ghc-9.6.1: GHC/Tc/Errors/Types.hs
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE KindSignatures #-}
module GHC.Tc.Errors.Types (
-- * Main types
TcRnMessage(..)
, mkTcRnUnknownMessage
, TcRnMessageDetailed(..)
, TypeDataForbids(..)
, ErrInfo(..)
, FixedRuntimeRepProvenance(..)
, pprFixedRuntimeRepProvenance
, ShadowedNameProvenance(..)
, RecordFieldPart(..)
, IllegalNewtypeReason(..)
, InjectivityErrReason(..)
, HasKinds(..)
, hasKinds
, SuggestUndecidableInstances(..)
, suggestUndecidableInstances
, SuggestUnliftedTypes(..)
, DataSort(..), ppDataSort
, AllowedDataResKind(..)
, NotClosedReason(..)
, SuggestPartialTypeSignatures(..)
, suggestPartialTypeSignatures
, DeriveInstanceErrReason(..)
, UsingGeneralizedNewtypeDeriving(..)
, usingGeneralizedNewtypeDeriving
, DeriveAnyClassEnabled(..)
, deriveAnyClassEnabled
, DeriveInstanceBadConstructor(..)
, HasWildcard(..)
, hasWildcard
, BadAnonWildcardContext(..)
, SoleExtraConstraintWildcardAllowed(..)
, DeriveGenericsErrReason(..)
, HasAssociatedDataFamInsts(..)
, hasAssociatedDataFamInsts
, AssociatedTyLastVarInKind(..)
, associatedTyLastVarInKind
, AssociatedTyNotParamOverLastTyVar(..)
, associatedTyNotParamOverLastTyVar
, MissingSignature(..)
, Exported(..)
, HsDocContext(..)
, FixedRuntimeRepErrorInfo(..)
, ErrorItem(..), errorItemOrigin, errorItemEqRel, errorItemPred, errorItemCtLoc
, SolverReport(..), SolverReportSupplementary(..)
, SolverReportWithCtxt(..)
, SolverReportErrCtxt(..)
, getUserGivens, discardProvCtxtGivens
, TcSolverReportMsg(..)
, CannotUnifyVariableReason(..)
, MismatchMsg(..)
, MismatchEA(..)
, mkPlainMismatchMsg, mkBasicMismatchMsg
, WhenMatching(..)
, ExpectedActualInfo(..)
, TyVarInfo(..), SameOccInfo(..)
, AmbiguityInfo(..)
, CND_Extra(..)
, FitsMbSuppressed(..)
, ValidHoleFits(..), noValidHoleFits
, HoleFitDispConfig(..)
, RelevantBindings(..), pprRelevantBindings
, PromotionErr(..), pprPECategory, peCategory
, NotInScopeError(..), mkTcRnNotInScope
, ImportError(..)
, HoleError(..)
, CoercibleMsg(..)
, PotentialInstances(..)
, UnsupportedCallConvention(..)
, ExpectedBackends
, ArgOrResult(..)
, MatchArgsContext(..), MatchArgBadMatches(..)
, ConversionFailReason(..)
, UnrepresentableTypeDescr(..)
, LookupTHInstNameErrReason(..)
, SplicePhase(..)
, THDeclDescriptor(..)
, RunSpliceFailReason(..)
, ThingBeingConverted(..)
, IllegalDecls(..)
, EmptyStatementGroupErrReason(..)
, UnexpectedStatement(..)
) where
import GHC.Prelude
import GHC.Hs
import {-# SOURCE #-} GHC.Tc.Types (TcIdSigInfo, TcTyThing)
import {-# SOURCE #-} GHC.Tc.Errors.Hole.FitTypes (HoleFit)
import GHC.Tc.Types.Constraint
import GHC.Tc.Types.Evidence (EvBindsVar)
import GHC.Tc.Types.Origin ( CtOrigin (ProvCtxtOrigin), SkolemInfoAnon (SigSkol)
, UserTypeCtxt (PatSynCtxt), TyVarBndrs, TypedThing
, FixedRuntimeRepOrigin(..) )
import GHC.Tc.Types.Rank (Rank)
import GHC.Tc.Utils.TcType (IllegalForeignTypeReason, TcType)
import GHC.Types.Error
import GHC.Types.Hint (UntickedPromotedThing(..))
import GHC.Types.ForeignCall (CLabelString)
import GHC.Types.Name (Name, OccName, getSrcLoc, getSrcSpan)
import qualified GHC.Types.Name.Occurrence as OccName
import GHC.Types.Name.Reader
import GHC.Types.SrcLoc
import GHC.Types.TyThing (TyThing)
import GHC.Types.Var (Id, TyCoVar, TyVar, TcTyVar)
import GHC.Types.Var.Env (TidyEnv)
import GHC.Types.Var.Set (TyVarSet, VarSet)
import GHC.Unit.Types (Module)
import GHC.Utils.Outputable
import GHC.Core.Class (Class, ClassMinimalDef)
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.PatSyn (PatSyn)
import GHC.Core.Predicate (EqRel, predTypeEqRel)
import GHC.Core.TyCon (TyCon, TyConFlavour)
import GHC.Core.Type (Kind, Type, ThetaType, PredType)
import GHC.Driver.Backend (Backend)
import GHC.Unit.State (UnitState)
import GHC.Types.Basic
import GHC.Utils.Misc (capitalise, filterOut)
import qualified GHC.LanguageExtensions as LangExt
import GHC.Data.FastString (FastString)
import GHC.Exception.Type (SomeException)
import Language.Haskell.Syntax.Basic (FieldLabelString(..))
import qualified Data.List.NonEmpty as NE
import Data.Typeable (Typeable)
import GHC.Unit.Module.Warnings (WarningTxt)
import qualified Language.Haskell.TH.Syntax as TH
import GHC.Generics ( Generic )
{-
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 bulleted 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
deriving Generic
mkTcRnUnknownMessage :: (Diagnostic a, Typeable a, DiagnosticOpts a ~ NoDiagnosticOpts)
=> a -> TcRnMessage
mkTcRnUnknownMessage diag = TcRnUnknownMessage (UnknownDiagnostic diag)
-- | An error which might arise during typechecking/renaming.
data TcRnMessage where
{-| Simply wraps an unknown 'Diagnostic' message @a@. It can be used by plugins
to provide custom diagnostic messages originated during typechecking/renaming.
-}
TcRnUnknownMessage :: UnknownDiagnostic -> 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
{-| TcRnWithHsDocContext annotates an error message with the context in which
it originated.
-}
TcRnWithHsDocContext :: !HsDocContext
-> !TcRnMessage
-> TcRnMessage
{-| TcRnSolverReport is the constructor used to report unsolved constraints
after constraint solving, as well as other errors such as hole fit errors.
See the documentation of the 'TcSolverReportMsg' datatype for an overview
of the different errors.
-}
TcRnSolverReport :: SolverReportWithCtxt
-> DiagnosticReason
-> [GhcHint]
-> TcRnMessage
-- TODO: split up TcRnSolverReport into several components,
-- so that we can compute the reason and hints, as opposed
-- to having to pass them here.
{-| TcRnRedundantConstraints is a warning that is emitted when a binding
has a user-written type signature which contains superfluous constraints.
Example:
f :: (Eq a, Ord a) => a -> a -> a
f x y = (x < y) || x == y
-- `Eq a` is superfluous: the `Ord a` constraint suffices.
Test cases: T9939, T10632, T18036a, T20602, PluralS, T19296.
-}
TcRnRedundantConstraints :: [Id]
-> (SkolemInfoAnon, Bool)
-- ^ The contextual skolem info.
-- The boolean controls whether we
-- want to show it in the user message.
-- (Nice to keep track of the info in either case,
-- for other users of the GHC API.)
-> TcRnMessage
{-| TcRnInaccessibleCode is a warning that is emitted when the RHS of a pattern
match is inaccessible, because the constraint solver has detected a contradiction.
Example:
data B a where { MkTrue :: B True; MkFalse :: B False }
foo :: B False -> Bool
foo MkFalse = False
foo MkTrue = True -- Inaccessible: requires True ~ False
Test cases: T7293, T7294, T15558, T17646, T18572, T18610, tcfail167.
-}
TcRnInaccessibleCode :: Implication -- ^ The implication containing a contradiction.
-> SolverReportWithCtxt -- ^ The contradiction.
-> TcRnMessage
{-| A type which was expected to have a fixed runtime representation
does not have a fixed runtime representation.
Example:
data D (a :: TYPE r) = MkD a
Test cases: T11724, T18534,
RepPolyPatSynArg, RepPolyPatSynUnliftedNewtype,
RepPolyPatSynRes, T20423
-}
TcRnTypeDoesNotHaveFixedRuntimeRep :: !Type
-> !FixedRuntimeRepProvenance
-> !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 :: Name -> !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 occurs 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
{-| TcRnIllegalWildcardInType is an error that occurs
when a wildcard appears in a type in a location in which
wildcards aren't allowed.
Examples:
Type synonyms:
type T = _
Class declarations and instances:
class C _
instance C _
Standalone kind signatures:
type D :: _
data D
Test cases:
ExtraConstraintsWildcardInTypeSplice2
ExtraConstraintsWildcardInTypeSpliceUsed
ExtraConstraintsWildcardNotLast
ExtraConstraintsWildcardTwice
NestedExtraConstraintsWildcard
NestedNamedExtraConstraintsWildcard
PartialClassMethodSignature
PartialClassMethodSignature2
T12039
T13324_fail1
UnnamedConstraintWildcard1
UnnamedConstraintWildcard2
WildcardInADT1
WildcardInADT2
WildcardInADT3
WildcardInADTContext1
WildcardInDefault
WildcardInDefaultSignature
WildcardInDeriving
WildcardInForeignExport
WildcardInForeignImport
WildcardInGADT1
WildcardInGADT2
WildcardInInstanceHead
WildcardInInstanceSig
WildcardInNewtype
WildcardInPatSynSig
WildcardInStandaloneDeriving
WildcardInTypeFamilyInstanceRHS
WildcardInTypeSynonymRHS
saks_fail003
T15433a
-}
TcRnIllegalWildcardInType
:: Maybe Name
-- ^ the wildcard name, or 'Nothing' for an anonymous wildcard
-> !BadAnonWildcardContext
-> 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
{-| TcRnTagToEnumResTyTypeData is an error that occurs when the 'tagToEnum#'
function is given a result type that is headed by a @type data@ type, as
the data constructors of a @type data@ do not exist at the term level.
Example(s):
type data Letter = A | B | C
foo :: Letter
foo = tagToEnum# 0#
Test cases: type-data/should_fail/TDTagToEnum.hs
-}
TcRnTagToEnumResTyTypeData :: 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
{-| 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 -- ^ user-written name of type variable being quantified
-> Name -- ^ function name
-> Maybe Type -- ^ type the variable unified with, if known
-> LHsSigWcType GhcRn -- ^ partial type signature
-> TcRnMessage
{-| TcRnMissingSignature is a warning that occurs when a top-level binding
or a pattern synonym does not have a type signature.
