import DynFlags
import StaticFlags( opt_PprStyle_Debug )
import Data.List( partition )
-import Control.Monad( unless )
+import Control.Monad( when, unless )
\end{code}
%************************************************************************
reportTidyWanteds :: ReportErrCtxt -> WantedConstraints -> TcM ()
reportTidyWanteds ctxt unsolved
- = do { let (flats, implics) = splitWanteds unsolved
- (ambigs, others) = partition is_ambiguous (bagToList flats)
- ; groupErrs (reportFlat ctxt) others
- ; mapBagM_ (reportTidyImplic ctxt) implics
- ; ifErrsM (return ()) $
- -- Only report ambiguity if no other errors happened
- -- See Note [Avoiding spurious errors]
- reportAmbigErrs ctxt skols ambigs }
+ = do { let (flats, implics) = splitWanteds unsolved
+ (ambigs, non_ambigs) = partition is_ambiguous (bagToList flats)
+ (tv_eqs, others) = partition is_tv_eq non_ambigs
+
+ ; groupErrs (reportEqErrs ctxt) tv_eqs
+ ; when (null tv_eqs) $ groupErrs (reportFlat ctxt) others
+ ; when (null tv_eqs) $ mapBagM_ (reportTidyImplic ctxt) implics
+
+ -- Only report ambiguity if no other errors (at all) happened
+ -- See Note [Avoiding spurious errors] in TcSimplify
+ ; ifErrsM (return ()) $ reportAmbigErrs ctxt skols ambigs }
where
skols = foldr (unionVarSet . ic_skols) emptyVarSet (cec_encl ctxt)
+ -- Report equalities of form (a~ty) first. They are usually
+ -- skolem-equalities, and they cause confusing knock-on
+ -- effects in other errors; see test T4093b.
+ is_tv_eq c | EqPred ty1 ty2 <- wantedEvVarPred c
+ = tcIsTyVarTy ty1 || tcIsTyVarTy ty2
+ | otherwise = False
+
-- Treat it as "ambiguous" if
-- (a) it is a class constraint
-- (b) it constrains only type variables
| Just tv <- tcGetTyVar_maybe ty
, isTcTyVar tv
, isSkolemTyVar tv || isSigTyVar tv
- , not (isUnk tv)
+ , not (isUnkSkol tv)
, let (env1, tv1) = tidySkolemTyVar env tv
= (env1, pprSkolTvBinding tv1)
where
-- ASSUMPTION: the Insts are fully zonked
mkMonomorphismMsg ctxt inst_tvs
= do { dflags <- getDOpts
- ; (tidy_env, docs) <- findGlobals ctxt (mkVarSet inst_tvs)
+ ; traceTc "Mono" (vcat (map pprSkolTvBinding inst_tvs))
+ ; (tidy_env, docs) <- findGlobals ctxt (mkVarSet inst_tvs)
; return (tidy_env, mk_msg dflags docs) }
where
- mk_msg _ _ | any isRuntimeUnk inst_tvs
+ mk_msg _ _ | any isRuntimeUnkSkol inst_tvs -- See Note [Runtime skolems]
= vcat [ptext (sLit "Cannot resolve unknown runtime types:") <+>
(pprWithCommas ppr inst_tvs),
ptext (sLit "Use :print or :force to determine these types")]
(loc, ppr_wanteds) = pprWithArising wanteds
\end{code}
+Note [Runtime skolems]
+~~~~~~~~~~~~~~~~~~~~~~
+We want to give a reasonably helpful error message for ambiguity
+arising from *runtime* skolems in the debugger. These
+are created by in RtClosureInspect.zonkRTTIType.
+
+
%************************************************************************
%* *
Error from the canonicaliser
%************************************************************************
\begin{code}
-kindErrorTcS :: CtFlavor -> TcType -> TcType -> TcS ()
+kindErrorTcS :: CtFlavor -> TcType -> TcType -> TcS a
-- 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
do { let ctxt = CEC { cec_encl = []
, cec_extra = extra
, cec_tidy = env0 }
- ; reportEqErr ctxt ty1 ty2 }
+ ; reportEqErr ctxt ty1 ty2
+ ; failM
+ }
misMatchErrorTcS :: CtFlavor -> TcType -> TcType -> TcS a
misMatchErrorTcS fl ty1 ty2
\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
+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 -> TcType -> TcType -> SDoc -> TcM a)
; wrapErrTcS $ setCtFlavorLoc fl $
do { -- Apply the current substitition
-- and zonk to get rid of flatten-skolems
- ; ty_binds_bag <- readTcRef ty_binds_var
- ; let subst = mkOpenTvSubst (mkVarEnv (bagToList ty_binds_bag))
+ ; ty_binds_map <- readTcRef ty_binds_var
+ ; let subst = mkOpenTvSubst (mapVarEnv snd ty_binds_map)
; env0 <- tcInitTidyEnv
; (env1, ty1) <- zonkSubstTidy env0 subst ty1
; (env2, ty2) <- zonkSubstTidy env1 subst ty2
(ctLocOrigin loc) ty1 ty2
; thing_inside env3 ty1 ty2 extra }
; case fl of
- Wanted loc -> do_wanted loc
- Derived loc -> do_wanted loc
- Given {} -> thing_inside env2 ty1 ty2 empty
- -- We could print more info, but it
+ Wanted loc -> do_wanted loc
+ Derived loc _ -> do_wanted loc
+ Given {} -> thing_inside env2 ty1 ty2 empty
+ -- We could print more info, but it
-- seems to be coming out already
} }
where