Add test case for #2904

Author: martijnbastiaan

tests/Main.hs

@@ -666,6 +666,7 @@ runClashTest = defaultMain
         , runTest "T2831" def{hdlLoad=[],hdlSim=[],hdlTargets=[VHDL]}
         , runTest "T2839" def{hdlLoad=[],hdlSim=[],hdlTargets=[VHDL]}
         , runTest "T2845" def{hdlSim=[],hdlTargets=[Verilog]}
+        , runTest "T2904" def
         ] <>
         if compiledWith == Cabal then
           -- This tests fails without environment files present, which are only

tests/shouldwork/Issues/T2904.hs

@@ -0,0 +1,19 @@
+{-# LANGUAGE CPP #-}
+
+module T2904 where
+
+import Clash.Prelude
+import Clash.Explicit.Testbench
+
+topEntity :: Vec 3 (Index 3)
+topEntity = case indicesI @3 of
+  (Cons x xs) -> Cons maxBound xs
+{-# CLASH_OPAQUE topEntity #-}
+
+testBench :: Signal System Bool
+testBench = done
+ where
+  done = outputVerifier' clk rst ((maxBound :> 1 :> 2 :> Nil) :> Nil) (pure topEntity)
+  clk  = tbSystemClockGen (not <$> done)
+  rst  = systemResetGen
+{-# CLASH_OPAQUE testBench #-}