Controlled by the flags:
-Wmissing-signatures
-Wmissing-exported-signatures
-Wmissing-pattern-synonym-signatures
-Wmissing-exported-pattern-synonym-signatures
-Wmissing-kind-signatures
Test cases:
T11077 (top-level bindings)
T12484 (pattern synonyms)
T19564 (kind signatures)
-}
TcRnMissingSignature :: MissingSignature
-> Exported
-> Bool -- ^ True: -Wmissing-signatures overrides -Wmissing-exported-signatures,
-- or -Wmissing-pattern-synonym-signatures overrides -Wmissing-exported-pattern-synonym-signatures
-> 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
or unboxed sum type is specified as a function argument, when the appropriate
extension (`-XUnboxedTuples` or `-XUnboxedSums`) isn't enabled.
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
-}
TcRnUnboxedTupleOrSumTypeFuncArg
:: UnboxedTupleOrSum -- ^ whether this is an unboxed tuple or an unboxed sum
-> !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 :: !(Maybe 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
{-| TcRnLazyBangOnUnliftedType is a warning (controlled by -Wredundant-strictness-flags) that
occurs when a lazy annotation is applied to an unlifted type.
Example(s):
data T = MkT ~Int# -- Lazy flag has no effect on unlifted types
Test cases: typecheck/should_compile/T21951a
typecheck/should_compile/T21951b
-}
TcRnLazyBangOnUnliftedType :: !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
{-| TcRnSpecialClassInst is an error that occurs when a user
attempts to define an instance for a built-in typeclass such as
'Coercible', 'Typeable', or 'KnownNat', outside of a signature file.
Test cases: deriving/should_fail/T9687
deriving/should_fail/T14916
polykinds/T8132
typecheck/should_fail/TcCoercibleFail2
typecheck/should_fail/T12837
typecheck/should_fail/T14390
-}
TcRnSpecialClassInst :: !Class
-> !Bool -- ^ Whether the error is due to Safe Haskell being enabled
-> 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
{-| TcRnLazyGADTPattern is an error that occurs when a user writes a nested
GADT pattern match inside a lazy (~) pattern.
Test case: gadt/lazypat
-}
TcRnLazyGADTPattern :: TcRnMessage
{-| TcRnArrowProcGADTPattern is an error that occurs when a user writes a
GADT pattern inside arrow proc notation.
Test case: arrows/should_fail/arrowfail004.
-}
TcRnArrowProcGADTPattern :: TcRnMessage
{-| TcRnForallIdentifier is a warning (controlled with -Wforall-identifier) that occurs
when a definition uses 'forall' as an identifier.
Example:
forall x = ()
g forall = ()
Test cases: T20609 T20609a T20609b T20609c T20609d
-}
TcRnForallIdentifier :: RdrName -> TcRnMessage
{-| TcRnTypeEqualityOutOfScope is a warning (controlled by -Wtype-equality-out-of-scope)
that occurs when the type equality (a ~ b) is not in scope.
Test case: T18862b
-}
TcRnTypeEqualityOutOfScope :: TcRnMessage
{-| TcRnTypeEqualityRequiresOperators is a warning (controlled by -Wtype-equality-requires-operators)
that occurs when the type equality (a ~ b) is used without the TypeOperators extension.
Example:
{-# LANGUAGE NoTypeOperators #-}
f :: (a ~ b) => a -> b
Test case: T18862a
-}
TcRnTypeEqualityRequiresOperators :: TcRnMessage
{-| TcRnIllegalTypeOperator is an error that occurs when a type operator
is used without the TypeOperators extension.
Example:
{-# LANGUAGE NoTypeOperators #-}
f :: Vec a n -> Vec a m -> Vec a (n + m)
Test case: T12811
-}
TcRnIllegalTypeOperator :: !SDoc -> !RdrName -> TcRnMessage
{-| TcRnIllegalTypeOperatorDecl is an error that occurs when a type or class
operator is declared without the TypeOperators extension.
See Note [Type and class operator definitions]
Example:
{-# LANGUAGE Haskell2010 #-}
{-# LANGUAGE MultiParamTypeClasses #-}
module T3265 where
data a :+: b = Left a | Right b
class a :*: b where {}
Test cases: T3265, tcfail173
-}
TcRnIllegalTypeOperatorDecl :: !RdrName -> TcRnMessage
{-| TcRnGADTMonoLocalBinds is a warning controlled by -Wgadt-mono-local-binds
that occurs when pattern matching on a GADT when -XMonoLocalBinds is off.
Example(s): None
Test cases: T20485, T20485a
-}
TcRnGADTMonoLocalBinds :: TcRnMessage
{-| The TcRnNotInScope constructor is used for various not-in-scope errors.
See 'NotInScopeError' for more details. -}
TcRnNotInScope :: NotInScopeError -- ^ what the problem is
-> RdrName -- ^ the name that is not in scope
-> [ImportError] -- ^ import errors that are relevant
-> [GhcHint] -- ^ hints, e.g. enable DataKinds to refer to a promoted data constructor
-> TcRnMessage
{-| TcRnUntickedPromotedThing is a warning (controlled with -Wunticked-promoted-constructors)
that is triggered by an unticked occurrence of a promoted data constructor.
Examples:
data A = MkA
type family F (a :: A) where { F MkA = Bool }
type B = [ Int, Bool ]
Test cases: T9778, T19984.
-}
TcRnUntickedPromotedThing :: UntickedPromotedThing
-> TcRnMessage
{-| TcRnIllegalBuiltinSyntax is an error that occurs when built-in syntax appears
in an unexpected location, e.g. as a data constructor or in a fixity declaration.
Examples:
infixl 5 :
data P = (,)
Test cases: rnfail042, T14907b, T15124, T15233.
-}
TcRnIllegalBuiltinSyntax :: SDoc -- ^ what kind of thing this is (a binding, fixity declaration, ...)
-> RdrName
-> TcRnMessage
-- TODO: remove the SDoc argument.
{-| TcRnWarnDefaulting is a warning (controlled by -Wtype-defaults)
that is triggered whenever a Wanted typeclass constraint
is solving through the defaulting of a type variable.
Example:
one = show 1
-- We get Wanteds Show a0, Num a0, and default a0 to Integer.
Test cases:
none (which are really specific to defaulting),
but see e.g. tcfail204.
-}
TcRnWarnDefaulting :: [Ct] -- ^ Wanted constraints in which defaulting occurred
-> Maybe TyVar -- ^ The type variable being defaulted
-> Type -- ^ The default type
-> TcRnMessage
{-| TcRnIncorrectNameSpace is an error that occurs when a 'Name'
is used in the incorrect 'NameSpace', e.g. a type constructor
or class used in a term, or a term variable used in a type.
Example:
f x = Int
Test cases: T18740a, T20884.
-}
TcRnIncorrectNameSpace :: Name
-> Bool -- ^ whether the error is happening
-- in a Template Haskell tick
-- (so we should give a Template Haskell hint)
-> TcRnMessage
{- TcRnForeignImportPrimExtNotSet is an error occurring when a foreign import
is declared using the @prim@ calling convention without having turned on
the -XGHCForeignImportPrim extension.
Example(s):
foreign import prim "foo" foo :: ByteArray# -> (# Int#, Int# #)
Test cases: ffi/should_fail/T20116
-}
TcRnForeignImportPrimExtNotSet :: ForeignImport GhcRn -> TcRnMessage
{- TcRnForeignImportPrimSafeAnn is an error declaring that the safe/unsafe
annotation should not be used with @prim@ foreign imports.
Example(s):
foreign import prim unsafe "my_primop_cmm" :: ...
Test cases: None
-}
TcRnForeignImportPrimSafeAnn :: ForeignImport GhcRn -> TcRnMessage
{- TcRnForeignFunctionImportAsValue is an error explaining that foreign @value@
imports cannot have function types.
Example(s):
foreign import capi "math.h value sqrt" f :: CInt -> CInt
Test cases: ffi/should_fail/capi_value_function
-}
TcRnForeignFunctionImportAsValue :: ForeignImport GhcRn -> TcRnMessage
{- TcRnFunPtrImportWithoutAmpersand is a warning controlled by @-Wdodgy-foreign-imports@
that informs the user of a possible missing @&@ in the declaration of a
foreign import with a 'FunPtr' return type.
Example(s):
foreign import ccall "f" f :: FunPtr (Int -> IO ())
Test cases: ffi/should_compile/T1357
-}
TcRnFunPtrImportWithoutAmpersand :: ForeignImport GhcRn -> TcRnMessage
{- TcRnIllegalForeignDeclBackend is an error occurring when a foreign import declaration
is not compatible with the code generation backend being used.
Example(s): None
Test cases: None
-}
TcRnIllegalForeignDeclBackend
:: Either (ForeignExport GhcRn) (ForeignImport GhcRn)
-> Backend
-> ExpectedBackends
-> TcRnMessage
{- TcRnUnsupportedCallConv informs the user that the calling convention specified
for a foreign export declaration is not compatible with the target platform.
It is a warning controlled by @-Wunsupported-calling-conventions@ in the case of
@stdcall@ but is otherwise considered an error.
Example(s): None
Test cases: None
-}
TcRnUnsupportedCallConv :: Either (ForeignExport GhcRn) (ForeignImport GhcRn)
-> UnsupportedCallConvention
-> TcRnMessage
{- TcRnIllegalForeignType is an error for when a type appears in a foreign
function signature that is not compatible with the FFI.
Example(s): None
Test cases: ffi/should_fail/T3066
ffi/should_fail/ccfail004
ffi/should_fail/T10461
ffi/should_fail/T7506
ffi/should_fail/T5664
safeHaskell/ghci/p6
safeHaskell/safeLanguage/SafeLang08
ffi/should_fail/T16702
linear/should_fail/LinearFFI
ffi/should_fail/T7243
-}
TcRnIllegalForeignType :: !(Maybe ArgOrResult) -> !IllegalForeignTypeReason -> TcRnMessage
{- TcRnInvalidCIdentifier indicates a C identifier that is not valid.
Example(s):
foreign import prim safe "not valid" cmm_test2 :: Int# -> Int#
Test cases: th/T10638
-}
TcRnInvalidCIdentifier :: !CLabelString -> TcRnMessage
{- TcRnExpectedValueId is an error occurring when something that is not a
value identifier is used where one is expected.
Example(s): none
Test cases: none
-}
TcRnExpectedValueId :: !TcTyThing -> TcRnMessage
{- TcRnNotARecordSelector is an error for when something that is not a record
selector is used in a record pattern.
