{-# LANGUAGE GADTs #-} module GHC.Tc.Errors.Types ( -- * Main types TcRnMessage(..) , TcRnMessageDetailed(..) , ErrInfo(..) , FixedRuntimeRepProvenance(..) , pprFixedRuntimeRepProvenance , ShadowedNameProvenance(..) , RecordFieldPart(..) , InjectivityErrReason(..) , HasKinds(..) , hasKinds , SuggestUndecidableInstances(..) , suggestUndecidableInstances , 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(..), TcSolverReportInfo(..) , CND_Extra(..) , mkTcReportWithInfo , FitsMbSuppressed(..) , ValidHoleFits(..), noValidHoleFits , HoleFitDispConfig(..) , RelevantBindings(..), pprRelevantBindings , NotInScopeError(..), mkTcRnNotInScope , ImportError(..) , HoleError(..) , CoercibleMsg(..) , PotentialInstances(..) , UnsupportedCallConvention(..) , ExpectedBackends(..) , ArgOrResult(..) ) where import GHC.Prelude import GHC.Hs import {-# SOURCE #-} GHC.Tc.Types (TcIdSigInfo) 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.FieldLabel (FieldLabelString) import GHC.Types.ForeignCall (CLabelString) import GHC.Types.Name (Name, OccName, getSrcLoc) 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) 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.Unit.Module.Name (ModuleName) import GHC.Types.Basic import GHC.Utils.Misc (filterOut) import qualified GHC.LanguageExtensions as LangExt import GHC.Data.FastString (FastString) import qualified Data.List.NonEmpty as NE import Data.Typeable hiding (TyCon) import qualified Data.Semigroup as Semigroup {- Note [Migrating TcM Messages] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ As part of #18516, we are slowly migrating the diagnostic messages emitted and reported in the TcM from SDoc to TcRnMessage. Historically, GHC emitted some diagnostics in 3 pieces, i.e. there were lots of error-reporting functions that accepted 3 SDocs an input: one for the important part of the message, one for the context and one for any supplementary information. Consider the following: • Couldn't match expected type ‘Int’ with actual type ‘Char’ • In the expression: x4 In a stmt of a 'do' block: return (x2, x4) In the expression: Under the hood, the reporting functions in Tc.Utils.Monad were emitting "Couldn't match" as the important part, "In the expression" as the context and "In a stmt..In the expression" as the supplementary, with the context and supplementary usually smashed together so that the final message would be composed only by two SDoc (which would then be bulletted like in the example). In order for us to smooth out the migration to the new diagnostic infrastructure, we introduce the 'ErrInfo' and 'TcRnMessageDetailed' types, which serve exactly the purpose of bridging the two worlds together without breaking the external API or the existing format of messages reported by GHC. Using 'ErrInfo' and 'TcRnMessageDetailed' also allows us to move away from the SDoc-ridden diagnostic API inside Tc.Utils.Monad, enabling further refactorings. In the future, once the conversion will be complete and we will successfully eradicate any use of SDoc in the diagnostic reporting of GHC, we can surely revisit the usage and existence of these two types, which for now remain a "necessary evil". -} -- The majority of TcRn messages come with extra context about the error, -- and this newtype captures it. See Note [Migrating TcM Messages]. data ErrInfo = ErrInfo { errInfoContext :: !SDoc -- ^ Extra context associated to the error. , errInfoSupplementary :: !SDoc -- ^ Extra supplementary info associated to the error. } -- | 'TcRnMessageDetailed' is an \"internal\" type (used only inside -- 'GHC.Tc.Utils.Monad' that wraps a 'TcRnMessage' while also providing -- any extra info needed to correctly pretty-print this diagnostic later on. data TcRnMessageDetailed = TcRnMessageDetailed !ErrInfo -- ^ Extra info associated with the message !TcRnMessage -- | An error which might arise during typechecking/renaming. data TcRnMessage where {-| Simply wraps a generic 'Diagnostic' message @a@. It can be used by plugins to provide custom diagnostic messages originated during typechecking/renaming. -} TcRnUnknownMessage :: (Diagnostic a, Typeable a) => a -> TcRnMessage {-| TcRnMessageWithInfo is a constructor which is used when extra information is needed to be provided in order to qualify a diagnostic and where it was originated (and why). It carries an extra 'UnitState' which can be used to pretty-print some names and it wraps a 'TcRnMessageDetailed', which includes any extra context associated with this diagnostic. -} TcRnMessageWithInfo :: !UnitState -- ^ The 'UnitState' will allow us to pretty-print -- some diagnostics with more detail. -> !TcRnMessageDetailed -> TcRnMessage {-| 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. -> NE.NonEmpty SolverReportWithCtxt -- ^ The contradiction(s). -> 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 :: Outputable var => var -> !ErrInfo -> TcRnMessage {-| TcRnUnusedPatternBinds is a warning (controlled with -Wunused-pattern-binds) that occurs if a pattern binding binds no variables at all, unless it is a lone wild-card pattern, or a banged pattern. Example: Just _ = rhs3 -- Warning: unused pattern binding (_, _) = rhs4 -- Warning: unused pattern binding _ = rhs3 -- No warning: lone wild-card pattern !