import TcSMonad
import TcType
import TypeRep
+import Type( isTyVarTy )
import Inst
import InstEnv
reportTyVarEqErr :: ReportErrCtxt -> TcTyVar -> TcType -> TcM ()
-- tv1 and ty2 are already tidied
reportTyVarEqErr ctxt tv1 ty2
- | not is_meta1
- , Just tv2 <- tcGetTyVar_maybe ty2
- , isMetaTyVar tv2
- = -- sk ~ alpha: swap
- reportTyVarEqErr ctxt tv2 ty1
-
- | (not is_meta1)
- = -- sk ~ ty, where ty isn't a meta-tyvar: mis-match
- addErrorReport (addExtraInfo ctxt ty1 ty2)
+ | isSkolemTyVar tv1 -- ty2 won't be a meta-tyvar, or else the thing would
+ -- be oriented the other way round; see TcCanonical.reOrient
+ || isSigTyVar tv1 && not (isTyVarTy ty2)
+ = addErrorReport (addExtraInfo ctxt ty1 ty2)
(misMatchOrCND ctxt ty1 ty2)
-- So tv is a meta tyvar, and presumably it is
, ptext (sLit "bound at") <+> ppr (ctLocOrigin implic_loc)]
; addErrorReport (addExtraInfo ctxt ty1 ty2) (msg $$ nest 2 extra) }
- | otherwise -- This can happen, by a recursive decomposition of frozen
- -- occurs check constraints
- -- Example: alpha ~ T Int alpha has frozen.
- -- Then alpha gets unified to T beta gamma
- -- So now we have T beta gamma ~ T Int (T beta gamma)
- -- Decompose to (beta ~ Int, gamma ~ T beta gamma)
- -- The (gamma ~ T beta gamma) is the occurs check, but
- -- the (beta ~ Int) isn't an error at all. So return ()
- = return ()
-
+ | otherwise
+ = pprTrace "reportTyVarEqErr" (ppr tv1 $$ ppr ty2 $$ ppr (cec_encl ctxt)) $
+ return ()
+ -- I don't think this should happen, and if it does I want to know
+ -- Trac #5130 happened because an actual type error was not
+ -- reported at all! So not reporting is pretty dangerous.
+ --
+ -- OLD, OUT OF DATE COMMENT
+ -- This can happen, by a recursive decomposition of frozen
+ -- occurs check constraints
+ -- Example: alpha ~ T Int alpha has frozen.
+ -- Then alpha gets unified to T beta gamma
+ -- So now we have T beta gamma ~ T Int (T beta gamma)
+ -- Decompose to (beta ~ Int, gamma ~ T beta gamma)
+ -- The (gamma ~ T beta gamma) is the occurs check, but
+ -- the (beta ~ Int) isn't an error at all. So return ()
where
- is_meta1 = isMetaTyVar tv1
- k1 = tyVarKind tv1
- k2 = typeKind ty2
- ty1 = mkTyVarTy tv1
+ k1 = tyVarKind tv1
+ k2 = typeKind ty2
+ ty1 = mkTyVarTy tv1
mkTyFunInfoMsg :: TcType -> TcType -> SDoc
-- See Note [Non-injective type functions]
-- Shows a bit of extra info about skolem constants
typeExtraInfoMsg implics ty
| Just tv <- tcGetTyVar_maybe ty
- , isTcTyVar tv
- , isSkolemTyVar tv
- = pprSkolTvBinding implics tv
- where
-typeExtraInfoMsg _ _ = empty -- Normal case
-
+ , isTcTyVar tv, isSkolemTyVar tv
+ , let pp_tv = quotes (ppr tv)
+ = case tcTyVarDetails tv of
+ SkolemTv {} -> pp_tv <+> ppr_skol (getSkolemInfo implics tv) (getSrcLoc tv)
+ FlatSkol {} -> pp_tv <+> ptext (sLit "is a flattening type variable")
+ RuntimeUnk {} -> pp_tv <+> ptext (sLit "is an interactive-debugger skolem")
+ MetaTv {} -> empty
+
+ | otherwise -- Normal case
+ = empty
+
+ where
+ ppr_skol UnkSkol _ = ptext (sLit "is an unknown type variable") -- Unhelpful
+ ppr_skol info loc = sep [ptext (sLit "is a rigid type variable bound by"),
+ sep [ppr info, ptext (sLit "at") <+> ppr loc]]
+
--------------------
unifyCtxt :: EqOrigin -> TidyEnv -> TcM (TidyEnv, SDoc)
unifyCtxt (UnifyOrigin { uo_actual = act_ty, uo_expected = exp_ty }) tidy_env
-- ASSUMPTION: the Insts are fully zonked
mkMonomorphismMsg ctxt inst_tvs
= do { dflags <- getDOpts
- ; traceTc "Mono" (vcat (map (pprSkolTvBinding (cec_encl ctxt)) inst_tvs))
; (tidy_env, docs) <- findGlobals ctxt (mkVarSet inst_tvs)
; return (tidy_env, mk_msg dflags docs) }
where
else empty] -- Only suggest adding "-XNoMonomorphismRestriction"
-- if it is not already set!
-
-pprSkolTvBinding :: [Implication] -> TcTyVar -> SDoc
--- Print info about the binding of a skolem tyvar,
--- or nothing if we don't have anything useful to say
-pprSkolTvBinding implics tv
- | isTcTyVar tv = quotes (ppr tv) <+> ppr_details (tcTyVarDetails tv)
- | otherwise = quotes (ppr tv) <+> ppr_skol (getSkolemInfo implics tv)
- where
- ppr_details (SkolemTv {}) = ppr_skol (getSkolemInfo implics tv)
- ppr_details (FlatSkol {}) = ptext (sLit "is a flattening type variable")
- ppr_details (RuntimeUnk {}) = ptext (sLit "is an interactive-debugger skolem")
- ppr_details (MetaTv (SigTv n) _) = ptext (sLit "is bound by the type signature for")
- <+> quotes (ppr n)
- ppr_details (MetaTv _ _) = ptext (sLit "is a meta type variable")
-
-
- ppr_skol UnkSkol = ptext (sLit "is an unknown type variable") -- Unhelpful
- ppr_skol RuntimeUnkSkol = ptext (sLit "is an unknown runtime type")
- ppr_skol info = sep [ptext (sLit "is a rigid type variable bound by"),
- sep [ppr info,
- ptext (sLit "at") <+> ppr (getSrcLoc tv)]]
-
getSkolemInfo :: [Implication] -> TcTyVar -> SkolemInfo
getSkolemInfo [] tv
= WARN( True, ptext (sLit "No skolem info:") <+> ppr tv )
projects / ghc-hetmet.git / blobdiff