Example(s):
data Rec = MkRec { field :: Int }
r = Mkrec 1
r' = r { notAField = 2 }
Test cases: rename/should_fail/rnfail054
typecheck/should_fail/tcfail114
-}
TcRnNotARecordSelector :: !Name -> TcRnMessage
{- TcRnRecSelectorEscapedTyVar is an error indicating that a record field selector
containing an existential type variable is used as a function rather than in
a pattern match.
Example(s):
data Rec = forall a. Rec { field :: a }
field (Rec True)
Test cases: patsyn/should_fail/records-exquant
typecheck/should_fail/T3176
-}
TcRnRecSelectorEscapedTyVar :: !OccName -> TcRnMessage
{- TcRnPatSynNotBidirectional is an error for when a non-bidirectional pattern
synonym is used as a constructor.
Example(s):
pattern Five :: Int
pattern Five <- 5
five = Five
Test cases: patsyn/should_fail/records-no-uni-update
patsyn/should_fail/records-no-uni-update2
-}
TcRnPatSynNotBidirectional :: !Name -> TcRnMessage
{- TcRnSplicePolymorphicLocalVar is the error that occurs when the expression
inside typed template haskell brackets is a polymorphic local variable.
Example(s):
x = \(y :: forall a. a -> a) -> [|| y ||]
Test cases: quotes/T10384
-}
TcRnSplicePolymorphicLocalVar :: !Id -> TcRnMessage
{- TcRnIllegalDerivingItem is an error for when something other than a type class
appears in a deriving statement.
Example(s):
data X = X deriving Int
Test cases: deriving/should_fail/T5922
-}
TcRnIllegalDerivingItem :: !(LHsSigType GhcRn) -> TcRnMessage
{- TcRnUnexpectedAnnotation indicates the erroroneous use of an annotation such
as strictness, laziness, or unpacking.
Example(s):
data T = T { t :: Maybe {-# UNPACK #-} Int }
data C = C { f :: !IntMap Int }
Test cases: parser/should_fail/unpack_inside_type
typecheck/should_fail/T7210
-}
TcRnUnexpectedAnnotation :: !(HsType GhcRn) -> !HsSrcBang -> TcRnMessage
{- TcRnIllegalRecordSyntax is an error indicating an illegal use of record syntax.
Example(s):
data T = T Int { field :: Int }
Test cases: rename/should_fail/T7943
rename/should_fail/T9077
-}
TcRnIllegalRecordSyntax :: !(HsType GhcRn) -> TcRnMessage
{- TcRnUnexpectedTypeSplice is an error for a typed template haskell splice
appearing unexpectedly.
Example(s): none
Test cases: none
-}
TcRnUnexpectedTypeSplice :: !(HsType GhcRn) -> TcRnMessage
{- TcRnInvalidVisibleKindArgument is an error for a kind application on a
target type that cannot accept it.
Example(s):
bad :: Int @Type
bad = 1
type Foo :: forall a {b}. a -> b -> b
type Foo x y = y
type Bar = Foo @Bool @Int True 42
Test cases: indexed-types/should_fail/T16356_Fail3
typecheck/should_fail/ExplicitSpecificity7
typecheck/should_fail/T12045b
typecheck/should_fail/T12045c
typecheck/should_fail/T15592a
typecheck/should_fail/T15816
-}
TcRnInvalidVisibleKindArgument
:: !(LHsType GhcRn) -- ^ The visible kind argument
-> !Type -- ^ Target of the kind application
-> TcRnMessage
{- TcRnTooManyBinders is an error for a type constructor that is declared with
more arguments then its kind specifies.
Example(s):
type T :: Type -> (Type -> Type) -> Type
data T a (b :: Type -> Type) x1 (x2 :: Type -> Type)
Test cases: saks/should_fail/saks_fail008
-}
TcRnTooManyBinders :: !Kind -> ![LHsTyVarBndr () GhcRn] -> TcRnMessage
{- TcRnDifferentNamesForTyVar is an error that indicates different names being
used for the same type variable.
Example(s):
data SameKind :: k -> k -> *
data Q (a :: k1) (b :: k2) c = MkQ (SameKind a b)
Test cases: polykinds/T11203
polykinds/T11821a
saks/should_fail/T20916
typecheck/should_fail/T17566b
typecheck/should_fail/T17566c
-}
TcRnDifferentNamesForTyVar :: !Name -> !Name -> TcRnMessage
{- TcRnInvalidReturnKind is an error for a data declaration that has a kind signature
with an invalid result kind.
Example(s):
data family Foo :: Constraint
Test cases: typecheck/should_fail/T14048b
typecheck/should_fail/UnliftedNewtypesConstraintFamily
typecheck/should_fail/T12729
typecheck/should_fail/T15883
typecheck/should_fail/T16829a
typecheck/should_fail/T16829b
typecheck/should_fail/UnliftedNewtypesNotEnabled
typecheck/should_fail/tcfail079
-}
TcRnInvalidReturnKind
:: !DataSort -- ^ classification of thing being returned
-> !AllowedDataResKind -- ^ allowed kind
-> !Kind -- ^ the return kind
-> !(Maybe SuggestUnliftedTypes) -- ^ suggested extension
-> TcRnMessage
{- TcRnClassKindNotConstraint is an error for a type class that has a kind that
is not equivalent to Constraint.
Example(s):
type C :: Type -> Type
class C a
Test cases: saks/should_fail/T16826
-}
TcRnClassKindNotConstraint :: !Kind -> TcRnMessage
{- TcRnUnpromotableThing is an error that occurs when the user attempts to
use the promoted version of something which is not promotable.
Example(s):
data T :: T -> *
data X a where
MkX :: Show a => a -> X a
foo :: Proxy ('MkX 'True)
foo = Proxy
Test cases: dependent/should_fail/PromotedClass
dependent/should_fail/T14845_fail1
dependent/should_fail/T14845_fail2
dependent/should_fail/T15215
dependent/should_fail/T13780c
dependent/should_fail/T15245
polykinds/T5716
polykinds/T5716a
polykinds/T6129
polykinds/T7433
patsyn/should_fail/T11265
patsyn/should_fail/T9161-1
patsyn/should_fail/T9161-2
dependent/should_fail/SelfDep
polykinds/PolyKinds06
polykinds/PolyKinds07
polykinds/T13625
polykinds/T15116
polykinds/T15116a
saks/should_fail/T16727a
saks/should_fail/T16727b
rename/should_fail/T12686
-}
TcRnUnpromotableThing :: !Name -> !PromotionErr -> TcRnMessage
{- TcRnMatchesHaveDiffNumArgs is an error occurring when something has matches
that have different numbers of arguments
Example(s):
foo x = True
foo x y = False
Test cases: rename/should_fail/rnfail045
typecheck/should_fail/T20768_fail
-}
TcRnMatchesHaveDiffNumArgs
:: !(HsMatchContext GhcTc) -- ^ Pattern match specifics
-> !MatchArgBadMatches
-> TcRnMessage
{- TcRnCannotBindScopedTyVarInPatSig is an error stating that scoped type
variables cannot be used in pattern bindings.
Example(s):
let (x :: a) = 5
Test cases: typecheck/should_compile/tc141
-}
TcRnCannotBindScopedTyVarInPatSig :: !(NE.NonEmpty (Name, TcTyVar)) -> TcRnMessage
{- TcRnCannotBindTyVarsInPatBind is an error for when type
variables are introduced in a pattern binding
Example(s):
Just @a x = Just True
Test cases: typecheck/should_fail/TyAppPat_PatternBinding
typecheck/should_fail/TyAppPat_PatternBindingExistential
-}
TcRnCannotBindTyVarsInPatBind :: !(NE.NonEmpty (Name, TcTyVar)) -> TcRnMessage
{- TcRnTooManyTyArgsInConPattern is an error occurring when a constructor pattern
has more than the expected number of type arguments
Example(s):
f (Just @Int @Bool x) = x
Test cases: typecheck/should_fail/TyAppPat_TooMany
typecheck/should_fail/T20443b
-}
TcRnTooManyTyArgsInConPattern
:: !ConLike
-> !Int -- ^ Expected number of args
-> !Int -- ^ Actual number of args
-> TcRnMessage
{- TcRnMultipleInlinePragmas is a warning signifying that multiple inline pragmas
reference the same definition.
Example(s):
{-# INLINE foo #-}
{-# INLINE foo #-}
foo :: Bool -> Bool
foo = id
Test cases: none
-}
TcRnMultipleInlinePragmas
:: !Id -- ^ Target of the pragmas
-> !(LocatedA InlinePragma) -- ^ The first pragma
-> !(NE.NonEmpty (LocatedA InlinePragma)) -- ^ Other pragmas
-> TcRnMessage
{- TcRnUnexpectedPragmas is a warning that occurs when unexpected pragmas appear
in the source.
Example(s):
Test cases: none
-}
TcRnUnexpectedPragmas :: !Id -> !(NE.NonEmpty (LSig GhcRn)) -> TcRnMessage
{- TcRnNonOverloadedSpecialisePragma is a warning for a specialise pragma being
placed on a definition that is not overloaded.
Example(s):
{-# SPECIALISE foo :: Bool -> Bool #-}
foo :: Bool -> Bool
foo = id
Test cases: simplCore/should_compile/T8537
typecheck/should_compile/T10504
-}
TcRnNonOverloadedSpecialisePragma :: !(LIdP GhcRn) -> TcRnMessage
{- TcRnSpecialiseNotVisible is a warning that occurs when the subject of a
SPECIALISE pragma has a definition that is not visible from the current module.
Example(s): none
Test cases: none
-}
TcRnSpecialiseNotVisible :: !Name -> TcRnMessage
{- TcRnNameByTemplateHaskellQuote is an error that occurs when one tries
to use a Template Haskell splice to define a top-level identifier with
an already existing name.
(See issue #13968 (closed) on GHC's issue tracker for more details)
Example(s):
$(pure [ValD (VarP 'succ) (NormalB (ConE 'True)) []])
Test cases:
T13968
-}
TcRnNameByTemplateHaskellQuote :: !RdrName -> TcRnMessage
{- TcRnIllegalBindingOfBuiltIn is an error that occurs when one uses built-in
syntax for data constructors or class names.
Use an OccName here because we don't want to print Prelude.(,)
Test cases:
rename/should_fail/T14907b
rename/should_fail/rnfail042
-}
TcRnIllegalBindingOfBuiltIn :: !OccName -> TcRnMessage
{- TcRnPragmaWarning is a warning that can happen when usage of something
is warned or deprecated by pragma.
Test cases:
DeprU
T5281
T5867
rn050
rn066 (here is a warning, not deprecation)
T3303
-}
TcRnPragmaWarning :: {
pragma_warning_occ :: OccName,
pragma_warning_msg :: WarningTxt GhcRn,
pragma_warning_import_mod :: ModuleName,
pragma_warning_defined_mod :: ModuleName
} -> TcRnMessage
{-| TcRnIllegalHsigDefaultMethods is an error that occurs when a binding for
a class default method is provided in a Backpack signature file.
