{-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE LambdaCase #-} {-# LANGUAGE NamedFieldPuns #-} {-# LANGUAGE RecordWildCards #-} {-# OPTIONS_GHC -fno-warn-orphans #-} -- instance Diagnostic TcRnMessage module GHC.Tc.Errors.Ppr ( pprTypeDoesNotHaveFixedRuntimeRep , pprScopeError -- , tidySkolemInfo , tidySkolemInfoAnon -- , withHsDocContext , pprHsDocContext , inHsDocContext ) where import GHC.Prelude import GHC.Builtin.Names import GHC.Core.Coercion import GHC.Core.Unify ( tcMatchTys ) import GHC.Core.TyCon import GHC.Core.Class import GHC.Core.DataCon import GHC.Core.Coercion.Axiom (coAxiomTyCon, coAxiomSingleBranch) import GHC.Core.ConLike import GHC.Core.FamInstEnv (famInstAxiom) import GHC.Core.InstEnv import GHC.Core.TyCo.Rep (Type(..)) import GHC.Core.TyCo.Ppr (pprWithExplicitKindsWhen, pprSourceTyCon, pprTyVars, pprWithTYPE) import GHC.Core.PatSyn ( patSynName, pprPatSynType ) import GHC.Core.Predicate import GHC.Core.Type import GHC.Driver.Flags import GHC.Hs import GHC.Tc.Errors.Types import GHC.Tc.Types.Constraint import {-# SOURCE #-} GHC.Tc.Types (getLclEnvLoc) import GHC.Tc.Types.Origin import GHC.Tc.Types.Rank (Rank(..)) import GHC.Tc.Utils.TcType import GHC.Types.Error import GHC.Types.FieldLabel (flIsOverloaded) import GHC.Types.Hint (UntickedPromotedThing(..), pprUntickedConstructor, isBareSymbol) import GHC.Types.Hint.Ppr () -- Outputable GhcHint import GHC.Types.Basic import GHC.Types.Id import GHC.Types.Name import GHC.Types.Name.Reader ( GreName(..), pprNameProvenance , RdrName, rdrNameOcc, greMangledName ) import GHC.Types.Name.Set import GHC.Types.SrcLoc import GHC.Types.TyThing import GHC.Types.Unique.Set ( nonDetEltsUniqSet ) import GHC.Types.Var import GHC.Types.Var.Set import GHC.Types.Var.Env import GHC.Unit.State (pprWithUnitState, UnitState) import GHC.Unit.Module import GHC.Data.Bag import GHC.Data.FastString import GHC.Data.List.SetOps ( nubOrdBy ) import GHC.Data.Maybe import GHC.Utils.Misc import GHC.Utils.Outputable import GHC.Utils.Panic import qualified GHC.LanguageExtensions as LangExt import Data.List.NonEmpty (NonEmpty(..)) import qualified Data.List.NonEmpty as NE import Data.Function (on) import Data.List ( groupBy, sortBy, tails , partition, unfoldr ) import Data.Ord ( comparing ) import Data.Bifunctor import GHC.Types.Name.Env instance Diagnostic TcRnMessage where diagnosticMessage = \case TcRnUnknownMessage m -> diagnosticMessage m TcRnMessageWithInfo unit_state msg_with_info -> case msg_with_info of TcRnMessageDetailed err_info msg -> messageWithInfoDiagnosticMessage unit_state err_info (diagnosticMessage msg) TcRnSolverReport msgs _ _ -> mkDecorated $ map pprSolverReportWithCtxt msgs TcRnRedundantConstraints redundants (info, show_info) -> mkSimpleDecorated $ text "Redundant constraint" <> plural redundants <> colon <+> pprEvVarTheta redundants $$ if show_info then text "In" <+> ppr info else empty TcRnInaccessibleCode implic contras -> mkSimpleDecorated $ hang (text "Inaccessible code in") 2 (ppr (ic_info implic)) $$ vcat (map pprSolverReportWithCtxt (NE.toList contras)) TcRnTypeDoesNotHaveFixedRuntimeRep ty prov (ErrInfo extra supplementary) -> mkDecorated [pprTypeDoesNotHaveFixedRuntimeRep ty prov, extra, supplementary] TcRnImplicitLift id_or_name ErrInfo{..} -> mkDecorated $ ( text "The variable" <+> quotes (ppr id_or_name) <+> text "is implicitly lifted in the TH quotation" ) : [errInfoContext, errInfoSupplementary] TcRnUnusedPatternBinds bind -> mkDecorated [hang (text "This pattern-binding binds no variables:") 2 (ppr bind)] TcRnDodgyImports name -> mkDecorated [dodgy_msg (text "import") name (dodgy_msg_insert name :: IE GhcPs)] TcRnDodgyExports name -> mkDecorated [dodgy_msg (text "export") name (dodgy_msg_insert name :: IE GhcRn)] TcRnMissingImportList ie -> mkDecorated [ text "The import item" <+> quotes (ppr ie) <+> text "does not have an explicit import list" ] TcRnUnsafeDueToPlugin -> mkDecorated [text "Use of plugins makes the module unsafe"] TcRnModMissingRealSrcSpan mod -> mkDecorated [text "Module does not have a RealSrcSpan:" <+> ppr mod] TcRnIdNotExportedFromModuleSig name mod -> mkDecorated [ text "The identifier" <+> ppr (occName name) <+> text "does not exist in the signature for" <+> ppr mod ] TcRnIdNotExportedFromLocalSig name -> mkDecorated [ text "The identifier" <+> ppr (occName name) <+> text "does not exist in the local signature." ] TcRnShadowedName occ provenance -> let shadowed_locs = case provenance of ShadowedNameProvenanceLocal n -> [text "bound at" <+> ppr n] ShadowedNameProvenanceGlobal gres -> map pprNameProvenance gres in mkSimpleDecorated $ sep [text "This binding for" <+> quotes (ppr occ) <+> text "shadows the existing binding" <> plural shadowed_locs, nest 2 (vcat shadowed_locs)] TcRnDuplicateWarningDecls d rdr_name -> mkSimpleDecorated $ vcat [text "Multiple warning declarations for" <+> quotes (ppr rdr_name), text "also at " <+> ppr (getLocA d)] TcRnSimplifierTooManyIterations simples limit wc -> mkSimpleDecorated $ hang (text "solveWanteds: too many iterations" <+> parens (text "limit =" <+> ppr limit)) 2 (vcat [ text "Unsolved:" <+> ppr wc , text "Simples:" <+> ppr simples ]) TcRnIllegalPatSynDecl rdrname -> mkSimpleDecorated $ hang (text "Illegal pattern synonym declaration for" <+> quotes (ppr rdrname)) 2 (text "Pattern synonym declarations are only valid at top level") TcRnLinearPatSyn ty -> mkSimpleDecorated $ hang (text "Pattern synonyms do not support linear fields (GHC #18806):") 2 (ppr ty) TcRnEmptyRecordUpdate -> mkSimpleDecorated $ text "Empty record update" TcRnIllegalFieldPunning fld -> mkSimpleDecorated $ text "Illegal use of punning for field" <+> quotes (ppr fld) TcRnIllegalWildcardsInRecord fld_part -> mkSimpleDecorated $ text "Illegal `..' in record" <+> pprRecordFieldPart fld_part TcRnIllegalWildcardInType mb_name bad mb_ctxt -> mkSimpleDecorated $ vcat [ main_msg, context_msg ] where main_msg :: SDoc main_msg = case bad of WildcardNotLastInConstraint -> hang notAllowed 2 constraint_hint_msg ExtraConstraintWildcardNotAllowed allow_sole -> case allow_sole of SoleExtraConstraintWildcardNotAllowed -> notAllowed SoleExtraConstraintWildcardAllowed -> hang notAllowed 2 sole_msg WildcardsNotAllowedAtAll -> notAllowed context_msg :: SDoc context_msg = case mb_ctxt of Just ctxt -> nest 2 (text "in" <+> pprHsDocContext ctxt) _ -> empty notAllowed, what, wildcard, how :: SDoc notAllowed = what <+> quotes wildcard <+> how wildcard = case mb_name of Nothing -> pprAnonWildCard Just name -> ppr name what | Just _ <- mb_name = text "Named wildcard" | ExtraConstraintWildcardNotAllowed {} <- bad = text "Extra-constraint wildcard" | otherwise = text "Wildcard" how = case bad of WildcardNotLastInConstraint -> text "not allowed in a constraint" _ -> text "not allowed" constraint_hint_msg :: SDoc constraint_hint_msg | Just _ <- mb_name = vcat [ text "Extra-constraint wildcards must be anonymous" , nest 2 (text "e.g f :: (Eq a, _) => blah") ] | otherwise = vcat [ text "except as the last top-level constraint of a type signature" , nest 2 (text "e.g f :: (Eq a, _) => blah") ] sole_msg :: SDoc sole_msg = vcat [ text "except as the sole constraint" , nest 2 (text "e.g., deriving instance _ => Eq (Foo a)") ] TcRnDuplicateFieldName fld_part dups -> mkSimpleDecorated $ hsep [text "duplicate field name", quotes (ppr (NE.head dups)), text "in record", pprRecordFieldPart fld_part] TcRnIllegalViewPattern pat -> mkSimpleDecorated $ vcat [text "Illegal view pattern: " <+> ppr pat] TcRnCharLiteralOutOfRange c -> mkSimpleDecorated $ text "character literal out of range: '\\" <> char c <> char '\'' TcRnIllegalWildcardsInConstructor con -> mkSimpleDecorated $ vcat [ text "Illegal `..' notation for constructor" <+> quotes (ppr con) , nest 2 (text "The constructor has no labelled fields") ] TcRnIgnoringAnnotations anns -> mkSimpleDecorated $ text "Ignoring ANN annotation" <> plural anns <> comma <+> text "because this is a stage-1 compiler without -fexternal-interpreter or doesn't support GHCi" TcRnAnnotationInSafeHaskell -> mkSimpleDecorated $ vcat [ text "Annotations are not compatible with Safe Haskell." , text "See https://gitlab.haskell.org/ghc/ghc/issues/10826" ] TcRnInvalidTypeApplication fun_ty hs_ty -> mkSimpleDecorated $ text "Cannot apply expression of type" <+> quotes (ppr fun_ty) $$ text "to a visible type argument" <+> quotes (ppr hs_ty) TcRnTagToEnumMissingValArg -> mkSimpleDecorated $ text "tagToEnum# must appear applied to one value argument" TcRnTagToEnumUnspecifiedResTy ty -> mkSimpleDecorated $ hang (text "Bad call to tagToEnum# at type" <+> ppr ty) 2 (vcat [ text "Specify the type by giving a type signature" , text "e.g. (tagToEnum# x) :: Bool" ]) TcRnTagToEnumResTyNotAnEnum ty -> mkSimpleDecorated $ hang (text "Bad call to tagToEnum# at type" <+> ppr ty) 2 (text "Result type must be an enumeration type") TcRnArrowIfThenElsePredDependsOnResultTy -> mkSimpleDecorated $ text "Predicate type of `ifThenElse' depends on result type" TcRnIllegalHsBootFileDecl -> mkSimpleDecorated $ text "Illegal declarations in an hs-boot file" TcRnRecursivePatternSynonym binds -> mkSimpleDecorated $ hang (text "Recursive pattern synonym definition with following bindings:") 2 (vcat $ map pprLBind . bagToList $ binds) where pprLoc loc = parens (text "defined at" <+> ppr loc) pprLBind :: CollectPass GhcRn => GenLocated (SrcSpanAnn' a) (HsBindLR GhcRn idR) -> SDoc pprLBind (L loc bind) = pprWithCommas ppr (collectHsBindBinders CollNoDictBinders bind) <+> pprLoc (locA loc) TcRnPartialTypeSigTyVarMismatch n1 n2 fn_name hs_ty -> mkSimpleDecorated $ hang (text "Couldn't match" <+> quotes (ppr n1) <+> text "with" <+> quotes (ppr n2)) 2 (hang (text "both bound by the partial type signature:") 2 (ppr fn_name <+> dcolon <+> ppr hs_ty)) TcRnPartialTypeSigBadQuantifier n fn_name m_unif_ty hs_ty -> mkSimpleDecorated $ hang (text "Can't quantify over" <+> quotes (ppr n)) 2 (vcat [ hang (text "bound by the partial type signature:") 2 (ppr fn_name <+> dcolon <+> ppr hs_ty) , extra ]) where extra | Just rhs_ty <- m_unif_ty = sep [ quotes (ppr n), text "should really be", quotes (ppr rhs_ty) ] | otherwise = empty TcRnMissingSignature what _ _ -> mkSimpleDecorated $ case what of MissingPatSynSig p -> hang (text "Pattern synonym with no type signature:") 2 (text "pattern" <+> pprPrefixName (patSynName p) <+> dcolon <+> pprPatSynType p) MissingTopLevelBindingSig name ty -> hang (text "Top-level binding with no type signature:") 2 (pprPrefixName name <+> dcolon <+> pprSigmaType ty) MissingTyConKindSig tc cusks_enabled -> hang msg 2 (text "type" <+> pprPrefixName (tyConName tc) <+> dcolon <+> pprKind (tyConKind tc)) where msg | cusks_enabled = text "Top-level type constructor with no standalone kind signature or CUSK:" | otherwise = text "Top-level type constructor with no standalone kind signature:" TcRnPolymorphicBinderMissingSig n ty -> mkSimpleDecorated $ sep [ text "Polymorphic local binding with no type signature:" , nest 2 $ pprPrefixName n <+> dcolon <+> ppr ty ] TcRnOverloadedSig sig -> mkSimpleDecorated $ hang (text "Overloaded signature conflicts with monomorphism restriction") 2 (ppr sig) TcRnTupleConstraintInst _ -> mkSimpleDecorated $ text "You can't specify an instance for a tuple constraint" TcRnAbstractClassInst clas -> mkSimpleDecorated $ text "Cannot define instance for abstract class" <+> quotes (ppr (className clas)) TcRnNoClassInstHead tau -> mkSimpleDecorated $ hang (text "Instance head is not headed by a class:") 2 (pprType tau) TcRnUserTypeError ty -> mkSimpleDecorated (pprUserTypeErrorTy ty) TcRnConstraintInKind ty -> mkSimpleDecorated $ text "Illegal constraint in a kind:" <+> pprType ty TcRnUnboxedTupleOrSumTypeFuncArg tuple_or_sum ty -> mkSimpleDecorated $ sep [ text "Illegal unboxed" <+> what <+> text "type as function argument:" , pprType ty ] where what = case tuple_or_sum of UnboxedTupleType -> text "tuple" UnboxedSumType -> text "sum" TcRnLinearFuncInKind ty -> mkSimpleDecorated $ text "Illegal linear function in a kind:" <+> pprType ty TcRnForAllEscapeError ty kind -> mkSimpleDecorated $ vcat [ hang (text "Quantified type's kind mentions quantified type variable") 2 (text "type:" <+> quotes (ppr ty)) , hang (text "where the body of the forall has this kind:") 2 (quotes (pprKind kind)) ] TcRnVDQInTermType ty -> mkSimpleDecorated $ vcat [ hang (text "Illegal visible, dependent quantification" <+> text "in the type of a term:") 2 (pprType ty) , text "(GHC does not yet support this)" ] TcRnBadQuantPredHead ty -> mkSimpleDecorated $ hang (text "Quantified predicate must have a class or type variable head:") 2 (pprType ty) TcRnIllegalTupleConstraint ty -> mkSimpleDecorated $ text "Illegal tuple constraint:" <+> pprType ty TcRnNonTypeVarArgInConstraint ty -> mkSimpleDecorated $ hang (text "Non type-variable argument") 2 (text "in the constraint:" <+> pprType ty) TcRnIllegalImplicitParam ty -> mkSimpleDecorated $ text "Illegal implicit parameter" <+> quotes (pprType ty) TcRnIllegalConstraintSynonymOfKind kind -> mkSimpleDecorated $ text "Illegal constraint synonym of kind:" <+> quotes (pprKind kind) TcRnIllegalClassInst tcf -> mkSimpleDecorated $ vcat [ text "Illegal instance for a" <+> ppr tcf , text "A class instance must be for a class" ] TcRnOversaturatedVisibleKindArg ty -> mkSimpleDecorated $ text "Illegal oversaturated visible kind argument:" <+> quotes (char '@' <> pprParendType ty) TcRnBadAssociatedType clas tc -> mkSimpleDecorated $ hsep [ text "Class", quotes (ppr clas) , text "does not have