() = rhs4 -- No warning: banged pattern; behaves like seq Test cases: rename/{T13646,T17c,T17e,T7085} -} TcRnUnusedPatternBinds :: HsBind GhcRn -> TcRnMessage {-| TcRnDodgyImports is a warning (controlled with -Wdodgy-imports) that occurs when a datatype 'T' is imported with all constructors, i.e. 'T(..)', but has been exported abstractly, i.e. 'T'. Test cases: rename/should_compile/T7167 -} TcRnDodgyImports :: RdrName -> TcRnMessage {-| TcRnDodgyExports is a warning (controlled by -Wdodgy-exports) that occurs when a datatype 'T' is exported with all constructors, i.e. 'T(..)', but is it just a type synonym or a type/data family. Example: module Foo ( T(..) -- Warning: T is a type synonym , A(..) -- Warning: A is a type family , C(..) -- Warning: C is a data family ) where type T = Int type family A :: * -> * data family C :: * -> * Test cases: warnings/should_compile/DodgyExports01 -} TcRnDodgyExports :: Name -> TcRnMessage {-| TcRnMissingImportList is a warning (controlled by -Wmissing-import-lists) that occurs when an import declaration does not explicitly list all the names brought into scope. Test cases: rename/should_compile/T4489 -} TcRnMissingImportList :: IE GhcPs -> TcRnMessage {-| When a module marked trustworthy or unsafe (using -XTrustworthy or -XUnsafe) is compiled with a plugin, the TcRnUnsafeDueToPlugin warning (controlled by -Wunsafe) is used as the reason the module was inferred to be unsafe. This warning is not raised if the -fplugin-trustworthy flag is passed. Test cases: plugins/T19926 -} TcRnUnsafeDueToPlugin :: TcRnMessage {-| TcRnModMissingRealSrcSpan is an error that occurrs when compiling a module that lacks an associated 'RealSrcSpan'. Test cases: None -} TcRnModMissingRealSrcSpan :: Module -> TcRnMessage {-| TcRnIdNotExportedFromModuleSig is an error pertaining to backpack that occurs when an identifier required by a signature is not exported by the module or signature that is being used as a substitution for that signature. Example(s): None Test cases: backpack/should_fail/bkpfail36 -} TcRnIdNotExportedFromModuleSig :: Name -> Module -> TcRnMessage {-| TcRnIdNotExportedFromLocalSig is an error pertaining to backpack that occurs when an identifier which is necessary for implementing a module signature is not exported from that signature. Example(s): None Test cases: backpack/should_fail/bkpfail30 backpack/should_fail/bkpfail31 backpack/should_fail/bkpfail34 -} TcRnIdNotExportedFromLocalSig :: Name -> TcRnMessage {-| TcRnShadowedName is a warning (controlled by -Wname-shadowing) that occurs whenever an inner-scope value has the same name as an outer-scope value, i.e. the inner value shadows the outer one. This can catch typographical errors that turn into hard-to-find bugs. The warning is suppressed for names beginning with an underscore. Examples(s): f = ... let f = id in ... f ... -- NOT OK, 'f' is shadowed f x = do { _ignore <- this; _ignore <- that; return (the other) } -- suppressed via underscore Test cases: typecheck/should_compile/T10971a rename/should_compile/rn039 rename/should_compile/rn064 rename/should_compile/T1972 rename/should_fail/T2723 rename/should_compile/T3262 driver/werror -} TcRnShadowedName :: OccName -> ShadowedNameProvenance -> TcRnMessage {-| TcRnDuplicateWarningDecls is an error that occurs whenever a warning is declared twice. Examples(s): None. Test cases: None. -} TcRnDuplicateWarningDecls :: !(LocatedN RdrName) -> !RdrName -> TcRnMessage {-| TcRnDuplicateWarningDecls is an error that occurs whenever the constraint solver in the simplifier hits the iterations' limit. Examples(s): None. Test cases: None. -} TcRnSimplifierTooManyIterations :: Cts -> !IntWithInf -- ^ The limit. -> WantedConstraints -> TcRnMessage {-| TcRnIllegalPatSynDecl is an error that occurs whenever there is an illegal pattern synonym declaration. Examples(s): varWithLocalPatSyn x = case x of P -> () where pattern P = () -- not valid, it can't be local, it must be defined at top-level. Test cases: patsyn/should_fail/local -} TcRnIllegalPatSynDecl :: !(LIdP GhcPs) -> TcRnMessage {-| TcRnLinearPatSyn is an error that occurs whenever a pattern synonym signature uses a field that is not unrestricted. Example(s): None Test cases: linear/should_fail/LinearPatSyn2 -} TcRnLinearPatSyn :: !Type -> TcRnMessage {-| TcRnEmptyRecordUpdate is an error that occurs whenever a record is updated without specifying any field. Examples(s): $(deriveJSON defaultOptions{} ''Bad) -- not ok, no fields selected for update of defaultOptions Test cases: th/T12788 -} TcRnEmptyRecordUpdate :: TcRnMessage {-| TcRnIllegalFieldPunning is an error that occurs whenever field punning is used without the 'NamedFieldPuns' extension enabled. Examples(s): data Foo = Foo { a :: Int } foo :: Foo -> Int foo Foo{a} = a -- Not ok, punning used without extension. Test cases: parser/should_fail/RecordDotSyntaxFail12 -} TcRnIllegalFieldPunning :: !(Located RdrName) -> TcRnMessage {-| TcRnIllegalWildcardsInRecord is an error that occurs whenever wildcards (..) are used in a record without the relevant extension being enabled. Examples(s): data Foo = Foo { a :: Int } foo :: Foo -> Int foo Foo{..