Test case:
bkpfail40
-}
TcRnIllegalHsigDefaultMethods :: !Name -- ^ 'Name' of the class
-> NE.NonEmpty (LHsBind GhcRn) -- ^ default methods
-> TcRnMessage
{-| TcRnBadGenericMethod
This test ensures that if you provide a "more specific" type signatures
for the default method, you must also provide a binding.
Example:
{-# LANGUAGE DefaultSignatures #-}
class C a where
meth :: a
default meth :: Num a => a
meth = 0
Test case:
testsuite/tests/typecheck/should_fail/MissingDefaultMethodBinding.hs
-}
TcRnBadGenericMethod :: !Name -- ^ 'Name' of the class
-> !Name -- ^ Problematic method
-> TcRnMessage
{-| TcRnWarningMinimalDefIncomplete is a warning that one must
specify which methods must be implemented by all instances.
Example:
class Cheater a where -- WARNING LINE
cheater :: a
{-# MINIMAL #-} -- warning!
Test case:
testsuite/tests/warnings/minimal/WarnMinimal.hs:
-}
TcRnWarningMinimalDefIncomplete :: ClassMinimalDef -> TcRnMessage
{-| TcRnDefaultMethodForPragmaLacksBinding is an error that occurs when
a default method pragma is missing an accompanying binding.
Test cases:
testsuite/tests/typecheck/should_fail/T5084.hs
testsuite/tests/typecheck/should_fail/T2354.hs
-}
TcRnDefaultMethodForPragmaLacksBinding
:: Id -- ^ method
-> Sig GhcRn -- ^ the pragma
-> TcRnMessage
{-| TcRnIgnoreSpecialisePragmaOnDefMethod is a warning that occurs when
a specialise pragma is put on a default method.
Test cases: none
-}
TcRnIgnoreSpecialisePragmaOnDefMethod
:: !Name
-> TcRnMessage
{-| TcRnBadMethodErr is an error that happens when one attempts to provide a method
in a class instance, when the class doesn't have a method by that name.
Test case:
testsuite/tests/th/T12387
-}
TcRnBadMethodErr
:: { badMethodErrClassName :: !Name
, badMethodErrMethodName :: !Name
} -> TcRnMessage
{-| TcRnNoExplicitAssocTypeOrDefaultDeclaration is an error that occurs
when a class instance does not provide an expected associated type
or default declaration.
Test cases:
testsuite/tests/deriving/should_compile/T14094
testsuite/tests/indexed-types/should_compile/Simple2
testsuite/tests/typecheck/should_compile/tc254
-}
TcRnNoExplicitAssocTypeOrDefaultDeclaration
:: Name
-> TcRnMessage
{-| TcRnIllegalNewtype is an error that occurs when a newtype:
* Does not have exactly one field, or
* is non-linear, or
* is a GADT, or
* has a context in its constructor's type, or
* has existential type variables in its constructor's type, or
* has strictness annotations.
Test cases:
testsuite/tests/gadt/T14719
testsuite/tests/indexed-types/should_fail/T14033
testsuite/tests/indexed-types/should_fail/T2334A
testsuite/tests/linear/should_fail/LinearGADTNewtype
testsuite/tests/parser/should_fail/readFail008
testsuite/tests/polykinds/T11459
testsuite/tests/typecheck/should_fail/T15523
testsuite/tests/typecheck/should_fail/T15796
testsuite/tests/typecheck/should_fail/T17955
testsuite/tests/typecheck/should_fail/T18891a
testsuite/tests/typecheck/should_fail/T21447
testsuite/tests/typecheck/should_fail/tcfail156
-}
TcRnIllegalNewtype
:: DataCon
-> Bool -- ^ True if linear types enabled
-> IllegalNewtypeReason
-> TcRnMessage
{-| TcRnIllegalTypeData is an error that occurs when a @type data@
declaration occurs without the TypeOperators extension.
See Note [Type data declarations]
Test case:
testsuite/tests/type-data/should_fail/TDNoPragma
-}
TcRnIllegalTypeData :: TcRnMessage
{-| TcRnTypeDataForbids is an error that occurs when a @type data@
declaration contains @data@ declaration features that are
forbidden in a @type data@ declaration.
See Note [Type data declarations]
Test cases:
testsuite/tests/type-data/should_fail/TDDeriving
testsuite/tests/type-data/should_fail/TDRecordsGADT
testsuite/tests/type-data/should_fail/TDRecordsH98
testsuite/tests/type-data/should_fail/TDStrictnessGADT
testsuite/tests/type-data/should_fail/TDStrictnessH98
-}
TcRnTypeDataForbids :: !TypeDataForbids -> TcRnMessage
{-| TcRnTypedTHWithPolyType is an error that signifies the illegal use
of a polytype in a typed template haskell expression.
Example(s):
bad :: (forall a. a -> a) -> ()
bad = $$( [|| \_ -> () ||] )
Test cases: th/T11452
-}
TcRnTypedTHWithPolyType :: !TcType -> TcRnMessage
{-| TcRnSpliceThrewException is an error that occurrs when running a template
haskell splice throws an exception.
Example(s):
Test cases: annotations/should_fail/annfail12
perf/compiler/MultiLayerModulesTH_Make
perf/compiler/MultiLayerModulesTH_OneShot
th/T10796b
th/T19470
th/T19709d
th/T5358
th/T5976
th/T7276a
th/T8987
th/TH_exn1
th/TH_exn2
th/TH_runIO
-}
TcRnSpliceThrewException
:: !SplicePhase
-> !SomeException
-> !String -- ^ Result of showing the exception (cannot be done safely outside IO)
-> !(LHsExpr GhcTc)
-> !Bool -- True <=> Print the expression
-> TcRnMessage
{-| TcRnInvalidTopDecl is a template haskell error occurring when one of the 'Dec's passed to
'addTopDecls' is not a function, value, annotation, or foreign import declaration.
Example(s):
Test cases:
-}
TcRnInvalidTopDecl :: !(HsDecl GhcPs) -> TcRnMessage
{-| TcRnNonExactName is a template haskell error for when a declaration being
added is bound to a name that is not fully known.
Example(s):
Test cases:
-}
TcRnNonExactName :: !RdrName -> TcRnMessage
{-| TcRnAddInvalidCorePlugin is a template haskell error indicating that a
core plugin being added has an invalid module due to being in the current package.
Example(s):
Test cases:
-}
TcRnAddInvalidCorePlugin
:: !String -- ^ Module name
-> TcRnMessage
{-| TcRnAddDocToNonLocalDefn is a template haskell error for documentation being added to a
definition which is not in the current module.
Example(s):
Test cases: showIface/should_fail/THPutDocExternal
-}
TcRnAddDocToNonLocalDefn :: !TH.DocLoc -> TcRnMessage
{-| TcRnFailedToLookupThInstName is a template haskell error that occurrs when looking up an
instance fails.
Example(s):
Test cases: showIface/should_fail/THPutDocNonExistent
-}
TcRnFailedToLookupThInstName :: !TH.Type -> !LookupTHInstNameErrReason -> TcRnMessage
{-| TcRnCannotReifyInstance is a template haskell error for when an instance being reified
via `reifyInstances` is not a class constraint or type family application.
Example(s):
Test cases:
-}
TcRnCannotReifyInstance :: !Type -> TcRnMessage
{-| TcRnCannotReifyOutOfScopeThing is a template haskell error indicating
that the given name is not in scope and therefore cannot be reified.
Example(s):
Test cases: th/T16976f
-}
TcRnCannotReifyOutOfScopeThing :: !TH.Name -> TcRnMessage
{-| TcRnCannotReifyThingNotInTypeEnv is a template haskell error occurring
when the given name is not in the type environment and therefore cannot be reified.
Example(s):
Test cases:
-}
TcRnCannotReifyThingNotInTypeEnv :: !Name -> TcRnMessage
{-| TcRnNoRolesAssociatedWithName is a template haskell error for when the user
tries to reify the roles of a given name but it is not something that has
roles associated with it.
Example(s):
Test cases:
-}
TcRnNoRolesAssociatedWithThing :: !TcTyThing -> TcRnMessage
{-| TcRnCannotRepresentThing is a template haskell error indicating that a
type cannot be reified because it does not have a representation in template haskell.
Example(s):
Test cases:
-}
TcRnCannotRepresentType :: !UnrepresentableTypeDescr -> !Type -> TcRnMessage
{-| TcRnRunSpliceFailure is an error indicating that a template haskell splice
failed to be converted into a valid expression.
Example(s):
Test cases: th/T10828a
th/T10828b
th/T12478_4
th/T15270A
th/T15270B
th/T16895a
th/T16895b
th/T16895c
th/T16895d
th/T16895e
th/T17379a
th/T17379b
th/T18740d
th/T2597b
th/T2674
th/T3395
th/T7484
th/T7667a
th/TH_implicitParamsErr1
th/TH_implicitParamsErr2
th/TH_implicitParamsErr3
th/TH_invalid_add_top_decl
-}
TcRnRunSpliceFailure
:: !(Maybe String) -- ^ Name of the function used to run the splice
-> !RunSpliceFailReason
-> TcRnMessage
{-| TcRnUserErrReported is an error or warning thrown using 'qReport' from
the 'Quasi' instance of 'TcM'.
Example(s):
Test cases:
-}
TcRnReportCustomQuasiError
:: !Bool -- True => Error, False => Warning
-> !String -- Error body
-> TcRnMessage
{-| TcRnInterfaceLookupError is an error resulting from looking up a name in an interface file.
Example(s):
Test cases:
-}
TcRnInterfaceLookupError :: !Name -> !SDoc -> TcRnMessage
{- | TcRnUnsatisfiedMinimalDef is a warning that occurs when a class instance
is missing methods that are required by the minimal definition.
Example:
class C a where
foo :: a -> a
instance C () -- | foo needs to be defined here
Test cases:
testsuite/tests/typecheck/prog001/typecheck.prog001
testsuite/tests/typecheck/should_compile/tc126
testsuite/tests/typecheck/should_compile/T7903
testsuite/tests/typecheck/should_compile/tc116
testsuite/tests/typecheck/should_compile/tc175
testsuite/tests/typecheck/should_compile/HasKey
testsuite/tests/typecheck/should_compile/tc125
testsuite/tests/typecheck/should_compile/tc078
testsuite/tests/typecheck/should_compile/tc161
testsuite/tests/typecheck/should_fail/T5051
testsuite/tests/typecheck/should_compile/T21583
testsuite/tests/backpack/should_compile/bkp47
testsuite/tests/backpack/should_fail/bkpfail25
testsuite/tests/parser/should_compile/T2245
testsuite/tests/parser/should_compile/read014
testsuite/tests/indexed-types/should_compile/Class3
testsuite/tests/indexed-types/should_compile/Simple2
testsuite/tests/indexed-types/should_fail/T7862
testsuite/tests/deriving/should_compile/deriving-1935
testsuite/tests/deriving/should_compile/T9968a
testsuite/tests/deriving/should_compile/drv003
testsuite/tests/deriving/should_compile/T4966
testsuite/tests/deriving/should_compile/T14094
testsuite/tests/perf/compiler/T15304
testsuite/tests/warnings/minimal/WarnMinimal
testsuite/tests/simplCore/should_compile/simpl020
testsuite/tests/deSugar/should_compile/T14546d
testsuite/tests/ghci/scripts/T5820
testsuite/tests/ghci/scripts/ghci019
-}
TcRnUnsatisfiedMinimalDef :: ClassMinimalDef -> TcRnMessage
{- | 'TcRnMisplacedInstSig' is an error that happens when a method in
a class instance is given a type signature, but the user has not
enabled the @InstanceSigs@ extension.
