\begin{code}
module TcErrors(
reportUnsolved, reportUnsolvedImplication, reportUnsolvedDeriv,
- reportUnsolvedWantedEvVars, warnDefaulting, typeExtraInfoMsg,
+ reportUnsolvedWantedEvVars, warnDefaulting,
+ unifyCtxt, typeExtraInfoMsg,
kindErrorTcS, misMatchErrorTcS, flattenForAllErrorTcS,
occursCheckErrorTcS, solverDepthErrorTcS
) where
| null unsolved
= return ()
| otherwise
- = do { env0 <- tcInitTidyEnv
+ = setCtLoc loc $
+ do { env0 <- tcInitTidyEnv
; let tidy_env = tidyFreeTyVars env0 (tyVarsOfTheta unsolved)
tidy_unsolved = map (tidyPred tidy_env) unsolved
err_ctxt = CEC { cec_encl = []
, cec_extra = alt_fix
, cec_tidy = tidy_env }
- ; reportFlat err_ctxt tidy_unsolved loc }
+ ; reportFlat err_ctxt tidy_unsolved (ctLocOrigin loc) }
where
alt_fix = vcat [ptext (sLit "Alternatively, use a standalone 'deriving instance' declaration,"),
nest 2 $ ptext (sLit "so you can specify the instance context yourself")]
where
pred = wantedEvVarPred d
-reportFlat :: ReportErrCtxt -> [PredType] -> WantedLoc -> TcM ()
-reportFlat ctxt flats loc
- = do { unless (null dicts) $ reportDictErrs ctxt dicts loc
- ; unless (null eqs) $ reportEqErrs ctxt eqs loc
- ; unless (null ips) $ reportIPErrs ctxt ips loc
+reportFlat :: ReportErrCtxt -> [PredType] -> CtOrigin -> TcM ()
+reportFlat ctxt flats origin
+ = do { unless (null dicts) $ reportDictErrs ctxt dicts origin
+ ; unless (null eqs) $ reportEqErrs ctxt eqs origin
+ ; unless (null ips) $ reportIPErrs ctxt ips origin
; ASSERT( null others ) return () }
where
(dicts, non_dicts) = partition isClassPred flats
-- Support code
--------------------------------------------
-groupErrs :: ([PredType] -> WantedLoc -> TcM ()) -- Deal with one group
- -> [WantedEvVar] -- Unsolved wanteds
+groupErrs :: ([PredType] -> CtOrigin -> TcM ()) -- Deal with one group
+ -> [WantedEvVar] -- Unsolved wanteds
-> TcM ()
-- Group together insts with the same origin
-- We want to report them together in error messages
groupErrs _ []
= return ()
groupErrs report_err (wanted : wanteds)
- = do { setCtLoc the_loc $ report_err the_vars the_loc
+ = do { setCtLoc the_loc $
+ report_err the_vars (ctLocOrigin the_loc)
; groupErrs report_err others }
where
the_loc = wantedEvVarLoc wanted
-- and it avoids need equality on InstLocs.