} = a -- Not ok, wildcards used without extension. Test cases: parser/should_fail/RecordWildCardsFail -} TcRnIllegalWildcardsInRecord :: !RecordFieldPart -> TcRnMessage {-| 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 -> !(Maybe HsDocContext) -> TcRnMessage {-| TcRnDuplicateFieldName is an error that occurs whenever there are duplicate field names in a record. Examples(s): None. Test cases: None. -} TcRnDuplicateFieldName :: !RecordFieldPart -> NE.NonEmpty RdrName -> TcRnMessage {-| TcRnIllegalViewPattern is an error that occurs whenever the ViewPatterns syntax is used but the ViewPatterns language extension is not enabled. Examples(s): data Foo = Foo { a :: Int } foo :: Foo -> Int foo (a -> l) = l -- not OK, the 'ViewPattern' extension is not enabled. Test cases: parser/should_fail/ViewPatternsFail -} TcRnIllegalViewPattern :: !(Pat GhcPs) -> TcRnMessage {-| TcRnCharLiteralOutOfRange is an error that occurs whenever a character is out of range. Examples(s): None Test cases: None -} TcRnCharLiteralOutOfRange :: !Char -> TcRnMessage {-| TcRnIllegalWildcardsInConstructor is an error that occurs whenever the record wildcards '..' are used inside a constructor without labeled fields. Examples(s): None Test cases: None -} TcRnIllegalWildcardsInConstructor :: !Name -> TcRnMessage {-| TcRnIgnoringAnnotations is a warning that occurs when the source code contains annotation pragmas but the platform in use does not support an external interpreter such as GHCi and therefore the annotations are ignored. Example(s): None Test cases: None -} TcRnIgnoringAnnotations :: [LAnnDecl GhcRn] -> TcRnMessage {-| TcRnAnnotationInSafeHaskell is an error that occurs if annotation pragmas are used in conjunction with Safe Haskell. Example(s): None Test cases: annotations/should_fail/T10826 -} TcRnAnnotationInSafeHaskell :: TcRnMessage {-| TcRnInvalidTypeApplication is an error that occurs when a visible type application is used with an expression that does not accept "specified" type arguments. Example(s): foo :: forall {a}. a -> a foo x = x bar :: () bar = let x = foo @Int 42 in () Test cases: overloadedrecflds/should_fail/overloadedlabelsfail03 typecheck/should_fail/ExplicitSpecificity1 typecheck/should_fail/ExplicitSpecificity10 typecheck/should_fail/ExplicitSpecificity2 typecheck/should_fail/T17173 typecheck/should_fail/VtaFail -} TcRnInvalidTypeApplication :: Type -> LHsWcType GhcRn -> TcRnMessage {-| TcRnTagToEnumMissingValArg is an error that occurs when the 'tagToEnum#' function is not applied to a single value argument. Example(s): tagToEnum# 1 2 Test cases: None -} TcRnTagToEnumMissingValArg :: TcRnMessage {-| TcRnTagToEnumUnspecifiedResTy is an error that occurs when the 'tagToEnum#' function is not given a concrete result type. Example(s): foo :: forall a. a foo = tagToEnum# 0# Test cases: typecheck/should_fail/tcfail164 -} TcRnTagToEnumUnspecifiedResTy :: Type -> TcRnMessage {-| TcRnTagToEnumResTyNotAnEnum is an error that occurs when the 'tagToEnum#' function is given a result type that is not an enumeration type. Example(s): foo :: Int -- not an enumeration TyCon foo = tagToEnum# 0# Test cases: typecheck/should_fail/tcfail164 -} TcRnTagToEnumResTyNotAnEnum :: Type -> TcRnMessage {-| TcRnArrowIfThenElsePredDependsOnResultTy is an error that occurs when the predicate type of an ifThenElse expression in arrow notation depends on the type of the result. Example(s): None Test cases: None -} TcRnArrowIfThenElsePredDependsOnResultTy :: TcRnMessage {-| 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 :: !Type -> TcRnMessage {-| TcRnBadQuantPredHead is an error that occurs whenever a quantified predicate lacks a class or type variable head. Examples(s): class (forall a. A t a => A t [a]) => B t where type A t a :: Constraint Test cases: quantified-constraints/T16474 -} TcRnBadQuantPredHead :: !Type -> TcRnMessage {-| TcRnIllegalTupleConstraint is an error that occurs whenever an illegal tuple constraint is specified. Examples(s): g :: ((Show a, Num a), Eq a) => a -> a g = undefined Test cases: typecheck/should_fail/tcfail209a -} TcRnIllegalTupleConstraint :: !Type -> TcRnMessage {-| TcRnNonTypeVarArgInConstraint is an error that occurs whenever a non type-variable argument is specified in a constraint. Examples(s): data T instance Eq Int => Eq T Test cases: ghci/scripts/T13202 ghci/scripts/T13202a polykinds/T12055a typecheck/should_fail/T10351 typecheck/should_fail/T19187 typecheck/should_fail/T6022 typecheck/should_fail/T8883 -} TcRnNonTypeVarArgInConstraint :: !Type -> TcRnMessage {-| TcRnIllegalImplicitParam is an error that occurs whenever an illegal implicit parameter is specified. Examples(s): type Bla = ?x::Int data T = T instance Bla => Eq T Test cases: polykinds/T11466 typecheck/should_fail/T8912 typecheck/should_fail/tcfail041 typecheck/should_fail/tcfail211 typecheck/should_fail/tcrun045 -} TcRnIllegalImplicitParam :: !Type -> TcRnMessage {-| TcRnIllegalConstraintSynonymOfKind is an error that occurs whenever an illegal constraint synonym of kind is specified. Examples(s): type Showish = Show f :: (Showish a) => a -> a f = undefined Test cases: typecheck/should_fail/tcfail209 -} TcRnIllegalConstraintSynonymOfKind :: !Type -> TcRnMessage {-| TcRnIllegalClassInst is an error that occurs whenever a class instance is specified for a