Test case:
testsuite/tests/module/mod45
-}
TcRnMisplacedInstSig :: Name -> (LHsSigType GhcRn) -> TcRnMessage
{- | 'TcRnBadBootFamInstDecl' is an error that is triggered by a
type family instance being declared in an hs-boot file.
Test case:
testsuite/tests/indexed-types/should_fail/HsBootFam
-}
TcRnBadBootFamInstDecl :: {} -> TcRnMessage
{- | 'TcRnIllegalFamilyInstance' is an error that occurs when an associated
type or data family is given a top-level instance.
Test case:
testsuite/tests/indexed-types/should_fail/T3092
-}
TcRnIllegalFamilyInstance :: TyCon -> TcRnMessage
{- | 'TcRnMissingClassAssoc' is an error that occurs when a class instance
for a class with an associated type or data family is missing a corresponding
family instance declaration.
Test case:
testsuite/tests/indexed-types/should_fail/SimpleFail7
-}
TcRnMissingClassAssoc :: TyCon -> TcRnMessage
{- | 'TcRnBadFamInstDecl' is an error that is triggered by a type or data family
instance without the @TypeFamilies@ extension.
Test case:
testsuite/tests/indexed-types/should_fail/BadFamInstDecl
-}
TcRnBadFamInstDecl :: TyCon -> TcRnMessage
{- | 'TcRnNotOpenFamily' is an error that is triggered by attempting to give
a top-level (open) type family instance for a closed type family.
Test cases:
testsuite/tests/indexed-types/should_fail/Overlap7
testsuite/tests/indexed-types/should_fail/Overlap3
-}
TcRnNotOpenFamily :: TyCon -> TcRnMessage
{-| TcRnNoRebindableSyntaxRecordDot is an error triggered by an overloaded record update
without RebindableSyntax enabled.
Example(s):
Test cases: parser/should_fail/RecordDotSyntaxFail5
-}
TcRnNoRebindableSyntaxRecordDot :: TcRnMessage
{-| TcRnNoFieldPunsRecordDot is an error triggered by the use of record field puns
in an overloaded record update without enabling NamedFieldPuns.
Example(s):
print $ a{ foo.bar.baz.quux }
Test cases: parser/should_fail/RecordDotSyntaxFail12
-}
TcRnNoFieldPunsRecordDot :: TcRnMessage
{-| TcRnIllegalStaticExpression is an error thrown when user creates a static
pointer via TemplateHaskell without enabling the StaticPointers extension.
Example(s):
Test cases: th/T14204
-}
TcRnIllegalStaticExpression :: HsExpr GhcPs -> TcRnMessage
{-| TcRnIllegalStaticFormInSplice is an error when a user attempts to define
a static pointer in a Template Haskell splice.
Example(s):
Test cases: th/TH_StaticPointers02
-}
TcRnIllegalStaticFormInSplice :: HsExpr GhcPs -> TcRnMessage
{-| TcRnListComprehensionDuplicateBinding is an error triggered by duplicate
let-bindings in a list comprehension.
Example(s):
[ () | let a = 13 | let a = 17 ]
Test cases: typecheck/should_fail/tcfail092
-}
TcRnListComprehensionDuplicateBinding :: Name -> TcRnMessage
{-| TcRnEmptyStmtsGroup is an error triggered by an empty list of statements
in a statement block. For more information, see 'EmptyStatementGroupErrReason'
Example(s):
[() | then ()]
do
proc () -> do
Test cases: rename/should_fail/RnEmptyStatementGroup1
-}
TcRnEmptyStmtsGroup:: EmptyStatementGroupErrReason -> TcRnMessage
{-| TcRnLastStmtNotExpr is an error caused by the last statement
in a statement block not being an expression.
Example(s):
do x <- pure ()
do let x = 5
Test cases: rename/should_fail/T6060
parser/should_fail/T3811g
parser/should_fail/readFail028
-}
TcRnLastStmtNotExpr
:: HsStmtContext GhcRn
-> UnexpectedStatement
-> TcRnMessage
{-| TcRnUnexpectedStatementInContext is an error when a statement appears
in an unexpected context (e.g. an arrow statement appears in a list comprehension).
Example(s):
Test cases: parser/should_fail/readFail042
parser/should_fail/readFail038
parser/should_fail/readFail043
-}
TcRnUnexpectedStatementInContext
:: HsStmtContext GhcRn
-> UnexpectedStatement
-> Maybe LangExt.Extension
-> TcRnMessage
{-| TcRnIllegalTupleSection is an error triggered by usage of a tuple section
without enabling the TupleSections extension.
Example(s):
(5,)
Test cases: rename/should_fail/rnfail056
-}
TcRnIllegalTupleSection :: TcRnMessage
{-| TcRnIllegalImplicitParameterBindings is an error triggered by binding
an implicit parameter in an mdo block.
Example(s):
mdo { let { ?x = 5 }; () }
Test cases: rename/should_fail/RnImplicitBindInMdoNotation
-}
TcRnIllegalImplicitParameterBindings
:: Either (HsLocalBindsLR GhcPs GhcPs) (HsLocalBindsLR GhcRn GhcPs)
-> TcRnMessage
{-| TcRnSectionWithoutParentheses is an error triggered by attempting to
use an operator section without parentheses.
Example(s):
(`head` x, ())
Test cases: rename/should_fail/T2490
rename/should_fail/T5657
-}
TcRnSectionWithoutParentheses :: HsExpr GhcPs -> TcRnMessage
{-| TcRnLoopySuperclassSolve is a warning, controlled by @-Wloopy-superclass-solve@,
that is triggered when GHC solves a constraint in a possibly-loopy way,
violating the class instance termination rules described in the section
"Undecidable instances and loopy superclasses" of the user's guide.
Example:
class Foo f
class Foo f => Bar f g
instance Bar f f => Bar f (h k)
Test cases: T20666, T20666{a,b}, T22891, T22912.
-}
TcRnLoopySuperclassSolve :: CtLoc -- ^ Wanted 'CtLoc'
-> PredType -- ^ Wanted 'PredType'
-> TcRnMessage
deriving Generic
-- | Things forbidden in @type data@ declarations.
-- See Note [Type data declarations]
data TypeDataForbids
= TypeDataForbidsDatatypeContexts
| TypeDataForbidsLabelledFields
| TypeDataForbidsStrictnessAnnotations
| TypeDataForbidsDerivingClauses
deriving Generic
instance Outputable TypeDataForbids where
ppr TypeDataForbidsDatatypeContexts = text "Data type contexts"
ppr TypeDataForbidsLabelledFields = text "Labelled fields"
ppr TypeDataForbidsStrictnessAnnotations = text "Strictness flags"
ppr TypeDataForbidsDerivingClauses = text "Deriving clauses"
data RunSpliceFailReason
= ConversionFail !ThingBeingConverted !ConversionFailReason
deriving Generic
-- | Identifies the TH splice attempting to be converted
data ThingBeingConverted
= ConvDec !TH.Dec
| ConvExp !TH.Exp
| ConvPat !TH.Pat
| ConvType !TH.Type
-- | The reason a TH splice could not be converted to a Haskell expression
data ConversionFailReason
= IllegalOccName !OccName.NameSpace !String
| SumAltArityExceeded !TH.SumAlt !TH.SumArity
| IllegalSumAlt !TH.SumAlt
| IllegalSumArity !TH.SumArity
| MalformedType !TypeOrKind !TH.Type
| IllegalLastStatement !HsDoFlavour !(LStmt GhcPs (LHsExpr GhcPs))
| KindSigsOnlyAllowedOnGADTs
| IllegalDeclaration !THDeclDescriptor !IllegalDecls
| CannotMixGADTConsWith98Cons
| EmptyStmtListInDoBlock
| NonVarInInfixExpr
| MultiWayIfWithoutAlts
| CasesExprWithoutAlts
| ImplicitParamsWithOtherBinds
| InvalidCCallImpent !String -- ^ Source
| RecGadtNoCons
| GadtNoCons
| InvalidTypeInstanceHeader !TH.Type
| InvalidTyFamInstLHS !TH.Type
| InvalidImplicitParamBinding
| DefaultDataInstDecl ![LDataFamInstDecl GhcPs]
| FunBindLacksEquations !TH.Name
deriving Generic
data IllegalDecls
= IllegalDecls !(NE.NonEmpty (LHsDecl GhcPs))
| IllegalFamDecls !(NE.NonEmpty (LFamilyDecl GhcPs))
-- | Label for a TH declaration
data THDeclDescriptor
= InstanceDecl
| WhereClause
| LetBinding
| LetExpression
| ClssDecl
-- | Specifies which back ends can handle a requested foreign import or export
type ExpectedBackends = [Backend]
-- | Specifies which calling convention is unsupported on the current platform
data UnsupportedCallConvention
= StdCallConvUnsupported
| PrimCallConvUnsupported
| JavaScriptCallConvUnsupported
deriving Eq
-- | Whether the error pertains to a function argument or a result.
data ArgOrResult
= Arg | Result
-- | 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.
-- | In what context did we require a type to have a fixed runtime representation?
--
-- Used by 'GHC.Tc.Utils.TcMType.checkTypeHasFixedRuntimeRep' for throwing
-- representation polymorphism errors when validity checking.
--
-- See Note [Representation polymorphism checking] in GHC.Tc.Utils.Concrete
data FixedRuntimeRepProvenance
-- | Data constructor fields must have a fixed runtime representation.
--
-- Tests: T11734, T18534.
= FixedRuntimeRepDataConField
-- | Pattern synonym signature arguments must have a fixed runtime representation.
--
-- Test: RepPolyPatSynArg.
| FixedRuntimeRepPatSynSigArg
-- | Pattern synonym signature scrutinee must have a fixed runtime representation.