-- Add the "arising from..." part to a message about bunch of dicts
-addArising :: WantedLoc -> SDoc -> SDoc
-addArising loc msg = msg $$ nest 2 (pprArising loc)
+addArising :: CtOrigin -> SDoc -> SDoc
+addArising orig msg = msg $$ nest 2 (pprArising orig)
pprWithArising :: [WantedEvVar] -> (WantedLoc, SDoc)
-- Print something like
pprWithArising []
= panic "pprWithArising"
pprWithArising [WantedEvVar ev loc]
- = (loc, pprEvVarTheta [ev] <+> pprArising loc)
+ = (loc, pprEvVarTheta [ev] <+> pprArising (ctLocOrigin loc))
pprWithArising ev_vars
= (first_loc, vcat (map ppr_one ev_vars))
where
%************************************************************************
\begin{code}
-reportIPErrs :: ReportErrCtxt -> [PredType] -> WantedLoc -> TcM ()
-reportIPErrs ctxt ips loc
- = addErrorReport ctxt $ addArising loc msg
+reportIPErrs :: ReportErrCtxt -> [PredType] -> CtOrigin -> TcM ()
+reportIPErrs ctxt ips orig
+ = addErrorReport ctxt $ addArising orig msg
where
msg | Just givens <- getUserGivens ctxt
= couldNotDeduce givens ips
%************************************************************************
\begin{code}
-reportEqErrs :: ReportErrCtxt -> [PredType] -> WantedLoc -> TcM ()
-reportEqErrs ctxt eqs loc = mapM_ (reportEqErr ctxt loc) eqs
-
-reportEqErr :: ReportErrCtxt -> WantedLoc -> PredType -> TcM ()
-reportEqErr ctxt loc pred@(EqPred ty1 ty2)
- | Just tv1 <- tcGetTyVar_maybe ty1 = reportTyVarEqErr ctxt loc tv1 ty2
- | Just tv2 <- tcGetTyVar_maybe ty2 = reportTyVarEqErr ctxt loc tv2 ty1
+reportEqErrs :: ReportErrCtxt -> [PredType] -> CtOrigin -> TcM ()
+reportEqErrs ctxt eqs orig
+ = mapM_ report_one eqs
+ where
+ env0 = cec_tidy ctxt
+ report_one (EqPred ty1 ty2)
+ = getWantedEqExtra emptyTvSubst env0 orig ty1 ty2 $ \ env1 extra ->
+ let ctxt' = ctxt { cec_tidy = env1
+ , cec_extra = cec_extra ctxt $$ extra }
+ in reportEqErr ctxt' ty1 ty2
+ report_one pred
+ = pprPanic "reportEqErrs" (ppr pred)
+
+reportEqErr :: ReportErrCtxt -> TcType -> TcType -> TcM ()
+reportEqErr ctxt ty1 ty2
+ | Just tv1 <- tcGetTyVar_maybe ty1 = reportTyVarEqErr ctxt tv1 ty2
+ | Just tv2 <- tcGetTyVar_maybe ty2 = reportTyVarEqErr ctxt tv2 ty1
| otherwise -- Neither side is a type variable
-- Since the unsolved constraint is canonical,
-- it must therefore be of form (F tys ~ ty)
= addErrorReport ctxt (msg $$ mkTyFunInfoMsg ty1 ty2)
where
msg = case getUserGivens ctxt of
- Just givens -> couldNotDeduce givens [pred]
+ Just givens -> couldNotDeduce givens [EqPred ty1 ty2]
Nothing -> misMatchMsg ty1 ty2
-reportEqErr _ _ _ = panic "reportEqErr" -- Must be equality pred
-
-reportTyVarEqErr :: ReportErrCtxt -> WantedLoc
- -> TcTyVar -> TcType -> TcM ()
-reportTyVarEqErr ctxt loc tv1 ty2
+reportTyVarEqErr :: ReportErrCtxt -> TcTyVar -> TcType -> TcM ()
+reportTyVarEqErr ctxt tv1 ty2
| not is_meta1
, Just tv2 <- tcGetTyVar_maybe ty2
, isMetaTyVar tv2
= -- sk ~ alpha: swap
- reportTyVarEqErr ctxt loc tv2 ty1
+ reportTyVarEqErr ctxt tv2 ty1
| not is_meta1
= -- sk ~ ty, where ty isn't a meta-tyvar: mis-match
= (env1, pprSkolTvBinding tv1)
where
typeExtraInfoMsg env _ty = (env, empty) -- Normal case
+
+--------------------
+unifyCtxt :: EqOrigin -> TidyEnv -> TcM (TidyEnv, SDoc)
+unifyCtxt (UnifyOrigin { uo_actual = act_ty, uo_expected = exp_ty }) tidy_env
+ = do { act_ty' <- zonkTcType act_ty
+ ; exp_ty' <- zonkTcType exp_ty