an associated type", quotes (ppr tc) ] TcRnForAllRankErr rank ty -> let herald = case tcSplitForAllTyVars ty of ([], _) -> text "Illegal qualified type:" _ -> text "Illegal polymorphic type:" extra = case rank of MonoTypeConstraint -> text "A constraint must be a monotype" _ -> empty in mkSimpleDecorated $ vcat [hang herald 2 (pprType ty), extra] TcRnMonomorphicBindings bindings -> let pp_bndrs = pprBindings bindings in mkSimpleDecorated $ sep [ text "The Monomorphism Restriction applies to the binding" <> plural bindings , text "for" <+> pp_bndrs ] TcRnOrphanInstance inst -> mkSimpleDecorated $ hsep [ text "Orphan instance:" , pprInstanceHdr inst ] TcRnFunDepConflict unit_state sorted -> let herald = text "Functional dependencies conflict between instance declarations:" in mkSimpleDecorated $ pprWithUnitState unit_state $ (hang herald 2 (pprInstances $ NE.toList sorted)) TcRnDupInstanceDecls unit_state sorted -> let herald = text "Duplicate instance declarations:" in mkSimpleDecorated $ pprWithUnitState unit_state $ (hang herald 2 (pprInstances $ NE.toList sorted)) TcRnConflictingFamInstDecls sortedNE -> let sorted = NE.toList sortedNE in mkSimpleDecorated $ hang (text "Conflicting family instance declarations:") 2 (vcat [ pprCoAxBranchUser (coAxiomTyCon ax) (coAxiomSingleBranch ax) | fi <- sorted , let ax = famInstAxiom fi ]) TcRnFamInstNotInjective rea fam_tc (eqn1 NE.:| rest_eqns) -> let (herald, show_kinds) = case rea of InjErrRhsBareTyVar tys -> (injectivityErrorHerald $$ text "RHS of injective type family equation is a bare" <+> text "type variable" $$ text "but these LHS type and kind patterns are not bare" <+> text "variables:" <+> pprQuotedList tys, False) InjErrRhsCannotBeATypeFam -> (injectivityErrorHerald $$ text "RHS of injective type family equation cannot" <+> text "be a type family:", False) InjErrRhsOverlap -> (text "Type family equation right-hand sides overlap; this violates" $$ text "the family's injectivity annotation:", False) InjErrCannotInferFromRhs tvs has_kinds _ -> let show_kinds = has_kinds == YesHasKinds what = if show_kinds then text "Type/kind" else text "Type" body = sep [ what <+> text "variable" <> pluralVarSet tvs <+> pprVarSet tvs (pprQuotedList . scopedSort) , text "cannot be inferred from the right-hand side." ] in (injectivityErrorHerald $$ body $$ text "In the type family equation:", show_kinds) in mkSimpleDecorated $ pprWithExplicitKindsWhen show_kinds $ hang herald 2 (vcat (map (pprCoAxBranchUser fam_tc) (eqn1 : rest_eqns))) TcRnBangOnUnliftedType ty -> mkSimpleDecorated $ text "Strictness flag has no effect on unlifted type" <+> quotes (ppr ty) TcRnMultipleDefaultDeclarations dup_things -> mkSimpleDecorated $ hang (text "Multiple default declarations") 2 (vcat (map pp dup_things)) where pp :: LDefaultDecl GhcRn -> SDoc pp (L locn (DefaultDecl _ _)) = text "here was another default declaration" <+> ppr (locA locn) TcRnBadDefaultType ty deflt_clss -> mkSimpleDecorated $ hang (text "The default type" <+> quotes (ppr ty) <+> text "is not an instance of") 2 (foldr1 (\a b -> a <+> text "or" <+> b) (map (quotes. ppr) deflt_clss)) TcRnPatSynBundledWithNonDataCon -> mkSimpleDecorated $ text "Pattern synonyms can be bundled only with datatypes." TcRnPatSynBundledWithWrongType expected_res_ty res_ty -> mkSimpleDecorated $ text "Pattern synonyms can only be bundled with matching type constructors" $$ text "Couldn't match expected type of" <+> quotes (ppr expected_res_ty) <+> text "with actual type of" <+> quotes (ppr res_ty) TcRnDupeModuleExport mod -> mkSimpleDecorated $ hsep [ text "Duplicate" , quotes (text "Module" <+> ppr mod) , text "in export list" ] TcRnExportedModNotImported mod -> mkSimpleDecorated $ formatExportItemError (text "module" <+> ppr mod) "is not imported" TcRnNullExportedModule mod -> mkSimpleDecorated $ formatExportItemError (text "module" <+> ppr mod) "exports nothing" TcRnMissingExportList mod -> mkSimpleDecorated $ formatExportItemError (text "module" <+> ppr mod) "is missing an export list" TcRnExportHiddenComponents export_item -> mkSimpleDecorated $ formatExportItemError (ppr export_item) "attempts to export constructors or class methods that are not visible here" TcRnDuplicateExport child ie1 ie2 -> mkSimpleDecorated $ hsep [ quotes (ppr child) , text "is exported by", quotes (ppr ie1) , text "and", quotes (ppr ie2) ] TcRnExportedParentChildMismatch parent_name ty_thing child parent_names -> mkSimpleDecorated $ text "The type constructor" <+> quotes (ppr parent_name) <+> text "is not the parent of the" <+> text what_is <+> quotes thing <> char '.' $$ text (capitalise what_is) <> text "s can only be exported with their parent type constructor." $$ (case parents of [] -> empty [_] -> text "Parent:" _ -> text "Parents:") <+> fsep (punctuate comma parents) where pp_category :: TyThing -> String pp_category (AnId i) | isRecordSelector i = "record selector" pp_category i = tyThingCategory i what_is = pp_category ty_thing thing = ppr child parents = map ppr parent_names TcRnConflictingExports occ child1 gre1 ie1 child2 gre2 ie2 -> mkSimpleDecorated $ vcat [ text "Conflicting exports for" <+> quotes (ppr occ) <> colon , ppr_export child1 gre1 ie1 , ppr_export child2 gre2 ie2 ] where ppr_export child gre ie = nest 3 (hang (quotes (ppr ie) <+> text "exports" <+> quotes (ppr_name child)) 2 (pprNameProvenance gre)) -- DuplicateRecordFields means that nameOccName might be a -- mangled $sel-prefixed thing, in which case show the correct OccName -- alone (but otherwise show the Name so it will have a module -- qualifier) ppr_name (FieldGreName fl) | flIsOverloaded fl = ppr fl | otherwise = ppr (flSelector fl) ppr_name (NormalGreName name) = ppr name TcRnAmbiguousField rupd parent_type -> mkSimpleDecorated $ vcat [ text "The record update" <+> ppr rupd <+> text "with type" <+> ppr parent_type <+> text "is ambiguous." , text "This will not be supported by -XDuplicateRecordFields in future releases of GHC." ] TcRnMissingFields con fields -> mkSimpleDecorated $ vcat [header, nest 2 rest] where rest | null fields = empty | otherwise = vcat (fmap pprField fields) header = text "Fields of" <+> quotes (ppr con) <+> text "not initialised" <> if null fields then empty else colon TcRnFieldUpdateInvalidType prs -> mkSimpleDecorated $ hang (text "Record update for insufficiently polymorphic field" <> plural prs <> colon) 2 (vcat [ ppr f <+> dcolon <+> ppr ty | (f,ty) <- prs ]) TcRnNoConstructorHasAllFields conflictingFields -> mkSimpleDecorated $ hang (text "No constructor has all these fields:") 2 (pprQuotedList conflictingFields) TcRnMixedSelectors data_name data_sels pat_name pat_syn_sels -> mkSimpleDecorated $ text "Cannot use a mixture of pattern synonym and record selectors" $$ text "Record selectors defined by" <+> quotes (ppr data_name) <> colon <+> pprWithCommas ppr data_sels $$ text "Pattern synonym selectors defined by" <+> quotes (ppr pat_name) <> colon <+> pprWithCommas ppr pat_syn_sels TcRnMissingStrictFields con fields -> mkSimpleDecorated $ vcat [header, nest 2 rest] where rest | null fields = empty -- Happens for non-record constructors -- with strict fields | otherwise = vcat (fmap pprField fields) header = text "Constructor" <+> quotes (ppr con) <+> text "does not have the required strict field(s)" <> if null fields then empty else colon TcRnNoPossibleParentForFields rbinds -> mkSimpleDecorated $ hang (text "No type has all these fields:") 2 (pprQuotedList fields) where fields = map (hfbLHS . unLoc) rbinds TcRnBadOverloadedRecordUpdate _rbinds -> mkSimpleDecorated $ text "Record update is ambiguous, and requires a type signature" TcRnStaticFormNotClosed name reason -> mkSimpleDecorated $ quotes (ppr name) <+> text "is used in a static form but it is not closed" <+> text "because it" $$ sep (causes reason) where causes :: NotClosedReason -> [SDoc] causes NotLetBoundReason = [text "is not let-bound."] causes (NotTypeClosed vs) = [ text "has a non-closed type because it contains the" , text "type variables:" <+> pprVarSet vs (hsep . punctuate comma . map (quotes . ppr)) ] causes (NotClosed n reason) = let msg = text "uses" <+> quotes (ppr n) <+> text "which" in case reason of NotClosed _ _ -> msg : causes reason _ -> let (xs0, xs1) = splitAt 1 $ causes reason in fmap (msg <+>) xs0 ++ xs1 TcRnUselessTypeable -> mkSimpleDecorated $ text "Deriving" <+> quotes (ppr typeableClassName) <+> text "has no effect: all types now auto-derive Typeable" TcRnDerivingDefaults cls -> mkSimpleDecorated $ sep [ text "Both DeriveAnyClass and" <+> text "GeneralizedNewtypeDeriving are enabled" , text "Defaulting to the DeriveAnyClass strategy" <+> text "for instantiating" <+> ppr cls ] TcRnNonUnaryTypeclassConstraint ct -> mkSimpleDecorated $ quotes (ppr ct) <+> text "is not a unary constraint, as expected by a deriving clause" TcRnPartialTypeSignatures _ theta -> mkSimpleDecorated $ text "Found type wildcard" <+> quotes (char '_') <+> text "standing for" <+> quotes (pprTheta theta) TcRnCannotDeriveInstance cls cls_tys mb_strat newtype_deriving reason -> mkSimpleDecorated $ derivErrDiagnosticMessage cls cls_tys mb_strat newtype_deriving True reason TcRnLazyGADTPattern -> mkSimpleDecorated $ hang (text "An existential or GADT data constructor cannot be used") 2 (text "inside a lazy (~) pattern") TcRnArrowProcGADTPattern -> mkSimpleDecorated $ text "Proc patterns cannot use existential or GADT data constructors" TcRnSpecialClassInst cls because_safeHaskell -> mkSimpleDecorated $ text "Class" <+> quotes (ppr $ className cls) <+> text "does not support user-specified instances" <> safeHaskell_msg where safeHaskell_msg | because_safeHaskell = text " when Safe Haskell is enabled." | otherwise = dot TcRnForallIdentifier rdr_name -> mkSimpleDecorated $ fsep [ text "The use of" <+> quotes (ppr rdr_name) <+> text "as an identifier", text "will become an error in a future GHC release." ] TcRnTypeEqualityOutOfScope -> mkDecorated [ text "The" <+> quotes (text "~") <+> text "operator is out of scope." $$ text "Assuming it to stand for an equality constraint." , text "NB:" <+> (quotes (text "~") <+> text "used to be built-in syntax but now is a regular type operator" $$ text "exported from Data.Type.Equality and Prelude.") $$ text "If you are using a custom Prelude, consider re-exporting it." , text "This will become an error in a future GHC release." ] TcRnTypeEqualityRequiresOperators -> mkSimpleDecorated $ fsep [ text "The use of" <+> quotes (text "~") <+> text "without TypeOperators", text "will become an error in a future GHC release." ] TcRnIllegalTypeOperator overall_ty op -> mkSimpleDecorated $ text "Illegal operator" <+> quotes (ppr op) <+> text "in type" <+> quotes (ppr overall_ty) TcRnGADTMonoLocalBinds -> mkSimpleDecorated $ fsep [ text "Pattern matching on GADTs without MonoLocalBinds" , text "is fragile." ] TcRnIncorrectNameSpace name _ -> mkSimpleDecorated $ msg where msg -- We are in a type-level namespace, -- and the name is incorrectly at the term-level. | isValNameSpace ns = text "The" <+> what <+> text "does not live in the type-level namespace" -- We are in a term-level namespace, -- and the name is incorrectly at the type-level. | otherwise = text "Illegal term-level use of the" <+> what ns = nameNameSpace name what = pprNameSpace ns <+> quotes (ppr name) TcRnNotInScope err name imp_errs _ -> mkSimpleDecorated $ pprScopeError name err $$ vcat (map ppr imp_errs) TcRnUntickedPromotedThing thing -> mkSimpleDecorated $ text "Unticked promoted" <+> what where what :: SDoc what = case thing of UntickedExplicitList -> text "list" <> dot UntickedConstructor fixity nm -> let con = pprUntickedConstructor fixity nm bare_sym = isBareSymbol fixity nm in text "constructor:" <+> con <> if bare_sym then empty else dot TcRnIllegalBuiltinSyntax what rdr_name -> mkSimpleDecorated $ hsep [text "Illegal", what, text "of built-in syntax:", ppr rdr_name] TcRnWarnDefaulting tidy_wanteds tidy_tv default_ty -> mkSimpleDecorated $ hang (hsep $ [ text "Defaulting" ] ++ (case tidy_tv of Nothing -> [] Just tv -> [text "the type variable" , quotes (ppr tv)]) ++ [ text "to type" , quotes (ppr default_ty) , text "in the following constraint" <> plural tidy_wanteds ]) 2 (pprWithArising tidy_wanteds) TcRnForeignImportPrimExtNotSet _decl -> mkSimpleDecorated $ text "`foreign import prim' requires GHCForeignImportPrim." TcRnForeignImportPrimSafeAnn _decl -> mkSimpleDecorated $ text "The safe/unsafe annotation should not be used with `foreign import prim'." TcRnForeignFunctionImportAsValue _decl -> mkSimpleDecorated $ text "`value' imports cannot have function types" TcRnFunPtrImportWithoutAmpersand _decl -> mkSimpleDecorated $ text "possible missing & in foreign import of FunPtr" TcRnIllegalForeignDeclBackend _decl _backend expectedBknds -> mkSimpleDecorated $ text "Illegal foreign declaration:" <+> case expectedBknds of COrAsmOrLlvm -> text "requires unregisterised, llvm (-fllvm) or native code generation (-fasm)" COrAsmOrLlvmOrInterp -> text "requires interpreted, unregisterised, llvm or native code generation" TcRnUnsupportedCallConv _decl unsupportedCC -> mkSimpleDecorated $ case unsupportedCC of StdCallConvUnsupported -> text "the 'stdcall' calling convention is unsupported on this platform," $$ text "treating as ccall" PrimCallConvUnsupported -> text "The `prim' calling convention can only be used with `foreign import'" JavaScriptCallConvUnsupported -> text "The `javascript' calling convention is unsupported on this platform" TcRnIllegalForeignType mArgOrResult reason -> mkSimpleDecorated $ hang msg 2 extra where arg_or_res = case mArgOrResult of Nothing -> empty Just Arg -> text "argument" Just Result -> text "result" msg = hsep [ text "Unacceptable", arg_or_res , text "type in foreign declaration:"] extra = case reason of TypeCannotBeMarshaled ty why -> let innerMsg = quotes (ppr ty) <+> text "cannot be marshalled in a foreign call" in case why of NotADataType -> quotes (ppr ty) <+> text "is not a data type" NewtypeDataConNotInScope Nothing -> hang innerMsg 2 $ text "because its data constructor is not in scope" NewtypeDataConNotInScope (Just tc) -> hang innerMsg 2 $ text "because the data constructor for" <+> quotes (ppr tc) <+> text "is not in scope" UnliftedFFITypesNeeded -> innerMsg $$ text "UnliftedFFITypes is required to marshal unlifted types" NotABoxedMarshalableTyCon -> innerMsg ForeignLabelNotAPtr -> innerMsg $$ text "A foreign-imported address (via &foo) must have type (Ptr a) or (FunPtr a)" NotSimpleUnliftedType -> innerMsg $$ text "foreign import prim only accepts simple unlifted types" ForeignDynNotPtr expected ty -> vcat [ text "Expected: Ptr/FunPtr" <+> pprParendType expected <> comma, text " Actual:" <+> ppr ty ] SafeHaskellMustBeInIO -> text "Safe Haskell is on, all FFI imports must be in the IO monad" IOResultExpected -> text "IO result type expected" UnexpectedNestedForall -> text "Unexpected nested forall" LinearTypesNotAllowed -> text "Linear types are not supported in FFI declarations, see #18472" OneArgExpected -> text "One argument expected" AtLeastOneArgExpected -> text "At least one argument expected" TcRnInvalidCIdentifier target -> mkSimpleDecorated $ sep [quotes (ppr target) <+> text "is not a valid C identifier"] diagnosticReason = \case TcRnUnknownMessage m -> diagnosticReason m TcRnMessageWithInfo _ msg_with_info -> case msg_with_info of TcRnMessageDetailed _ m -> diagnosticReason m TcRnSolverReport _ reason _ -> reason -- Error, or a Warning if we are deferring type errors TcRnRedundantConstraints {} -> WarningWithFlag Opt_WarnRedundantConstraints TcRnInaccessibleCode {} -> WarningWithFlag Opt_WarnInaccessibleCode TcRnTypeDoesNotHaveFixedRuntimeRep{} -> ErrorWithoutFlag TcRnImplicitLift{} -> WarningWithFlag Opt_WarnImplicitLift TcRnUnusedPatternBinds{} -> WarningWithFlag Opt_WarnUnusedPatternBinds TcRnDodgyImports{} -> WarningWithFlag Opt_WarnDodgyImports TcRnDodgyExports{} -> WarningWithFlag Opt_WarnDodgyExports TcRnMissingImportList{} -> WarningWithFlag Opt_WarnMissingImportList TcRnUnsafeDueToPlugin{} -> WarningWithoutFlag TcRnModMissingRealSrcSpan{} -> ErrorWithoutFlag TcRnIdNotExportedFromModuleSig{} -> ErrorWithoutFlag TcRnIdNotExportedFromLocalSig{} -> ErrorWithoutFlag TcRnShadowedName{} -> WarningWithFlag Opt_WarnNameShadowing TcRnDuplicateWarningDecls{} -> ErrorWithoutFlag TcRnSimplifierTooManyIterations{} -> ErrorWithoutFlag TcRnIllegalPatSynDecl{} -> ErrorWithoutFlag TcRnLinearPatSyn{} -> ErrorWithoutFlag TcRnEmptyRecordUpdate -> ErrorWithoutFlag TcRnIllegalFieldPunning{} -> ErrorWithoutFlag TcRnIllegalWildcardsInRecord{} -> ErrorWithoutFlag TcRnIllegalWildcardInType{} -> ErrorWithoutFlag TcRnDuplicateFieldName{} -> ErrorWithoutFlag TcRnIllegalViewPattern{} -> ErrorWithoutFlag TcRnCharLiteralOutOfRange{} -> ErrorWithoutFlag TcRnIllegalWildcardsInConstructor{} -> ErrorWithoutFlag TcRnIgnoringAnnotations{} -> WarningWithoutFlag TcRnAnnotationInSafeHaskell -> ErrorWithoutFlag TcRnInvalidTypeApplication{} -> ErrorWithoutFlag TcRnTagToEnumMissingValArg -> ErrorWithoutFlag TcRnTagToEnumUnspecifiedResTy{} -> ErrorWithoutFlag TcRnTagToEnumResTyNotAnEnum{} -> ErrorWithoutFlag TcRnArrowIfThenElsePredDependsOnResultTy -> ErrorWithoutFlag TcRnIllegalHsBootFileDecl -> ErrorWithoutFlag TcRnRecursivePatternSynonym{} -> ErrorWithoutFlag TcRnPartialTypeSigTyVarMismatch{} -> ErrorWithoutFlag TcRnPartialTypeSigBadQuantifier{} -> ErrorWithoutFlag TcRnMissingSignature what exported overridden -> WarningWithFlag $ missingSignatureWarningFlag what exported overridden TcRnPolymorphicBinderMissingSig{} -> WarningWithFlag Opt_WarnMissingLocalSignatures TcRnOverloadedSig{} -> ErrorWithoutFlag TcRnTupleConstraintInst{} -> ErrorWithoutFlag TcRnAbstractClassInst{} -> ErrorWithoutFlag TcRnNoClassInstHead{} -> ErrorWithoutFlag TcRnUserTypeError{} -> ErrorWithoutFlag TcRnConstraintInKind{} -> ErrorWithoutFlag TcRnUnboxedTupleOrSumTypeFuncArg{} -> ErrorWithoutFlag TcRnLinearFuncInKind{} -> ErrorWithoutFlag TcRnForAllEscapeError{} -> ErrorWithoutFlag TcRnVDQInTermType{} -> ErrorWithoutFlag TcRnBadQuantPredHead{} -> ErrorWithoutFlag TcRnIllegalTupleConstraint{} -> ErrorWithoutFlag TcRnNonTypeVarArgInConstraint{} -> ErrorWithoutFlag TcRnIllegalImplicitParam{} -> ErrorWithoutFlag TcRnIllegalConstraintSynonymOfKind{} -> ErrorWithoutFlag TcRnIllegalClassInst{} -> ErrorWithoutFlag TcRnOversaturatedVisibleKindArg{} -> ErrorWithoutFlag TcRnBadAssociatedType{} -> ErrorWithoutFlag TcRnForAllRankErr{} -> ErrorWithoutFlag TcRnMonomorphicBindings{} -> WarningWithFlag Opt_WarnMonomorphism TcRnOrphanInstance{} -> WarningWithFlag Opt_WarnOrphans TcRnFunDepConflict{} -> ErrorWithoutFlag TcRnDupInstanceDecls{} -> ErrorWithoutFlag TcRnConflictingFamInstDecls{} -> ErrorWithoutFlag TcRnFamInstNotInjective{} -> ErrorWithoutFlag TcRnBangOnUnliftedType{} -> WarningWithFlag Opt_WarnRedundantStrictnessFlags TcRnMultipleDefaultDeclarations{} -> ErrorWithoutFlag TcRnBadDefaultType{} -> ErrorWithoutFlag TcRnPatSynBundledWithNonDataCon{} -> ErrorWithoutFlag TcRnPatSynBundledWithWrongType{} -> ErrorWithoutFlag TcRnDupeModuleExport{} -> WarningWithFlag Opt_WarnDuplicateExports TcRnExportedModNotImported{} -> ErrorWithoutFlag TcRnNullExportedModule{} -> WarningWithFlag Opt_WarnDodgyExports TcRnMissingExportList{} -> WarningWithFlag Opt_WarnMissingExportList TcRnExportHiddenComponents{} -> ErrorWithoutFlag TcRnDuplicateExport{} -> WarningWithFlag Opt_WarnDuplicateExports TcRnExportedParentChildMismatch{} -> ErrorWithoutFlag TcRnConflictingExports{} -> ErrorWithoutFlag TcRnAmbiguousField{} -> WarningWithFlag Opt_WarnAmbiguousFields TcRnMissingFields{} -> WarningWithFlag Opt_WarnMissingFields TcRnFieldUpdateInvalidType{} -> ErrorWithoutFlag TcRnNoConstructorHasAllFields{} -> ErrorWithoutFlag TcRnMixedSelectors{} -> ErrorWithoutFlag TcRnMissingStrictFields{} -> ErrorWithoutFlag TcRnNoPossibleParentForFields{} -> ErrorWithoutFlag TcRnBadOverloadedRecordUpdate{} -> ErrorWithoutFlag TcRnStaticFormNotClosed{} -> ErrorWithoutFlag TcRnUselessTypeable -> WarningWithFlag Opt_WarnDerivingTypeable TcRnDerivingDefaults{} -> WarningWithFlag Opt_WarnDerivingDefaults TcRnNonUnaryTypeclassConstraint{} -> ErrorWithoutFlag TcRnPartialTypeSignatures{} -> WarningWithFlag Opt_WarnPartialTypeSignatures TcRnCannotDeriveInstance _ _ _ _ rea -> case rea of DerivErrNotWellKinded{} -> ErrorWithoutFlag DerivErrSafeHaskellGenericInst -> ErrorWithoutFlag DerivErrDerivingViaWrongKind{} -> ErrorWithoutFlag DerivErrNoEtaReduce{} -> ErrorWithoutFlag DerivErrBootFileFound -> ErrorWithoutFlag DerivErrDataConsNotAllInScope{} -> ErrorWithoutFlag DerivErrGNDUsedOnData -> ErrorWithoutFlag DerivErrNullaryClasses -> ErrorWithoutFlag DerivErrLastArgMustBeApp -> ErrorWithoutFlag DerivErrNoFamilyInstance{} -> ErrorWithoutFlag DerivErrNotStockDeriveable{} -> ErrorWithoutFlag DerivErrHasAssociatedDatatypes{} -> ErrorWithoutFlag DerivErrNewtypeNonDeriveableClass -> ErrorWithoutFlag DerivErrCannotEtaReduceEnough{} -> ErrorWithoutFlag DerivErrOnlyAnyClassDeriveable{} -> ErrorWithoutFlag DerivErrNotDeriveable{} -> ErrorWithoutFlag DerivErrNotAClass{} -> ErrorWithoutFlag DerivErrNoConstructors{} -> ErrorWithoutFlag DerivErrLangExtRequired{} -> ErrorWithoutFlag DerivErrDunnoHowToDeriveForType{} -> ErrorWithoutFlag DerivErrMustBeEnumType{} -> ErrorWithoutFlag DerivErrMustHaveExactlyOneConstructor{} -> ErrorWithoutFlag DerivErrMustHaveSomeParameters{} -> ErrorWithoutFlag DerivErrMustNotHaveClassContext{} -> ErrorWithoutFlag DerivErrBadConstructor{} -> ErrorWithoutFlag DerivErrGenerics{} -> ErrorWithoutFlag DerivErrEnumOrProduct{} -> ErrorWithoutFlag TcRnLazyGADTPattern -> ErrorWithoutFlag TcRnArrowProcGADTPattern -> ErrorWithoutFlag TcRnSpecialClassInst {} -> ErrorWithoutFlag TcRnForallIdentifier {} -> WarningWithFlag Opt_WarnForallIdentifier TcRnTypeEqualityOutOfScope -> WarningWithFlag Opt_WarnTypeEqualityOutOfScope TcRnTypeEqualityRequiresOperators -> WarningWithFlag Opt_WarnTypeEqualityRequiresOperators TcRnIllegalTypeOperator {} -> ErrorWithoutFlag TcRnGADTMonoLocalBinds {} -> WarningWithFlag Opt_WarnGADTMonoLocalBinds TcRnIncorrectNameSpace {} -> ErrorWithoutFlag TcRnNotInScope {} -> ErrorWithoutFlag TcRnUntickedPromotedThing {} -> WarningWithFlag Opt_WarnUntickedPromotedConstructors TcRnIllegalBuiltinSyntax {} -> ErrorWithoutFlag TcRnWarnDefaulting {} -> WarningWithFlag Opt_WarnTypeDefaults TcRnForeignImportPrimExtNotSet{} -> ErrorWithoutFlag TcRnForeignImportPrimSafeAnn{} -> ErrorWithoutFlag TcRnForeignFunctionImportAsValue{} -> ErrorWithoutFlag TcRnFunPtrImportWithoutAmpersand{} -> WarningWithFlag Opt_WarnDodgyForeignImports TcRnIllegalForeignDeclBackend{} -> ErrorWithoutFlag TcRnUnsupportedCallConv _ unsupportedCC -> case unsupportedCC of StdCallConvUnsupported -> WarningWithFlag Opt_WarnUnsupportedCallingConventions _ -> ErrorWithoutFlag TcRnIllegalForeignType{} -> ErrorWithoutFlag TcRnInvalidCIdentifier{} -> ErrorWithoutFlag diagnosticHints = \case TcRnUnknownMessage m -> diagnosticHints m TcRnMessageWithInfo _ msg_with_info -> case msg_with_info of TcRnMessageDetailed _ m -> diagnosticHints m TcRnSolverReport _ _ hints -> hints TcRnRedundantConstraints{} -> noHints TcRnInaccessibleCode{} -> noHints TcRnTypeDoesNotHaveFixedRuntimeRep{} -> noHints TcRnImplicitLift{} -> noHints TcRnUnusedPatternBinds{} -> noHints TcRnDodgyImports{} -> noHints TcRnDodgyExports{} -> noHints TcRnMissingImportList{} -> noHints TcRnUnsafeDueToPlugin{} -> noHints TcRnModMissingRealSrcSpan{} -> noHints TcRnIdNotExportedFromModuleSig name mod -> [SuggestAddToHSigExportList name $ Just mod] TcRnIdNotExportedFromLocalSig name -> [SuggestAddToHSigExportList name Nothing] TcRnShadowedName{} -> noHints TcRnDuplicateWarningDecls{} -> noHints TcRnSimplifierTooManyIterations{} -> [SuggestIncreaseSimplifierIterations] TcRnIllegalPatSynDecl{} -> noHints TcRnLinearPatSyn{} -> noHints TcRnEmptyRecordUpdate{} -> noHints TcRnIllegalFieldPunning{} -> [suggestExtension LangExt.NamedFieldPuns] TcRnIllegalWildcardsInRecord{} -> [suggestExtension LangExt.RecordWildCards] TcRnIllegalWildcardInType{} -> noHints TcRnDuplicateFieldName{} -> noHints TcRnIllegalViewPattern{} -> [suggestExtension LangExt.ViewPatterns] TcRnCharLiteralOutOfRange{} -> noHints TcRnIllegalWildcardsInConstructor{} -> noHints TcRnIgnoringAnnotations{} -> noHints TcRnAnnotationInSafeHaskell -> noHints TcRnInvalidTypeApplication{} -> noHints TcRnTagToEnumMissingValArg -> noHints TcRnTagToEnumUnspecifiedResTy{} -> noHints TcRnTagToEnumResTyNotAnEnum{} -> noHints TcRnArrowIfThenElsePredDependsOnResultTy -> noHints TcRnIllegalHsBootFileDecl -> noHints TcRnRecursivePatternSynonym{} -> noHints TcRnPartialTypeSigTyVarMismatch{} -> noHints TcRnPartialTypeSigBadQuantifier{} -> noHints TcRnMissingSignature {} -> noHints TcRnPolymorphicBinderMissingSig{} -> noHints TcRnOverloadedSig{} -> noHints TcRnTupleConstraintInst{} -> noHints TcRnAbstractClassInst{} -> noHints TcRnNoClassInstHead{} -> noHints TcRnUserTypeError{} -> noHints TcRnConstraintInKind{} -> noHints TcRnUnboxedTupleOrSumTypeFuncArg tuple_or_sum _ -> [suggestExtension $ unboxedTupleOrSumExtension tuple_or_sum] TcRnLinearFuncInKind{} -> noHints TcRnForAllEscapeError{} -> noHints TcRnVDQInTermType{} -> noHints TcRnBadQuantPredHead{} -> noHints TcRnIllegalTupleConstraint{} -> [suggestExtension LangExt.ConstraintKinds] TcRnNonTypeVarArgInConstraint{} -> [suggestExtension LangExt.FlexibleContexts] TcRnIllegalImplicitParam{} -> noHints TcRnIllegalConstraintSynonymOfKind{} -> [suggestExtension LangExt.ConstraintKinds] TcRnIllegalClassInst{} -> noHints TcRnOversaturatedVisibleKindArg{} -> noHints TcRnBadAssociatedType{} -> noHints TcRnForAllRankErr rank _ -> case rank of LimitedRank{} -> [suggestExtension LangExt.RankNTypes] MonoTypeRankZero -> [suggestExtension LangExt.RankNTypes] MonoTypeTyConArg -> [suggestExtension LangExt.ImpredicativeTypes] MonoTypeSynArg -> [suggestExtension LangExt.LiberalTypeSynonyms] MonoTypeConstraint -> [suggestExtension LangExt.QuantifiedConstraints] _ -> noHints TcRnMonomorphicBindings bindings -> case bindings of [] -> noHints (x:xs) -> [SuggestAddTypeSignatures $ NamedBindings (x NE.:| xs)] TcRnOrphanInstance{} -> [SuggestFixOrphanInstance] TcRnFunDepConflict{} -> noHints TcRnDupInstanceDecls{} -> noHints TcRnConflictingFamInstDecls{} -> noHints TcRnFamInstNotInjective rea _ _ -> case rea of InjErrRhsBareTyVar{} -> noHints InjErrRhsCannotBeATypeFam -> noHints InjErrRhsOverlap -> noHints InjErrCannotInferFromRhs _ _ suggestUndInst | YesSuggestUndecidableInstaces <- suggestUndInst -> [suggestExtension LangExt.UndecidableInstances] | otherwise -> noHints TcRnBangOnUnliftedType{} -> noHints TcRnMultipleDefaultDeclarations{} -> noHints TcRnBadDefaultType{} -> noHints TcRnPatSynBundledWithNonDataCon{} -> noHints TcRnPatSynBundledWithWrongType{} -> noHints TcRnDupeModuleExport{} -> noHints TcRnExportedModNotImported{} -> noHints TcRnNullExportedModule{} -> noHints TcRnMissingExportList{} -> noHints TcRnExportHiddenComponents{} -> noHints TcRnDuplicateExport{} -> noHints TcRnExportedParentChildMismatch{} -> noHints