add test for #1131

testsuite/tests/ghc-regress/array/should_run/all.T

@@ -21,3 +21,4 @@ test('arr014', skip_if_fast, compile_and_run, [''])
 test('arr015', skip_if_fast, compile_and_run, [''])
 test('arr016', normal, compile_and_run, ['-fglasgow-exts'])
 test('arr017', skip_if_fast, compile_and_run, [''])
+test('arr018', skip_if_fast, compile_and_run, [''])

testsuite/tests/ghc-regress/array/should_run/arr018.hs

+-- test for #1131
+import Control.Monad.ST
+import Data.Array.ST
+import Data.Array
+import System.Mem
+
+tickle :: Int
+tickle = runST (do {
+     x <- newArray_ (0,100) ;
+     (readArray :: STUArray s Int Int -> Int -> ST s Int) x 3
+   })
+
+main :: IO ()
+main = do print $ length (replicate 100000 'a')
+          performGC
+          print tickle

testsuite/tests/ghc-regress/array/should_run/arr018.stdout

+100000
+0