--
-- Test: RepPolyPatSynRes.
| FixedRuntimeRepPatSynSigRes
pprFixedRuntimeRepProvenance :: FixedRuntimeRepProvenance -> SDoc
pprFixedRuntimeRepProvenance FixedRuntimeRepDataConField = text "data constructor field"
pprFixedRuntimeRepProvenance FixedRuntimeRepPatSynSigArg = text "pattern synonym argument"
pprFixedRuntimeRepProvenance FixedRuntimeRepPatSynSigRes = text "pattern synonym scrutinee"
-- | Why the particular illegal newtype error arose together with more
-- information, if any.
data IllegalNewtypeReason
= DoesNotHaveSingleField !Int
| IsNonLinear
| IsGADT
| HasConstructorContext
| HasExistentialTyVar
| HasStrictnessAnnotation
deriving Generic
-- | 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
data SuggestUnliftedTypes
= SuggestUnliftedNewtypes
| SuggestUnliftedDatatypes
-- | A description of whether something is a
--
-- * @data@ or @newtype@ ('DataDeclSort')
--
-- * @data instance@ or @newtype instance@ ('DataInstanceSort')
--
-- * @data family@ ('DataFamilySort')
--
-- At present, this data type is only consumed by 'checkDataKindSig'.
data DataSort
= DataDeclSort NewOrData
| DataInstanceSort NewOrData
| DataFamilySort
ppDataSort :: DataSort -> SDoc
ppDataSort data_sort = text $
case data_sort of
DataDeclSort DataType -> "Data type"
DataDeclSort NewType -> "Newtype"
DataInstanceSort DataType -> "Data instance"
DataInstanceSort NewType -> "Newtype instance"
DataFamilySort -> "Data family"
-- | Helper type used in 'checkDataKindSig'.
--
-- Superficially similar to 'ContextKind', but it lacks 'AnyKind'
-- and 'AnyBoxedKind', and instead of @'TheKind' liftedTypeKind@
-- provides 'LiftedKind', which is much simpler to match on and
-- handle in 'isAllowedDataResKind'.
data AllowedDataResKind
= AnyTYPEKind
| AnyBoxedKind
| LiftedKind
-- | 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 perhaps 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
deriving Generic
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 context in which we don't allow anonymous wildcards.
data BadAnonWildcardContext
= WildcardNotLastInConstraint
| ExtraConstraintWildcardNotAllowed
SoleExtraConstraintWildcardAllowed
| WildcardsNotAllowedAtAll
-- | Whether a sole extra-constraint wildcard is allowed,
-- e.g. @_ => ..@ as opposed to @( .., _ ) => ..@.
data SoleExtraConstraintWildcardAllowed
= SoleExtraConstraintWildcardNotAllowed
| SoleExtraConstraintWildcardAllowed
-- | 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
-- | What kind of thing is missing a type signature?
--
-- Used for reporting @"missing signature"@ warnings, see
-- 'tcRnMissingSignature'.
data MissingSignature
= MissingTopLevelBindingSig Name Type
| MissingPatSynSig PatSyn
| MissingTyConKindSig
TyCon
Bool -- ^ whether -XCUSKs is enabled
-- | Is the object we are dealing with exported or not?
--
-- Used for reporting @"missing signature"@ warnings, see
-- 'TcRnMissingSignature'.
data Exported
= IsNotExported
| IsExported
instance Outputable Exported where
ppr IsNotExported = text "IsNotExported"
ppr IsExported = text "IsExported"
--------------------------------------------------------------------------------
--
-- Errors used in GHC.Tc.Errors
--
--------------------------------------------------------------------------------
{- Note [Error report]
~~~~~~~~~~~~~~~~~~~~~~
The idea is that error msgs are divided into three parts: the main msg, the
context block ("In the second argument of ..."), and the relevant bindings
block, which are displayed in that order, with a mark to divide them. The
the main msg ('report_important') varies depending on the error
in question, but context and relevant bindings are always the same, which
should simplify visual parsing.
See 'GHC.Tc.Errors.Types.SolverReport' and 'GHC.Tc.Errors.mkErrorReport'.
-}
-- | A collection of main error messages and supplementary information.
--
-- In practice, we will:
-- - display the important messages first,
-- - then the error context (e.g. by way of a call to 'GHC.Tc.Errors.mkErrorReport'),
-- - then the supplementary information (e.g. relevant bindings, valid hole fits),
-- - then the hints ("Possible fix: ...").
--
-- So this is mostly just a way of making sure that the error context appears
-- early on rather than at the end of the message.
--
-- See Note [Error report] for details.
data SolverReport
= SolverReport
{ sr_important_msg :: SolverReportWithCtxt
, sr_supplementary :: [SolverReportSupplementary]
, sr_hints :: [GhcHint]
}
-- | Additional information to print in a 'SolverReport', after the
-- important messages and after the error context.
--
-- See Note [Error report].
data SolverReportSupplementary
= SupplementaryBindings RelevantBindings
| SupplementaryHoleFits ValidHoleFits
| SupplementaryCts [(PredType, RealSrcSpan)]
-- | A 'TcSolverReportMsg', together with context (e.g. enclosing implication constraints)
-- that are needed in order to report it.
data SolverReportWithCtxt =
SolverReportWithCtxt
{ reportContext :: SolverReportErrCtxt
-- ^ Context for what we wish to report.
-- This can change as we enter implications, so is
-- stored alongside the content.
, reportContent :: TcSolverReportMsg
-- ^ The content of the message to report.
}
deriving Generic
-- | Context needed when reporting a 'TcSolverReportMsg', such as
-- the enclosing implication constraints or whether we are deferring type errors.
data SolverReportErrCtxt
= CEC { cec_encl :: [Implication] -- ^ Enclosing implications
-- (innermost first)
-- ic_skols and givens are tidied, rest are not
, cec_tidy :: TidyEnv
, cec_binds :: EvBindsVar -- ^ We make some errors (depending on cec_defer)
-- into warnings, and emit evidence bindings
-- into 'cec_binds' for unsolved constraints
, cec_defer_type_errors :: DiagnosticReason -- ^ Whether to defer type errors until runtime
-- We might throw a warning on an error when encountering a hole,
-- depending on the type of hole (expression hole, type hole, out of scope hole).
-- We store the reasons for reporting a diagnostic for each type of hole.
, cec_expr_holes :: DiagnosticReason -- ^ Reason for reporting holes in expressions.
, cec_type_holes :: DiagnosticReason -- ^ Reason for reporting holes in types.
, cec_out_of_scope_holes :: DiagnosticReason -- ^ Reason for reporting out of scope holes.
, cec_warn_redundant :: Bool -- ^ True <=> -Wredundant-constraints
, cec_expand_syns :: Bool -- ^ True <=> -fprint-expanded-synonyms
, cec_suppress :: Bool -- ^ True <=> More important errors have occurred,
-- so create bindings if need be, but
-- don't issue any more errors/warnings
-- See Note [Suppressing error messages]
}
getUserGivens :: SolverReportErrCtxt -> [UserGiven]
-- One item for each enclosing implication
getUserGivens (CEC {cec_encl = implics}) = getUserGivensFromImplics implics
----------------------------------------------------------------------------
--
-- ErrorItem
--
----------------------------------------------------------------------------
-- | A predicate with its arising location; used to encapsulate a constraint
-- that will give rise to a diagnostic.
data ErrorItem
-- We could perhaps use Ct here (and indeed used to do exactly that), but
-- having a separate type gives to denote errors-in-formation gives us
-- a nice place to do pre-processing, such as calculating ei_suppress.
-- Perhaps some day, an ErrorItem could eventually evolve to contain
-- the error text (or some representation of it), so we can then have all
-- the errors together when deciding which to report.
= EI { ei_pred :: PredType -- report about this
-- The ei_pred field will never be an unboxed equality with
-- a (casted) tyvar on the right; this is guaranteed by the solver
, ei_evdest :: Maybe TcEvDest -- for Wanteds, where to put evidence
, ei_flavour :: CtFlavour
, ei_loc :: CtLoc
, ei_m_reason :: Maybe CtIrredReason -- if this ErrorItem was made from a
-- CtIrred, this stores the reason
, ei_suppress :: Bool -- Suppress because of Note [Wanteds rewrite Wanteds]
-- in GHC.Tc.Constraint
}
instance Outputable ErrorItem where
ppr (EI { ei_pred = pred
, ei_evdest = m_evdest
, ei_flavour = flav
, ei_suppress = supp })
= pp_supp <+> ppr flav <+> pp_dest m_evdest <+> ppr pred
where
pp_dest Nothing = empty
pp_dest (Just ev) = ppr ev <+> dcolon
pp_supp = if supp then text "suppress:" else empty
errorItemOrigin :: ErrorItem -> CtOrigin
errorItemOrigin = ctLocOrigin . ei_loc
errorItemEqRel :: ErrorItem -> EqRel
errorItemEqRel = predTypeEqRel . ei_pred
errorItemCtLoc :: ErrorItem -> CtLoc
errorItemCtLoc = ei_loc
errorItemPred :: ErrorItem -> PredType
errorItemPred = ei_pred
{- Note [discardProvCtxtGivens]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In most situations we call all enclosing implications "useful". There is one
exception, and that is when the constraint that causes the error is from the
"provided" context of a pattern synonym declaration:
pattern Pat :: (Num a, Eq a) => Show a => a -> Maybe a
-- required => provided => type
pattern Pat x <- (Just x, 4)
When checking the pattern RHS we must check that it does actually bind all
the claimed "provided" constraints; in this case, does the pattern (Just x, 4)
bind the (Show a) constraint. Answer: no!
But the implication we generate for this will look like
forall a. (Num a, Eq a) => [W] Show a
because when checking the pattern we must make the required
constraints available, since they are needed to match the pattern (in
this case the literal '4' needs (Num a, Eq a)).
BUT we don't want to suggest adding (Show a) to the "required" constraints
of the pattern synonym, thus:
pattern Pat :: (Num a, Eq a, Show a) => Show a => a -> Maybe a
It would then typecheck but it's silly. We want the /pattern/ to bind
the alleged "provided" constraints, Show a.
So we suppress that Implication in discardProvCtxtGivens. It's
painfully ad-hoc but the truth is that adding it to the "required"
constraints would work. Suppressing it solves two problems. First,
we never tell the user that we could not deduce a "provided"
constraint from the "required" context. Second, we never give a
possible fix that suggests to add a "provided" constraint to the
"required" context.
For example, without this distinction the above code gives a bad error
message (showing both problems):
error: Could not deduce (Show a) ... from the context: (Eq a)
... Possible fix: add (Show a) to the context of
the signature for pattern synonym `Pat' ...
-}
discardProvCtxtGivens :: CtOrigin -> [UserGiven] -> [UserGiven]
discardProvCtxtGivens orig givens -- See Note [discardProvCtxtGivens]
| ProvCtxtOrigin (PSB {psb_id = L _ name}) <- orig
= filterOut (discard name) givens
| otherwise
= givens
where
discard n (Implic { ic_info = SigSkol (PatSynCtxt n') _ _ }) = n == n'
discard _ _ = False
-- | An error reported after constraint solving.
-- This is usually, some sort of unsolved constraint error,
-- but we try to be specific about the precise problem we encountered.
data TcSolverReportMsg
-- | Quantified variables appear out of dependency order.