TcRnConflictingExports{} -> noHints TcRnAmbiguousField{} -> noHints TcRnMissingFields{} -> noHints TcRnFieldUpdateInvalidType{} -> noHints TcRnNoConstructorHasAllFields{} -> noHints TcRnMixedSelectors{} -> noHints TcRnMissingStrictFields{} -> noHints TcRnNoPossibleParentForFields{} -> noHints TcRnBadOverloadedRecordUpdate{} -> noHints TcRnStaticFormNotClosed{} -> noHints TcRnUselessTypeable -> noHints TcRnDerivingDefaults{} -> [useDerivingStrategies] TcRnNonUnaryTypeclassConstraint{} -> noHints TcRnPartialTypeSignatures suggestParSig _ -> case suggestParSig of YesSuggestPartialTypeSignatures -> let info = text "to use the inferred type" in [suggestExtensionWithInfo info LangExt.PartialTypeSignatures] NoSuggestPartialTypeSignatures -> noHints TcRnCannotDeriveInstance cls _ _ newtype_deriving rea -> deriveInstanceErrReasonHints cls newtype_deriving rea TcRnLazyGADTPattern -> noHints TcRnArrowProcGADTPattern -> noHints TcRnSpecialClassInst {} -> noHints TcRnForallIdentifier {} -> [SuggestRenameForall] TcRnTypeEqualityOutOfScope -> noHints TcRnTypeEqualityRequiresOperators -> [suggestExtension LangExt.TypeOperators] TcRnIllegalTypeOperator {} -> [suggestExtension LangExt.TypeOperators] TcRnGADTMonoLocalBinds {} -> [suggestAnyExtension [LangExt.GADTs, LangExt.TypeFamilies]] TcRnIncorrectNameSpace nm is_th_use | is_th_use -> [SuggestAppropriateTHTick $ nameNameSpace nm] | otherwise -> noHints TcRnNotInScope err _ _ hints -> scopeErrorHints err ++ hints TcRnUntickedPromotedThing thing -> [SuggestAddTick thing] TcRnIllegalBuiltinSyntax {} -> noHints TcRnWarnDefaulting {} -> noHints TcRnForeignImportPrimExtNotSet{} -> [suggestExtension LangExt.GHCForeignImportPrim] TcRnForeignImportPrimSafeAnn{} -> noHints TcRnForeignFunctionImportAsValue{} -> noHints TcRnFunPtrImportWithoutAmpersand{} -> noHints TcRnIllegalForeignDeclBackend{} -> noHints TcRnUnsupportedCallConv{} -> noHints TcRnIllegalForeignType _ reason -> case reason of TypeCannotBeMarshaled _ why | NewtypeDataConNotInScope{} <- why -> [SuggestImportingDataCon] | UnliftedFFITypesNeeded <- why -> [suggestExtension LangExt.UnliftedFFITypes] _ -> noHints TcRnInvalidCIdentifier{} -> noHints deriveInstanceErrReasonHints :: Class -> UsingGeneralizedNewtypeDeriving -> DeriveInstanceErrReason -> [GhcHint] deriveInstanceErrReasonHints cls newtype_deriving = \case DerivErrNotWellKinded _ _ n_args_to_keep | cls `hasKey` gen1ClassKey && n_args_to_keep >= 0 -> [suggestExtension LangExt.PolyKinds] | otherwise -> noHints DerivErrSafeHaskellGenericInst -> noHints DerivErrDerivingViaWrongKind{} -> noHints DerivErrNoEtaReduce{} -> noHints DerivErrBootFileFound -> noHints DerivErrDataConsNotAllInScope{} -> noHints DerivErrGNDUsedOnData -> noHints DerivErrNullaryClasses -> noHints DerivErrLastArgMustBeApp -> noHints DerivErrNoFamilyInstance{} -> noHints DerivErrNotStockDeriveable deriveAnyClassEnabled | deriveAnyClassEnabled == NoDeriveAnyClassEnabled -> [suggestExtension LangExt.DeriveAnyClass] | otherwise -> noHints DerivErrHasAssociatedDatatypes{} -> noHints DerivErrNewtypeNonDeriveableClass | newtype_deriving == NoGeneralizedNewtypeDeriving -> [useGND] | otherwise -> noHints DerivErrCannotEtaReduceEnough{} | newtype_deriving == NoGeneralizedNewtypeDeriving -> [useGND] | otherwise -> noHints DerivErrOnlyAnyClassDeriveable _ deriveAnyClassEnabled | deriveAnyClassEnabled == NoDeriveAnyClassEnabled -> [suggestExtension LangExt.DeriveAnyClass] | otherwise -> noHints DerivErrNotDeriveable deriveAnyClassEnabled | deriveAnyClassEnabled == NoDeriveAnyClassEnabled -> [suggestExtension LangExt.DeriveAnyClass] | otherwise -> noHints DerivErrNotAClass{} -> noHints DerivErrNoConstructors{} -> let info = text "to enable deriving for empty data types" in [useExtensionInOrderTo info LangExt.EmptyDataDeriving] DerivErrLangExtRequired{} -- This is a slightly weird corner case of GHC: we are failing -- to derive a typeclass instance because a particular 'Extension' -- is not enabled (and so we report in the main error), but here -- we don't want to /repeat/ to enable the extension in the hint. -> noHints DerivErrDunnoHowToDeriveForType{} -> noHints DerivErrMustBeEnumType rep_tc -- We want to suggest GND only if this /is/ a newtype. | newtype_deriving == NoGeneralizedNewtypeDeriving && isNewTyCon rep_tc -> [useGND] | otherwise -> noHints DerivErrMustHaveExactlyOneConstructor{} -> noHints DerivErrMustHaveSomeParameters{} -> noHints DerivErrMustNotHaveClassContext{} -> noHints DerivErrBadConstructor wcard _ -> case wcard of Nothing -> noHints Just YesHasWildcard -> [SuggestFillInWildcardConstraint] Just NoHasWildcard -> [SuggestAddStandaloneDerivation] DerivErrGenerics{} -> noHints DerivErrEnumOrProduct{} -> noHints messageWithInfoDiagnosticMessage :: UnitState -> ErrInfo -> DecoratedSDoc -> DecoratedSDoc messageWithInfoDiagnosticMessage unit_state ErrInfo{..} important = let err_info' = map (pprWithUnitState unit_state) [errInfoContext, errInfoSupplementary] in (mapDecoratedSDoc (pprWithUnitState unit_state) important) `unionDecoratedSDoc` mkDecorated err_info' dodgy_msg :: (Outputable a, Outputable b) => SDoc -> a -> b -> SDoc dodgy_msg kind tc ie = sep [ text "The" <+> kind <+> text "item" <+> quotes (ppr ie) <+> text "suggests that", quotes (ppr tc) <+> text "has (in-scope) constructors or class methods,", text "but it has none" ] dodgy_msg_insert :: forall p . IdP (GhcPass p) -> IE (GhcPass p) dodgy_msg_insert tc = IEThingAll noAnn ii where ii :: LIEWrappedName (IdP (GhcPass p)) ii = noLocA (IEName $ noLocA tc) pprTypeDoesNotHaveFixedRuntimeRep :: Type -> FixedRuntimeRepProvenance -> SDoc pprTypeDoesNotHaveFixedRuntimeRep ty prov = let what = pprFixedRuntimeRepProvenance prov in text "The" <+> what <+> text "does not have a fixed runtime representation:" $$ format_frr_err ty format_frr_err :: Type -- ^ the type which doesn't have a fixed runtime representation -> SDoc format_frr_err ty = (bullet <+> ppr tidy_ty <+> dcolon <+> ppr tidy_ki) where (tidy_env, tidy_ty) = tidyOpenType emptyTidyEnv ty tidy_ki = tidyType tidy_env (tcTypeKind ty) pprField :: (FieldLabelString, TcType) -> SDoc pprField (f,ty) = ppr f <+> dcolon <+> ppr ty pprRecordFieldPart :: RecordFieldPart -> SDoc pprRecordFieldPart = \case RecordFieldConstructor{} -> text "construction" RecordFieldPattern{} -> text "pattern" RecordFieldUpdate -> text "update" pprBindings :: [Name] -> SDoc pprBindings = pprWithCommas (quotes . ppr) injectivityErrorHerald :: SDoc injectivityErrorHerald = text "Type family equation violates the family's injectivity annotation." formatExportItemError :: SDoc -> String -> SDoc formatExportItemError exportedThing reason = hsep [ text "The export item" , quotes exportedThing , text reason ] -- | What warning flag is associated with the given missing signature? missingSignatureWarningFlag :: MissingSignature -> Exported -> Bool -> WarningFlag missingSignatureWarningFlag (MissingTopLevelBindingSig {}) exported overridden | IsExported <- exported , not overridden = Opt_WarnMissingExportedSignatures | otherwise = Opt_WarnMissingSignatures missingSignatureWarningFlag (MissingPatSynSig {}) exported overridden | IsExported <- exported , not overridden = Opt_WarnMissingExportedPatternSynonymSignatures | otherwise = Opt_WarnMissingPatternSynonymSignatures missingSignatureWarningFlag (MissingTyConKindSig {}) _ _ = Opt_WarnMissingKindSignatures useDerivingStrategies :: GhcHint useDerivingStrategies = useExtensionInOrderTo (text "to pick a different strategy") LangExt.DerivingStrategies useGND :: GhcHint useGND = let info = text "for GHC's" <+> text "newtype-deriving extension" in suggestExtensionWithInfo info LangExt.GeneralizedNewtypeDeriving cannotMakeDerivedInstanceHerald :: Class -> [Type] -> Maybe (DerivStrategy GhcTc) -> UsingGeneralizedNewtypeDeriving -> Bool -- ^ If False, only prints the why. -> SDoc -> SDoc cannotMakeDerivedInstanceHerald cls cls_args mb_strat newtype_deriving pprHerald why = if pprHerald then sep [(hang (text "Can't make a derived instance of") 2 (quotes (ppr pred) <+> via_mechanism) $$ nest 2 extra) <> colon, nest 2 why] else why where strat_used = isJust mb_strat extra | not strat_used, (newtype_deriving == YesGeneralizedNewtypeDeriving) = text "(even with cunning GeneralizedNewtypeDeriving)" | otherwise = empty pred = mkClassPred cls cls_args via_mechanism | strat_used , Just strat <- mb_strat = text "with the" <+> (derivStrategyName strat) <+> text "strategy" | otherwise = empty badCon :: DataCon -> SDoc -> SDoc badCon con msg = text "Constructor" <+> quotes (ppr con) <+> msg derivErrDiagnosticMessage :: Class -> [Type] -> Maybe (DerivStrategy GhcTc) -> UsingGeneralizedNewtypeDeriving -> Bool -- If True, includes the herald \"can't make a derived..\" -> DeriveInstanceErrReason -> SDoc derivErrDiagnosticMessage cls cls_tys mb_strat newtype_deriving pprHerald = \case DerivErrNotWellKinded tc cls_kind _ -> sep [ hang (text "Cannot derive well-kinded instance of form" <+> quotes (pprClassPred cls cls_tys <+> parens (ppr tc <+> text "..."))) 2 empty , nest 2 (text "Class" <+> quotes (ppr cls) <+> text "expects an argument of kind" <+> quotes (pprKind cls_kind)) ] DerivErrSafeHaskellGenericInst -> text "Generic instances can only be derived in" <+> text "Safe Haskell using the stock strategy." DerivErrDerivingViaWrongKind cls_kind via_ty via_kind -> hang (text "Cannot derive instance via" <+> quotes (pprType via_ty)) 2 (text "Class" <+> quotes (ppr cls) <+> text "expects an argument of kind" <+> quotes (pprKind cls_kind) <> char ',' $+$ text "but" <+> quotes (pprType via_ty) <+> text "has kind" <+> quotes (pprKind via_kind)) DerivErrNoEtaReduce inst_ty -> sep [text "Cannot eta-reduce to an instance of form", nest 2 (text "instance (...) =>" <+> pprClassPred cls (cls_tys ++ [inst_ty]))] DerivErrBootFileFound -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (text "Cannot derive instances in hs-boot files" $+$ text "Write an instance declaration instead") DerivErrDataConsNotAllInScope tc -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (hang (text "The data constructors of" <+> quotes (ppr tc) <+> text "are not all in scope") 2 (text "so you cannot derive an instance for it")) DerivErrGNDUsedOnData -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (text "GeneralizedNewtypeDeriving cannot be used on non-newtypes") DerivErrNullaryClasses -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (text "Cannot derive instances for nullary classes") DerivErrLastArgMustBeApp -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald ( text "The last argument of the instance must be a" <+> text "data or newtype application") DerivErrNoFamilyInstance tc tc_args -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (text "No family instance for" <+> quotes (pprTypeApp tc tc_args)) DerivErrNotStockDeriveable _ -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (quotes (ppr cls) <+> text "is not a stock derivable class (Eq, Show, etc.)") DerivErrHasAssociatedDatatypes hasAdfs at_last_cls_tv_in_kinds at_without_last_cls_tv -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald $ vcat [ ppWhen (hasAdfs == YesHasAdfs) adfs_msg , case at_without_last_cls_tv of YesAssociatedTyNotParamOverLastTyVar tc -> at_without_last_cls_tv_msg tc NoAssociatedTyNotParamOverLastTyVar -> empty , case at_last_cls_tv_in_kinds of YesAssocTyLastVarInKind tc -> at_last_cls_tv_in_kinds_msg tc NoAssocTyLastVarInKind -> empty ] where adfs_msg = text "the class has associated data types" at_without_last_cls_tv_msg at_tc = hang (text "the associated type" <+> quotes (ppr at_tc) <+> text "is not parameterized over the last type variable") 2 (text "of the class" <+> quotes (ppr cls)) at_last_cls_tv_in_kinds_msg at_tc = hang (text "the associated type" <+> quotes (ppr at_tc) <+> text "contains the last type variable") 2 (text "of the class" <+> quotes (ppr cls) <+> text "in a kind, which is not (yet) allowed") DerivErrNewtypeNonDeriveableClass -> derivErrDiagnosticMessage cls cls_tys mb_strat newtype_deriving pprHerald (DerivErrNotStockDeriveable NoDeriveAnyClassEnabled) DerivErrCannotEtaReduceEnough eta_ok -> let cant_derive_err = ppUnless eta_ok eta_msg eta_msg = text "cannot eta-reduce the representation type enough" in cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald cant_derive_err DerivErrOnlyAnyClassDeriveable tc _ -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (quotes (ppr tc) <+> text "is a type class," <+> text "and can only have a derived instance" $+$ text "if DeriveAnyClass is enabled") DerivErrNotDeriveable _ -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald empty DerivErrNotAClass predType -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (quotes (ppr predType) <+> text "is not a class") DerivErrNoConstructors rep_tc -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (quotes (pprSourceTyCon rep_tc) <+> text "must have at least one data constructor") DerivErrLangExtRequired ext -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (text "You need " <> ppr ext <+> text "to derive an instance for this class") DerivErrDunnoHowToDeriveForType ty -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (hang (text "Don't know how to derive" <+> quotes (ppr cls)) 2 (text "for type" <+> quotes (ppr ty))) DerivErrMustBeEnumType rep_tc -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (sep [ quotes (pprSourceTyCon rep_tc) <+> text "must be an enumeration type" , text "(an enumeration consists of one or more nullary, non-GADT constructors)" ]) DerivErrMustHaveExactlyOneConstructor