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bpo-29587: Enable implicit exception chaining with gen.throw() #19823

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Merged
merged 4 commits into from
May 2, 2020
Merged

bpo-29587: Enable implicit exception chaining with gen.throw() #19823

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e757c76
Add a failing test for issue 29587.
cjerdonek Apr 30, 2020
57597f2
bpo-29587: set exc.__context__ when calling gen.throw() (GH-19811)
cjerdonek Apr 30, 2020
c321731
Wrap the long line.
cjerdonek May 1, 2020
1bf3309
Address the CI failures on Fedora, etc.
cjerdonek May 1, 2020
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17 changes: 17 additions & 0 deletions Lib/test/test_generators.py
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Original file line number Diff line number Diff line change
Expand Up @@ -316,6 +316,23 @@ def g():
self.assertEqual(cm.exception.value.value, 2)


class GeneratorThrowTest(unittest.TestCase):

def test_exception_context_set(self):
def f():
try:
raise KeyError('a')
except Exception:
yield

gen = f()
gen.send(None)
with self.assertRaises(ValueError) as cm:
gen.throw(ValueError)
context = cm.exception.__context__
self.assertEqual((type(context), context.args), (KeyError, ('a',)))


class YieldFromTests(unittest.TestCase):
def test_generator_gi_yieldfrom(self):
def a():
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2020-04-30-00-50-25.bpo-29587.oEwSq.rst
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@@ -0,0 +1 @@
Enable implicit exception chaining when calling :meth:`generator.throw`.
9 changes: 9 additions & 0 deletions Objects/genobject.c
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Expand Up @@ -512,6 +512,15 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
}

PyErr_Restore(typ, val, tb);
/* XXX Should we also handle the case where exc_type is true and
exc_value is false? */
if (gen->gi_exc_state.exc_type && gen->gi_exc_state.exc_value) {
Py_INCREF(gen->gi_exc_state.exc_type);
Py_INCREF(gen->gi_exc_state.exc_value);
Py_XINCREF(gen->gi_exc_state.exc_traceback);
_PyErr_ChainExceptions(gen->gi_exc_state.exc_type,
gen->gi_exc_state.exc_value, gen->gi_exc_state.exc_traceback);
}
return gen_send_ex(gen, Py_None, 1, 0);

failed_throw:
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