--
-- Example:
--
-- forall (a :: k) k. ...
--
-- Test cases: BadTelescope2, T16418, T16247, T16726, T18451.
= BadTelescope TyVarBndrs [TyCoVar]
-- | We came across a custom type error and we have decided to report it.
--
-- Example:
--
-- type family F a where
-- F a = TypeError (Text "error")
--
-- err :: F ()
-- err = ()
--
-- Test cases: CustomTypeErrors0{1,2,3,4,5}, T12104.
| UserTypeError Type
-- | We want to report an out of scope variable or a typed hole.
-- See 'HoleError'.
| ReportHoleError Hole HoleError
-- | Trying to unify an untouchable variable, e.g. a variable from an outer scope.
--
-- Test case: Simple14
| UntouchableVariable
{ untouchableTyVar :: TyVar
, untouchableTyVarImplication :: Implication
}
-- | Cannot unify a variable, because of a type mismatch.
| CannotUnifyVariable
{ mismatchMsg :: MismatchMsg
, cannotUnifyReason :: CannotUnifyVariableReason }
-- | A mismatch between two types.
| Mismatch
{ mismatchMsg :: MismatchMsg
, mismatchTyVarInfo :: Maybe TyVarInfo
, mismatchAmbiguityInfo :: [AmbiguityInfo]
, mismatchCoercibleInfo :: Maybe CoercibleMsg }
-- | A violation of the representation-polymorphism invariants.
--
-- See 'FixedRuntimeRepErrorInfo' and 'FixedRuntimeRepContext' for more information.
| FixedRuntimeRepError [FixedRuntimeRepErrorInfo]
-- | An equality between two types is blocked on a kind equality
-- between their kinds.
--
-- Test cases: none.
| BlockedEquality ErrorItem
-- These are for the "blocked" equalities, as described in
-- Note [Equalities with incompatible kinds] in GHC.Tc.Solver.Canonical,
-- wrinkle (2). There should always be another unsolved wanted around,
-- which will ordinarily suppress this message. But this can still be printed out
-- with -fdefer-type-errors (sigh), so we must produce a message.
-- | Something was not applied to sufficiently many arguments.
--
-- Example:
--
-- instance Eq Maybe where {..}
--
-- Test case: T11563.
| ExpectingMoreArguments Int TypedThing
-- | Trying to use an unbound implicit parameter.
--
-- Example:
--
-- foo :: Int
-- foo = ?param
--
-- Test case: tcfail130.
| UnboundImplicitParams
(NE.NonEmpty ErrorItem)
-- | A constraint couldn't be solved because it contains
-- ambiguous type variables.
--
-- Example:
--
-- class C a b where
-- f :: (a,b)
--
-- x = fst f
--
--
-- Test case: T4921.
| AmbiguityPreventsSolvingCt
ErrorItem -- ^ always a class constraint
([TyVar], [TyVar]) -- ^ ambiguous kind and type variables, respectively
-- | Could not solve a constraint; there were several unifying candidate instances
-- but no matching instances. This is used to report as much useful information
-- as possible about why we couldn't choose any instance, e.g. because of
-- ambiguous type variables.
| CannotResolveInstance
{ cannotResolve_item :: ErrorItem
, cannotResolve_unifiers :: [ClsInst]
, cannotResolve_candidates :: [ClsInst]
, cannotResolve_importErrors :: [ImportError]
, cannotResolve_suggestions :: [GhcHint]
, cannotResolve_relevant_bindings :: RelevantBindings }
-- TODO: remove the fields of type [GhcHint] and RelevantBindings,
-- in order to handle them uniformly with other diagnostic messages.
-- | Could not solve a constraint using available instances
-- because the instances overlap.
--
-- Test cases: tcfail118, tcfail121, tcfail218.
| OverlappingInstances
{ overlappingInstances_item :: ErrorItem
, overlappingInstances_matches :: NE.NonEmpty ClsInst
, overlappingInstances_unifiers :: [ClsInst] }
-- | Could not solve a constraint from instances because
-- instances declared in a Safe module cannot overlap instances
-- from other modules (with -XSafeHaskell).
--
-- Test cases: SH_Overlap{1,2,5,6,7,11}.
| UnsafeOverlap
{ unsafeOverlap_item :: ErrorItem
, unsafeOverlap_match :: ClsInst
, unsafeOverlapped :: NE.NonEmpty ClsInst }
deriving Generic
data MismatchMsg
= -- | Couldn't unify two types or kinds.
--
-- Example:
--
-- 3 + 3# -- can't match a lifted type with an unlifted type
--
-- Test cases: T1396, T8263, ...
BasicMismatch
{ mismatch_ea :: MismatchEA -- ^ Should this be phrased in terms of expected vs actual?
, mismatch_item :: ErrorItem -- ^ The constraint in which the mismatch originated.
, mismatch_ty1 :: Type -- ^ First type (the expected type if if mismatch_ea is True)
, mismatch_ty2 :: Type -- ^ Second type (the actual type if mismatch_ea is True)
, mismatch_whenMatching :: Maybe WhenMatching
, mismatch_mb_same_occ :: Maybe SameOccInfo
}
-- | A type has an unexpected kind.
--
-- Test cases: T2994, T7609, ...
| KindMismatch
{ kmismatch_what :: TypedThing -- ^ What thing is 'kmismatch_actual' the kind of?
, kmismatch_expected :: Type
, kmismatch_actual :: Type
}
-- TODO: combine with 'BasicMismatch'.
-- | A mismatch between two types, which arose from a type equality.
--
-- Test cases: T1470, tcfail212.
| TypeEqMismatch
{ teq_mismatch_ppr_explicit_kinds :: Bool
, teq_mismatch_item :: ErrorItem
, teq_mismatch_ty1 :: Type
, teq_mismatch_ty2 :: Type
, teq_mismatch_expected :: Type -- ^ The overall expected type
, teq_mismatch_actual :: Type -- ^ The overall actual type
, teq_mismatch_what :: Maybe TypedThing -- ^ What thing is 'teq_mismatch_actual' the kind of?
, teq_mb_same_occ :: Maybe SameOccInfo
}
-- TODO: combine with 'BasicMismatch'.
-- | Couldn't solve some Wanted constraints using the Givens.
-- Used for messages such as @"No instance for ..."@ and
-- @"Could not deduce ... from"@.
| CouldNotDeduce
{ cnd_user_givens :: [Implication]
-- | The Wanted constraints we couldn't solve.
--
-- N.B.: the 'ErrorItem' at the head of the list has been tidied,
-- perhaps not the others.
, cnd_wanted :: NE.NonEmpty ErrorItem
-- | Some additional info consumed by 'mk_supplementary_ea_msg'.
, cnd_extra :: Maybe CND_Extra
}
deriving Generic
-- | Construct a basic mismatch message between two types.
--
-- See 'pprMismatchMsg' for how such a message is displayed to users.
mkBasicMismatchMsg :: MismatchEA -> ErrorItem -> Type -> Type -> MismatchMsg
mkBasicMismatchMsg ea item ty1 ty2
= BasicMismatch
{ mismatch_ea = ea
, mismatch_item = item
, mismatch_ty1 = ty1
, mismatch_ty2 = ty2
, mismatch_whenMatching = Nothing
, mismatch_mb_same_occ = Nothing
}
-- | Whether to use expected/actual in a type mismatch message.
data MismatchEA
-- | Don't use expected/actual.
= NoEA
-- | Use expected/actual.
| EA
{ mismatch_mbEA :: Maybe ExpectedActualInfo
-- ^ Whether to also mention type synonym expansion.
}
data CannotUnifyVariableReason
= -- | A type equality between a type variable and a polytype.
--
-- Test cases: T12427a, T2846b, T10194, ...
CannotUnifyWithPolytype ErrorItem TyVar Type (Maybe TyVarInfo)
-- | An occurs check.
| OccursCheck
{ occursCheckInterestingTyVars :: [TyVar]
, occursCheckAmbiguityInfos :: [AmbiguityInfo] }
-- | A skolem type variable escapes its scope.
--
-- Example:
--
-- data Ex where { MkEx :: a -> MkEx }
-- foo (MkEx x) = x
--
-- Test cases: TypeSkolEscape, T11142.
| SkolemEscape ErrorItem Implication [TyVar]
-- | Can't unify the type variable with the other type
-- due to the kind of type variable it is.
--
-- For example, trying to unify a 'SkolemTv' with the
-- type Int, or with a 'TyVarTv'.
| DifferentTyVars TyVarInfo
| RepresentationalEq TyVarInfo (Maybe CoercibleMsg)
deriving Generic
-- | Report a mismatch error without any extra
-- information.
mkPlainMismatchMsg :: MismatchMsg -> TcSolverReportMsg
mkPlainMismatchMsg msg
= Mismatch
{ mismatchMsg = msg
, mismatchTyVarInfo = Nothing
, mismatchAmbiguityInfo = []
, mismatchCoercibleInfo = Nothing }
-- | Additional information to be given in a 'CouldNotDeduce' message,
-- which is then passed on to 'mk_supplementary_ea_msg'.
data CND_Extra = CND_Extra TypeOrKind Type Type
-- | A cue to print out information about type variables,
-- e.g. where they were bound, when there is a mismatch @tv1 ~ ty2@.
data TyVarInfo =
TyVarInfo { thisTyVar :: TyVar
, thisTyVarIsUntouchable :: Maybe Implication
, otherTy :: Maybe TyVar }
-- | Add some information to disambiguate errors in which
-- two 'Names' would otherwise appear to be identical.
--
-- See Note [Disambiguating (X ~ X) errors].
data SameOccInfo
= SameOcc
{ sameOcc_same_pkg :: Bool -- ^ Whether the two 'Name's also came from the same package.
, sameOcc_lhs :: Name
, sameOcc_rhs :: Name }
-- | Add some information about ambiguity
data AmbiguityInfo
-- | Some type variables remained ambiguous: print them to the user.
= Ambiguity
{ lead_with_ambig_msg :: Bool -- ^ True <=> start the message with "Ambiguous type variable ..."
-- False <=> create a message of the form "The type variable is ambiguous."
, ambig_tyvars :: ([TyVar], [TyVar]) -- ^ Ambiguous kind and type variables, respectively.
-- Guaranteed to not both be empty.
}
-- | Remind the user that a particular type family is not injective.
| NonInjectiveTyFam TyCon
-- | Expected/actual information.
data ExpectedActualInfo
-- | Display the expected and actual types.
= ExpectedActual
{ ea_expected, ea_actual :: Type }
-- | Display the expected and actual types, after expanding type synonyms.
| ExpectedActualAfterTySynExpansion
{ ea_expanded_expected, ea_expanded_actual :: Type }
-- | Explain how a kind equality originated.
data WhenMatching
= WhenMatching TcType TcType CtOrigin (Maybe TypeOrKind)
deriving Generic
-- | Some form of @"not in scope"@ error. See also the 'OutOfScopeHole'
-- constructor of 'HoleError'.
data NotInScopeError
-- | A run-of-the-mill @"not in scope"@ error.
