Close #20105: set __traceback__ when chaining exceptions in C
diff --git a/Doc/c-api/exceptions.rst b/Doc/c-api/exceptions.rst
index 8658a58..d4065e0 100644
--- a/Doc/c-api/exceptions.rst
+++ b/Doc/c-api/exceptions.rst
@@ -90,6 +90,16 @@
the class in that case. If the values are already normalized, nothing happens.
The delayed normalization is implemented to improve performance.
+ .. note::
+
+ This function *does not* implicitly set the ``__traceback__``
+ attribute on the exception value. If setting the traceback
+ appropriately is desired, the following additional snippet is needed::
+
+ if (tb != NULL) {
+ PyException_SetTraceback(val, tb);
+ }
+
.. c:function:: void PyErr_Clear()
diff --git a/Doc/whatsnew/3.4.rst b/Doc/whatsnew/3.4.rst
index 5d397fe..1d88965 100644
--- a/Doc/whatsnew/3.4.rst
+++ b/Doc/whatsnew/3.4.rst
@@ -264,6 +264,9 @@
>>> import codecs
>>> codecs.decode(b"abcdefgh", "hex")
+ Traceback (most recent call last):
+ File "/usr/lib/python3.4/encodings/hex_codec.py", line 20, in hex_decode
+ return (binascii.a2b_hex(input), len(input))
binascii.Error: Non-hexadecimal digit found
The above exception was the direct cause of the following exception:
@@ -273,6 +276,11 @@
binascii.Error: decoding with 'hex' codec failed (Error: Non-hexadecimal digit found)
>>> codecs.encode("hello", "bz2")
+ Traceback (most recent call last):
+ File "/usr/lib/python3.4/encodings/bz2_codec.py", line 17, in bz2_encode
+ return (bz2.compress(input), len(input))
+ File "/usr/lib/python3.4/bz2.py", line 498, in compress
+ return comp.compress(data) + comp.flush()
TypeError: 'str' does not support the buffer interface
The above exception was the direct cause of the following exception:
diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py
index f9c9e69..a32ce76 100644
--- a/Lib/test/test_codecs.py
+++ b/Lib/test/test_codecs.py
@@ -2522,6 +2522,7 @@
with self.assertRaisesRegex(exc_type, full_msg) as caught:
yield caught
self.assertIsInstance(caught.exception.__cause__, exc_type)
+ self.assertIsNotNone(caught.exception.__cause__.__traceback__)
def raise_obj(self, *args, **kwds):
# Helper to dynamically change the object raised by a test codec
diff --git a/Misc/NEWS b/Misc/NEWS
index c248d7c..2516735 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -36,6 +36,9 @@
Library
-------
+- Issue #20105: the codec exception chaining now correctly sets the
+ traceback of the original exception as its __traceback__ attribute.
+
- asyncio: Various improvements and small changes not all covered by
issues listed below. E.g. wait_for() now cancels the inner task if
the timeout occcurs; tweaked the set of exported symbols; renamed
diff --git a/Objects/exceptions.c b/Objects/exceptions.c
index bff7f08..2531ead 100644
--- a/Objects/exceptions.c
+++ b/Objects/exceptions.c
@@ -2689,8 +2689,11 @@
* types as well, but that's quite a bit trickier due to the extra
* state potentially stored on OSError instances.
*/
-
- Py_XDECREF(tb);
+ /* Ensure the traceback is set correctly on the existing exception */
+ if (tb != NULL) {
+ PyException_SetTraceback(val, tb);
+ Py_DECREF(tb);
+ }
#ifdef HAVE_STDARG_PROTOTYPES
va_start(vargs, format);