Issue2221: in Idle, exec('xx') raised a SystemError('error return without exception set')

amaury.forgeotdarc · amaury.forgeotdarc · commit 9b975be1df06 · 2008-04-04T23:25:27.000Z
instead of the expected NameError This happens when sys.stdout is redirected to something that cannot flush(). the flush_io() function must be exception-neutral: don't raise, and don't clear exceptions. Next step: exec() is not supposed to flush sys.stdout... git-svn-id: http://svn.python.org/projects/python/branches/py3k@62157 6015fed2-1504-0410-9fe1-9d1591cc4771
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
@@ -448,6 +448,17 @@ def test_exec(self):
             del l['__builtins__']
         self.assertEqual((g, l), ({'a': 1}, {'b': 2}))
 
+    def test_exec_redirected(self):
+        savestdout = sys.stdout
+        sys.stdout = None # Whatever that cannot flush()
+        try:
+            # Used to raise SystemError('error return without exception set')
+            exec('a')
+        except NameError:
+            pass
+        finally:
+            sys.stdout = savestdout
+
     def test_filter(self):
         self.assertEqual(list(filter(lambda c: 'a' <= c <= 'z', 'Hello World')), list('elloorld'))
         self.assertEqual(list(filter(None, [1, 'hello', [], [3], '', None, 9, 0])), [1, 'hello', [3], 9])
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
@@ -1467,6 +1467,11 @@ static void
 flush_io(void)
 {
 	PyObject *f, *r;
+	PyObject *type, *value, *traceback;
+
+	/* Save the current exception */
+	PyErr_Fetch(&type, &value, &traceback);
+
 	f = PySys_GetObject("stderr");
 	if (f != NULL) {
 		r = PyObject_CallMethod(f, "flush", "");
@@ -1483,6 +1488,8 @@ flush_io(void)
 		else
 			PyErr_Clear();
 	}
+
+	PyErr_Restore(type, value, traceback);
 }
 
 static PyObject *

Original file line number	Diff line number	Diff line change
`@@ -1467,6 +1467,11 @@ static void`
`1467`	`1467`	`flush_io(void)`
`1468`	`1468`	`{`
`1469`	`1469`	`PyObject f, r;`
	`1470`	`+ PyObject type, value, *traceback;`
	`1471`	`+`
	`1472`	`+ /* Save the current exception */`
	`1473`	`+ PyErr_Fetch(&type, &value, &traceback);`
	`1474`	`+`
`1470`	`1475`	`f = PySys_GetObject("stderr");`
`1471`	`1476`	`if (f != NULL) {`
`1472`	`1477`	`r = PyObject_CallMethod(f, "flush", "");`
`@@ -1483,6 +1488,8 @@ flush_io(void)`
`1483`	`1488`	`else`
`1484`	`1489`	`PyErr_Clear();`
`1485`	`1490`	`}`
	`1491`	`+`
	`1492`	`+ PyErr_Restore(type, value, traceback);`
`1486`	`1493`	`}`
`1487`	`1494`
`1488`	`1495`	`static PyObject *`