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bpo-33041: Fixed bytecode generation for "async for" with a complex target. (#6052) 

A StopAsyncIteration raised on assigning or unpacking will be now propagated
instead of stopping the iteration.
This commit is contained in:
Serhiy Storchaka 2018-03-10 18:22:34 +02:00 committed by GitHub
parent 5e80a71ab6
commit 24d3201eb7
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 70 additions and 2 deletions
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65
Lib/test/test_coroutines.py
View File

@ -1949,6 +1949,71 @@ class CoroutineTest(unittest.TestCase):
support.gc_collect()
self.assertIn("was never awaited", stderr.getvalue())
def test_for_assign_raising_stop_async_iteration(self):
class BadTarget:
def __setitem__(self, key, value):
raise StopAsyncIteration(42)
tgt = BadTarget()
async def source():
yield 10
async def run_for():
with self.assertRaises(StopAsyncIteration) as cm:
async for tgt[0] in source():
pass
self.assertEqual(cm.exception.args, (42,))
return 'end'
self.assertEqual(run_async(run_for()), ([], 'end'))
async def run_list():
with self.assertRaises(StopAsyncIteration) as cm:
return [0 async for tgt[0] in source()]
self.assertEqual(cm.exception.args, (42,))
return 'end'
self.assertEqual(run_async(run_list()), ([], 'end'))
async def run_gen():
gen = (0 async for tgt[0] in source())
a = gen.asend(None)
with self.assertRaises(RuntimeError) as cm:
await a
self.assertIsInstance(cm.exception.__cause__, StopAsyncIteration)
self.assertEqual(cm.exception.__cause__.args, (42,))
return 'end'
self.assertEqual(run_async(run_gen()), ([], 'end'))
def test_for_assign_raising_stop_async_iteration_2(self):
class BadIterable:
def __iter__(self):
raise StopAsyncIteration(42)
async def badpairs():
yield BadIterable()
async def run_for():
with self.assertRaises(StopAsyncIteration) as cm:
async for i, j in badpairs():
pass
self.assertEqual(cm.exception.args, (42,))
return 'end'
self.assertEqual(run_async(run_for()), ([], 'end'))
async def run_list():
with self.assertRaises(StopAsyncIteration) as cm:
return [0 async for i, j in badpairs()]
self.assertEqual(cm.exception.args, (42,))
return 'end'
self.assertEqual(run_async(run_list()), ([], 'end'))
async def run_gen():
gen = (0 async for i, j in badpairs())
a = gen.asend(None)
with self.assertRaises(RuntimeError) as cm:
await a
self.assertIsInstance(cm.exception.__cause__, StopAsyncIteration)
self.assertEqual(cm.exception.__cause__.args, (42,))
return 'end'
self.assertEqual(run_async(run_gen()), ([], 'end'))
class CoroAsyncIOCompatTest(unittest.TestCase):

3
Misc/NEWS.d/next/Core and Builtins/2018-03-10-15-16-40.bpo-33041.-ak5Fk.rst Normal file
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@ -0,0 +1,3 @@
Fixed bytecode generation for "async for" with a complex target. A
StopAsyncIteration raised on assigning or unpacking will be now propagated
instead of stopping the iteration.

4
Python/compile.c
View File

@ -2473,8 +2473,8 @@ compiler_async_for(struct compiler *c, stmt_ty s)
ADDOP(c, GET_ANEXT);
ADDOP_O(c, LOAD_CONST, Py_None, consts);
ADDOP(c, YIELD_FROM);
VISIT(c, expr, s->v.AsyncFor.target);
ADDOP(c, POP_BLOCK); /* for SETUP_FINALLY */
VISIT(c, expr, s->v.AsyncFor.target);
compiler_pop_fblock(c, EXCEPT, try);
ADDOP_JREL(c, JUMP_FORWARD, after_try);
@ -4060,8 +4060,8 @@ compiler_async_comprehension_generator(struct compiler *c,
ADDOP(c, GET_ANEXT);
ADDOP_O(c, LOAD_CONST, Py_None, consts);
ADDOP(c, YIELD_FROM);
VISIT(c, expr, gen->target);
ADDOP(c, POP_BLOCK);
VISIT(c, expr, gen->target);
compiler_pop_fblock(c, EXCEPT, try);
ADDOP_JREL(c, JUMP_FORWARD, after_try);