:: a typeCtrl KGHC 10.0.0.20260917 · lts/ghc-10.0.x · fc4e598 · 2026-10-11
Moduleghc-10.0.0.20260917GHC2024
Describes the provenance of types as they flow through the type-checker. The datatypes here are mainly used for error message generation.
SkolemInfo stores the origin of a skolem type variable, so that we can display this information to the user in case of a type error.
The Unique field allows us to report all skolem type variables bound in the same place in a single report.
Outputable SkolemInfoDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginUniquable SkolemInfoDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginSkolemInfoAnon stores the origin of a skolem type variable (e.g. bound by a user-written forall, the header of a data declaration, a deriving clause, ...).
This information is displayed when reporting an error message, such as
"Couldn't match k with l"This allows us to explain where the type variable came from.
When several skolem type variables are bound at once, prefer using SkolemInfo, which stores a Unique which allows these type variables to be reported
SigSkol UserTypeCtxt TcType [(Name, TcTyVar)]InferSkol [(Name, TcType)]SigTypeSkol UserTypeCtxtForAllSkol TyVarBndrsDerivSkol TypeInstSkol ClsInstOrQC PatersonSizeMethSkol Name BoolFamInstSkolPatSkol ConLike HsMatchContextRnIPSkol [HsIPName]RuleSkol RuleNameSpecESkol NameBracketSkolUnifyForAllSkol TcTypeTyConSkol (TyConFlavour TyCon) NameDataConSkol NameReifySkolRuntimeUnkSkolArrowReboundIfSkolUnkSkol CallStackDefaultSkolStaticFormSkolOutputable SkolemInfoAnonDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginWrap up the origin of a skolem type variable with a new Unique, so that we can common up skolem type variables whose SkolemInfo shares a certain Unique.
Use this when you can't specify a helpful origin for some skolem type variable.
We're hoping to be able to get rid of this entirely, but for the moment it's still needed.
GivenOrigin SkolemInfoAnonA given constraint from a user-written type signature. The SkolemInfo inside gives more information.
GivenSCOrigin SkolemInfoAnon ScDepth BoolGivenSCOrigin is used for a Given constraint obtained by superclass selection
from the context of an instance declaration. E.g.
instance (Foo a, Bar a) => C [a] where ...
When typechecking the instance decl itself, including producing evidence
for the superclasses of C, the superclasses of (Foo a) and (Bar a) will
have GivenSCOrigin origin.
OccurrenceOf NameOccurrence of an overloaded identifier
OccurrenceOfRecSel (LocatedN RdrName)Occurrence of a record selector
AppOriginAn application of some kind
SpecPragOrigin UserTypeCtxtSpecialisation pragma for function or instance
TypeEqOriginuo_actual :: TcTypeuo_expected :: TcTypeuo_thing :: Maybe TypedThingThe thing that has type "actual"
uo_invisible :: Maybe InvisibleBitDoes this equality arise from an invisible component? (Errors from the polymorphic subsumption check are considered visible.) Only used for prioritizing error messages.
KindEqOrigin TcType TcType CtOrigin (Maybe TypeOrKind)A kind equality arising from unifying two types
DefaultReprEqOrigin TcType TcType CtOriginA constraint that arose from defaulting a representational equality to a nominal equality
IPOccOrigin HsIPNameOverLabelOrigin FastStringLiteralOrigin (HsOverLit GhcRn)QualLiteralOrigin (HsQualLit GhcRn)NegateOriginArithSeqOrigin (ArithSeqInfo GhcRn)AssocFamPatOriginSectionOriginGetFieldOrigin (LocatedN FastString)RecordFieldProjectionOrigin (FieldLabelStrings GhcRn)A overloaded record field projection like .fld or .fld1.fld2.fld.
TupleOriginExprSigOriginPatSigOriginPatOriginProvCtxtOrigin (PatSynBind GhcRn GhcRn)RecordUpdOriginViewPatOriginScOrigin ClsInstOrQC NakedScFlagScOrigin is used only for the Wanted constraints for the superclasses of an instance declaration.