non-class. Examples(s): type C1 a = (Show (a -> Bool)) instance C1 Int where Test cases: polykinds/T13267 -} TcRnIllegalClassInst :: !TyConFlavour -> TcRnMessage {-| TcRnOversaturatedVisibleKindArg is an error that occurs whenever an illegal oversaturated visible kind argument is specified. Examples(s): type family F2 :: forall (a :: Type). Type where F2 @a = Maybe a Test cases: typecheck/should_fail/T15793 typecheck/should_fail/T16255 -} TcRnOversaturatedVisibleKindArg :: !Type -> TcRnMessage {-| TcRnBadAssociatedType is an error that occurs whenever a class doesn't have an associated type. Examples(s): $(do d <- instanceD (cxt []) (conT ''Eq `appT` conT ''Foo) [tySynInstD $ tySynEqn Nothing (conT ''Rep `appT` conT ''Foo) (conT ''Maybe)] return [d]) ======> instance Eq Foo where type Rep Foo = Maybe Test cases: th/T12387a -} TcRnBadAssociatedType :: {-Class-} !Name -> {-TyCon-} !Name -> TcRnMessage {-| TcRnForAllRankErr is an error that occurs whenever an illegal ranked type is specified. Examples(s): foo :: (a,b) -> (a~b => t) -> (a,b) foo p x = p Test cases: - ghci/should_run/T15806 - indexed-types/should_fail/SimpleFail15 - typecheck/should_fail/T11355 - typecheck/should_fail/T12083a - typecheck/should_fail/T12083b - typecheck/should_fail/T16059c - typecheck/should_fail/T16059e - typecheck/should_fail/T17213 - typecheck/should_fail/T18939_Fail - typecheck/should_fail/T2538 - typecheck/should_fail/T5957 - typecheck/should_fail/T7019 - typecheck/should_fail/T7019a - typecheck/should_fail/T7809 - typecheck/should_fail/T9196 - typecheck/should_fail/tcfail127 - typecheck/should_fail/tcfail184 - typecheck/should_fail/tcfail196 - typecheck/should_fail/tcfail197 -} TcRnForAllRankErr :: !Rank -> !Type -> TcRnMessage {-| TcRnMonomorphicBindings is a warning (controlled by -Wmonomorphism-restriction) that arise when the monomorphism restriction applies to the given bindings. Examples(s): {-# OPTIONS_GHC -Wmonomorphism-restriction #-} bar = 10 foo :: Int foo = bar main :: IO () main = print foo The example above emits the warning (for 'bar'), because without monomorphism restriction the inferred type for 'bar' is 'bar :: Num p => p'. This warning tells us that /if/ we were to enable '-XMonomorphismRestriction' we would make 'bar' less polymorphic, as its type would become 'bar :: Int', so GHC warns us about that. Test cases: typecheck/should_compile/T13785 -} TcRnMonomorphicBindings :: [Name] -> TcRnMessage {-| TcRnOrphanInstance is a warning (controlled by -Wwarn-orphans) that arises when a typeclass instance is an \"orphan\", i.e. if it appears in a module in which neither the class nor the type being instanced are declared in the same module. Examples(s): None Test cases: warnings/should_compile/T9178 typecheck/should_compile/T4912 -} TcRnOrphanInstance :: ClsInst -> TcRnMessage {-| TcRnFunDepConflict is an error that occurs when there are functional dependencies conflicts between instance declarations. Examples(s): None Test cases: typecheck/should_fail/T2307 typecheck/should_fail/tcfail096 typecheck/should_fail/tcfail202 -} TcRnFunDepConflict :: !UnitState -> NE.NonEmpty ClsInst -> TcRnMessage {-| TcRnDupInstanceDecls is an error that occurs when there are duplicate instance declarations. Examples(s): class Foo a where foo :: a -> Int instance Foo Int where foo = id instance Foo Int where foo = const 42 Test cases: cabal/T12733/T12733 typecheck/should_fail/tcfail035 typecheck/should_fail/tcfail023 backpack/should_fail/bkpfail18 typecheck/should_fail/TcNullaryTCFail typecheck/should_fail/tcfail036 typecheck/should_fail/tcfail073 module/mod51 module/mod52 module/mod44 -} TcRnDupInstanceDecls :: !UnitState -> NE.NonEmpty ClsInst -> TcRnMessage {-| TcRnConflictingFamInstDecls is an error that occurs when there are conflicting family instance declarations. Examples(s): None. Test cases: indexed-types/should_fail/ExplicitForAllFams4b indexed-types/should_fail/NoGood indexed-types/should_fail/Over indexed-types/should_fail/OverDirectThisMod indexed-types/should_fail/OverIndirectThisMod indexed-types/should_fail/SimpleFail11a indexed-types/should_fail/SimpleFail11b indexed-types/should_fail/SimpleFail11c indexed-types/should_fail/SimpleFail11d indexed-types/should_fail/SimpleFail2a indexed-types/should_fail/SimpleFail2b indexed-types/should_fail/T13092/T13092 indexed-types/should_fail/T13092c/T13092c indexed-types/should_fail/T14179 indexed-types/should_fail/T2334A indexed-types/should_fail/T2677 indexed-types/should_fail/T3330b indexed-types/should_fail/T4246 indexed-types/should_fail/T7102a indexed-types/should_fail/T9371 polykinds/T7524 typecheck/should_fail/UnliftedNewtypesOverlap -} TcRnConflictingFamInstDecls :: NE.NonEmpty FamInst -> TcRnMessage TcRnFamInstNotInjective :: InjectivityErrReason -> TyCon -> NE.NonEmpty CoAxBranch -> TcRnMessage {-| TcRnBangOnUnliftedType is a warning (controlled by -Wredundant-strictness-flags) that occurs when a strictness annotation is applied to an unlifted type. Example(s): data T = MkT !Int# -- Strictness flag has no effect on unlifted types Test cases: typecheck/should_compile/T20187a typecheck/should_compile/T20187b -} TcRnBangOnUnliftedType :: !Type -> TcRnMessage {-| TcRnMultipleDefaultDeclarations is an error that occurs when