rep_tc -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (quotes (pprSourceTyCon rep_tc) <+> text "must have precisely one constructor") DerivErrMustHaveSomeParameters rep_tc -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (text "Data type" <+> quotes (ppr rep_tc) <+> text "must have some type parameters") DerivErrMustNotHaveClassContext rep_tc bad_stupid_theta -> cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (text "Data type" <+> quotes (ppr rep_tc) <+> text "must not have a class context:" <+> pprTheta bad_stupid_theta) DerivErrBadConstructor _ reasons -> let why = vcat $ map renderReason reasons in cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald why where renderReason = \case DerivErrBadConExistential con -> badCon con $ text "must be truly polymorphic in the last argument of the data type" DerivErrBadConCovariant con -> badCon con $ text "must not use the type variable in a function argument" DerivErrBadConFunTypes con -> badCon con $ text "must not contain function types" DerivErrBadConWrongArg con -> badCon con $ text "must use the type variable only as the last argument of a data type" DerivErrBadConIsGADT con -> badCon con $ text "is a GADT" DerivErrBadConHasExistentials con -> badCon con $ text "has existential type variables in its type" DerivErrBadConHasConstraints con -> badCon con $ text "has constraints in its type" DerivErrBadConHasHigherRankType con -> badCon con $ text "has a higher-rank type" DerivErrGenerics reasons -> let why = vcat $ map renderReason reasons in cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald why where renderReason = \case DerivErrGenericsMustNotHaveDatatypeContext tc_name -> ppr tc_name <+> text "must not have a datatype context" DerivErrGenericsMustNotHaveExoticArgs dc -> ppr dc <+> text "must not have exotic unlifted or polymorphic arguments" DerivErrGenericsMustBeVanillaDataCon dc -> ppr dc <+> text "must be a vanilla data constructor" DerivErrGenericsMustHaveSomeTypeParams rep_tc -> text "Data type" <+> quotes (ppr rep_tc) <+> text "must have some type parameters" DerivErrGenericsMustNotHaveExistentials con -> badCon con $ text "must not have existential arguments" DerivErrGenericsWrongArgKind con -> badCon con $ text "applies a type to an argument involving the last parameter" $$ text "but the applied type is not of kind * -> *" DerivErrEnumOrProduct this that -> let ppr1 = derivErrDiagnosticMessage cls cls_tys mb_strat newtype_deriving False this ppr2 = derivErrDiagnosticMessage cls cls_tys mb_strat newtype_deriving False that in cannotMakeDerivedInstanceHerald cls cls_tys mb_strat newtype_deriving pprHerald (ppr1 $$ text " or" $$ ppr2) {- ********************************************************************* * * Outputable SolverReportErrCtxt (for debugging) * * **********************************************************************-} instance Outputable SolverReportErrCtxt where ppr (CEC { cec_binds = bvar , cec_defer_type_errors = dte , cec_expr_holes = eh , cec_type_holes = th , cec_out_of_scope_holes = osh , cec_warn_redundant = wr , cec_expand_syns = es , cec_suppress = sup }) = text "CEC" <+> braces (vcat [ text "cec_binds" <+> equals <+> ppr bvar , text "cec_defer_type_errors" <+> equals <+> ppr dte , text "cec_expr_holes" <+> equals <+> ppr eh , text "cec_type_holes" <+> equals <+> ppr th , text "cec_out_of_scope_holes" <+> equals <+> ppr osh , text "cec_warn_redundant" <+> equals <+> ppr wr , text "cec_expand_syns" <+> equals <+> ppr es , text "cec_suppress" <+> equals <+> ppr sup ]) {- ********************************************************************* * * Outputting TcSolverReportMsg errors * * **********************************************************************-} -- | Pretty-print a 'SolverReportWithCtxt', containing a 'TcSolverReportMsg' -- with its enclosing 'SolverReportErrCtxt'. pprSolverReportWithCtxt :: SolverReportWithCtxt -> SDoc pprSolverReportWithCtxt (SolverReportWithCtxt { reportContext = ctxt, reportContent = msg }) = pprTcSolverReportMsg ctxt msg -- | Pretty-print a 'TcSolverReportMsg', with its enclosing 'SolverReportErrCtxt'. pprTcSolverReportMsg :: SolverReportErrCtxt -> TcSolverReportMsg -> SDoc pprTcSolverReportMsg ctxt (TcReportWithInfo msg (info :| infos)) = vcat ( pprTcSolverReportMsg ctxt msg : pprTcSolverReportInfo ctxt info : map (pprTcSolverReportInfo ctxt) infos ) pprTcSolverReportMsg _ (BadTelescope telescope skols) = hang (text "These kind and type variables:" <+> ppr telescope $$ text "are out of dependency order. Perhaps try this ordering:") 2 (pprTyVars sorted_tvs) where sorted_tvs = scopedSort skols pprTcSolverReportMsg _ (UserTypeError ty) = pprUserTypeErrorTy ty pprTcSolverReportMsg ctxt (ReportHoleError hole err) = pprHoleError ctxt hole err pprTcSolverReportMsg _ (CannotUnifyWithPolytype item tv1 ty2) = vcat [ (if isSkolemTyVar tv1 then text "Cannot equate type variable" else text "Cannot instantiate unification variable") <+> quotes (ppr tv1) , hang (text "with a" <+> what <+> text "involving polytypes:") 2 (ppr ty2) ] where what = text $ levelString $ ctLocTypeOrKind_maybe (errorItemCtLoc item) `orElse` TypeLevel pprTcSolverReportMsg _ (Mismatch { mismatch_ea = add_ea , mismatch_item = item , mismatch_ty1 = ty1 , mismatch_ty2 = ty2 }) = addArising (errorItemOrigin item) msg where msg | (isLiftedRuntimeRep ty1 && isUnliftedRuntimeRep ty2) || (isLiftedRuntimeRep ty2 && isUnliftedRuntimeRep ty1) || (isLiftedLevity ty1 && isUnliftedLevity ty2) || (isLiftedLevity ty2 && isUnliftedLevity ty1) = text "Couldn't match a lifted type with an unlifted type" | isAtomicTy ty1 || isAtomicTy ty2 = -- Print with quotes sep [ text herald1 <+> quotes (ppr ty1) , nest padding $ text herald2 <+> quotes (ppr ty2) ] | otherwise = -- Print with vertical layout vcat [ text herald1 <> colon <+> ppr ty1 , nest padding $ text herald2 <> colon <+> ppr ty2 ] herald1 = conc [ "Couldn't match" , if is_repr then "representation of" else "" , if add_ea then "expected" else "" , what ] herald2 = conc [ "with" , if is_repr then "that of" else "" , if add_ea then ("actual " ++ what) else "" ] padding = length herald1 - length herald2 is_repr = case errorItemEqRel item of { ReprEq -> True; NomEq -> False } what = levelString (ctLocTypeOrKind_maybe (errorItemCtLoc item) `orElse` TypeLevel) conc :: [String] -> String conc = foldr1 add_space add_space :: String -> String -> String add_space s1 s2 | null s1 = s2 | null s2 = s1 | otherwise = s1 ++ (' ' : s2) pprTcSolverReportMsg _ (KindMismatch { kmismatch_what = thing , kmismatch_expected = exp , kmismatch_actual = act }) = hang (text "Expected" <+> kind_desc <> comma) 2 (text "but" <+> quotes (ppr thing) <+> text "has kind" <+> quotes (ppr act)) where kind_desc | tcIsConstraintKind exp = text "a constraint" | Just arg <- kindRep_maybe exp -- TYPE t0 , tcIsTyVarTy arg = sdocOption sdocPrintExplicitRuntimeReps $ \case True -> text "kind" <+> quotes (ppr exp) False -> text "a type" | otherwise = text "kind" <+> quotes (ppr exp) pprTcSolverReportMsg ctxt (TypeEqMismatch { teq_mismatch_ppr_explicit_kinds = ppr_explicit_kinds , teq_mismatch_item = item , teq_mismatch_ty1 = ty1 , teq_mismatch_ty2 = ty2 , teq_mismatch_expected = exp , teq_mismatch_actual = act , teq_mismatch_what = mb_thing }) = addArising orig $ pprWithExplicitKindsWhen ppr_explicit_kinds msg where msg | isUnliftedTypeKind act, isLiftedTypeKind exp = sep [ text "Expecting a lifted type, but" , thing_msg mb_thing (text "an") (text "unlifted") ] | isLiftedTypeKind act, isUnliftedTypeKind exp = sep [ text "Expecting an unlifted type, but" , thing_msg mb_thing (text "a") (text "lifted") ] | tcIsLiftedTypeKind exp = maybe_num_args_msg $$ sep [ text "Expected a type, but" , case mb_thing of Nothing -> text "found something with kind" Just thing -> quotes (ppr thing) <+> text "has kind" , quotes (pprWithTYPE act) ] | Just nargs_msg <- num_args_msg , Right ea_msg <- mk_ea_msg ctxt (Just item) level orig = nargs_msg $$ pprTcSolverReportMsg ctxt ea_msg | -- pprTrace "check" (ppr ea_looks_same $$ ppr exp $$ ppr act $$ ppr ty1 $$ ppr ty2) $ ea_looks_same ty1 ty2 exp act , Right ea_msg <- mk_ea_msg ctxt (Just item) level orig = pprTcSolverReportMsg ctxt ea_msg -- The mismatched types are /inside/ exp and act | let mismatch_err = Mismatch False item ty1 ty2 errs = case mk_ea_msg ctxt Nothing level orig of Left ea_info -> [ mkTcReportWithInfo mismatch_err ea_info ] Right ea_err -> [ mismatch_err, ea_err ] = vcat $ map (pprTcSolverReportMsg ctxt) errs ct_loc = errorItemCtLoc item orig = errorItemOrigin item level = ctLocTypeOrKind_maybe ct_loc `orElse` TypeLevel thing_msg (Just thing) _ levity = quotes (ppr thing) <+> text "is" <+> levity thing_msg Nothing an levity = text "got" <+> an <+> levity <+> text "type" num_args_msg = case level of KindLevel | not (isMetaTyVarTy exp) && not (isMetaTyVarTy act) -- if one is a meta-tyvar, then it's possible that the user -- has asked for something impredicative, and we couldn't unify. -- Don't bother with counting arguments. -> let n_act = count_args act n_exp = count_args exp in case n_act - n_exp of n | n > 0 -- we don't know how many args there are, so don't -- recommend removing args that aren't , Just thing <- mb_thing -> Just $ pprTcSolverReportMsg ctxt (ExpectingMoreArguments n thing) _ -> Nothing _ -> Nothing maybe_num_args_msg = num_args_msg `orElse` empty count_args ty = count isVisibleBinder $ fst $ splitPiTys ty pprTcSolverReportMsg _ (FixedRuntimeRepError frr_origs) = vcat (map make_msg frr_origs) where -- Assemble the error message: pair up each origin with the corresponding type, e.g. -- • FixedRuntimeRep origin msg 1 ... -- a :: TYPE r1 -- • FixedRuntimeRep origin msg 2 ... -- b :: TYPE r2 make_msg :: FixedRuntimeRepErrorInfo -> SDoc make_msg (FRR_Info { frr_info_origin = FixedRuntimeRepOrigin { frr_type = ty , frr_context = frr_ctxt } , frr_info_not_concrete = mb_not_conc }) = -- Add bullet points if there is more than one error. (if length frr_origs > 1 then (bullet <+>) else id) $ vcat [ sep [ pprFixedRuntimeRepContext frr_ctxt , text "does not have a fixed runtime representation." ] , type_printout ty , case mb_not_conc of Nothing -> empty Just (conc_tv, not_conc) -> unsolved_concrete_eq_explanation conc_tv not_conc ] -- Don't print out the type (only the kind), if the type includes -- a confusing cast, unless the user passed -fprint-explicit-coercions. -- -- Example: -- -- In T20363, we have a representation-polymorphism error with a type -- of the form -- -- ( (# #) |> co ) :: TYPE NilRep -- -- where NilRep is a nullary type family application which reduces to TupleRep '[]. -- We prefer avoiding showing the cast to the user, but we also don't want to -- print the confusing: -- -- (# #) :: TYPE NilRep -- -- So in this case we simply don't print the type, only the kind. confusing_cast :: Type -> Bool confusing_cast ty = case ty of CastTy inner_ty _ -- A confusing cast is one that is responsible -- for a representation-polymorphism error. -> isConcrete (typeKind inner_ty) _ -> False type_printout :: Type -> SDoc type_printout ty = sdocOption sdocPrintExplicitCoercions $ \ show_coercions -> if confusing_cast ty && not show_coercions then vcat [ text "Its kind is:" , nest 2 $ pprWithTYPE (typeKind ty) , text "(Use -fprint-explicit-coercions to see the full type.)" ] else vcat [ text "Its type is:" , nest 2 $ ppr ty <+> dcolon <+> pprWithTYPE (typeKind ty) ] unsolved_concrete_eq_explanation :: TcTyVar -> Type -> SDoc unsolved_concrete_eq_explanation tv not_conc = text "Cannot unify" <+> quotes (ppr not_conc) <+> text "with the type variable" <+> quotes (ppr tv) $$ text "because it is not a concrete" <+> what <> dot where ki = tyVarKind tv what :: SDoc what | isRuntimeRepTy ki = quotes (text "RuntimeRep") | isLevityTy ki = quotes (text "Levity") | otherwise = text "type" pprTcSolverReportMsg _ (SkolemEscape item implic esc_skols) = let esc_doc = sep [ text "because" <+> what <+> text "variable" <> plural esc_skols <+> pprQuotedList esc_skols , text "would escape" <+> if isSingleton esc_skols then text "its scope" else text "their scope" ] in vcat [ nest 2 $ esc_doc , sep [ (if isSingleton esc_skols then text "This (rigid, skolem)" <+> what <+> text "variable is" else text "These (rigid, skolem)" <+> what <+> text "variables are") <+> text "bound by" , nest 2 $ ppr (ic_info implic) , nest 2 $ text "at" <+> ppr (getLclEnvLoc (ic_env implic)) ] ] where what = text $ levelString $ ctLocTypeOrKind_maybe (errorItemCtLoc item) `orElse` TypeLevel pprTcSolverReportMsg _ (UntouchableVariable tv implic) | Implic { ic_given = given, ic_info = skol_info } <- implic = sep [ quotes (ppr tv) <+> text "is untouchable" , nest 2 $ text "inside the constraints:" <+> pprEvVarTheta given , nest 2 $ text "bound by" <+> ppr skol_info , nest 2 $ text "at" <+> ppr (getLclEnvLoc (ic_env implic)) ] pprTcSolverReportMsg _ (BlockedEquality item) = vcat [ hang (text "Cannot use equality for substitution:") 2 (ppr (errorItemPred item)) , text "Doing so would be ill-kinded." ] pprTcSolverReportMsg _ (ExpectingMoreArguments n thing) = text "Expecting" <+> speakN (abs n) <+> more <+> quotes (ppr thing) where more | n == 1 = text "more argument to" | otherwise = text "more arguments to" -- n > 1 pprTcSolverReportMsg ctxt (UnboundImplicitParams (item :| items)) = let givens = getUserGivens ctxt in if null givens then addArising (errorItemOrigin item) $ sep [ text "Unbound implicit parameter" <> plural preds , nest 2 (pprParendTheta preds) ] else pprTcSolverReportMsg