 'DataCon' has a higher-rank type.
| DerivErrBadConHasHigherRankType !DataCon
data DeriveGenericsErrReason
= -- | The type must not have some datatype context.
DerivErrGenericsMustNotHaveDatatypeContext !TyCon
-- | The data constructor must not have exotic unlifted
-- or polymorphic arguments.
| DerivErrGenericsMustNotHaveExoticArgs !DataCon
-- | The data constructor must be a vanilla constructor.
| DerivErrGenericsMustBeVanillaDataCon !DataCon
-- | The type must have some type parameters.
-- check (d) from Note [Requirements for deriving Generic and Rep]
-- in GHC.Tc.Deriv.Generics.
| DerivErrGenericsMustHaveSomeTypeParams !TyCon
-- | The data constructor must not have existential arguments.
| DerivErrGenericsMustNotHaveExistentials !DataCon
-- | The derivation applies a type to an argument involving
-- the last parameter but the applied type is not of kind * -> *.
| DerivErrGenericsWrongArgKind !DataCon
data HasWildcard
= YesHasWildcard
| NoHasWildcard
deriving Eq
hasWildcard :: Bool -> HasWildcard
hasWildcard True = YesHasWildcard
hasWildcard False = NoHasWildcard
-- | A type representing whether or not the input type has associated data family instances.
data HasAssociatedDataFamInsts
= YesHasAdfs
| NoHasAdfs
deriving Eq
hasAssociatedDataFamInsts :: Bool -> HasAssociatedDataFamInsts
hasAssociatedDataFamInsts True = YesHasAdfs
hasAssociatedDataFamInsts False = NoHasAdfs
-- | If 'YesAssocTyLastVarInKind', the associated type of a typeclass
-- contains the last type variable of the class in a kind, which is not (yet) allowed
-- by GHC.
data AssociatedTyLastVarInKind
= YesAssocTyLastVarInKind !TyCon -- ^ The associated type family of the class
| NoAssocTyLastVarInKind
deriving Eq
associatedTyLastVarInKind :: Maybe TyCon -> AssociatedTyLastVarInKind
associatedTyLastVarInKind (Just tc) = YesAssocTyLastVarInKind tc
associatedTyLastVarInKind Nothing = NoAssocTyLastVarInKind
-- | If 'NoAssociatedTyNotParamOverLastTyVar', the associated type of a
-- typeclass is not parameterized over the last type variable of the class
data AssociatedTyNotParamOverLastTyVar
= YesAssociatedTyNotParamOverLastTyVar !TyCon -- ^ The associated type family of the class
| NoAssociatedTyNotParamOverLastTyVar
deriving Eq
associatedTyNotParamOverLastTyVar :: Maybe TyCon -> AssociatedTyNotParamOverLastTyVar
associatedTyNotParamOverLastTyVar (Just tc) = YesAssociatedTyNotParamOverLastTyVar tc
associatedTyNotParamOverLastTyVar Nothing = NoAssociatedTyNotParamOverLastTyVar
|