DerivOrigin StandaloneDerivDerivOriginDC DataCon Int StandaloneDerivDerivOriginCoerce Id Type Type StandaloneDerivDefaultOriginDoStmtOriginDoPatOrigin (LPat GhcRn)MCompOriginMCompPatOrigin (LPat GhcRn)ProcOriginArrowCmdOriginAnnOriginFunDepOriginExprHoleOrigin (Maybe RdrName)TypeHoleOrigin OccNamePatCheckOriginListOriginIfThenElseOriginBracketOriginStaticOriginImpedanceMatching IdShouldn'tHappenOrigin StringInstProvidedOrigin Module ClsInstTesting whether the constraint associated with an instance declaration in a signature file is satisfied upon instantiation.
Test cases: backpackshould_failbkpfail{11,43}.bkp
NonLinearPatternOrigin NonLinearPatternReason (LPat GhcRn)OmittedFieldOrigin (Maybe FieldLabel)UsageEnvironmentOf NameCycleBreakerOrigin CtOriginSee Detail (7) of Note [Type equality cycles] in GHC.Tc.Solver.Equality
FRROrigin FixedRuntimeRepOriginWantedSuperclassOrigin PredType CtOriginInstanceSigOrigin Name Type TypeAmbiguityCheckOrigin UserTypeCtxtImplicitLiftOrigin HsImplicitLiftSpliceOutputable CtOriginDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginExtract a suitable CtOrigin from a HsExpr
Extract a suitable CtOrigin from a MatchGroup
Extract a suitable CtOrigin from guarded RHSs
Print CtOrigin briefly, with a one-liner
Did this constraint arise from defaulting a representational equality?
That is, this function extracts all occurrences of the DefaultReprEqOrigin constructor from within a CtOrigin.
Did a constraint arise from expanding a Wanted constraint to look at superclasses?
Does this constraint arise from GHC internal mechanisms that desugar to
usage of the HasField typeclass (e.g. OverloadedRecordDot, etc)?
Used in two places:
When reporting an unsolved HasField constraint, to decide whether to
print an informative message to the user.
See (H2e) in Note [Error messages for unsolved HasField constraints]
in GHC.Tc.Errors.
To avoid emitting a poor "incomplete record selector" warning directly in typechecker, in cases when the desugarer will be able to emit a better error message, due to having better pattern match checking information. See (IRS7) in Note [Detecting incomplete record selectors] in GHC.HsToCore.Pmc
Outputable NakedScFlagDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginInformation about an implicit lift, discovered by the renamer See Note [Lifecycle of an untyped splice, and PendingRnSplice]
HsImplicitLiftSpliceimplicit_lift_bind_lvl :: Set ThLevelIndeximplicit_lift_used_lvl :: ThLevelIndeximplicit_lift_gre :: Maybe GlobalRdrEltNothing iff LevelCheckReason is LevelCheckInstance
implicit_lift_lid :: LIdOccP GhcRnData HsImplicitLiftSpliceDefined in ghc-10.0.0.20260917 · GHC.Hs.Instances · orphanSome thing which has a type.
This datatype is used when we want to report to the user that something has an unexpected type.
Outputable TypedThingDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginSome kind of type variable binder.
Used for reporting errors, in SkolemInfo and TcSolverReportMsg.
forall flag. OutputableBndrFlag flag 'Renamed => HsTyVarBndrsRn [HsTyVarBndr flag GhcRn]Outputable TyVarBndrsDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginThe context for a representation-polymorphism check.
For example, when typechecking (a :: k) -> ...,
we are checking the type a because it's the type of
a term variable bound in a lambda, so we use FRRBinder.
FixedRuntimeRepOriginfrr_type :: TypeWhat type are we checking?
For example, a[tau] in a[tau] :: TYPE rr[tau].
frr_context :: FixedRuntimeRepContextWhat context requires a fixed runtime representation?
Outputable FixedRuntimeRepOriginDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginThe context in which a representation-polymorphism check was performed.
Does not include the type on which the check was performed; see FixedRuntimeRepOrigin for that.
FRRRecordCon !RdrName !(HsExpr GhcTc)Record fields in record construction must have a fixed runtime representation.
FRRRecordUpdate !Name !(HsExpr GhcRn)Record fields in record updates must have a fixed runtime representation.
Test case: RepPolyRecordUpdate.
FRRBinder !NameVariable binders must have a fixed runtime representation.
Test cases: LevPolyLet, RepPolyPatBind.
FRRRepPolyId !Name !RepPolyId !(Position 'Neg)Types appearing in negative position in the type of a representation-polymorphic Id must have a fixed runtime representation.
This includes:
arguments,
Test cases: RepPolyMagic, RepPolyRightSection, RepPolyWrappedVar, T14561b, T17817.
continuation result types, such as in catch#, keepAlive#
and control0#.
Test case: T21906.
FRRPatBindPattern binds must have a fixed runtime representation.
Test case: RepPolyInferPatBind.
FRRPatSynArgPattern synonym arguments must have a fixed runtime representation.
Test case: RepPolyInferPatSyn.
FRRCaseThe type of the scrutinee in a case statement must have a fixed runtime representation.
Test cases: RepPolyCase{1,2}.
FRRDataConPatArg !DataCon !IntAn instantiation of a newtype/data constructor pattern in which an argument type does not have a fixed runtime representation.
Test case: T20363.
FRRUnboxedTuple !IntThe RuntimeRep arguments to unboxed tuples must be concrete RuntimeReps.
Test case: RepPolyTuple.
FRRUnboxedTupleSection !IntTuple sections must have a fixed runtime representation.
Test case: RepPolyTupleSection.
FRRUnboxedSum !(Maybe Int)The RuntimeRep arguments to unboxed sums must be concrete RuntimeReps.
Test cases: RepPolySum.
FRRBodyStmt !StmtOrigin !IntThe body of a do expression or a monad comprehension must
have a fixed runtime representation.
Test cases: RepPolyDoBody{1,2}, RepPolyMcBody.
FRRBodyStmtGuardArguments to a guard in a monad comprehension must have a fixed runtime representation.
Test case: RepPolyMcGuard.
FRRBindStmt !StmtOriginArguments to (>>=) arising from a do expression
or a monad comprehension must have a fixed runtime representation.
Test cases: RepPolyDoBind, RepPolyMcBind.
FRRBindStmtGuardA value bound by a pattern guard must have a fixed runtime representation.
Test cases: none.
FRRArrow !FRRArrowContextA representation-polymorphism check arising from arrow notation.
See FRRArrowContext for more details.
FRRExpectedFunTy !ExpectedFunTyCtxt !IntA representation-polymorphism check arising from a call
to matchExpectedFunTys or matchActualFunTy.
See ExpectedFunTyCtxt for more details.
forall p. FRRDeepSubsumptionA representation-polymorphism check arising from eta-expansion performed as part of deep subsumption.
frrDSExpected :: BoolfrrDSPosition :: Position pfrrAppHead :: Maybe (HsExpr GhcTc)Outputable FixedRuntimeRepContextDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginPrint the context for a FixedRuntimeRep representation-polymorphism check.
Note that this function does not include the specific RuntimeRep which is not fixed. That information is stored in FixedRuntimeRepOrigin and is reported separately.
Are we in a do expression or a monad comprehension?
This datatype is only used to report this context to the user in error messages.
Outputable StmtOriginDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginThe position of an argument (to be reported in an error message).
ArgPosInvisInvisible argument: don't report its position to the user.
ArgPosVis !IntVisible argument in i-th position.
A synonym for FRRUnboxedTuple exposed in the hs-boot file for GHC.Tc.Types.Origin.
A synonym for FRRUnboxedSum exposed in the hs-boot file for GHC.Tc.Types.Origin.
