+--------------------- The stupid theta (sigh) ---------------------------------
+
+\begin{code}
+dataConsStupidTheta :: [DataCon] -> ThetaType
+-- Union the stupid thetas from all the specified constructors (non-empty)
+-- All the constructors should have the same result type, modulo alpha conversion
+-- The resulting ThetaType uses type variables from the *first* constructor in the list
+--
+-- It's here because it's used in MkId.mkRecordSelId, and in TcExpr
+dataConsStupidTheta (con1:cons)
+ = nubBy tcEqPred all_preds
+ where
+ all_preds = dataConStupidTheta con1 ++ other_stupids
+ res_tys1 = dataConResTys con1
+ tvs1 = tyVarsOfTypes res_tys1
+ other_stupids = [ substPred subst pred
+ | con <- cons
+ , let Just subst = tcMatchTys tvs1 res_tys1 (dataConResTys con)
+ , pred <- dataConStupidTheta con ]
+\end{code}
+