= NotInScope
-- | An exact 'Name' was not in scope.
--
-- This usually indicates a problem with a Template Haskell splice.
--
-- Test cases: T5971, T18263.
| NoExactName Name
-- The same exact 'Name' occurs in multiple name-spaces.
--
-- This usually indicates a problem with a Template Haskell splice.
--
-- Test case: T7241.
| SameName [GlobalRdrElt] -- ^ always at least 2 elements
-- A type signature, fixity declaration, pragma, standalone kind signature...
-- is missing an associated binding.
| MissingBinding SDoc [GhcHint]
-- TODO: remove the SDoc argument.
-- | Couldn't find a top-level binding.
--
-- Happens when specifying an annotation for something that
-- is not in scope.
--
-- Test cases: annfail01, annfail02, annfail11.
| NoTopLevelBinding
-- | A class doesn't have a method with this name,
-- or, a class doesn't have an associated type with this name,
-- or, a record doesn't have a record field with this name.
| UnknownSubordinate SDoc
deriving Generic
-- | Create a @"not in scope"@ error message for the given 'RdrName'.
mkTcRnNotInScope :: RdrName -> NotInScopeError -> TcRnMessage
mkTcRnNotInScope rdr err = TcRnNotInScope err rdr [] noHints
-- | Configuration for pretty-printing valid hole fits.
data HoleFitDispConfig =
HFDC { showWrap, showWrapVars, showType, showProv, showMatches
:: Bool }
-- | Report an error involving a 'Hole'.
--
-- This could be an out of scope data constructor or variable,
-- a typed hole, or a wildcard in a type.
data HoleError
-- | Report an out-of-scope data constructor or variable
-- masquerading as an expression hole.
--
-- See Note [Insoluble holes] in GHC.Tc.Types.Constraint.
-- See 'NotInScopeError' for other not-in-scope errors.
--
-- Test cases: T9177a.
= OutOfScopeHole [ImportError]
-- | Report a typed hole, or wildcard, with additional information.
| HoleError HoleSort
[TcTyVar] -- Other type variables which get computed on the way.
[(SkolemInfoAnon, [TcTyVar])] -- Zonked and grouped skolems for the type of the hole.
-- | A message that aims to explain why two types couldn't be seen
-- to be representationally equal.
data CoercibleMsg
-- | Not knowing the role of a type constructor prevents us from
-- concluding that two types are representationally equal.
--
-- Example:
--
-- foo :: Applicative m => m (Sum Int)
-- foo = coerce (pure $ 1 :: Int)
--
-- We don't know what role `m` has, so we can't coerce `m Int` to `m (Sum Int)`.
--
-- Test cases: T8984, TcCoercibleFail.
= UnknownRoles Type
-- | The fact that a 'TyCon' is abstract prevents us from decomposing
-- a 'TyConApp' and deducing that two types are representationally equal.
--
-- Test cases: none.
| TyConIsAbstract TyCon
-- | We can't unwrap a newtype whose constructor is not in scope.
--
-- Example:
--
-- import Data.Ord (Down) -- NB: not importing the constructor
-- foo :: Int -> Down Int
-- foo = coerce
--
-- Test cases: TcCoercibleFail.
| OutOfScopeNewtypeConstructor TyCon DataCon
-- | Explain a problem with an import.
data ImportError
-- | Couldn't find a module with the requested name.
= MissingModule ModuleName
-- | The imported modules don't export what we're looking for.
| ModulesDoNotExport (NE.NonEmpty Module) OccName
-- | This datatype collates instances that match or unifier,
-- in order to report an error message for an unsolved typeclass constraint.
data PotentialInstances
= PotentialInstances
{ matches :: [ClsInst]
, unifiers :: [ClsInst]
}
-- | A collection of valid hole fits or refinement fits,
-- in which some fits might have been suppressed.
data FitsMbSuppressed
= Fits
{ fits :: [HoleFit]
, fitsSuppressed :: Bool -- ^ Whether we have suppressed any fits because there were too many.
}
-- | A collection of hole fits and refinement fits.
data ValidHoleFits
= ValidHoleFits
{ holeFits :: FitsMbSuppressed
, refinementFits :: FitsMbSuppressed
}
noValidHoleFits :: ValidHoleFits
noValidHoleFits = ValidHoleFits (Fits [] False) (Fits [] False)
data RelevantBindings
= RelevantBindings
{ relevantBindingNamesAndTys :: [(Name, Type)]
, ranOutOfFuel :: Bool -- ^ Whether we ran out of fuel generating the bindings.
}
-- | Display some relevant bindings.
pprRelevantBindings :: RelevantBindings -> SDoc
-- This function should be in "GHC.Tc.Errors.Ppr",
-- but it's here for the moment as it's needed in "GHC.Tc.Errors".
pprRelevantBindings (RelevantBindings bds ran_out_of_fuel) =
ppUnless (null rel_bds) $
hang (text "Relevant bindings include")
2 (vcat (map ppr_binding rel_bds) $$ ppWhen ran_out_of_fuel discardMsg)
where
ppr_binding (nm, tidy_ty) =
sep [ pprPrefixOcc nm <+> dcolon <+> ppr tidy_ty
, nest 2 (parens (text "bound at"
<+> ppr (getSrcLoc nm)))]
rel_bds = filter (not . isGeneratedSrcSpan . getSrcSpan . fst) bds
discardMsg :: SDoc
discardMsg = text "(Some bindings suppressed;" <+>
text "use -fmax-relevant-binds=N or -fno-max-relevant-binds)"
data PromotionErr
= TyConPE -- TyCon used in a kind before we are ready
-- data T :: T -> * where ...
| ClassPE -- Ditto Class
| FamDataConPE -- Data constructor for a data family
-- See Note [AFamDataCon: not promoting data family constructors]
-- in GHC.Tc.Utils.Env.
| ConstrainedDataConPE PredType
-- Data constructor with a non-equality context
-- See Note [Constraints in kinds] in GHC.Core.TyCo.Rep
| PatSynPE -- Pattern synonyms
-- See Note [Don't promote pattern synonyms] in GHC.Tc.Utils.Env
| RecDataConPE -- Data constructor in a recursive loop
-- See Note [Recursion and promoting data constructors] in GHC.Tc.TyCl
| TermVariablePE -- See Note [Promoted variables in types]
| NoDataKindsDC -- -XDataKinds not enabled (for a datacon)
instance Outputable PromotionErr where
ppr ClassPE = text "ClassPE"
ppr TyConPE = text "TyConPE"
ppr PatSynPE = text "PatSynPE"
ppr FamDataConPE = text "FamDataConPE"
ppr (ConstrainedDataConPE pred) = text "ConstrainedDataConPE"
<+> parens (ppr pred)
ppr RecDataConPE = text "RecDataConPE"
ppr NoDataKindsDC = text "NoDataKindsDC"
ppr TermVariablePE = text "TermVariablePE"
pprPECategory :: PromotionErr -> SDoc
pprPECategory = text . capitalise . peCategory
peCategory :: PromotionErr -> String
peCategory ClassPE = "class"
peCategory TyConPE = "type constructor"
peCategory PatSynPE = "pattern synonym"
peCategory FamDataConPE = "data constructor"
peCategory ConstrainedDataConPE{} = "data constructor"
peCategory RecDataConPE = "data constructor"
peCategory NoDataKindsDC = "data constructor"
peCategory TermVariablePE = "term variable"
-- | Stores the information to be reported in a representation-polymorphism
-- error message.
data FixedRuntimeRepErrorInfo
= FRR_Info
{ frr_info_origin :: FixedRuntimeRepOrigin
-- ^ What is the original type we checked for
-- representation-polymorphism, and what specific
-- check did we perform?
, frr_info_not_concrete :: Maybe (TcTyVar, TcType)
-- ^ Which non-concrete type did we try to
-- unify this concrete type variable with?
}
{-
************************************************************************
* *
\subsection{Contexts for renaming errors}
* *
************************************************************************
-}
-- AZ:TODO: Change these all to be Name instead of RdrName.
-- Merge TcType.UserTypeContext in to it.
data HsDocContext
= TypeSigCtx SDoc
| StandaloneKindSigCtx SDoc
| PatCtx
| SpecInstSigCtx
| DefaultDeclCtx
| ForeignDeclCtx (LocatedN RdrName)
| DerivDeclCtx
| RuleCtx FastString
| TyDataCtx (LocatedN RdrName)
| TySynCtx (LocatedN RdrName)
| TyFamilyCtx (LocatedN RdrName)
| FamPatCtx (LocatedN RdrName) -- The patterns of a type/data family instance
| ConDeclCtx [LocatedN Name]
| ClassDeclCtx (LocatedN RdrName)
| ExprWithTySigCtx
| TypBrCtx
| HsTypeCtx
| HsTypePatCtx
| GHCiCtx
| SpliceTypeCtx (LHsType GhcPs)
| ClassInstanceCtx
| GenericCtx SDoc
-- | Context for a mismatch in the number of arguments
data MatchArgsContext
= EquationArgs
!Name -- ^ Name of the function
| PatternArgs
!(HsMatchContext GhcTc) -- ^ Pattern match specifics
-- | The information necessary to report mismatched
-- numbers of arguments in a match group.
data MatchArgBadMatches where
MatchArgMatches
:: { matchArgFirstMatch :: LocatedA (Match GhcRn body)
, matchArgBadMatches :: NE.NonEmpty (LocatedA (Match GhcRn body)) }
-> MatchArgBadMatches
-- | The phase in which an exception was encountered when dealing with a TH splice
data SplicePhase
= SplicePhase_Run
| SplicePhase_CompileAndLink
data LookupTHInstNameErrReason
= NoMatchesFound
| CouldNotDetermineInstance
data UnrepresentableTypeDescr
= LinearInvisibleArgument
| CoercionsInTypes
-- | The context for an "empty statement group" error.
data EmptyStatementGroupErrReason
= EmptyStmtsGroupInParallelComp
-- ^ Empty statement group in a parallel list comprehension
| EmptyStmtsGroupInTransformListComp
-- ^ Empty statement group in a transform list comprehension
--
-- Example:
-- [() | then ()]
| EmptyStmtsGroupInDoNotation HsDoFlavour
-- ^ Empty statement group in do notation
--
-- Example:
-- do
| EmptyStmtsGroupInArrowNotation
-- ^ Empty statement group in arrow notation
--
-- Example:
-- proc () -> do
deriving (Generic)
-- | An existential wrapper around @'StmtLR' GhcPs GhcPs body@.
data UnexpectedStatement where
UnexpectedStatement
:: Outputable (StmtLR GhcPs GhcPs body)
=> StmtLR GhcPs GhcPs body
-> UnexpectedStatement