diff options
Diffstat (limited to 'compiler/GHC/Tc/Types/Origin.hs')
| -rw-r--r-- | compiler/GHC/Tc/Types/Origin.hs | 352 |
1 files changed, 345 insertions, 7 deletions
diff --git a/compiler/GHC/Tc/Types/Origin.hs b/compiler/GHC/Tc/Types/Origin.hs index 3d55427ae6..25c96b6437 100644 --- a/compiler/GHC/Tc/Types/Origin.hs +++ b/compiler/GHC/Tc/Types/Origin.hs @@ -21,7 +21,15 @@ module GHC.Tc.Types.Origin ( pprCtOrigin, isGivenOrigin, -- CtOrigin and CallStack - isPushCallStackOrigin, callStackOriginFS + isPushCallStackOrigin, callStackOriginFS, + -- FixedRuntimeRep origin + FRROrigin(..), pprFRROrigin, + StmtOrigin(..), + + -- Arrow command origin + FRRArrowOrigin(..), pprFRRArrowOrigin, + -- HsWrapper WpFun origin + WpFunOrigin(..), pprWpFunOrigin, ) where @@ -226,8 +234,6 @@ data SkolemInfo -- The pattern MkT x will allocate an existential type -- variable for 'a'. - | ArrowSkol -- An arrow form (see GHC.Tc.Gen.Arrow) - | IPSkol [HsIPName] -- Binding site of an implicit parameter | RuleSkol RuleName -- The LHS of a RULE @@ -272,7 +278,6 @@ pprSkolInfo (InstSC n) = text "the instance declaration" <> whenPprDebug pprSkolInfo FamInstSkol = text "a family instance declaration" pprSkolInfo BracketSkol = text "a Template Haskell bracket" pprSkolInfo (RuleSkol name) = text "the RULE" <+> pprRuleName name -pprSkolInfo ArrowSkol = text "an arrow form" pprSkolInfo (PatSkol cl mc) = sep [ pprPatSkolInfo cl , text "in" <+> pprMatchContext mc ] pprSkolInfo (InferSkol ids) = hang (text "the inferred type" <> plural ids <+> text "of") @@ -437,6 +442,7 @@ data CtOrigin | MCompPatOrigin (LPat GhcRn) -- Arising from a failable pattern in a -- monad comprehension | ProcOrigin -- Arising from a proc expression + | ArrowCmdOrigin -- Arising from an arrow command | AnnOrigin -- An annotation | FunDepOrigin1 -- A functional dependency from combining @@ -460,15 +466,25 @@ data CtOrigin -- the user should never see this one, -- unless ImpredicativeTypes is on, where all -- bets are off - | InstProvidedOrigin Module ClsInst - -- Skolem variable arose when we were testing if an instance - -- is solvable or not. + + -- | Testing whether the constraint associated with an instance declaration + -- in a signature file is satisfied upon instantiation. + -- + -- Test cases: backpack/should_fail/bkpfail{11,43}.bkp + | InstProvidedOrigin + Module -- ^ Module in which the instance was declared + ClsInst -- ^ The declared typeclass instance + | NonLinearPatternOrigin | UsageEnvironmentOf Name | CycleBreakerOrigin CtOrigin -- origin of the original constraint -- See Detail (7) of Note [Type variable cycles] in GHC.Tc.Solver.Canonical + | FixedRuntimeRepOrigin + !Type -- ^ The type being checked for representation polymorphism. + -- We record it here for access in 'GHC.Tc.Errors.mkFRRErr'. + !FRROrigin -- An origin is visible if the place where the constraint arises is manifest -- in user code. Currently, all origins are visible except for invisible @@ -637,6 +653,12 @@ pprCtOrigin (InstProvidedOrigin mod cls_inst) pprCtOrigin (CycleBreakerOrigin orig) = pprCtOrigin orig +pprCtOrigin (FixedRuntimeRepOrigin _ frrOrig) + -- We ignore the type argument, as we would prefer + -- to report all types that don't have a fixed runtime representation at once, + -- in 'GHC.Tc.Errors.mkFRRErr'. + = pprFRROrigin frrOrig + pprCtOrigin simple_origin = ctoHerald <+> pprCtO simple_origin @@ -668,6 +690,7 @@ pprCtO DefaultOrigin = text "a 'default' declaration" pprCtO DoOrigin = text "a do statement" pprCtO MCompOrigin = text "a statement in a monad comprehension" pprCtO ProcOrigin = text "a proc expression" +pprCtO ArrowCmdOrigin = text "an arrow command" pprCtO AnnOrigin = text "an annotation" pprCtO (ExprHoleOrigin occ) = text "a use of" <+> quotes (ppr occ) pprCtO (TypeHoleOrigin occ) = text "a use of wildcard" <+> quotes (ppr occ) @@ -696,6 +719,7 @@ pprCtO (Shouldn'tHappenOrigin note) = text note pprCtO (ProvCtxtOrigin {}) = text "a provided constraint" pprCtO (InstProvidedOrigin {}) = text "a provided constraint" pprCtO (CycleBreakerOrigin orig) = pprCtO orig +pprCtO (FixedRuntimeRepOrigin {}) = text "a representation polymorphism check" {- ********************************************************************* * * @@ -717,3 +741,317 @@ callStackOriginFS :: CtOrigin -> FastString -- This is the string that appears in the CallStack callStackOriginFS (OccurrenceOf fun) = occNameFS (getOccName fun) callStackOriginFS orig = mkFastString (showSDocUnsafe (pprCtO orig)) + +{- +************************************************************************ +* * + Checking for representation polymorphism +* * +************************************************************************ + +Note [Reporting representation-polymorphism errors] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +When we emit a 'Concrete#' Wanted constraint using GHC.Tc.Utils.Concrete.hasFixedRuntimeRep, +we provide a 'CtOrigin' using the 'FixedRuntimeRepOrigin' constructor of, +which keeps track of two things: + - the type which we want to ensure has a fixed runtime representation, + - the 'FRROrigin' explaining the nature of the check, e.g. a pattern, + a function application, a record update, ... + +If the constraint goes unsolved, we report it as follows: + - we detect that the unsolved Wanted is a Concrete# constraint in + GHC.Tc.Errors.reportWanteds using is_FRR, + - we assemble an error message in GHC.Tc.Errors.mkFRRErr. + +For example, if we try to write the program + + foo :: forall r1 r2 (a :: TYPE r1) (b :: TYPE r2). a -> b -> () + foo x y = () + +we will get two unsolved Concrete# wanted constraints, namely +'Concrete# r1' and 'Concrete# r2', and their 'CtOrigin's will be: + + FixedRuntimeRepOrigin a (FRRVarPattern x) + FixedRuntimeRepOrigin b (FRRVarPattern y) + +These constraints will be processed in tandem by mkFRRErr, +producing an error message of the form: + + Representation-polymorphic types are not allowed here. + * The variable 'x' bound by the pattern + does not have a fixed runtime representation: + a :: TYPE r1 + * The variable 'y' bound by the pattern + does not have a fixed runtime representation: + b :: TYPE r2 +-} + +-- | Where are we checking that a type has a fixed runtime representation? +-- Equivalently: what is the origin of an emitted 'Concrete#' constraint? +data FRROrigin + + -- | Function arguments must have a fixed runtime representation. + -- + -- Test case: RepPolyApp. + = FRRApp !(HsExpr GhcRn) + + -- | Record fields in record updates must have a fixed runtime representation. + -- + -- Test case: RepPolyRecordUpdate. + | FRRRecordUpdate !RdrName !(HsExpr GhcRn) + + -- | Variable binders must have a fixed runtime representation. + -- + -- Test cases: LevPolyLet, RepPolyPatBind. + | FRRBinder !Name + + -- | The type of a pattern in a match group must have a fixed runtime representation. + -- + -- This rules out: + -- - individual patterns which don't have a fixed runtime representation, + -- - a representation-polymorphic empty case statement, + -- - representation-polymorphic GADT pattern matches + -- in which individual pattern types have a fixed runtime representation. + -- + -- Test cases: RepPolyRecordPattern, RepPolyUnboxedPatterns, + -- RepPolyBinder, RepPolyWildcardPattern, RepPolyMatch, + -- RepPolyNPlusK, RepPolyPatBind, T20426. + | FRRMatch !(HsMatchContext GhcTc) !Int + + -- | An instantiation of a newtype/data constructor in which + -- one of the remaining arguments types does not have a fixed runtime representation. + -- + -- Test case: UnliftedNewtypesLevityBinder. + | FRRDataConArg !DataCon !Int + + -- | An instantiation of an 'Id' with no binding (e.g. `coerce`, `unsafeCoerce#`) + -- in which one of the remaining arguments types does not have a fixed runtime representation. + -- + -- Test cases: RepPolyWrappedVar, T14561, UnliftedNewtypesCoerceFail. + | FRRNoBindingResArg !Id !Int + + -- | Arguments to unboxed tuples must have fixed runtime representations. + -- + -- Test case: RepPolyTuple. + | FRRTupleArg !Int + + -- | Tuple sections must have a fixed runtime representation. + -- + -- Test