+ ; let (env1, exp_ty'') = tidyOpenType tidy_env exp_ty'
+ (env2, act_ty'') = tidyOpenType env1 act_ty'
+ ; return (env2, mkExpectedActualMsg act_ty'' exp_ty'') }
+
+mkExpectedActualMsg :: Type -> Type -> SDoc
+mkExpectedActualMsg act_ty exp_ty
+ = vcat [ text "Expected type" <> colon <+> ppr exp_ty
+ , text " Actual type" <> colon <+> ppr act_ty ]
\end{code}
Note [Non-injective type functions]
%************************************************************************
\begin{code}
-reportDictErrs :: ReportErrCtxt -> [PredType] -> WantedLoc -> TcM ()
-reportDictErrs ctxt wanteds loc
+reportDictErrs :: ReportErrCtxt -> [PredType] -> CtOrigin -> TcM ()
+reportDictErrs ctxt wanteds orig
= do { inst_envs <- tcGetInstEnvs
; let (others, overlaps) = partitionWith (check_overlap inst_envs) wanteds
; unless (null others) $
mk_overlap_msg pred (matches, unifiers)
= ASSERT( not (null matches) )
- vcat [ addArising loc (ptext (sLit "Overlapping instances for")
+ vcat [ addArising orig (ptext (sLit "Overlapping instances for")
<+> pprPred pred)
, sep [ptext (sLit "Matching instances") <> colon,
nest 2 (vcat [pprInstances ispecs, pprInstances unifiers])]
mk_no_inst_err :: [PredType] -> SDoc
mk_no_inst_err wanteds
| Just givens <- getUserGivens ctxt
- = vcat [ addArising loc $ couldNotDeduce givens wanteds
+ = vcat [ addArising orig $ couldNotDeduce givens wanteds
, show_fixes (fix1 : fixes2) ]
| otherwise -- Top level
- = vcat [ addArising loc $
+ = vcat [ addArising orig $
ptext (sLit "No instance") <> plural wanteds
<+> ptext (sLit "for") <+> pprTheta wanteds
, show_fixes fixes2 ]
monomorphism_fix dflags
= ptext (sLit "Probable fix:") <+> vcat
[ptext (sLit "give these definition(s) an explicit type signature"),
- if dopt Opt_MonomorphismRestriction dflags
+ if xopt Opt_MonomorphismRestriction dflags
then ptext (sLit "or use -XNoMonomorphismRestriction")
else empty] -- Only suggest adding "-XNoMonomorphismRestriction"
-- if it is not already set!
%************************************************************************
\begin{code}
-kindErrorTcS :: CtFlavor -> TcType -> TcType -> TcS a
+kindErrorTcS :: CtFlavor -> TcType -> TcType -> TcS ()
+-- If there's a kind error, we don't want to blindly say "kind error"
+-- We might, say, be unifying a skolem 'a' with a type 'Int',
+-- in which case that's the error to report. So we set things
+-- up to call reportEqErr, which does the business properly
kindErrorTcS fl ty1 ty2
- = wrapErrTcS $
- setCtFlavorLoc fl $
- do { env0 <- tcInitTidyEnv
- ; let (env1, ty1') = tidyOpenType env0 ty1
+ = wrapEqErrTcS fl ty1 ty2 $ \ env0 extra ->
+ do { let (env1, ty1') = tidyOpenType env0 ty1
(env2, ty2') = tidyOpenType env1 ty2
- ; failWithTcM (env2, kindErrorMsg ty1' ty2') }
+ ctxt = CEC { cec_encl = []
+ , cec_extra = extra
+ , cec_tidy = env2 }
+ ; reportEqErr ctxt ty1' ty2' }
misMatchErrorTcS :: CtFlavor -> TcType -> TcType -> TcS a
misMatchErrorTcS fl ty1 ty2
- = wrapErrTcS $
- setCtFlavorLoc fl $
- do { env0 <- tcInitTidyEnv
- ; let (env1, ty1') = tidyOpenType env0 ty1
+ = wrapEqErrTcS fl ty1 ty2 $ \ env0 extra ->
+ do { let (env1, ty1') = tidyOpenType env0 ty1
(env2, ty2') = tidyOpenType env1 ty2
(env3, msg) = misMatchMsgWithExtras env2 ty1' ty2'
- ; failWithTcM (env3, inaccessible_msg $$ msg) }
+ ; failWithTcM (env3, inaccessible_msg $$ msg $$ extra) }
where
inaccessible_msg
= case fl of
occursCheckErrorTcS :: CtFlavor -> TcTyVar -> TcType -> TcS a