ctxt (CouldNotDeduce givens (item :| items) Nothing) where preds = map errorItemPred (item : items) pprTcSolverReportMsg ctxt (CouldNotDeduce useful_givens (item :| others) mb_extra) = main_msg $$ case supplementary of Left infos -> vcat (map (pprTcSolverReportInfo ctxt) infos) Right other_msg -> pprTcSolverReportMsg ctxt other_msg where main_msg | null useful_givens = addArising orig (no_instance_msg <+> missing) | otherwise = vcat (addArising orig (no_deduce_msg <+> missing) : pp_givens useful_givens) supplementary = case mb_extra of Nothing -> Left [] Just (CND_Extra level ty1 ty2) -> mk_supplementary_ea_msg ctxt level ty1 ty2 orig orig = errorItemOrigin item wanteds = map errorItemPred (item:others) no_instance_msg = case wanteds of [wanted] | Just (tc, _) <- splitTyConApp_maybe wanted -- Don't say "no instance" for a constraint such as "c" for a type variable c. , isClassTyCon tc -> text "No instance for" _ -> text "Could not solve:" no_deduce_msg = case wanteds of [_wanted] -> text "Could not deduce" _ -> text "Could not deduce:" missing = case wanteds of [wanted] -> pprParendType wanted _ -> pprTheta wanteds pprTcSolverReportMsg ctxt (AmbiguityPreventsSolvingCt item ambigs) = pprTcSolverReportInfo ctxt (Ambiguity True ambigs) <+> pprArising (errorItemOrigin item) $$ text "prevents the constraint" <+> quotes (pprParendType $ errorItemPred item) <+> text "from being solved." pprTcSolverReportMsg ctxt@(CEC {cec_encl = implics}) (CannotResolveInstance item unifiers candidates imp_errs suggs binds) = vcat [ pprTcSolverReportMsg ctxt no_inst_msg , nest 2 extra_note , mb_patsyn_prov `orElse` empty , ppWhen (has_ambigs && not (null unifiers && null useful_givens)) (vcat [ ppUnless lead_with_ambig $ pprTcSolverReportInfo ctxt (Ambiguity False (ambig_kvs, ambig_tvs)) , pprRelevantBindings binds , potential_msg ]) , ppWhen (isNothing mb_patsyn_prov) $ -- Don't suggest fixes for the provided context of a pattern -- synonym; the right fix is to bind more in the pattern show_fixes (ctxtFixes has_ambigs pred implics ++ drv_fixes) , ppWhen (not (null candidates)) (hang (text "There are instances for similar types:") 2 (vcat (map ppr candidates))) -- See Note [Report candidate instances] , vcat $ map ppr imp_errs , vcat $ map ppr suggs ] where orig = errorItemOrigin item pred = errorItemPred item (clas, tys) = getClassPredTys pred -- See Note [Highlighting ambiguous type variables] (ambig_kvs, ambig_tvs) = ambigTkvsOfTy pred ambigs = ambig_kvs ++ ambig_tvs has_ambigs = not (null ambigs) useful_givens = discardProvCtxtGivens orig (getUserGivensFromImplics implics) -- useful_givens are the enclosing implications with non-empty givens, -- modulo the horrid discardProvCtxtGivens lead_with_ambig = not (null ambigs) && not (any isRuntimeUnkSkol ambigs) && not (null unifiers) && null useful_givens no_inst_msg :: TcSolverReportMsg no_inst_msg | lead_with_ambig = AmbiguityPreventsSolvingCt item (ambig_kvs, ambig_tvs) | otherwise = CouldNotDeduce useful_givens (item :| []) Nothing -- Report "potential instances" only when the constraint arises -- directly from the user's use of an overloaded function want_potential (TypeEqOrigin {}) = False want_potential _ = True potential_msg = ppWhen (not (null unifiers) && want_potential orig) $ potential_hdr $$ potentialInstancesErrMsg (PotentialInstances { matches = [], unifiers }) potential_hdr = ppWhen lead_with_ambig $ text "Probable fix: use a type annotation to specify what" <+> pprQuotedList ambig_tvs <+> text "should be." mb_patsyn_prov :: Maybe SDoc mb_patsyn_prov | not lead_with_ambig , ProvCtxtOrigin PSB{ psb_def = L _ pat } <- orig = Just (vcat [ text "In other words, a successful match on the pattern" , nest 2 $ ppr pat , text "does not provide the constraint" <+> pprParendType pred ]) | otherwise = Nothing extra_note | any isFunTy (filterOutInvisibleTypes (classTyCon clas) tys) = text "(maybe you haven't applied a function to enough arguments?)" | className clas == typeableClassName -- Avoid mysterious "No instance for (Typeable T) , [_,ty] <- tys -- Look for (Typeable (k->*) (T k)) , Just (tc,_) <- tcSplitTyConApp_maybe ty , not (isTypeFamilyTyCon tc) = hang (text "GHC can't yet do polykinded") 2 (text "Typeable" <+> parens (ppr ty <+> dcolon <+> ppr (tcTypeKind ty))) | otherwise = empty drv_fixes = case orig of DerivClauseOrigin -> [drv_fix False] StandAloneDerivOrigin -> [drv_fix True] DerivOriginDC _ _ standalone -> [drv_fix standalone] DerivOriginCoerce _ _ _ standalone -> [drv_fix standalone] _ -> [] drv_fix standalone_wildcard | standalone_wildcard = text "fill in the wildcard constraint yourself" | otherwise = hang (text "use a standalone 'deriving instance' declaration,") 2 (text "so you can specify the instance context yourself") pprTcSolverReportMsg (CEC {cec_encl = implics}) (OverlappingInstances item matches unifiers) = vcat [ addArising orig $ (text "Overlapping instances for" <+> pprType (mkClassPred clas tys)) , ppUnless (null matching_givens) $ sep [text "Matching givens (or their superclasses):" , nest 2 (vcat matching_givens)] , potentialInstancesErrMsg (PotentialInstances { matches, unifiers }) , ppWhen (null matching_givens && isSingleton matches && null unifiers) $ -- Intuitively, some given matched the wanted in their -- flattened or rewritten (from given equalities) form -- but the matcher can't figure that out because the -- constraints are non-flat and non-rewritten so we -- simply report back the whole given -- context. Accelerate Smart.hs showed this problem. sep [ text "There exists a (perhaps superclass) match:" , nest 2 (vcat (pp_givens useful_givens))] , ppWhen (isSingleton matches) $ parens (vcat [ ppUnless (null tyCoVars) $ text "The choice depends on the instantiation of" <+> quotes (pprWithCommas ppr tyCoVars) , ppUnless (null famTyCons) $ if (null tyCoVars) then text "The choice depends on the result of evaluating" <+> quotes (pprWithCommas ppr famTyCons) else text "and the result of evaluating" <+> quotes (pprWithCommas ppr famTyCons) , ppWhen (null (matching_givens)) $ vcat [ text "To pick the first instance above, use IncoherentInstances" , text "when compiling the other instance declarations"] ])] where orig = errorItemOrigin item pred = errorItemPred item (clas, tys) = getClassPredTys pred tyCoVars = tyCoVarsOfTypesList tys famTyCons = filter isFamilyTyCon $ concatMap (nonDetEltsUniqSet . tyConsOfType) tys useful_givens = discardProvCtxtGivens orig (getUserGivensFromImplics implics) matching_givens = mapMaybe matchable useful_givens matchable implic@(Implic { ic_given = evvars, ic_info = skol_info }) = case ev_vars_matching of [] -> Nothing _ -> Just $ hang (pprTheta ev_vars_matching) 2 (sep [ text "bound by" <+> ppr skol_info , text "at" <+> ppr (getLclEnvLoc (ic_env implic)) ]) where ev_vars_matching = [ pred | ev_var <- evvars , let pred = evVarPred ev_var , any can_match (pred : transSuperClasses pred) ] can_match pred = case getClassPredTys_maybe pred of Just (clas', tys') -> clas' == clas && isJust (tcMatchTys tys tys') Nothing -> False pprTcSolverReportMsg _ (UnsafeOverlap item matches unsafe_overlapped) = vcat [ addArising orig (text "Unsafe overlapping instances for" <+> pprType (mkClassPred clas tys)) , sep [text "The matching instance is:", nest 2 (pprInstance $ head matches)] , vcat [ text "It is compiled in a Safe module and as such can only" , text "overlap instances from the same module, however it" , text "overlaps the following instances from different" <+> text "modules:" , nest 2 (vcat [pprInstances $ unsafe_overlapped]) ] ] where orig = errorItemOrigin item pred = errorItemPred item (clas, tys) = getClassPredTys pred {- ********************************************************************* * * Displaying potential instances * * **********************************************************************-} -- | Directly display the given matching and unifying instances, -- with a header for each: `Matching instances`/`Potentially matching instances`. pprPotentialInstances :: (ClsInst -> SDoc) -> PotentialInstances -> SDoc pprPotentialInstances ppr_inst (PotentialInstances { matches, unifiers }) = vcat [ ppWhen (not $ null matches) $ text "Matching instance" <> plural matches <> colon $$ nest 2 (vcat (map ppr_inst matches)) , ppWhen (not $ null unifiers) $ (text "Potentially matching instance" <> plural unifiers <> colon) $$ nest 2 (vcat (map ppr_inst unifiers)) ] -- | Display a summary of available instances, omitting those involving -- out-of-scope types, in order to explain why we couldn't solve a particular -- constraint, e.g. due to instance overlap or out-of-scope types. -- -- To directly display a collection of matching/unifying instances, -- use 'pprPotentialInstances'. potentialInstancesErrMsg :: PotentialInstances -> SDoc -- See Note [Displaying potential instances] potentialInstancesErrMsg potentials = sdocOption sdocPrintPotentialInstances $ \print_insts -> getPprStyle $ \sty -> potentials_msg_with_options potentials print_insts sty -- | Display a summary of available instances, omitting out-of-scope ones. -- -- Use 'potentialInstancesErrMsg' to automatically set the pretty-printing -- options. potentials_msg_with_options :: PotentialInstances -> Bool -- ^ Whether to print /all/ potential instances -> PprStyle -> SDoc potentials_msg_with_options (PotentialInstances { matches, unifiers }) show_all_potentials sty | null matches && null unifiers = empty | null show_these_matches && null show_these_unifiers = vcat [ not_in_scope_msg empty , flag_hint ] | otherwise = vcat [ pprPotentialInstances pprInstance -- print instance + location info (PotentialInstances { matches = show_these_matches , unifiers = show_these_unifiers }) , overlapping_but_not_more_specific_msg sorted_matches , nest 2 $ vcat [ ppWhen (n_in_scope_hidden > 0) $ text "...plus" <+> speakNOf n_in_scope_hidden (text "other") , ppWhen (not_in_scopes > 0) $ not_in_scope_msg (text "...plus") , flag_hint ] ] where n_show_matches, n_show_unifiers :: Int n_show_matches = 3 n_show_unifiers = 2 (in_scope_matches, not_in_scope_matches) = partition inst_in_scope matches (in_scope_unifiers, not_in_scope_unifiers) = partition inst_in_scope unifiers sorted_matches = sortBy fuzzyClsInstCmp in_scope_matches sorted_unifiers = sortBy fuzzyClsInstCmp in_scope_unifiers (show_these_matches, show_these_unifiers) | show_all_potentials = (sorted_matches, sorted_unifiers) | otherwise = (take n_show_matches sorted_matches ,take n_show_unifiers sorted_unifiers) n_in_scope_hidden = length sorted_matches + length sorted_unifiers - length show_these_matches - length show_these_unifiers -- "in scope" means that all the type constructors -- are lexically in scope; these instances are likely -- to be more useful inst_in_scope :: ClsInst -> Bool inst_in_scope cls_inst = nameSetAll name_in_scope $ orphNamesOfTypes (is_tys cls_inst) name_in_scope name | pretendNameIsInScope name = True -- E.g. (->); see Note [pretendNameIsInScope] in GHC.Builtin.Names | Just mod <- nameModule_maybe name = qual_in_scope (qualName sty mod (nameOccName name)) | otherwise = True qual_in_scope :: QualifyName -> Bool qual_in_scope NameUnqual = True qual_in_scope (NameQual {}) = True qual_in_scope _ = False not_in_scopes :: Int not_in_scopes = length not_in_scope_matches + length not_in_scope_unifiers not_in_scope_msg herald = hang (herald <+> speakNOf not_in_scopes (text "instance") <+> text "involving out-of-scope types") 2 (ppWhen show_all_potentials $ pprPotentialInstances pprInstanceHdr -- only print the header, not the instance location info (PotentialInstances { matches = not_in_scope_matches , unifiers = not_in_scope_unifiers })) flag_hint = ppUnless (show_all_potentials || (equalLength show_these_matches matches && equalLength show_these_unifiers unifiers)) $ text "(use -fprint-potential-instances to see them all)" -- | Compute a message informing the user of any instances that are overlapped -- but were not discarded because the instance overlapping them wasn't -- strictly more specific. overlapping_but_not_more_specific_msg :: [ClsInst] -> SDoc overlapping_but_not_more_specific_msg insts -- Only print one example of "overlapping but not strictly more specific", -- to avoid information overload. | overlap : _ <- overlapping_but_not_more_specific = overlap_header $$ ppr_overlapping overlap | otherwise = empty where overlap_header :: SDoc overlap_header | [_] <- overlapping_but_not_more_specific = text "An overlapping instance can only be chosen when it is strictly more specific." | otherwise = text "Overlapping instances can only be chosen when they are strictly more specific." overlapping_but_not_more_specific :: [(ClsInst, ClsInst)] overlapping_but_not_more_specific = nubOrdBy (comparing (is_dfun . fst)) [ (overlapper, overlappee) | these <- groupBy ((==) `on` is_cls_nm) insts -- Take all pairs of distinct instances... , one:others <- tails these -- if `these = [inst_1, inst_2, ...]