add test for threadStatus

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

@@ -11,6 +11,9 @@ test('conc006', normal, compile_and_run, [''])
 test('conc027', normal, compile_and_run, [''])
 test('conc051', normal, compile_and_run, [''])
 test('conc069', only_ways(['ghci','threaded1','threaded2']), compile_and_run, [''])
+# this test gives slightly different results for non-threaded ways, so omit
+# those for now.
+test('conc070', only_ways(['ghci','threaded1','threaded2']), compile_and_run, [''])
 
 # -----------------------------------------------------------------------------
 # These tests we only do for a full run

testsuite/tests/ghc-regress/concurrent/should_run/conc070.hs

+import Control.Concurrent
+import GHC.Conc
+import Data.List
+import Data.Maybe
+
+main = do
+  t1 <- forkIO (threadDelay 100000000)
+  m <- newEmptyMVar
+  t2 <- forkIO (takeMVar m)
+  t3 <- forkIO (let loop = do r <- tryTakeMVar m; 
+                              _ <- newEmptyMVar -- do some allocation :(
+                              if isNothing r then loop else return ()
+                in loop)
+  t4 <- forkIO (return ())
+  yield
+  threadDelay 10000
+  print =<< mapM threadStatus [t1,t2,t3,t4]
+  putMVar m ()

testsuite/tests/ghc-regress/concurrent/should_run/conc070.stdout

+[ThreadBlocked BlockedOnMVar,ThreadBlocked BlockedOnMVar,ThreadRunning,ThreadFinished]