diff options
| -rw-r--r-- | Lib/contextlib.py | 3 | ||||
| -rw-r--r-- | Lib/test/test_contextlib.py | 28 | ||||
| -rw-r--r-- | Misc/NEWS | 6 |
3 files changed, 37 insertions, 0 deletions
diff --git a/Lib/contextlib.py b/Lib/contextlib.py index 6cf112a..7d94a57 100644 --- a/Lib/contextlib.py +++ b/Lib/contextlib.py @@ -105,6 +105,9 @@ class _GeneratorContextManager(ContextDecorator, AbstractContextManager): # raised inside the "with" statement from being suppressed. return exc is not value except RuntimeError as exc: + # Don't re-raise the passed in exception. (issue27112) + if exc is value: + return False # Likewise, avoid suppressing if a StopIteration exception # was passed to throw() and later wrapped into a RuntimeError # (see PEP 479). diff --git a/Lib/test/test_contextlib.py b/Lib/test/test_contextlib.py index 5c8bc98..2c6e0e7 100644 --- a/Lib/test/test_contextlib.py +++ b/Lib/test/test_contextlib.py @@ -795,6 +795,34 @@ class TestExitStack(unittest.TestCase): stack.push(cm) self.assertIs(stack._exit_callbacks[-1], cm) + def test_dont_reraise_RuntimeError(self): + """https://bugs.python.org/issue27122""" + class UniqueException(Exception): pass + + @contextmanager + def second(): + try: + yield 1 + except Exception as exc: + raise UniqueException("new exception") from exc + + @contextmanager + def first(): + try: + yield 1 + except Exception as exc: + raise exc + + # The RuntimeError should be caught by second()'s exception + # handler which chain raised a new UniqueException. + with self.assertRaises(UniqueException) as err_ctx: + with ExitStack() as es_ctx: + es_ctx.enter_context(second()) + es_ctx.enter_context(first()) + raise RuntimeError("please no infinite loop.") + + self.assertEqual(err_ctx.exception.args[0], "new exception") + class TestRedirectStream: @@ -10,6 +10,12 @@ What's New in Python 3.6.0 alpha 3 Library ------- +- Issue #27123: When an exception is raised within the context being managed + by a contextlib.ExitStack() and one of the exit stack generators + catches and raises it in a chain, do not re-raise the original exception + when exiting, let the new chained one through. This avoids the PEP 479 + bug described in issue25782. + - Issue #27278: Fix os.urandom() implementation using getrandom() on Linux. Truncate size to INT_MAX and loop until we collected enough random bytes, instead of casting a directly Py_ssize_t to int. |