` , other <- others -- then we get pairs `(one, other) = (inst_i, inst_j)` with `i < j` -- ... such that one instance in the pair overlaps the other... , let mb_overlapping | hasOverlappingFlag (overlapMode $ is_flag one) || hasOverlappableFlag (overlapMode $ is_flag other) = [(one, other)] | hasOverlappingFlag (overlapMode $ is_flag other) || hasOverlappableFlag (overlapMode $ is_flag one) = [(other, one)] | otherwise = [] , (overlapper, overlappee) <- mb_overlapping -- ... but the overlapper is not more specific than the overlappee. , not (overlapper `more_specific_than` overlappee) ] more_specific_than :: ClsInst -> ClsInst -> Bool is1 `more_specific_than` is2 = isJust (tcMatchTys (is_tys is1) (is_tys is2)) ppr_overlapping :: (ClsInst, ClsInst) -> SDoc ppr_overlapping (overlapper, overlappee) = text "The first instance that follows overlaps the second, but is not more specific than it:" $$ nest 2 (vcat $ map pprInstanceHdr [overlapper, overlappee]) {- Note [Displaying potential instances] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When showing a list of instances for - overlapping instances (show ones that match) - no such instance (show ones that could match) we want to give it a bit of structure. Here's the plan * Say that an instance is "in scope" if all of the type constructors it mentions are lexically in scope. These are the ones most likely to be useful to the programmer. * Show at most n_show in-scope instances, and summarise the rest ("plus N others") * Summarise the not-in-scope instances ("plus 4 not in scope") * Add the flag -fshow-potential-instances which replaces the summary with the full list -} {- ********************************************************************* * * Outputting TcSolverReportInfo * * **********************************************************************-} -- | Pretty-print an informational message, to accompany a 'TcSolverReportMsg'. pprTcSolverReportInfo :: SolverReportErrCtxt -> TcSolverReportInfo -> SDoc pprTcSolverReportInfo _ (Ambiguity prepend_msg (ambig_kvs, ambig_tvs)) = msg where msg | any isRuntimeUnkSkol ambig_kvs -- See Note [Runtime skolems] || any isRuntimeUnkSkol ambig_tvs = vcat [ text "Cannot resolve unknown runtime type" <> plural ambig_tvs <+> pprQuotedList ambig_tvs , text "Use :print or :force to determine these types"] | not (null ambig_tvs) = pp_ambig (text "type") ambig_tvs | otherwise = pp_ambig (text "kind") ambig_kvs pp_ambig what tkvs | prepend_msg -- "Ambiguous type variable 't0'" = text "Ambiguous" <+> what <+> text "variable" <> plural tkvs <+> pprQuotedList tkvs | otherwise -- "The type variable 't0' is ambiguous" = text "The" <+> what <+> text "variable" <> plural tkvs <+> pprQuotedList tkvs <+> isOrAre tkvs <+> text "ambiguous" pprTcSolverReportInfo ctxt (TyVarInfo tv ) = case tcTyVarDetails tv of SkolemTv sk_info _ _ -> pprSkols ctxt [(getSkolemInfo sk_info, [tv])] RuntimeUnk {} -> quotes (ppr tv) <+> text "is an interactive-debugger skolem" MetaTv {} -> empty pprTcSolverReportInfo _ (NonInjectiveTyFam tc) = text "NB:" <+> quotes (ppr tc) <+> text "is a non-injective type family" pprTcSolverReportInfo _ (ReportCoercibleMsg msg) = pprCoercibleMsg msg pprTcSolverReportInfo _ (ExpectedActual { ea_expected = exp, ea_actual = act }) = vcat [ text "Expected:" <+> ppr exp , text " Actual:" <+> ppr act ] pprTcSolverReportInfo _ (ExpectedActualAfterTySynExpansion { ea_expanded_expected = exp , ea_expanded_actual = act } ) = vcat [ text "Type synonyms expanded:" , text "Expected type:" <+> ppr exp , text " Actual type:" <+> ppr act ] pprTcSolverReportInfo ctxt (WhenMatching cty1 cty2 sub_o mb_sub_t_or_k) = sdocOption sdocPrintExplicitCoercions $ \printExplicitCoercions -> if printExplicitCoercions || not (cty1 `pickyEqType` cty2) then vcat [ hang (text "When matching" <+> sub_whats) 2 (vcat [ ppr cty1 <+> dcolon <+> ppr (tcTypeKind cty1) , ppr cty2 <+> dcolon <+> ppr (tcTypeKind cty2) ]) , supplementary ] else text "When matching the kind of" <+> quotes (ppr cty1) where sub_t_or_k = mb_sub_t_or_k `orElse` TypeLevel sub_whats = text (levelString sub_t_or_k) <> char 's' supplementary = case mk_supplementary_ea_msg ctxt sub_t_or_k cty1 cty2 sub_o of Left infos -> vcat $ map (pprTcSolverReportInfo ctxt) infos Right msg -> pprTcSolverReportMsg ctxt msg pprTcSolverReportInfo _ (SameOcc same_pkg n1 n2) = text "NB:" <+> (ppr_from same_pkg n1 $$ ppr_from same_pkg n2) where ppr_from same_pkg nm | isGoodSrcSpan loc = hang (quotes (ppr nm) <+> text "is defined at") 2 (ppr loc) | otherwise -- Imported things have an UnhelpfulSrcSpan = hang (quotes (ppr nm)) 2 (sep [ text "is defined in" <+> quotes (ppr (moduleName mod)) , ppUnless (same_pkg || pkg == mainUnit) $ nest 4 $ text "in package" <+> quotes (ppr pkg) ]) where pkg = moduleUnit mod mod = nameModule nm loc = nameSrcSpan nm pprTcSolverReportInfo ctxt (OccursCheckInterestingTyVars (tv :| tvs)) = hang (text "Type variable kinds:") 2 $ vcat (map (tyvar_binding . tidyTyCoVarOcc (cec_tidy ctxt)) (tv:tvs)) where tyvar_binding tyvar = ppr tyvar <+> dcolon <+> ppr (tyVarKind tyvar) pprCoercibleMsg :: CoercibleMsg -> SDoc pprCoercibleMsg (UnknownRoles ty) = hang (text "NB: We cannot know what roles the parameters to" <+> quotes (ppr ty) <+> text "have;") 2 (text "we must assume that the role is nominal") pprCoercibleMsg (TyConIsAbstract tc) = hsep [ text "NB: The type constructor" , quotes (pprSourceTyCon tc) , text "is abstract" ] pprCoercibleMsg (OutOfScopeNewtypeConstructor tc dc) = hang (text "The data constructor" <+> quotes (ppr $ dataConName dc)) 2 (sep [ text "of newtype" <+> quotes (pprSourceTyCon tc) , text "is not in scope" ]) {- ********************************************************************* * * Outputting HoleError messages * * **********************************************************************-} pprHoleError :: SolverReportErrCtxt -> Hole -> HoleError -> SDoc pprHoleError _ (Hole { hole_ty, hole_occ = occ }) (OutOfScopeHole imp_errs) = out_of_scope_msg $$ vcat (map ppr imp_errs) where herald | isDataOcc occ = text "Data constructor not in scope:" | otherwise = text "Variable not in scope:" out_of_scope_msg -- Print v :: ty only if the type has structure | boring_type = hang herald 2 (ppr occ) | otherwise = hang herald 2 (pp_occ_with_type occ hole_ty) boring_type = isTyVarTy hole_ty pprHoleError ctxt (Hole { hole_ty, hole_occ}) (HoleError sort other_tvs hole_skol_info) = vcat [ hole_msg , tyvars_msg , case sort of { ExprHole {} -> expr_hole_hint; _ -> type_hole_hint } ] where hole_msg = case sort of ExprHole {} -> hang (text "Found hole:") 2 (pp_occ_with_type hole_occ hole_ty) TypeHole -> hang (text "Found type wildcard" <+> quotes (ppr hole_occ)) 2 (text "standing for" <+> quotes pp_hole_type_with_kind) ConstraintHole -> hang (text "Found extra-constraints wildcard standing for") 2 (quotes $ pprType hole_ty) -- always kind constraint hole_kind = tcTypeKind hole_ty pp_hole_type_with_kind | isLiftedTypeKind hole_kind || isCoVarType hole_ty -- Don't print the kind of unlifted -- equalities (#15039) = pprType hole_ty | otherwise = pprType hole_ty <+> dcolon <+> pprKind hole_kind tyvars = tyCoVarsOfTypeList hole_ty tyvars_msg = ppUnless (null tyvars) $ text "Where:" <+> (vcat (map loc_msg other_tvs) $$ pprSkols ctxt hole_skol_info) -- Coercion variables can be free in the -- hole, via kind casts expr_hole_hint -- Give hint for, say, f x = _x | lengthFS (occNameFS hole_occ) > 1 -- Don't give this hint for plain "_" = text "Or perhaps" <+> quotes (ppr hole_occ) <+> text "is mis-spelled, or not in scope" | otherwise = empty type_hole_hint | ErrorWithoutFlag <- cec_type_holes ctxt = text "To use the inferred type, enable PartialTypeSignatures" | otherwise = empty loc_msg tv | isTyVar tv = case tcTyVarDetails tv of MetaTv {} -> quotes (ppr tv) <+> text "is an ambiguous type variable" _ -> empty -- Skolems dealt with already | otherwise -- A coercion variable can be free in the hole type = ppWhenOption sdocPrintExplicitCoercions $ quotes (ppr tv) <+> text "is a coercion variable" pp_occ_with_type :: OccName -> Type -> SDoc pp_occ_with_type occ hole_ty = hang (pprPrefixOcc occ) 2 (dcolon <+> pprType hole_ty) {- ********************************************************************* * * Outputting ScopeError messages * * **********************************************************************-} pprScopeError :: RdrName -> NotInScopeError -> SDoc pprScopeError rdr_name scope_err = case scope_err of NotInScope {} -> hang (text "Not in scope:") 2 (what <+> quotes (ppr rdr_name)) NoExactName name -> text "The Name" <+> quotes (ppr name) <+> text "is not in scope." SameName gres -> assertPpr (length gres >= 2) (text "pprScopeError SameName: fewer than 2 elements" $$ nest 2 (ppr gres)) $ hang (text "Same Name in multiple name-spaces:") 2 (vcat (map pp_one sorted_names)) where sorted_names = sortBy (leftmost_smallest `on` nameSrcSpan) (map greMangledName gres) pp_one name = hang (pprNameSpace (occNameSpace (getOccName name)) <+> quotes (ppr name) <> comma) 2 (text "declared at:" <+> ppr (nameSrcLoc name)) MissingBinding thing _ -> sep [ text "The" <+> thing <+> text "for" <+> quotes (ppr rdr_name) , nest 2 $ text "lacks an accompanying binding" ] NoTopLevelBinding -> hang (text "No top-level binding for") 2 (what <+> quotes (ppr rdr_name) <+> text "in this module") UnknownSubordinate doc -> quotes (ppr rdr_name) <+> text "is not a (visible)" <+> doc where what = pprNonVarNameSpace (occNameSpace (rdrNameOcc rdr_name)) scopeErrorHints :: NotInScopeError -> [GhcHint] scopeErrorHints scope_err = case scope_err of NotInScope -> noHints NoExactName {} -> [SuggestDumpSlices] SameName {} -> [SuggestDumpSlices] MissingBinding _ hints -> hints NoTopLevelBinding -> noHints UnknownSubordinate {} -> noHints {- ********************************************************************* * * Outputting ImportError messages * * **********************************************************************-} instance Outputable ImportError where ppr (MissingModule mod_name) = hsep [ text "NB: no module named" , quotes (ppr mod_name) , text "is imported." ] ppr (ModulesDoNotExport mods occ_name) | mod NE.:| [] <- mods = hsep [ text "NB: the module" , quotes (ppr mod) , text "does not export" , quotes (ppr occ_name) <> dot ] | otherwise = hsep [ text "NB: neither" , quotedListWithNor (map ppr $ NE.toList mods) , text "export" , quotes (ppr occ_name) <> dot ] {- ********************************************************************* * * Suggested fixes for implication constraints * * **********************************************************************-} -- TODO: these functions should use GhcHint instead. show_fixes :: [SDoc] -> SDoc show_fixes [] = empty show_fixes (f:fs) = sep [ text "Possible fix:" , nest 2 (vcat (f : map (text "or" <+>) fs))] ctxtFixes :: Bool -> PredType -> [Implication] -> [SDoc] ctxtFixes has_ambig_tvs pred implics | not has_ambig_tvs , isTyVarClassPred pred , (skol:skols) <- usefulContext implics pred , let what | null skols , SigSkol (PatSynCtxt {}) _ _ <- skol = text "\"required\"" | otherwise = empty = [sep [ text "add" <+> pprParendType pred <+> text "to the" <+> what <+> text "context of" , nest 2 $ ppr_skol skol $$ vcat [ text "or" <+> ppr_skol skol | skol <- skols ] ] ] | otherwise = [] where ppr_skol (PatSkol (RealDataCon dc) _) = text "the data constructor" <+> quotes (ppr dc) ppr_skol (PatSkol (PatSynCon ps) _) = text "the pattern synonym" <+> quotes (ppr ps) ppr_skol skol_info = ppr skol_info usefulContext :: [Implication] -> PredType -> [SkolemInfoAnon] -- usefulContext picks out the implications whose context -- the programmer might plausibly augment to solve 'pred' usefulContext implics pred = go implics where pred_tvs = tyCoVarsOfType pred go [] = [] go (ic : ics) | implausible ic = rest | otherwise = ic_info ic : rest where -- Stop when the context binds a variable free in the predicate rest | any (`elemVarSet` pred_tvs) (ic_skols ic) = [] | otherwise = go ics implausible ic | null (ic_skols ic) = True | implausible_info (ic_info ic) = True | otherwise = False implausible_info (SigSkol (InfSigCtxt {}) _ _) = True implausible_info _ = False -- Do not suggest adding constraints to an *inferred* type signature pp_givens :: [Implication] -> [SDoc] pp_givens givens = case givens of [] -> [] (g:gs) -> ppr_given (text "from the context:") g : map (ppr_given (text "or from:")) gs where ppr_given herald implic@(Implic { ic_given = gs, ic_info = skol_info }) = hang (herald <+> pprEvVarTheta (mkMinimalBySCs evVarPred gs)) -- See Note [Suppress redundant givens during error reporting] -- for why we use mkMinimalBySCs above. 