From 69806b9516dbe092381f3ef884c7c64bb9b8414a Mon Sep 17 00:00:00 2001 From: Mark Shannon Date: Wed, 8 Dec 2021 12:09:26 +0000 Subject: bpo-46009: Do not exhaust generator when send() method raises (GH-29986) --- Doc/library/dis.rst | 5 ++--- Lib/test/test_generators.py | 8 ++++++++ .../2021-12-08-11-06-53.bpo-46009.cL8pH0.rst | 5 +++++ Objects/genobject.c | 13 +++++++++++++ Python/ceval.c | 20 ++------------------ 5 files changed, 30 insertions(+), 21 deletions(-) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2021-12-08-11-06-53.bpo-46009.cL8pH0.rst diff --git a/Doc/library/dis.rst b/Doc/library/dis.rst index 62d2150..9665e8d 100644 --- a/Doc/library/dis.rst +++ b/Doc/library/dis.rst @@ -1170,9 +1170,8 @@ All of the following opcodes use their arguments. .. opcode:: GEN_START (kind) - Pops TOS. If TOS was not ``None``, raises an exception. The ``kind`` - operand corresponds to the type of generator or coroutine and determines - the error message. The legal kinds are 0 for generator, 1 for coroutine, + Pops TOS. The ``kind`` operand corresponds to the type of generator or + coroutine. The legal kinds are 0 for generator, 1 for coroutine, and 2 for async generator. .. versionadded:: 3.10 diff --git a/Lib/test/test_generators.py b/Lib/test/test_generators.py index 433204b..4f4fd9c 100644 --- a/Lib/test/test_generators.py +++ b/Lib/test/test_generators.py @@ -162,6 +162,14 @@ class GeneratorTest(unittest.TestCase): with self.assertRaises((TypeError, pickle.PicklingError)): pickle.dumps(g, proto) + def test_send_non_none_to_new_gen(self): + def f(): + yield 1 + g = f() + with self.assertRaises(TypeError): + g.send(0) + self.assertEqual(next(g), 1) + class ExceptionTest(unittest.TestCase): # Tests for the issue #23353: check that the currently handled exception diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-12-08-11-06-53.bpo-46009.cL8pH0.rst b/Misc/NEWS.d/next/Core and Builtins/2021-12-08-11-06-53.bpo-46009.cL8pH0.rst new file mode 100644 index 0000000..a80e66b --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2021-12-08-11-06-53.bpo-46009.cL8pH0.rst @@ -0,0 +1,5 @@ +Restore behavior from 3.9 and earlier when sending non-None to newly started +generator. In 3.9 this did not affect the state of the generator. In 3.10.0 +and 3.10.1 ``gen_func().send(0)`` is equivalent to +``gen_func().throw(TypeError(...)`` which exhausts the generator. In 3.10.2 +onward, the behavior has been reverted to that of 3.9. diff --git a/Objects/genobject.c b/Objects/genobject.c index c4ba660..147194c 100644 --- a/Objects/genobject.c +++ b/Objects/genobject.c @@ -157,6 +157,19 @@ gen_send_ex2(PyGenObject *gen, PyObject *arg, PyObject **presult, PyObject *result; *presult = NULL; + if (frame->f_lasti < 0 && arg && arg != Py_None) { + const char *msg = "can't send non-None value to a " + "just-started generator"; + if (PyCoro_CheckExact(gen)) { + msg = NON_INIT_CORO_MSG; + } + else if (PyAsyncGen_CheckExact(gen)) { + msg = "can't send non-None value to a " + "just-started async generator"; + } + PyErr_SetString(PyExc_TypeError, msg); + return PYGEN_ERROR; + } if (gen->gi_frame_valid && _PyFrame_IsExecuting(frame)) { const char *msg = "generator already executing"; if (PyCoro_CheckExact(gen)) { diff --git a/Python/ceval.c b/Python/ceval.c index 2e40c0f..4f5ccf5 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -2714,25 +2714,9 @@ check_eval_breaker: TARGET(GEN_START) { PyObject *none = POP(); + assert(none == Py_None); + assert(oparg < 3); Py_DECREF(none); - if (!Py_IsNone(none)) { - if (oparg > 2) { - _PyErr_SetString(tstate, PyExc_SystemError, - "Illegal kind for GEN_START"); - } - else { - static const char *gen_kind[3] = { - "generator", - "coroutine", - "async generator" - }; - _PyErr_Format(tstate, PyExc_TypeError, - "can't send non-None value to a " - "just-started %s", - gen_kind[oparg]); - } - goto error; - } DISPATCH(); } -- cgit v0.12