The description of a representation-polymorphic Id.
RepPolyPrimOpA representation-polymorphic PrimOp.
RepPolyTupleAn unboxed tuple constructor.
RepPolySumAn unboxed sum constructor.
RepPolyFunctionAn unspecified representation-polymorphic function,
e.g. a pseudo-op such as coerce.
A position in which a type variable appears in a type; in particular, whether it appears in a positive or a negative position.
See Note [Positional information in representation-polymorphism errors].
Show (Position p)Defined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginOutputable (Position p)Defined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginWhile typechecking arrow notation, in which context did a representation polymorphism check arise?
See FixedRuntimeRepContext for more general origins of representation polymorphism checks.
ArrowCmdResTy !(HsCmd GhcRn)The result of an arrow command does not have a fixed runtime representation.
Test case: RepPolyArrowCmd.
ArrowCmdApp !(HsCmd GhcRn) !(HsExpr GhcRn)The argument to an arrow in an arrow command application does not have a fixed runtime representation.
Test cases: none.
ArrowCmdArrApp !(HsExpr GhcRn) !(HsExpr GhcRn) !HsArrAppTypeA function in an arrow application does not have a fixed runtime representation.
Test cases: none.
ArrowCmdCaseThe scrutinee type in an arrow command case statement does not have a fixed runtime representation.
Test cases: none.
ArrowFun !(HsExpr GhcRn)The overall type of an arrow proc expression does not have a fixed runtime representation.
Test case: RepPolyArrowFun.
Outputable FRRArrowContextDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginIn what context are we calling matchExpectedFunTys
or matchActualFunTy?
Used for two things:
Reporting error messages which explain that a function has been given an unexpected number of arguments. Uses pprExpectedFunTyHerald. See Note [Herald for matchExpectedFunTys] in GHC.Tc.Utils.Unify.
Reporting representation-polymorphism errors when a function argument doesn't have a fixed RuntimeRep as per Note [Fixed RuntimeRep] in GHC.Tc.Utils.Concrete. Uses pprExpectedFunTyCtxt. See FixedRuntimeRepContext for the situations in which representation-polymorphism checks are performed.
forall p. OutputableBndrId p => ExpectedFunTySyntaxOp !CtOrigin !(HsExpr (GhcPass p))A rebindable syntax operator is expected to have a function type.
Test cases for representation-polymorphism checks: RepPolyMc{Bind,Body,Guard}, RepPolyNPlusK
ExpectedFunTyViewPat !(HsExpr GhcRn)A view pattern must have a function type.
Test cases for representation-polymorphism checks: RepPolyBinder
forall p. Outputable (HsExpr (GhcPass p)) => ExpectedFunTyArg !TypedThing !(HsExpr (GhcPass p))Need to be able to extract an argument type from a function type.
Test cases for representation-polymorphism checks: RepPolyApp
ExpectedFunTyMatches !TypedThing !(MatchGroup GhcRn (LHsExpr GhcRn))Ensure that a function defined by equations indeed has a function type with the appropriate number of arguments.
Test cases for representation-polymorphism checks: RepPolyBinder, RepPolyRecordPattern, RepPolyWildcardPattern
ExpectedFunTyLam HsLamVariant !(HsExpr GhcRn)Ensure that a lambda abstraction has a function type.
Test cases for representation-polymorphism checks: RepPolyLambda, RepPolyMatch
FRRRepPolyUnliftedNewtype !DataConA partial application of the constructor of a representation-polymorphic unlifted newtype in which the argument type does not have a fixed runtime representation.
Test cases: UnliftedNewtypesLevityBinder, UnliftedNewtypesCoerceFail.
Outputable InstanceWhatDefined in ghc-10.0.0.20260917 · GHC.Tc.Types.OriginIndicates if Instance met the Safe Haskell overlapping instances safety check.
See Note [Safe Haskell Overlapping Instances] in GHC.Tc.Solver See Note [Safe Haskell Overlapping Instances Implementation] in GHC.Tc.Solver