[commit: ghc] master: Do not print the result of 'main' after invoking ':main' (fixes #9086). (55e7ab1)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/55e7ab1210975e6276f3cab3ac0e1f35bcd772f0/ghc

>---------------------------------------------------------------

commit 55e7ab1210975e6276f3cab3ac0e1f35bcd772f0
Author: Gintautas Miliauskas <gintautas.miliauskas at gmail.com>
Date:   Sun Jun 8 11:49:29 2014 +0000

    Do not print the result of 'main' after invoking ':main' (fixes #9086).


>---------------------------------------------------------------

55e7ab1210975e6276f3cab3ac0e1f35bcd772f0
 ghc/InteractiveUI.hs                                               | 7 ++++---
 testsuite/tests/ghc-e/should_run/Makefile                          | 2 ++
 testsuite/tests/ghc-e/should_run/T9086.hs                          | 1 +
 testsuite/tests/ghc-e/should_run/all.T                             | 1 +
 testsuite/tests/ghci/scripts/T9086b.script                         | 2 ++
 .../{ffi/should_run/ffi021.stdout => ghci/scripts/T9086b.stdout}   | 0
 testsuite/tests/ghci/scripts/all.T                                 | 1 +
 7 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/ghc/InteractiveUI.hs b/ghc/InteractiveUI.hs
index 0a56799..c3d9f25 100644
--- a/ghc/InteractiveUI.hs
+++ b/ghc/InteractiveUI.hs
@@ -1141,9 +1141,10 @@ runMain s = case toArgs s of
             Left err   -> liftIO (hPutStrLn stderr err)
             Right args ->
                 do dflags <- getDynFlags
-                   case mainFunIs dflags of
-                       Nothing -> doWithArgs args "main"
-                       Just f  -> doWithArgs args f
+                   let main = fromMaybe "main" (mainFunIs dflags)
+                   -- Wrap the main function in 'void' to discard its value instead
+                   -- of printing it (#9086). See Haskell 2010 report Chapter 5.
+                   doWithArgs args $ "Control.Monad.void (" ++ main ++ ")"
 
 -----------------------------------------------------------------------------
 -- :run
diff --git a/testsuite/tests/ghc-e/should_run/Makefile b/testsuite/tests/ghc-e/should_run/Makefile
index 1971004..5ed1ec2 100644
--- a/testsuite/tests/ghc-e/should_run/Makefile
+++ b/testsuite/tests/ghc-e/should_run/Makefile
@@ -30,3 +30,5 @@ T3890:
 T7299:
 	'$(TEST_HC)' $(TEST_HC_OPTS) -ignore-dot-ghci -e "Control.Concurrent.threadDelay (1000 * 1000)"
 
+T9086:
+	'$(TEST_HC)' $(TEST_HC_OPTS) -ignore-dot-ghci -e ":main" T9086.hs
diff --git a/testsuite/tests/ghc-e/should_run/T9086.hs b/testsuite/tests/ghc-e/should_run/T9086.hs
new file mode 100644
index 0000000..a2b4ace
--- /dev/null
+++ b/testsuite/tests/ghc-e/should_run/T9086.hs
@@ -0,0 +1 @@
+main = return "this should not be printed"
diff --git a/testsuite/tests/ghc-e/should_run/all.T b/testsuite/tests/ghc-e/should_run/all.T
index 4ab7567..9f64918 100644
--- a/testsuite/tests/ghc-e/should_run/all.T
+++ b/testsuite/tests/ghc-e/should_run/all.T
@@ -14,3 +14,4 @@ test('T2228',
 test('T2636', req_interp, run_command, ['$MAKE --no-print-directory -s T2636'])
 test('T3890', req_interp, run_command, ['$MAKE --no-print-directory -s T3890'])
 test('T7299', req_interp, run_command, ['$MAKE --no-print-directory -s T7299'])
+test('T9086', req_interp, run_command, ['$MAKE --no-print-directory -s T9086'])
diff --git a/testsuite/tests/ghci/scripts/T9086b.script b/testsuite/tests/ghci/scripts/T9086b.script
new file mode 100644
index 0000000..d60156a
--- /dev/null
+++ b/testsuite/tests/ghci/scripts/T9086b.script
@@ -0,0 +1,2 @@
+let main = do { putStrLn "hello"; return "discarded" }
+:main
diff --git a/testsuite/tests/ffi/should_run/ffi021.stdout b/testsuite/tests/ghci/scripts/T9086b.stdout
similarity index 100%
copy from testsuite/tests/ffi/should_run/ffi021.stdout
copy to testsuite/tests/ghci/scripts/T9086b.stdout
diff --git a/testsuite/tests/ghci/scripts/all.T b/testsuite/tests/ghci/scripts/all.T
index b71dfd1..d1e67eb 100755
--- a/testsuite/tests/ghci/scripts/all.T
+++ b/testsuite/tests/ghci/scripts/all.T
@@ -175,3 +175,4 @@ test('T8931', normal, ghci_script, ['T8931.script'])
 test('T8959', normal, ghci_script, ['T8959.script'])
 test('T8959b', expect_broken(8959), ghci_script, ['T8959b.script'])
 test('T9181', normal, ghci_script, ['T9181.script'])
+test('T9086b', normal, ghci_script, ['T9086b.script'])