From e0511e797c483e1203a096ff96e34dc95368f843 Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Fri, 25 Mar 2016 00:28:56 +0100
Subject: Fix test_warnings.test_improper_option()

test_warnings: only run test_improper_option() and test_warnings_bootstrap()
once. The unit test doesn't depend on self.module.
---
 Lib/test/test_warnings/__init__.py | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py
index cea9c57..eda755d 100644
--- a/Lib/test/test_warnings/__init__.py
+++ b/Lib/test/test_warnings/__init__.py
@@ -534,6 +534,14 @@ class WCmdLineTests(BaseTest):
             self.module._setoption('error::Warning::0')
             self.assertRaises(UserWarning, self.module.warn, 'convert to error')
 
+
+class CWCmdLineTests(WCmdLineTests, unittest.TestCase):
+    module = c_warnings
+
+
+class PyWCmdLineTests(WCmdLineTests, unittest.TestCase):
+    module = py_warnings
+
     def test_improper_option(self):
         # Same as above, but check that the message is printed out when
         # the interpreter is executed. This also checks that options are
@@ -550,12 +558,6 @@ class WCmdLineTests(BaseTest):
         self.assertFalse(out.strip())
         self.assertNotIn(b'RuntimeWarning', err)
 
-class CWCmdLineTests(WCmdLineTests, unittest.TestCase):
-    module = c_warnings
-
-class PyWCmdLineTests(WCmdLineTests, unittest.TestCase):
-    module = py_warnings
-
 
 class _WarningsTests(BaseTest, unittest.TestCase):
 
@@ -931,6 +933,7 @@ class BootstrapTest(unittest.TestCase):
             # Use -W to load warnings module at startup
             assert_python_ok('-c', 'pass', '-W', 'always', PYTHONPATH=cwd)
 
+
 class FinalizationTest(unittest.TestCase):
     def test_finalization(self):
         # Issue #19421: warnings.warn() should not crash
-- 
cgit v0.12


From 27461683a9491efe58331a695c856fbb28bd4cba Mon Sep 17 00:00:00 2001
From: Victor Stinner <victor.stinner@gmail.com>
Date: Fri, 25 Mar 2016 00:30:32 +0100
Subject: warnings.formatwarning(): catch exceptions

Issue #21925: warnings.formatwarning() now catches exceptions on
linecache.getline(...) to be able to log ResourceWarning emitted late during
the Python shutdown process.
---
 Lib/test/test_warnings/__init__.py | 17 +++++++++++++++++
 Lib/warnings.py                    | 10 ++++++++--
 Misc/NEWS                          |  4 ++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_warnings/__init__.py b/Lib/test/test_warnings/__init__.py
index eda755d..633b2ac 100644
--- a/Lib/test/test_warnings/__init__.py
+++ b/Lib/test/test_warnings/__init__.py
@@ -953,6 +953,23 @@ a=A()
         # of the script
         self.assertEqual(err, b'__main__:7: UserWarning: test')
 
+    def test_late_resource_warning(self):
+        # Issue #21925: Emitting a ResourceWarning late during the Python
+        # shutdown must be logged.
+
+        expected = b"sys:1: ResourceWarning: unclosed file "
+
+        # don't import the warnings module
+        # (_warnings will try to import it)
+        code = "f = open(%a)" % __file__
+        rc, out, err = assert_python_ok("-c", code)
+        self.assertTrue(err.startswith(expected), ascii(err))
+
+        # import the warnings module
+        code = "import warnings; f = open(%a)" % __file__
+        rc, out, err = assert_python_ok("-c", code)
+        self.assertTrue(err.startswith(expected), ascii(err))
+
 
 def setUpModule():
     py_warnings.onceregistry.clear()
diff --git a/Lib/warnings.py b/Lib/warnings.py
index 1d4fb20..cf9f5b2 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -21,9 +21,15 @@ def showwarning(message, category, filename, lineno, file=None, line=None):
 
 def formatwarning(message, category, filename, lineno, line=None):
     """Function to format a warning the standard way."""
-    import linecache
     s =  "%s:%s: %s: %s\n" % (filename, lineno, category.__name__, message)
-    line = linecache.getline(filename, lineno) if line is None else line
+    if line is None:
+        try:
+            import linecache
+            line = linecache.getline(filename, lineno)
+        except Exception:
+            # When a warning is logged during Python shutdown, linecache
+            # and the improt machinery don't work anymore
+            line = None
     if line:
         line = line.strip()
         s += "  %s\n" % line
diff --git a/Misc/NEWS b/Misc/NEWS
index 0058124..3baeeec 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -94,6 +94,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #21925: :func:`warnings.formatwarning` now catches exceptions on
+  ``linecache.getline(...)`` to be able to log :exc:`ResourceWarning` emitted
+  late during the Python shutdown process.
+
 - Issue #24266: Ctrl+C during Readline history search now cancels the search
   mode when compiled with Readline 7.
 
-- 
cgit v0.12