a module has more than one default declaration. Example: default (Integer, Int) default (Double, Float) -- 2nd default declaration not allowed Text cases: module/mod58 -} TcRnMultipleDefaultDeclarations :: [LDefaultDecl GhcRn] -> TcRnMessage {-| TcRnBadDefaultType is an error that occurs when a type used in a default declaration does not have an instance for any of the applicable classes. Example(s): data Foo default (Foo) Test cases: typecheck/should_fail/T11974b -} TcRnBadDefaultType :: Type -> [Class] -> TcRnMessage {-| TcRnPatSynBundledWithNonDataCon is an error that occurs when a module's export list bundles a pattern synonym with a type that is not a proper `data` or `newtype` construction. Example(s): module Foo (MyClass(.., P)) where pattern P = Nothing class MyClass a where foo :: a -> Int Test cases: patsyn/should_fail/export-class -} TcRnPatSynBundledWithNonDataCon :: TcRnMessage {-| TcRnPatSynBundledWithWrongType is an error that occurs when the export list of a module has a pattern synonym bundled with a type that does not match the type of the pattern synonym. Example(s): module Foo (R(P,x)) where data Q = Q Int data R = R pattern P{x} = Q x Text cases: patsyn/should_fail/export-ps-rec-sel patsyn/should_fail/export-type-synonym patsyn/should_fail/export-type -} TcRnPatSynBundledWithWrongType :: Type -> Type -> TcRnMessage {-| TcRnDupeModuleExport is a warning controlled by @-Wduplicate-exports@ that occurs when a module appears more than once in an export list. Example(s): module Foo (module Bar, module Bar) import Bar Text cases: None -} TcRnDupeModuleExport :: ModuleName -> TcRnMessage {-| TcRnExportedModNotImported is an error that occurs when an export list contains a module that is not imported. Example(s): None Text cases: module/mod135 module/mod8 rename/should_fail/rnfail028 backpack/should_fail/bkpfail48 -} TcRnExportedModNotImported :: ModuleName -> TcRnMessage {-| TcRnNullExportedModule is a warning controlled by -Wdodgy-exports that occurs when an export list contains a module that has no exports. Example(s): module Foo (module Bar) where import Bar () Test cases: None -} TcRnNullExportedModule :: ModuleName -> TcRnMessage {-| TcRnMissingExportList is a warning controlled by -Wmissing-export-lists that occurs when a module does not have an explicit export list. Example(s): None Test cases: typecheck/should_fail/MissingExportList03 -} TcRnMissingExportList :: ModuleName -> TcRnMessage {-| TcRnExportHiddenComponents is an error that occurs when an export contains constructor or class methods that are not visible. Example(s): None Test cases: None -} TcRnExportHiddenComponents :: IE GhcPs -> TcRnMessage {-| TcRnDuplicateExport is a warning (controlled by -Wduplicate-exports) that occurs when an identifier appears in an export list more than once. Example(s): None Test cases: module/MultiExport module/mod128 module/mod14 module/mod5 overloadedrecflds/should_fail/DuplicateExports patsyn/should_compile/T11959 -} TcRnDuplicateExport :: GreName -> IE GhcPs -> IE GhcPs -> TcRnMessage {-| TcRnExportedParentChildMismatch is an error that occurs when an export is bundled with a parent that it does not belong to Example(s): module Foo (T(a)) where data T a = True Test cases: module/T11970 module/T11970B module/mod17 module/mod3 overloadedrecflds/should_fail/NoParent -} TcRnExportedParentChildMismatch :: Name -> TyThing -> GreName -> [Name] -> TcRnMessage {-| TcRnConflictingExports is an error that occurs when different identifiers that have the same name are being exported by a module. Example(s): module Foo (Bar.f, module Baz) where import qualified Bar (f) import Baz (f) Test cases: module/mod131 module/mod142 module/mod143 module/mod144 module/mod145 module/mod146 module/mod150 module/mod155 overloadedrecflds/should_fail/T14953 overloadedrecflds/should_fail/overloadedrecfldsfail10 rename/should_fail/rnfail029 rename/should_fail/rnfail040 typecheck/should_fail/T16453E2 typecheck/should_fail/tcfail025 typecheck/should_fail/tcfail026 -} TcRnConflictingExports :: OccName -- ^ Occurrence name shared by both exports -> GreName -- ^ Name of first export -> GlobalRdrElt -- ^ Provenance for definition site of first export -> IE GhcPs -- ^ Export decl of first export -> GreName -- ^ Name of second export -> GlobalRdrElt -- ^ Provenance for definition site of second export -> IE GhcPs -- ^ Export decl of second export -> TcRnMessage {-| TcRnAmbiguousField is a warning controlled by -Wambiguous-fields occurring when a record update's type cannot be precisely determined. This will not be supported by -XDuplicateRecordFields in future releases. Example(s): data Person = MkPerson { personId :: Int, name :: String } data Address = MkAddress { personId :: Int, address :: String } bad1 x = x { personId = 4 } :: Person -- ambiguous bad2 (x :: Person) = x { personId = 4 } -- ambiguous good x = (x :: Person) { personId = 4 } -- not ambiguous Test cases: overloadedrecflds/should_fail/overloadedrecfldsfail06 -} TcRnAmbiguousField :: HsExpr GhcRn -- ^ Field update -> TyCon -- ^ Record type -> TcRnMessage {-| TcRnMissingFields is a warning controlled by -Wmissing-fields occurring when the intialisation of a record is missing one or more (lazy) fields. Example(s): data