checkValidDataCon tc con
= setSrcSpan (srcLocSpan (getSrcLoc con)) $
addErrCtxt (dataConCtxt con) $
- do { let tc_tvs = tyConTyVars tc
+ do { traceTc (ptext (sLit "Validity of data con") <+> ppr con)
+ ; let tc_tvs = tyConTyVars tc
res_ty_tmpl = mkFamilyTyConApp tc (mkTyVarTys tc_tvs)
actual_res_ty = dataConOrigResTy con
; checkTc (isJust (tcMatchTy (mkVarSet tc_tvs)