From e46d4e1de10a3e670066d8aab3e8b5f816320f56 Mon Sep 17 00:00:00 2001
From: Brad Neimann <brad.neimann@hotmail.com>
Date: Thu, 11 Jul 2019 17:08:16 +1000
Subject: [PATCH] Move stderr of stty to pipe

If stderr is left as its default value, any error messages arising from
stty are output to the stderr of the program calling `size`, causing
strange messages if stty fails.
---
 src/System/Console/Terminal/Windows.hs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/System/Console/Terminal/Windows.hs b/src/System/Console/Terminal/Windows.hs
index 962afd7..b4fc4d2 100644
--- a/src/System/Console/Terminal/Windows.hs
+++ b/src/System/Console/Terminal/Windows.hs
@@ -4,6 +4,7 @@ module System.Console.Terminal.Windows(size) where
 import System.Console.Terminal.Common
 
 import Control.Monad
+import Control.Exception (evaluate)
 import Data.Word
 import Foreign.Ptr
 import Foreign.Storable
@@ -42,9 +43,12 @@ size = do
                 let stty = (shell "stty size") {
                       std_in  = UseHandle stdin
                     , std_out = CreatePipe
+                    , std_err = CreatePipe
                     }
-                (_, mbStdout, _, rStty) <- createProcess stty
+                (_, mbStdout, mbStderr, rStty) <- createProcess stty
                 exStty <- waitForProcess rStty
+                -- Drain stderr by evaluating it fully
+                maybe (pure ()) ((void . evaluate . length) <=< hGetContents) mbStderr
                 case exStty of
                     ExitFailure _ -> return Nothing
                     ExitSuccess ->