Rec = Rec { a :: Int, b :: String, c :: Bool } x = Rec { a = 1, b = "two" } -- missing field 'c' Test cases: deSugar/should_compile/T13870 deSugar/should_compile/ds041 patsyn/should_compile/T11283 rename/should_compile/T5334 rename/should_compile/T12229 rename/should_compile/T5892a warnings/should_fail/WerrorFail2 -} TcRnMissingFields :: ConLike -> [(FieldLabelString, TcType)] -> TcRnMessage {-| TcRnFieldUpdateInvalidType is an error occurring when an updated field's type mentions something that is outside the universally quantified variables of the data constructor, such as an existentially quantified type. Example(s): data X = forall a. MkX { f :: a } x = (MkX ()) { f = False } Test cases: patsyn/should_fail/records-exquant typecheck/should_fail/T3323 -} TcRnFieldUpdateInvalidType :: [(FieldLabelString,TcType)] -> TcRnMessage {-| TcRnNoConstructorHasAllFields is an error that occurs when a record update has fields that no single constructor encompasses. Example(s): data Foo = A { x :: Bool } | B { y :: Int } foo = (A False) { x = True, y = 5 } Test cases: overloadedrecflds/should_fail/overloadedrecfldsfail08 patsyn/should_fail/mixed-pat-syn-record-sels typecheck/should_fail/T7989 -} TcRnNoConstructorHasAllFields :: [FieldLabelString] -> TcRnMessage {- TcRnMixedSelectors is an error for when a mixture of pattern synonym and record selectors are used in the same record update block. Example(s): data Rec = Rec { foo :: Int, bar :: String } pattern Pat { f1, f2 } = Rec { foo = f1, bar = f2 } illegal :: Rec -> Rec illegal r = r { f1 = 1, bar = "two" } Test cases: patsyn/should_fail/records-mixing-fields -} TcRnMixedSelectors :: Name -- ^ Record -> [Id] -- ^ Record selectors -> Name -- ^ Pattern synonym -> [Id] -- ^ Pattern selectors -> TcRnMessage {- TcRnMissingStrictFields is an error occurring when a record field marked as strict is omitted when constructing said record. Example(s): data R = R { strictField :: !Bool, nonStrict :: Int } x = R { nonStrict = 1 } Test cases: typecheck/should_fail/T18869 typecheck/should_fail/tcfail085 typecheck/should_fail/tcfail112 -} TcRnMissingStrictFields :: ConLike -> [(FieldLabelString, TcType)] -> TcRnMessage {- TcRnNoPossibleParentForFields is an error thrown when the fields used in a record update block do not all belong to any one type. Example(s): data R1 = R1 { x :: Int, y :: Int } data R2 = R2 { y :: Int, z :: Int } update r = r { x = 1, y = 2, z = 3 } Test cases: overloadedrecflds/should_fail/overloadedrecfldsfail01 overloadedrecflds/should_fail/overloadedrecfldsfail14 -} TcRnNoPossibleParentForFields :: [LHsRecUpdField GhcRn] -> TcRnMessage {- TcRnBadOverloadedRecordUpdate is an error for a record update that cannot be pinned down to any one constructor and thus must be given a type signature. Example(s): data R1 = R1 { x :: Int } data R2 = R2 { x :: Int } update r = r { x = 1 } -- needs a type signature Test cases: overloadedrecflds/should_fail/overloadedrecfldsfail01 -} TcRnBadOverloadedRecordUpdate :: [LHsRecUpdField GhcRn] -> TcRnMessage {- TcRnStaticFormNotClosed is an error pertaining to terms that are marked static using the -XStaticPointers extension but which are not closed terms. Example(s): f x = static x Test cases: rename/should_fail/RnStaticPointersFail01 rename/should_fail/RnStaticPointersFail03 -} TcRnStaticFormNotClosed :: Name -> NotClosedReason -> TcRnMessage {-| 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 {-| 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 -> 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 -> 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 -> 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 -> 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 ForeignImport -> 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 ForeignImport -> 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 -- | Specifies which backend code generators where expected for an FFI declaration data ExpectedBackends = COrAsmOrLlvm -- ^ C, Asm, or LLVM | COrAsmOrLlvmOrInterp -- ^ C, Asm, LLVM, or interpreted deriving Eq -- | 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 injectivity error arose together with more information, -- if any. data InjectivityErrReason = InjErrRhsBareTyVar [Type] | InjErrRhsCannotBeATypeFam | InjErrRhsOverlap | InjErrCannotInferFromRhs !TyVarSet !HasKinds !SuggestUndecidableInstances data HasKinds = YesHasKinds | NoHasKinds deriving (Show, Eq) hasKinds :: Bool -> HasKinds hasKinds True = YesHasKinds hasKinds False = NoHasKinds data SuggestUndecidableInstances = YesSuggestUndecidableInstaces | NoSuggestUndecidableInstaces deriving (Show, Eq) suggestUndecidableInstances :: Bool -> SuggestUndecidableInstances suggestUndecidableInstances True = YesSuggestUndecidableInstaces suggestUndecidableInstances False = NoSuggestUndecidableInstaces -- | A data type to describe why a variable is not closed. -- See Note [Not-closed error messages] in GHC.Tc.Gen.Expr data NotClosedReason = NotLetBoundReason | NotTypeClosed VarSet | NotClosed Name NotClosedReason data SuggestPartialTypeSignatures = YesSuggestPartialTypeSignatures | NoSuggestPartialTypeSignatures deriving (Show, Eq) suggestPartialTypeSignatures :: Bool -> SuggestPartialTypeSignatures