test if interproedural DVE bug does not apply to simple DVE

grin/test/Transformations/Optimising/SimpleDeadVariableEliminationSpec.hs

@@ -258,3 +258,46 @@ spec = do
           effMap = effectMap (tyEnv, before)
           dveExp = simpleDeadVariableElimination tyEnv effMap before
       dveExp `sameAs` after
+
+    describe "interprocedural DVE regression tests" $ do
+      it "Not explicitly covered alternatives trigger undefined replacements" $ do
+        let before = [prog|
+              grinMain =
+                v0 <- _prim_int_add 1 1
+                v1 <- case v0 of
+                  2 ->
+                    v2 <- _prim_int_lt 1 3
+                    v3 <- case v2 of
+                      #False -> pure v0
+                      #True -> pure 1
+                    case v3 of
+                      0 -> pure (CGT)
+                      1 -> pure (CLT)
+                  1 -> pure (CEQ)
+                -- If #default is changed to explicit alternatives the undefineds are not introduced.
+                -- Undefineds are introduced for missing alternatives too.
+                case v1 of
+                  (CEQ) -> _prim_int_print 1
+                  #default -> _prim_int_print 2
+            |]
+        let after = [prog|
+              grinMain =
+                v0 <- _prim_int_add 1 1
+                v1 <- case v0 of
+                  2 ->
+                    v2 <- _prim_int_lt 1 3
+                    v3 <- case v2 of
+                      #False -> pure v0
+                      #True -> pure 1
+                    case v3 of
+                      0 -> pure (CGT)
+                      1 -> pure (CLT)
+                  1 -> pure (CEQ)
+                case v1 of
+                  (CEQ) -> _prim_int_print 1
+                  #default -> _prim_int_print 2
+            |]
+        let tyEnv = inferTypeEnv before
+            effMap = effectMap (tyEnv, before)
+            dveExp = simpleDeadVariableElimination tyEnv effMap before
+        dveExp `sameAs` after