2 (sep [ text "bound by" <+> ppr skol_info , text "at" <+> ppr (getLclEnvLoc (ic_env implic)) ]) {- ********************************************************************* * * CtOrigin information * * **********************************************************************-} levelString :: TypeOrKind -> String levelString TypeLevel = "type" levelString KindLevel = "kind" pprArising :: CtOrigin -> SDoc -- Used for the main, top-level error message -- We've done special processing for TypeEq, KindEq, givens pprArising (TypeEqOrigin {}) = empty pprArising (KindEqOrigin {}) = empty pprArising (AmbiguityCheckOrigin {}) = empty -- the "In the ambiguity check" context -- is sufficient; this would just be -- repetitive pprArising orig | isGivenOrigin orig = empty | otherwise = pprCtOrigin orig -- Add the "arising from..." part to a message addArising :: CtOrigin -> SDoc -> SDoc addArising orig msg = hang msg 2 (pprArising orig) pprWithArising :: [Ct] -> SDoc -- Print something like -- (Eq a) arising from a use of x at y -- (Show a) arising from a use of p at q -- Also return a location for the error message -- Works for Wanted/Derived only pprWithArising [] = panic "pprWithArising" pprWithArising (ct:cts) | null cts = addArising (ctLocOrigin loc) (pprTheta [ctPred ct]) | otherwise = vcat (map ppr_one (ct:cts)) where loc = ctLoc ct ppr_one ct' = hang (parens (pprType (ctPred ct'))) 2 (pprCtLoc (ctLoc ct')) {- ********************************************************************* * * SkolemInfo * * **********************************************************************-} tidySkolemInfo :: TidyEnv -> SkolemInfo -> SkolemInfo tidySkolemInfo env (SkolemInfo u sk_anon) = SkolemInfo u (tidySkolemInfoAnon env sk_anon) ---------------- tidySkolemInfoAnon :: TidyEnv -> SkolemInfoAnon -> SkolemInfoAnon tidySkolemInfoAnon env (DerivSkol ty) = DerivSkol (tidyType env ty) tidySkolemInfoAnon env (SigSkol cx ty tv_prs) = tidySigSkol env cx ty tv_prs tidySkolemInfoAnon env (InferSkol ids) = InferSkol (mapSnd (tidyType env) ids) tidySkolemInfoAnon env (UnifyForAllSkol ty) = UnifyForAllSkol (tidyType env ty) tidySkolemInfoAnon _ info = info tidySigSkol :: TidyEnv -> UserTypeCtxt -> TcType -> [(Name,TcTyVar)] -> SkolemInfoAnon -- We need to take special care when tidying SigSkol -- See Note [SigSkol SkolemInfo] in "GHC.Tc.Types.Origin" tidySigSkol env cx ty tv_prs = SigSkol cx (tidy_ty env ty) tv_prs' where tv_prs' = mapSnd (tidyTyCoVarOcc env) tv_prs inst_env = mkNameEnv tv_prs' tidy_ty env (ForAllTy (Bndr tv vis) ty) = ForAllTy (Bndr tv' vis) (tidy_ty env' ty) where (env', tv') = tidy_tv_bndr env tv tidy_ty env ty@(FunTy InvisArg w arg res) -- Look under c => t = ty { ft_mult = tidy_ty env w, ft_arg = tidyType env arg, ft_res = tidy_ty env res } tidy_ty env ty = tidyType env ty tidy_tv_bndr :: TidyEnv -> TyCoVar -> (TidyEnv, TyCoVar) tidy_tv_bndr env@(occ_env, subst) tv | Just tv' <- lookupNameEnv inst_env (tyVarName tv) = ((occ_env, extendVarEnv subst tv tv'), tv') | otherwise = tidyVarBndr env tv pprSkols :: SolverReportErrCtxt -> [(SkolemInfoAnon, [TcTyVar])] -> SDoc pprSkols ctxt zonked_ty_vars = let tidy_ty_vars = map (bimap (tidySkolemInfoAnon (cec_tidy ctxt)) id) zonked_ty_vars in vcat (map pp_one tidy_ty_vars) where no_msg = text "No skolem info - we could not find the origin of the following variables" <+> ppr zonked_ty_vars $$ text "This should not happen, please report it as a bug following the instructions at:" $$ text "https://gitlab.haskell.org/ghc/ghc/wikis/report-a-bug" pp_one (UnkSkol cs, tvs) = vcat [ hang (pprQuotedList tvs) 2 (is_or_are tvs "a" "(rigid, skolem)") , nest 2 (text "of unknown origin") , nest 2 (text "bound at" <+> ppr (skolsSpan tvs)) , no_msg , prettyCallStackDoc cs ] pp_one (RuntimeUnkSkol, tvs) = hang (pprQuotedList tvs) 2 (is_or_are tvs "an" "unknown runtime") pp_one (skol_info, tvs) = vcat [ hang (pprQuotedList tvs) 2 (is_or_are tvs "a" "rigid" <+> text "bound by") , nest 2 (pprSkolInfo skol_info) , nest 2 (text "at" <+> ppr (skolsSpan tvs)) ] is_or_are [_] article adjective = text "is" <+> text article <+> text adjective <+> text "type variable" is_or_are _ _ adjective = text "are" <+> text adjective <+> text "type variables" skolsSpan :: [TcTyVar] -> SrcSpan skolsSpan skol_tvs = foldr1 combineSrcSpans (map getSrcSpan skol_tvs) {- ********************************************************************* * * Utilities for expected/actual messages * * **********************************************************************-} mk_supplementary_ea_msg :: SolverReportErrCtxt -> TypeOrKind -> Type -> Type -> CtOrigin -> Either [TcSolverReportInfo] TcSolverReportMsg mk_supplementary_ea_msg ctxt level ty1 ty2 orig | TypeEqOrigin { uo_expected = exp, uo_actual = act } <- orig , not (ea_looks_same ty1 ty2 exp act) = mk_ea_msg ctxt Nothing level orig | otherwise = Left [] ea_looks_same :: Type -> Type -> Type -> Type -> Bool -- True if the faulting types (ty1, ty2) look the same as -- the expected/actual types (exp, act). -- If so, we don't want to redundantly report the latter ea_looks_same ty1 ty2 exp act = (act `looks_same` ty1 && exp `looks_same` ty2) || (exp `looks_same` ty1 && act `looks_same` ty2) where looks_same t1 t2 = t1 `pickyEqType` t2 || t1 `eqType` liftedTypeKind && t2 `eqType` liftedTypeKind -- pickyEqType is sensitive to synonyms, so only replies True -- when the types really look the same. However, -- (TYPE 'LiftedRep) and Type both print the same way. mk_ea_msg :: SolverReportErrCtxt -> Maybe ErrorItem -> TypeOrKind -> CtOrigin -> Either [TcSolverReportInfo] TcSolverReportMsg -- Constructs a "Couldn't match" message -- The (Maybe ErrorItem) says whether this is the main top-level message (Just) -- or a supplementary message (Nothing) mk_ea_msg ctxt at_top level (TypeEqOrigin { uo_actual = act, uo_expected = exp, uo_thing = mb_thing }) | Just thing <- mb_thing , KindLevel <- level = Right $ KindMismatch { kmismatch_what = thing , kmismatch_expected = exp , kmismatch_actual = act } | Just item <- at_top , let mismatch = Mismatch { mismatch_ea = True , mismatch_item = item , mismatch_ty1 = exp , mismatch_ty2 = act } = Right $ if expanded_syns then mkTcReportWithInfo mismatch [ea_expanded] else mismatch | otherwise = Left $ if expanded_syns then [ea,ea_expanded] else [ea] where ea = ExpectedActual { ea_expected = exp, ea_actual = act } ea_expanded = ExpectedActualAfterTySynExpansion { ea_expanded_expected = expTy1 , ea_expanded_actual = expTy2 } expanded_syns = cec_expand_syns ctxt && not (expTy1 `pickyEqType` exp && expTy2 `pickyEqType` act) (expTy1, expTy2) = expandSynonymsToMatch exp act mk_ea_msg _ _ _ _ = Left [] {- Note [Expanding type synonyms to make types similar] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In type error messages, if -fprint-expanded-types is used, we want to expand type synonyms to make expected and found types as similar as possible, but we shouldn't expand types too much to make type messages even more verbose and harder to understand. The whole point here is to make the difference in expected and found types clearer. `expandSynonymsToMatch` does this, it takes two types, and expands type synonyms only as much as necessary. Given two types t1 and t2: * If they're already same, it just returns the types. * If they're in form `C1 t1_1 .. t1_n` and `C2 t2_1 .. t2_m` (C1 and C2 are type constructors), it expands C1 and C2 if they're different type synonyms. Then it recursively does the same thing on expanded types. If C1 and C2 are same, then it applies the same procedure to arguments of C1 and arguments of C2 to make them as similar as possible. Most important thing here is to keep number of synonym expansions at minimum. For example, if t1 is `T (T3, T5, Int)` and t2 is `T (T5, T3, Bool)` where T5 = T4, T4 = T3, ..., T1 = X, it returns `T (T3, T3, Int)` and `T (T3, T3, Bool)`. * Otherwise types don't have same shapes and so the difference is clearly visible. It doesn't do any expansions and show these types. Note that we only expand top-layer type synonyms. Only when top-layer constructors are the same we start expanding inner type synonyms. Suppose top-layer type synonyms of t1 and t2 can expand N and M times, respectively. If their type-synonym-expanded forms will meet at some point (i.e. will have same shapes according to `sameShapes` function), it's possible to find where they meet in O(N+M) top-layer type synonym expansions and O(min(N,M)) comparisons. We first collect all the top-layer expansions of t1 and t2 in two lists, then drop the prefix of the longer list so that they have same lengths. Then we search through both lists in parallel, and return the first pair of types that have same shapes. Inner types of these two types with same shapes are then expanded using the same algorithm. In case they don't meet, we return the last pair of types in the lists, which has top-layer type synonyms completely expanded. (in this case the inner types are not expanded at all, as the current form already shows the type error) -} -- | Expand type synonyms in given types only enough to make them as similar as -- possible. Returned types are the same in terms of used type synonyms. -- -- To expand all synonyms, see 'Type.expandTypeSynonyms'. -- -- See `ExpandSynsFail` tests in tests testsuite/tests/typecheck/should_fail for -- some examples of how this should work. expandSynonymsToMatch :: Type -> Type -> (Type, Type) expandSynonymsToMatch ty1 ty2 = (ty1_ret, ty2_ret) where (ty1_ret, ty2_ret) = go ty1 ty2 -- Returns (type synonym expanded version of first type, -- type synonym expanded version of second type) go :: Type -> Type -> (Type, Type) go t1 t2 | t1 `pickyEqType` t2 = -- Types are same, nothing to do (t1, t2) go (TyConApp tc1 tys1) (TyConApp tc2 tys2) | tc1 == tc2 , tys1 `equalLength` tys2 = -- Type constructors are same. They may be synonyms, but we don't -- expand further. The lengths of tys1 and tys2 must be equal; -- for example, with type S a = a, we don't want -- to zip (S Monad Int) and (S Bool). let (tys1', tys2') = unzip (zipWithEqual "expandSynonymsToMatch" go tys1 tys2) in (TyConApp tc1 tys1', TyConApp tc2 tys2') go (AppTy t1_1 t1_2) (AppTy t2_1 t2_2) = let (t1_1', t2_1') = go t1_1 t2_1 (t1_2', t2_2') = go t1_2 t2_2 in (mkAppTy t1_1' t1_2', mkAppTy t2_1' t2_2') go ty1@(FunTy _ w1 t1_1 t1_2) ty2@(FunTy _ w2 t2_1 t2_2) | w1 `eqType` w2 = let (t1_1', t2_1') = go t1_1 t2_1 (t1_2', t2_2') = go t1_2 t2_2 in ( ty1 { ft_arg = t1_1', ft_res = t1_2' } , ty2 { ft_arg = t2_1', ft_res = t2_2' }) go (ForAllTy b1 t1) (ForAllTy b2 t2) = -- NOTE: We may have a bug here, but we just can't reproduce it easily. -- See D1016 comments for details and our attempts at producing a test -- case. Short version: We probably need RnEnv2 to really get this right. let (t1', t2') = go t1 t2 in (ForAllTy b1 t1', ForAllTy b2 t2') go (CastTy ty1 _) ty2 = go ty1 ty2 go ty1 (CastTy ty2 _) = go ty1 ty2 go t1 t2 = -- See Note [Expanding type synonyms to make types similar] for how this -- works let t1_exp_tys = t1 : tyExpansions t1 t2_exp_tys = t2 : tyExpansions t2 t1_exps = length t1_exp_tys t2_exps = length t2_exp_tys dif = abs (t1_exps - t2_exps) in followExpansions $ zipEqual "expandSynonymsToMatch.go" (if t1_exps > t2_exps then drop dif t1_exp_tys else t1_exp_tys) (if t2_exps > t1_exps then drop dif t2_exp_tys else t2_exp_tys) -- Expand the top layer type synonyms repeatedly, collect expansions in a -- list. The list does not include the original type. -- -- Example, if you have: -- -- type T10 = T9 -- type T9 = T8 -- ... -- type T0 = Int -- -- `tyExpansions T10` returns [T9, T8, T7, ... Int] -- -- This only expands the top layer, so if you have: -- -- type M a = Maybe a -- -- `tyExpansions (M T10)` returns [Maybe T10] (T10 is not expanded) tyExpansions :: Type -> [Type] tyExpansions = unfoldr (\t -> (\x -> (x, x)) `fmap` tcView t) -- Drop the type pairs until types in a pair look alike (i.e. the outer -- constructors are the same). followExpansions :: [(Type, Type)] -> (Type, Type) followExpansions [] = pprPanic "followExpansions" empty followExpansions [(t1, t2)] | sameShapes t1 t2 = go t1 t2 -- expand subtrees | otherwise = (t1, t2) -- the difference is already visible followExpansions ((t1, t2) : tss) -- Traverse subtrees when the outer shapes are the same | sameShapes t1 t2 = go t1 t2 -- Otherwise follow the expansions until they look alike | otherwise = followExpansions tss sameShapes :: Type -> Type -> Bool sameShapes AppTy{} AppTy{} = True sameShapes (TyConApp tc1 _) (TyConApp tc2 _) = tc1 == tc2 sameShapes (FunTy {}) (FunTy {}) = True sameShapes (ForAllTy {}) (ForAllTy {}) = True sameShapes (CastTy ty1 _) ty2 = sameShapes ty1 ty2 sameShapes ty1 (CastTy ty2 _) = sameShapes ty1 ty2 sameShapes _ _ = False {- ************************************************************************ * * \subsection{Contexts for renaming errors} * * ************************************************************************ -} withHsDocContext :: HsDocContext -> SDoc -> SDoc withHsDocContext ctxt doc = doc $$ inHsDocContext ctxt inHsDocContext :: HsDocContext -> SDoc inHsDocContext ctxt = text "In" <+> pprHsDocContext ctxt pprHsDocContext :: HsDocContext -> SDoc pprHsDocContext (GenericCtx doc) = doc pprHsDocContext (TypeSigCtx doc) = text "the type signature for" <+> doc pprHsDocContext (StandaloneKindSigCtx doc) = text "the standalone kind signature for" <+> doc pprHsDocContext PatCtx = text "a pattern type-signature" pprHsDocContext SpecInstSigCtx = text "a SPECIALISE instance pragma" pprHsDocContext DefaultDeclCtx = text "a `default' declaration" pprHsDocContext DerivDeclCtx = text "a deriving declaration" pprHsDocContext (RuleCtx name) = text "the rewrite rule" <+> doubleQuotes (ftext name) pprHsDocContext (TyDataCtx tycon) = text "the data type declaration for" <+> quotes (ppr tycon) pprHsDocContext (FamPatCtx tycon) = text "a type pattern of family instance for" <+> quotes (ppr tycon) pprHsDocContext (TySynCtx name) = text "the declaration for type synonym" <+> quotes (ppr name) pprHsDocContext (TyFamilyCtx name) = text "the declaration for type family" <+> quotes (ppr name) pprHsDocContext (ClassDeclCtx name) = text "the declaration for class" <+> quotes (ppr name) pprHsDocContext ExprWithTySigCtx = text "an expression type signature" pprHsDocContext TypBrCtx = text "a Template-Haskell quoted type" pprHsDocContext HsTypeCtx = text "a type argument" pprHsDocContext HsTypePatCtx = text "a type argument in a pattern" pprHsDocContext GHCiCtx = text "GHCi input" pprHsDocContext (SpliceTypeCtx hs_ty) = text "the spliced type" <+> quotes (ppr hs_ty) pprHsDocContext ClassInstanceCtx = text "GHC.Tc.Gen.Splice.reifyInstances" pprHsDocContext (ForeignDeclCtx name) = text "the foreign declaration for" <+> quotes (ppr name) pprHsDocContext (ConDeclCtx [name]) = text "the definition of data constructor" <+> quotes (ppr name) pprHsDocContext (ConDeclCtx names) = text "the definition of data constructors" <+> interpp'SP names