suggestPartialTypeSignatures True = YesSuggestPartialTypeSignatures suggestPartialTypeSignatures False = NoSuggestPartialTypeSignatures data UsingGeneralizedNewtypeDeriving = YesGeneralizedNewtypeDeriving | NoGeneralizedNewtypeDeriving deriving Eq usingGeneralizedNewtypeDeriving :: Bool -> UsingGeneralizedNewtypeDeriving usingGeneralizedNewtypeDeriving True = YesGeneralizedNewtypeDeriving usingGeneralizedNewtypeDeriving False = NoGeneralizedNewtypeDeriving data DeriveAnyClassEnabled = YesDeriveAnyClassEnabled | NoDeriveAnyClassEnabled deriving Eq deriveAnyClassEnabled :: Bool -> DeriveAnyClassEnabled deriveAnyClassEnabled True = YesDeriveAnyClassEnabled deriveAnyClassEnabled False = NoDeriveAnyClassEnabled -- | Why a particular typeclass instance couldn't be derived. data DeriveInstanceErrReason = -- | The typeclass instance is not well-kinded. DerivErrNotWellKinded !TyCon -- ^ The type constructor that occurs in -- the typeclass instance declaration. !Kind -- ^ The typeclass kind. !Int -- ^ The number of typeclass arguments that GHC -- kept. See Note [tc_args and tycon arity] in -- GHC.Tc.Deriv. -- | Generic instances can only be derived using the stock strategy -- in Safe Haskell. | DerivErrSafeHaskellGenericInst | DerivErrDerivingViaWrongKind !Kind !Type !Kind | DerivErrNoEtaReduce !Type -- ^ The instance type -- | We cannot derive instances in boot files | DerivErrBootFileFound | DerivErrDataConsNotAllInScope !TyCon -- | We cannot use GND on non-newtype types | DerivErrGNDUsedOnData -- | We cannot derive instances of nullary classes | DerivErrNullaryClasses -- | Last arg must be newtype or data application | DerivErrLastArgMustBeApp | DerivErrNoFamilyInstance !TyCon [Type] | DerivErrNotStockDeriveable !DeriveAnyClassEnabled | DerivErrHasAssociatedDatatypes !HasAssociatedDataFamInsts !AssociatedTyLastVarInKind !AssociatedTyNotParamOverLastTyVar | DerivErrNewtypeNonDeriveableClass | DerivErrCannotEtaReduceEnough !Bool -- Is eta-reduction OK? | DerivErrOnlyAnyClassDeriveable !TyCon -- ^ Type constructor for which the instance -- is requested !DeriveAnyClassEnabled -- ^ Whether or not -XDeriveAnyClass is enabled -- already. -- | Stock deriving won't work, but perhas DeriveAnyClass will. | DerivErrNotDeriveable !DeriveAnyClassEnabled -- | The given 'PredType' is not a class. | DerivErrNotAClass !PredType -- | The given (representation of the) 'TyCon' has no -- data constructors. | DerivErrNoConstructors !TyCon | DerivErrLangExtRequired !LangExt.Extension -- | GHC simply doesn't how to how derive the input 'Class' for the given -- 'Type'. | DerivErrDunnoHowToDeriveForType !Type -- | The given 'TyCon' must be an enumeration. -- See Note [Enumeration types] in GHC.Core.TyCon | DerivErrMustBeEnumType !TyCon -- | The given 'TyCon' must have /precisely/ one constructor. | DerivErrMustHaveExactlyOneConstructor !TyCon -- | The given data type must have some parameters. | DerivErrMustHaveSomeParameters !TyCon -- | The given data type must not have a class context. | DerivErrMustNotHaveClassContext !TyCon !ThetaType -- | We couldn't derive an instance for a particular data constructor -- for a variety of reasons. | DerivErrBadConstructor !(Maybe HasWildcard) [DeriveInstanceBadConstructor] -- | We couldn't derive a 'Generic' instance for the given type for a -- variety of reasons | DerivErrGenerics [DeriveGenericsErrReason] -- | We couldn't derive an instance either because the type was not an -- enum type or because it did have more than one constructor. | DerivErrEnumOrProduct !DeriveInstanceErrReason !DeriveInstanceErrReason data DeriveInstanceBadConstructor = -- | The given 'DataCon' must be truly polymorphic in the -- last argument of the data type. DerivErrBadConExistential !DataCon -- | The given 'DataCon' must not use the type variable in a function argument" | DerivErrBadConCovariant !DataCon -- | The given 'DataCon' must not contain function types | DerivErrBadConFunTypes !DataCon -- | The given 'DataCon' must use the type variable only -- as the last argument of a data type | DerivErrBadConWrongArg !DataCon -- | The given 'DataCon' is a GADT so we cannot directly -- derive an istance for it. | DerivErrBadConIsGADT !DataCon -- | The given 'DataCon' has existentials type vars in its type. | DerivErrBadConHasExistentials !DataCon -- | The given 'DataCon' has constraints in its type. | DerivErrBadConHasConstraints !DataCon -- | The given 'DataCon' has a higher-rank type. | DerivErrBadConHasHigherRankType !DataCon data DeriveGenericsErrReason = -- | The type must not have some datatype context. DerivErrGenericsMustNotHaveDatatypeContext !TyCon -- | The data constructor must not have exotic unlifted -- or polymorphic arguments. | DerivErrGenericsMustNotHaveExoticArgs !DataCon -- | The data constructor must be a vanilla constructor. | DerivErrGenericsMustBeVanillaDataCon !DataCon -- | The type must have some type parameters. -- check (d) from Note [Requirements for deriving Generic and Rep] -- in GHC.Tc.Deriv.Generics. | DerivErrGenericsMustHaveSomeTypeParams !TyCon -- | The data constructor must not have existential arguments. | DerivErrGenericsMustNotHaveExistentials !DataCon -- | The derivation applies a type to an argument involving -- the last parameter but the applied type is not of kind * -> *. | DerivErrGenericsWrongArgKind !DataCon data HasWildcard = YesHasWildcard | NoHasWildcard deriving Eq hasWildcard :: Bool -> HasWildcard hasWildcard True = YesHasWildcard hasWildcard False = NoHasWildcard -- | A 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_msgs :: [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. } instance Semigroup SolverReport where SolverReport main1 supp1 hints1 <> SolverReport main2 supp2 hints2 = SolverReport (main1 ++ main2) (supp1 ++ supp2) (hints1 ++ hints2) instance Monoid SolverReport where mempty = SolverReport [] [] [] mappend = (Semigroup.