occursCheckErrorTcS fl tv ty
- = wrapErrTcS $
- setCtFlavorLoc fl $
- do { env0 <- tcInitTidyEnv
- ; let (env1, tv') = tidyOpenTyVar env0 tv
+ = wrapEqErrTcS fl (mkTyVarTy tv) ty $ \ env0 extra2 ->
+ do { let (env1, tv') = tidyOpenTyVar env0 tv
(env2, ty') = tidyOpenType env1 ty
- extra = sep [ppr tv', char '=', ppr ty']
- ; failWithTcM (env2, hang msg 2 extra) }
+ extra1 = sep [ppr tv', char '=', ppr ty']
+ ; failWithTcM (env2, hang msg 2 (extra1 $$ extra2)) }
where
msg = text $ "Occurs check: cannot construct the infinite type:"
-setCtFlavorLoc :: CtFlavor -> TcM a -> TcM a
-setCtFlavorLoc (Wanted loc) thing = setCtLoc loc thing
-setCtFlavorLoc (Derived loc) thing = setCtLoc loc thing
-setCtFlavorLoc (Given loc) thing = setCtLoc loc thing
-
solverDepthErrorTcS :: Int -> [CanonicalCt] -> TcS a
solverDepthErrorTcS depth stack
| null stack -- Shouldn't happen unless you say -fcontext-stack=0
flattenForAllErrorTcS :: CtFlavor -> TcType -> Bag CanonicalCt -> TcS a
flattenForAllErrorTcS fl ty _bad_eqs
- = wrapErrTcS $
+ = wrapErrTcS $
setCtFlavorLoc fl $
do { env0 <- tcInitTidyEnv
; let (env1, ty') = tidyOpenType env0 ty
, ppr ty' ]
; failWithTcM (env1, msg) }
\end{code}
+
+%************************************************************************
+%* *
+ Setting the context
+%* *
+%************************************************************************
+
+\begin{code}
+setCtFlavorLoc :: CtFlavor -> TcM a -> TcM a
+setCtFlavorLoc (Wanted loc) thing = setCtLoc loc thing
+setCtFlavorLoc (Derived loc) thing = setCtLoc loc thing
+setCtFlavorLoc (Given loc) thing = setCtLoc loc thing
+
+wrapEqErrTcS :: CtFlavor -> TcType -> TcType
+ -> (TidyEnv -> SDoc -> TcM a)
+ -> TcS a
+wrapEqErrTcS fl ty1 ty2 thing_inside
+ = do { ty_binds_var <- getTcSTyBinds
+ ; wrapErrTcS $ setCtFlavorLoc fl $
+ do { env0 <- tcInitTidyEnv
+ ; ty_binds_bag <- readTcRef ty_binds_var
+ ; let subst = mkOpenTvSubst (mkVarEnv (bagToList ty_binds_bag))
+ ; case fl of
+ Wanted loc -> getWantedEqExtra subst env0 (ctLocOrigin loc) ty1 ty2 thing_inside
+ Derived loc -> getWantedEqExtra subst env0 (ctLocOrigin loc) ty1 ty2 thing_inside
+ Given {} -> thing_inside env0 empty -- We could print more info, but it
+ -- seems to be coming out already
+ } }
+
+getWantedEqExtra :: TvSubst -> TidyEnv -> CtOrigin -> TcType -> TcType
+ -> (TidyEnv -> SDoc -> TcM a)
+ -> TcM a
+getWantedEqExtra subst env0 (TypeEqOrigin item) ty1 ty2 thing_inside
+ -- If the types in the error message are the same
+ -- as the types we are unifying (remember to zonk the latter)
+ -- don't add the extra expected/actual message
+ --
+ -- The complication is that the types in the TypeEqOrigin must
+ -- (a) be zonked
+ -- (b) have any TcS-monad pending equalities applied to them
+ -- (hence the passed-in substitution)
+ = do { act0 <- zonkTcType (uo_actual item)
+ ; exp0 <- zonkTcType (uo_expected item)
+ ; let act1 = substTy subst act0
+ exp1 = substTy subst exp0
+ (env1, exp2) = tidyOpenType env0 exp1
+ (env2, act2) = tidyOpenType env1 act1
+ ; if (act1 `tcEqType` ty1 && exp1 `tcEqType` ty2)
+ || (exp1 `tcEqType` ty1 && act1 `tcEqType` ty2)
+ then
+ thing_inside env0 empty
+ else
+ thing_inside env2 (mkExpectedActualMsg act2 exp2) }
+
+getWantedEqExtra _ env0 orig _ _ thing_inside
+ = thing_inside env0 (pprArising orig)
+\end{code}
projects / ghc-hetmet.git / blobdiff