1 files changed, 30 insertions, 0 deletions
diff --git a/testsuite/tests/simplCore/should_compile/T4945.hs b/testsuite/tests/simplCore/should_compile/T4945.hs
new file mode 100644
index 0000000000..fba6e61ad6
--- /dev/null
+++ b/testsuite/tests/simplCore/should_compile/T4945.hs
@@ -0,0 +1,30 @@
+module Main where
+
+import Data.Int
+import Data.Array.Base
+import Data.Array.ST
+import Control.Monad.ST
+import System.Environment
+
+main :: IO ()
+main = do
+  [_nr, _len] <- getArgs
+  let nRounds = read _nr :: Int
+      len = read _len :: Int
+  stToIO $ do
+    arr <- newArray (1, len) 0
+   
+    let spin :: STUArray s Int Int -> Int -> Int -> Int -> ST s ()
+        spin _   r i n | i > n = return ()
+        spin arr r i n = do x <- unsafeRead arr i
+                            unsafeWrite arr i $ x + r
+                            spin arr r (i + 1) n
+       
+        loop :: STUArray s Int Int -> Int -> ST s ()
+        loop _   r | r > nRounds = return ()
+        loop arr r = do
+            k <- getNumElements arr
+            spin arr r 0 (k - 1)
+            loop arr (r + 1)
+   
+    loop arr 1