<>) -- | 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 -- NB: this datatype is only a first step in refactoring GHC.Tc.Errors -- to use the diagnostic infrastructure (TcRnMessage etc). -- If you see possible improvements, please go right ahead! -- | Wrap a message with additional information. -- -- Prefer using the 'mkTcReportWithInfo' smart constructor = TcReportWithInfo TcSolverReportMsg (NE.NonEmpty TcSolverReportInfo) -- | 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 -- | A type equality between a type variable and a polytype. -- -- Test cases: T12427a, T2846b, T10194, ... | CannotUnifyWithPolytype ErrorItem TyVar Type -- | Couldn't unify two types or kinds. -- -- Example: -- -- 3 + 3# -- can't match a lifted type with an unlifted type -- -- Test cases: T1396, T8263, ... | Mismatch { mismatch_ea :: Bool -- ^ 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) } -- | 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 'Mismatch' and 'KindMismatch' messages. -- | 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? } -- TODO: combine 'Mismatch' and 'TypeEqMismatch' messages. -- | A violation of the representation-polymorphism invariants. -- -- See 'FixedRuntimeRepErrorInfo' and 'FixedRuntimeRepContext' for more information. | FixedRuntimeRepError [FixedRuntimeRepErrorInfo] -- | 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] -- | Trying to unify an untouchable variable, e.g. a variable from an outer scope. -- -- Test case: Simple14 | UntouchableVariable TyVar Implication -- | An equality between two types is blocked on a kind equality -- beteen their kinds. -- -- Test cases: none. | BlockedEquality ErrorItem -- | 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) -- | Couldn't solve some Wanted constraints using the Givens. -- This is the most commonly used constructor, used for generic -- @"No instance for ..."@ and @"Could not deduce ... from"@ messages. | 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 } -- | 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 :: [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_matches :: [ClsInst] , unsafeOverlapped :: [ClsInst] } -- | 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 -- | Additional information that can be appended to an existing 'TcSolverReportMsg'. data TcSolverReportInfo -- NB: this datatype is only a first step in refactoring GHC.Tc.Errors -- to use the diagnostic infrastructure (TcRnMessage etc). -- It would be better for these constructors to not be so closely tied -- to the constructors of 'TcSolverReportMsg'. -- If you see possible improvements, please go right ahead! -- | 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. } -- | Specify some information about a type variable, -- e.g. its 'SkolemInfo'. | TyVarInfo TyVar -- | Remind the user that a particular type family is not injective. | NonInjectiveTyFam TyCon -- | Explain why we couldn't coerce between two types. See 'CoercibleMsg'. | ReportCoercibleMsg CoercibleMsg -- | 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. | WhenMatching TcType TcType CtOrigin (Maybe TypeOrKind) -- | Add some information to disambiguate errors in which -- two 'Names' would otherwise appear to be identical. -- -- See Note [Disambiguating (X ~ X) errors]. | SameOcc { sameOcc_same_pkg :: Bool -- ^ Whether the two 'Name's also came from the same package. , sameOcc_lhs :: Name , sameOcc_rhs :: Name } -- | Report some type variables that might be participating in an occurs-check failure. | OccursCheckInterestingTyVars (NE.NonEmpty TyVar) -- | 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 doesnt 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 -- | 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] } -- | Append additional information to a `TcSolverReportMsg`. mkTcReportWithInfo :: TcSolverReportMsg -> [TcSolverReportInfo] -> TcSolverReportMsg mkTcReportWithInfo msg [] = msg mkTcReportWithInfo (TcReportWithInfo msg (prev NE.:| prevs)) infos = TcReportWithInfo msg (prev NE.:| prevs ++ infos) mkTcReportWithInfo msg (info : infos) = TcReportWithInfo msg (info NE.:| infos) -- | 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's it's here for the moment as it's needed in "GHC.Tc.Errors". pprRelevantBindings (RelevantBindings bds ran_out_of_fuel) = ppUnless (null bds) $ hang (text "Relevant bindings include") 2 (vcat (map ppr_binding 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)))] discardMsg :: SDoc discardMsg = text "(Some bindings suppressed;" <+> text "use -fmax-relevant-binds=N or -fno-max-relevant-binds)" -- | 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