+
+isUnboxedTupleBind :: HsBind Id -> Bool
+isUnboxedTupleBind (PatBind { pat_rhs_ty = ty }) = isUnboxedTupleType ty
+isUnboxedTupleBind other = False
+
+scrungleMatch :: Id -> CoreExpr -> CoreExpr -> CoreExpr
+-- Returns something like (let var = scrut in body)
+-- but if var is an unboxed-tuple type, it inlines it in a fragile way
+-- Special case to handle unboxed tuple patterns; they can't appear nested
+-- The idea is that
+-- case e of (# p1, p2 #) -> rhs
+-- should desugar to
+-- case e of (# x1, x2 #) -> ... match p1, p2 ...
+-- NOT
+-- let x = e in case x of ....
+--
+-- But there may be a big
+-- let fail = ... in case e of ...
+-- wrapping the whole case, which complicates matters slightly
+-- It all seems a bit fragile. Test is dsrun013.
+
+scrungleMatch var scrut body
+ | isUnboxedTupleType (idType var) = scrungle body
+ | otherwise = bindNonRec var scrut body
+ where
+ scrungle (Case (Var x) bndr ty alts)
+ | x == var = Case scrut bndr ty alts
+ scrungle (Let binds body) = Let binds (scrungle body)
+ scrungle other = panic ("scrungleMatch: tuple pattern:\n" ++ showSDoc (ppr other))