Test Trac #7924

testsuite/tests/simplCore/should_run/T7924.hs

+{-# LANGUAGE DeriveDataTypeable #-}
+module Main where
+import Control.Exception (throwIO, Exception)
+import Control.Monad (when)
+import Data.Typeable (Typeable)
+
+data Boom = Boom deriving (Show, Typeable)
+instance Exception Boom
+
+main = do
+    args <- return []
+
+    -- Should throw this exception.
+    when (length args /= 1) (throwIO Boom)
+
+    -- With -O, instead throws this one from head [].
+    let n = read (head args)
+    print (n :: Int)
+
+    return ()
\ No newline at end of file

testsuite/tests/simplCore/should_run/T7924.stderr

+T7924: Boom

testsuite/tests/simplCore/should_run/all.T

@@ -57,3 +57,5 @@ test('T5915', only_ways(['normal','optasm']), compile_and_run, [''])
 test('T5920', only_ways(['normal','optasm']), compile_and_run, [''])
 test('T5997', normal, compile_and_run, [''])
 test('T7101', normal, compile_and_run, [''])
+test('T7924', exit_code(1), compile_and_run, [''])
+