From eef5554ca5c15f4519be6d5e1dc154ca792876e5 Mon Sep 17 00:00:00 2001
From: Xavier de Gaye <xdegaye@gmail.com>
Date: Sat, 1 Jul 2017 15:41:50 +0200
Subject: [PATCH] bpo-30817: Fix PyErr_PrintEx() when no memory

---
 Lib/test/test_exceptions.py                   | 19 ++++++++++++++++++-
 .../2017-07-01-15-11-13.bpo-30817.j7ZvN_.rst  |  2 ++
 Python/pythonrun.c                            | 12 +++++++++---
 3 files changed, 29 insertions(+), 4 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2017-07-01-15-11-13.bpo-30817.j7ZvN_.rst

diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index 3378ceb701c0442..3372bc67dec392b 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -10,7 +10,7 @@
 
 from test.support import (TESTFN, captured_stderr, check_impl_detail,
                           check_warnings, cpython_only, gc_collect, run_unittest,
-                          no_tracing, unlink, import_module)
+                          no_tracing, unlink, import_module, script_helper)
 
 class NaiveException(Exception):
     def __init__(self, x):
@@ -1069,6 +1069,23 @@ def test_unhandled(self):
                     self.assertIn("test message", report)
                 self.assertTrue(report.endswith("\n"))
 
+    @cpython_only
+    def test_memory_error_in_PyErr_PrintEx(self):
+        code = """if 1:
+            import _testcapi
+            class C(): pass
+            _testcapi.set_nomemory(0, %d)
+            C()
+        """
+
+        # Issue #30817: Abort in PyErr_PrintEx() when no memory.
+        # Span a large range of tests as the CPython code always evolves with
+        # changes that add or remove memory allocations.
+        for i in range(1, 20):
+            rc, out, err = script_helper.assert_python_failure("-c", code % i)
+            self.assertIn(rc, (1, 120))
+            self.assertIn(b'MemoryError', err)
+
 
 class ImportErrorTests(unittest.TestCase):
 
diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-07-01-15-11-13.bpo-30817.j7ZvN_.rst b/Misc/NEWS.d/next/Core and Builtins/2017-07-01-15-11-13.bpo-30817.j7ZvN_.rst
new file mode 100644
index 000000000000000..1e7bb8fdace2785
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2017-07-01-15-11-13.bpo-30817.j7ZvN_.rst	
@@ -0,0 +1,2 @@
+`PyErr_PrintEx()` does not ignore now when an exception is set after calling
+`_PySys_SetObjectId()`.
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index f31b3ee5a5dcd15..4b44c6b6ef464aa 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -626,9 +626,15 @@ PyErr_PrintEx(int set_sys_last_vars)
         return;
     /* Now we know v != NULL too */
     if (set_sys_last_vars) {
-        _PySys_SetObjectId(&PyId_last_type, exception);
-        _PySys_SetObjectId(&PyId_last_value, v);
-        _PySys_SetObjectId(&PyId_last_traceback, tb);
+        if (_PySys_SetObjectId(&PyId_last_type, exception) < 0) {
+            PyErr_Clear();
+        }
+        if (_PySys_SetObjectId(&PyId_last_value, v) < 0) {
+            PyErr_Clear();
+        }
+        if (_PySys_SetObjectId(&PyId_last_traceback, tb) < 0) {
+            PyErr_Clear();
+        }
     }
     hook = _PySys_GetObjectId(&PyId_excepthook);
     if (hook) {