diff --git a/Doc/c-api/exceptions.rst b/Doc/c-api/exceptions.rst index 3fd69ba80fa..1e708a81284 100644 --- a/Doc/c-api/exceptions.rst +++ b/Doc/c-api/exceptions.rst @@ -74,8 +74,8 @@ Printing and clearing :meth:`__del__` method. The function is called with a single argument *obj* that identifies the context - in which the unraisable exception occurred. The repr of *obj* will be printed in - the warning message. + in which the unraisable exception occurred. If possible, + the repr of *obj* will be printed in the warning message. Raising exceptions diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py index 8a490455949..458ddc1ed82 100644 --- a/Lib/test/test_exceptions.py +++ b/Lib/test/test_exceptions.py @@ -7,7 +7,7 @@ import pickle import weakref import errno -from test.support import (TESTFN, captured_output, check_impl_detail, +from test.support import (TESTFN, captured_stderr, check_impl_detail, check_warnings, cpython_only, gc_collect, run_unittest, no_tracing, unlink, import_module) @@ -20,6 +20,10 @@ class SlottedNaiveException(Exception): def __init__(self, x): self.x = x +class BrokenStrException(Exception): + def __str__(self): + raise Exception("str() is broken") + # XXX This is not really enough, each *operation* should be tested! class ExceptionTests(unittest.TestCase): @@ -882,7 +886,7 @@ class ExceptionTests(unittest.TestCase): class MyException(Exception, metaclass=Meta): pass - with captured_output("stderr") as stderr: + with captured_stderr() as stderr: try: raise KeyError() except MyException as e: @@ -1011,6 +1015,66 @@ class ExceptionTests(unittest.TestCase): os.listdir(__file__) self.assertEqual(cm.exception.errno, errno.ENOTDIR, cm.exception) + def test_unraisable(self): + # Issue #22836: PyErr_WriteUnraisable() should give sensible reports + class BrokenDel: + def __del__(self): + exc = ValueError("del is broken") + # The following line is included in the traceback report: + raise exc + + class BrokenRepr(BrokenDel): + def __repr__(self): + raise AttributeError("repr() is broken") + + class BrokenExceptionDel: + def __del__(self): + exc = BrokenStrException() + # The following line is included in the traceback report: + raise exc + + for test_class in (BrokenDel, BrokenRepr, BrokenExceptionDel): + with self.subTest(test_class): + obj = test_class() + with captured_stderr() as stderr: + del obj + report = stderr.getvalue() + self.assertIn("Exception ignored", report) + if test_class is BrokenRepr: + self.assertIn("", report) + else: + self.assertIn(test_class.__del__.__qualname__, report) + self.assertIn("test_exceptions.py", report) + self.assertIn("raise exc", report) + if test_class is BrokenExceptionDel: + self.assertIn("BrokenStrException", report) + self.assertIn("", report) + else: + self.assertIn("ValueError", report) + self.assertIn("del is broken", report) + self.assertTrue(report.endswith("\n")) + + def test_unhandled(self): + # Check for sensible reporting of unhandled exceptions + for exc_type in (ValueError, BrokenStrException): + with self.subTest(exc_type): + try: + exc = exc_type("test message") + # The following line is included in the traceback report: + raise exc + except exc_type: + with captured_stderr() as stderr: + sys.__excepthook__(*sys.exc_info()) + report = stderr.getvalue() + self.assertIn("test_exceptions.py", report) + self.assertIn("raise exc", report) + self.assertIn(exc_type.__name__, report) + if exc_type is BrokenStrException: + self.assertIn("", report) + else: + self.assertIn("test message", report) + self.assertTrue(report.endswith("\n")) + class ImportErrorTests(unittest.TestCase): diff --git a/Misc/NEWS b/Misc/NEWS index b75d0e3d0cd..b895ff6c0d3 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -10,6 +10,11 @@ Release date: tba Core and Builtins ----------------- +- Issue #22836: Ensure exception reports from PyErr_Display() and + PyErr_WriteUnraisable() are sensible even when formatting them produces + secondary errors. This affects the reports produced by + sys.__excepthook__() and when __del__() raises an exception. + - Issue #26302: Correct behavior to reject comma as a legal character for cookie names. diff --git a/Python/errors.c b/Python/errors.c index 5ff1e4c81a4..47d7c4b9924 100644 --- a/Python/errors.c +++ b/Python/errors.c @@ -900,8 +900,12 @@ PyErr_WriteUnraisable(PyObject *obj) if (obj) { if (PyFile_WriteString("Exception ignored in: ", f) < 0) goto done; - if (PyFile_WriteObject(obj, f, 0) < 0) - goto done; + if (PyFile_WriteObject(obj, f, 0) < 0) { + PyErr_Clear(); + if (PyFile_WriteString("", f) < 0) { + goto done; + } + } if (PyFile_WriteString("\n", f) < 0) goto done; } @@ -946,8 +950,12 @@ PyErr_WriteUnraisable(PyObject *obj) if (v && v != Py_None) { if (PyFile_WriteString(": ", f) < 0) goto done; - if (PyFile_WriteObject(v, f, Py_PRINT_RAW) < 0) - goto done; + if (PyFile_WriteObject(v, f, Py_PRINT_RAW) < 0) { + PyErr_Clear(); + if (PyFile_WriteString("", f) < 0) { + goto done; + } + } } if (PyFile_WriteString("\n", f) < 0) goto done; diff --git a/Python/pythonrun.c b/Python/pythonrun.c index ebedd123f39..c03b07378a9 100644 --- a/Python/pythonrun.c +++ b/Python/pythonrun.c @@ -766,8 +766,11 @@ print_exception(PyObject *f, PyObject *value) /* only print colon if the str() of the object is not the empty string */ - if (s == NULL) + if (s == NULL) { + PyErr_Clear(); err = -1; + PyFile_WriteString(": ", f); + } else if (!PyUnicode_Check(s) || PyUnicode_GetLength(s) != 0) err = PyFile_WriteString(": ", f); @@ -776,6 +779,9 @@ print_exception(PyObject *f, PyObject *value) Py_XDECREF(s); } /* try to write a newline in any case */ + if (err < 0) { + PyErr_Clear(); + } err += PyFile_WriteString("\n", f); Py_XDECREF(tb); Py_DECREF(value);