From db5947f0f3a662f1e8e9201295a3f2288b0bbe8c Mon Sep 17 00:00:00 2001
From: Ezio Melotti <ezio.melotti@gmail.com>
Date: Sun, 18 Nov 2012 13:46:38 +0200
Subject: [PATCH] #16306: Fix multiple error messages when unknown command line
 parameters where passed to the interpreter.  Patch by Hieu Nguyen.

---
 Lib/test/test_cmd_line.py | 11 ++++++++++-
 Misc/ACKS                 |  1 +
 Misc/NEWS                 |  3 +++
 Python/getopt.c           | 14 ++++++++------
 4 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/Lib/test/test_cmd_line.py b/Lib/test/test_cmd_line.py
index d12caeb0e1c..b803046c360 100644
--- a/Lib/test/test_cmd_line.py
+++ b/Lib/test/test_cmd_line.py
@@ -6,7 +6,8 @@ import test.test_support
 import sys
 import unittest
 from test.script_helper import (
-    assert_python_ok, spawn_python, kill_python, python_exit_code
+    assert_python_ok, assert_python_failure, spawn_python, kill_python,
+    python_exit_code
 )
 
 
@@ -116,6 +117,14 @@ class CmdLineTest(unittest.TestCase):
         assert_python_ok(filename)
 
 
+    def test_unknown_options(self):
+        # Add "without='-E'" to prevent _assert_python append env_vars -E
+        # which changes the output of stderr
+        rc, out, err = assert_python_failure('-z', without='-E')
+        self.assertIn(b'Unknown option', err)
+        self.assertEqual(err.splitlines().count(b'Unknown option: -z'), 1)
+        self.assertEqual(b'', out)
+
 def test_main():
     test.test_support.run_unittest(CmdLineTest)
     test.test_support.reap_children()
diff --git a/Misc/ACKS b/Misc/ACKS
index 3604dd03729..462145aa3b6 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -701,6 +701,7 @@ Tony Nelson
 Chad Netzer
 Max Neunhöffer
 George Neville-Neil
+Hieu Nguyen
 Johannes Nicolai
 Samuel Nicolary
 Gustavo Niemeyer
diff --git a/Misc/NEWS b/Misc/NEWS
index f50ed543064..b5b7a5042ce 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -9,6 +9,9 @@ What's New in Python 2.7.4
 Core and Builtins
 -----------------
 
+- Issue #16306: Fix multiple error messages when unknown command line
+  parameters where passed to the interpreter.  Patch by Hieu Nguyen.
+
 - Issue #15379: Fix passing of non-BMP characters as integers for the charmap
   decoder (already working as unicode strings).  Patch by Serhiy Storchaka.
 
diff --git a/Python/getopt.c b/Python/getopt.c
index e96eb6ccc3d..624da9ad895 100644
--- a/Python/getopt.c
+++ b/Python/getopt.c
@@ -41,7 +41,7 @@ static char *opt_ptr = "";
 
 void _PyOS_ResetGetOpt(void)
 {
-    _PyOS_opterr = 1;
+    _PyOS_opterr = 0;   /* prevent printing the error in 2nd loop in main.c */
     _PyOS_optind = 1;
     _PyOS_optarg = NULL;
     opt_ptr = "";
@@ -86,17 +86,19 @@ int _PyOS_GetOpt(int argc, char **argv, char *optstring)
         opt_ptr = &argv[_PyOS_optind++][1];
     }
 
-    if ( (option = *opt_ptr++) == '\0')
+    if ((option = *opt_ptr++) == '\0')
         return -1;
 
     if (option == 'J') {
-        fprintf(stderr, "-J is reserved for Jython\n");
+        if (_PyOS_opterr)
+            fprintf(stderr, "-J is reserved for Jython\n");
         return '_';
     }
 
     if (option == 'X') {
-        fprintf(stderr,
-          "-X is reserved for implementation-specific arguments\n");
+        if (_PyOS_opterr)
+            fprintf(stderr,
+                "-X is reserved for implementation-specific arguments\n");
         return '_';
     }
 
@@ -117,7 +119,7 @@ int _PyOS_GetOpt(int argc, char **argv, char *optstring)
             if (_PyOS_optind >= argc) {
                 if (_PyOS_opterr)
                     fprintf(stderr,
-                "Argument expected for the -%c option\n", option);
+                        "Argument expected for the -%c option\n", option);
                 return '_';
             }