| 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