case: RepPolyTupleSection. + | FRRTupleSection !Int + + -- | Unboxed sums must have a fixed runtime representation. + -- + -- Test cases: RepPolySum. + | FRRUnboxedSum + + -- | The body of a @do@ expression or a monad comprehension must + -- have a fixed runtime representation. + -- + -- Test cases: RepPolyDoBody{1,2}, RepPolyMcBody. + | FRRBodyStmt !StmtOrigin !Int + + -- | Arguments to a guard in a monad comprehesion must have + -- a fixed runtime representation. + -- + -- Test case: RepPolyMcGuard. + | FRRBodyStmtGuard + + -- | Arguments to `(>>=)` arising from a @do@ expression + -- or a monad comprehension must have a fixed runtime representation. + -- + -- Test cases: RepPolyDoBind, RepPolyMcBind. + | FRRBindStmt !StmtOrigin + + -- | A value bound by a pattern guard must have a fixed runtime representation. + -- + -- Test cases: none. + | FRRBindStmtGuard + + -- | A representation-polymorphism check arising from arrow notation. + -- + -- See 'FRRArrowOrigin' for more details. + | FRRArrow !FRRArrowOrigin + + -- | A representation-polymorphic check arising from an 'HsWrapper'. + -- + -- See 'WpFunOrigin' for more details. + | FRRWpFun !WpFunOrigin + +-- | Print the context for a @FixedRuntimeRep@ representation-polymorphism check. +-- +-- Note that this function does not include the specific 'RuntimeRep' +-- which is not fixed. That information is added by 'GHC.Tc.Errors.mkFRRErr'. +pprFRROrigin :: FRROrigin -> SDoc +pprFRROrigin (FRRApp arg) + = sep [ text "The function argument" + , nest 2 $ quotes (ppr arg) + , text "does not have a fixed runtime representation"] +pprFRROrigin (FRRRecordUpdate lbl _arg) + = hsep [ text "The record update at field" + , quotes (ppr lbl) + , text "does not have a fixed runtime representation"] +pprFRROrigin (FRRBinder binder) + = hsep [ text "The binder" + , quotes (ppr binder) + , text "does not have a fixed runtime representation"] +pprFRROrigin (FRRMatch matchCtxt i) + = vcat [ text "The type of the" <+> speakNth i <+> text "pattern in the" <+> pprMatchContextNoun matchCtxt + , text "does not have a fixed runtime representation"] +pprFRROrigin (FRRDataConArg con i) + = sep [ text "The" <+> what + , text "does not have a fixed runtime representation"] + where + what :: SDoc + what + | isNewDataCon con + = text "newtype constructor argument" + | otherwise + = text "data constructor argument in" <+> speakNth i <+> text "position" +pprFRROrigin (FRRNoBindingResArg fn i) + = vcat [ text "Unsaturated use of a representation-polymorphic primitive function." + , text "The" <+> speakNth i <+> text "argument of" <+> quotes (ppr $ getName fn) + , text "does not have a fixed runtime representation" ] +pprFRROrigin (FRRTupleArg i) + = hsep [ text "The tuple argument in" <+> speakNth i <+> text "position" + , text "does not have a fixed runtime representation"] +pprFRROrigin (FRRTupleSection i) + = hsep [ text "The tuple section does not have a fixed runtime representation" + , text "in the" <+> speakNth i <+> text "position" ] +pprFRROrigin FRRUnboxedSum + = hsep [ text "The unboxed sum result type" + , text "does not have a fixed runtime representation"] +pprFRROrigin (FRRBodyStmt stmtOrig i) + = vcat [ text "The" <+> speakNth i <+> text "argument to (>>)" <> comma + , text "arising from the" <+> ppr stmtOrig <> comma + , text "does not have a fixed runtime representation" ] +pprFRROrigin FRRBodyStmtGuard + = vcat [ text "The argument to" <+> quotes (text "guard") <> comma + , text "arising from the" <+> ppr MonadComprehension <> comma + , text "does not have a fixed runtime representation" ] +pprFRROrigin (FRRBindStmt stmtOrig) + = vcat [ text "The first argument to (>>=)" <> comma + , text "arising from the" <+> ppr stmtOrig <> comma + , text "does not have a fixed runtime representation" ] +pprFRROrigin FRRBindStmtGuard + = hsep [ text "The return type of the bind statement" + , text "does not have a fixed runtime representation" ] +pprFRROrigin (FRRArrow arrowOrig) + = pprFRRArrowOrigin arrowOrig +pprFRROrigin (FRRWpFun