Issue #3798: sys.exit(message) writes the message to sys.stderr file, instead

of the C file stderr, to use stderr encoding and error handler

Lib/test/test_sys.py

@@ -146,9 +146,9 @@ class SysModuleTest(unittest.TestCase):
                               "raise SystemExit(47)"])
         self.assertEqual(rc, 47)
 
-        def check_exit_message(code, expected):
+        def check_exit_message(code, expected, env=None):
             process = subprocess.Popen([sys.executable, "-c", code],
-                                       stderr=subprocess.PIPE)
+                                       stderr=subprocess.PIPE, env=env)
             stdout, stderr = process.communicate()
             self.assertEqual(process.returncode, 1)
             self.assertTrue(stderr.startswith(expected),
@@ -166,6 +166,14 @@ class SysModuleTest(unittest.TestCase):
             r'import sys; sys.exit("surrogates:\uDCFF")',
             b"surrogates:\\udcff")
 
+        # test that the unicode message is encoded to the stderr encoding
+        # instead of the default encoding (utf8)
+        env = os.environ.copy()
+        env['PYTHONIOENCODING'] = 'latin-1'
+        check_exit_message(
+            r'import sys; sys.exit("h\xe9")',
+            b"h\xe9", env=env)
+
     def test_getdefaultencoding(self):
         self.assertRaises(TypeError, sys.getdefaultencoding, 42)
         # can't check more than the type, as the user might have changed it

Misc/NEWS

@@ -393,6 +393,9 @@ C-API
 Library
 -------
 
+- Issue #3798: sys.exit(message) writes the message to sys.stderr file, instead
+  of the C file stderr, to use stderr encoding and error handler
+
 - Issue #8782: Add a trailing newline in linecache.updatecache to the last line
   of files without one.
 

Python/pythonrun.c

@@ -1386,10 +1386,12 @@ handle_system_exit(void)
         exitcode = (int)PyLong_AsLong(value);
     else {
         PyObject *sys_stderr = PySys_GetObject("stderr");
-        if (sys_stderr != NULL)
-            PyObject_CallMethod(sys_stderr, "flush", NULL);
+        if (sys_stderr != NULL && sys_stderr != Py_None) {
+            PyFile_WriteObject(value, sys_stderr, Py_PRINT_RAW);
+        } else {
             PyObject_Print(value, stderr, Py_PRINT_RAW);
             fflush(stderr);
+        }
         PySys_WriteStderr("\n");
         exitcode = 1;
     }