wpFunOrig) + = pprWpFunOrigin wpFunOrig + +instance Outputable FRROrigin where + ppr = pprFRROrigin + +-- | Are we in a @do@ expression or a monad comprehension? +-- +-- This datatype is only used to report this context to the user in error messages. +data StmtOrigin + = MonadComprehension + | DoNotation + +instance Outputable StmtOrigin where + ppr MonadComprehension = text "monad comprehension" + ppr DoNotation = quotes ( text "do" ) <+> text "statement" + +{- ********************************************************************* +* * + FixedRuntimeRep: arrows +* * +********************************************************************* -} + +-- | While typechecking arrow notation, in which context +-- did a representation polymorphism check arise? +-- +-- See 'FRROrigin' for more general origins of representation polymorphism checks. +data FRRArrowOrigin + + -- | The result of an arrow command does not have a fixed runtime representation. + -- + -- Test case: RepPolyArrowCmd. + = ArrowCmdResTy !(HsCmd GhcRn) + + -- | The argument to an arrow in an arrow command application does not have + -- a fixed runtime representation. + -- + -- Test cases: none. + | ArrowCmdApp !(HsCmd GhcRn) !(HsExpr GhcRn) + + -- | A function in an arrow application does not have + -- a fixed runtime representation. + -- + -- Test cases: none. + | ArrowCmdArrApp !(HsExpr GhcRn) !(HsExpr GhcRn) !HsArrAppType + + -- | A pattern in an arrow command abstraction does not have + -- a fixed runtime representation. + -- + -- Test cases: none. + | ArrowCmdLam !Int + + -- | The overall type of an arrow proc expression does not have + -- a fixed runtime representation. + -- + -- Test case: RepPolyArrowFun. + | ArrowFun !(HsExpr GhcRn) + +pprFRRArrowOrigin :: FRRArrowOrigin -> SDoc +pprFRRArrowOrigin (ArrowCmdResTy cmd) + = vcat [ hang (text "The arrow command") 2 (quotes (ppr cmd)) + , text "does not have a fixed runtime representation" ] +pprFRRArrowOrigin (ArrowCmdApp fun arg) + = vcat [ text "In the arrow command application of" + , nest 2 (quotes (ppr fun)) + , text "to" + , nest 2 (quotes (ppr arg)) <> comma + , text "the argument does not have a fixed runtime representation" ] +pprFRRArrowOrigin (ArrowCmdArrApp fun arg ho_app) + = vcat [ text "In the" <+> pprHsArrType ho_app <+> text "of" + , nest 2 (quotes (ppr fun)) + , text "to" + , nest 2 (quotes (ppr arg)) <> comma + , text "the function does not have a fixed runtime representation" ] +pprFRRArrowOrigin (ArrowCmdLam i) + = vcat [ text "The" <+> speakNth i <+> text "pattern of the arrow command abstraction" + , text "does not have a fixed runtime representation" ] +pprFRRArrowOrigin (ArrowFun fun) + = vcat [ text "The return type of the arrow function" + , nest 2 (quotes (ppr fun)) + , text "does not have a fixed runtime representation" ] + +instance Outputable FRRArrowOrigin where + ppr = pprFRRArrowOrigin + +{- ********************************************************************* +* * + FixedRuntimeRep: HsWrapper WpFun origin +* * +********************************************************************* -} + +-- | While typechecking a 'WpFun' 'HsWrapper', in which context +-- did a representation polymorphism check arise? +-- +-- See 'FRROrigin' for more general origins of representation polymorphism checks. +data WpFunOrigin + = WpFunSyntaxOp !CtOrigin + | WpFunViewPat !(HsExpr GhcRn) + | WpFunFunTy !Type + | WpFunFunExpTy !ExpType + +pprWpFunOrigin :: WpFunOrigin -> SDoc +pprWpFunOrigin (WpFunSyntaxOp orig) + = vcat [ text "When checking a rebindable syntax operator arising from" + , nest 2 (ppr orig) ] +pprWpFunOrigin (WpFunViewPat expr) + = vcat [ text "When checking the view pattern function:" + , nest 2 (ppr expr) ] +pprWpFunOrigin (WpFunFunTy fun_ty) + = vcat [ text "When inferring the argument type of a function with type" + , nest 2 (ppr fun_ty) ] +pprWpFunOrigin (WpFunFunExpTy fun_ty) + = vcat [ text "When inferring the argument type of a function with expected type" + , nest 2 (ppr fun_ty) ] + +instance Outputable WpFunOrigin where + ppr = pprWpFunOrigin |