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bpo-29922: Improve error messages in 'async with' (GH-6352) 

when __aenter__() or __aexit__() return non-awaitable object.
(cherry picked from commit a68f2f0578)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
This commit is contained in:
Miss Islington (bot) 2018-04-04 07:09:00 -07:00 committed by GitHub
parent b8fc2d6580
commit fcd4e03e08
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 36 additions and 4 deletions
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13
Lib/test/test_coroutines.py
View File

@ -1255,7 +1255,9 @@ class CoroutineTest(unittest.TestCase):
pass pass
with self.assertRaisesRegex( with self.assertRaisesRegex(
TypeError, "object int can't be used in 'await' expression"): TypeError,
"'async with' received an object from __aenter__ "
"that does not implement __await__: int"):
# it's important that __aexit__ wasn't called # it's important that __aexit__ wasn't called
run_async(foo()) run_async(foo())
@ -1275,7 +1277,9 @@ class CoroutineTest(unittest.TestCase):
run_async(foo()) run_async(foo())
except TypeError as exc: except TypeError as exc:
self.assertRegex( self.assertRegex(
exc.args[0], "object int can't be used in 'await' expression") exc.args[0],
"'async with' received an object from __aexit__ "
"that does not implement __await__: int")
self.assertTrue(exc.__context__ is not None) self.assertTrue(exc.__context__ is not None)
self.assertTrue(isinstance(exc.__context__, ZeroDivisionError)) self.assertTrue(isinstance(exc.__context__, ZeroDivisionError))
else: else:
@ -1299,8 +1303,9 @@ class CoroutineTest(unittest.TestCase):
with self.assertRaisesRegex( with self.assertRaisesRegex(
TypeError, "object int can't be used in 'await' expression"): TypeError,
"'async with' received an object from __aexit__ "
"that does not implement __await__: int"):
run_async(foo()) run_async(foo())
self.assertEqual(CNT, 1) self.assertEqual(CNT, 1)

2
Misc/NEWS.d/next/Core and Builtins/2018-04-03-00-30-25.bpo-29922.CdLuMl.rst Normal file
View File

@ -0,0 +1,2 @@
Improved error messages in 'async with' when ``__aenter__()`` or
``__aexit__()`` return non-awaitable object.

25
Python/ceval.c
View File

@ -69,6 +69,7 @@ static PyObject * unicode_concatenate(PyObject *, PyObject *,
static PyObject * special_lookup(PyObject *, _Py_Identifier *); static PyObject * special_lookup(PyObject *, _Py_Identifier *);
static int check_args_iterable(PyObject *func, PyObject *vararg); static int check_args_iterable(PyObject *func, PyObject *vararg);
static void format_kwargs_mapping_error(PyObject *func, PyObject *kwargs); static void format_kwargs_mapping_error(PyObject *func, PyObject *kwargs);
static void format_awaitable_error(PyTypeObject *, int);
#define NAME_ERROR_MSG \ #define NAME_ERROR_MSG \
"name '%.200s' is not defined" "name '%.200s' is not defined"
@ -1739,6 +1740,11 @@ _PyEval_EvalFrameDefault(PyFrameObject *f, int throwflag)
PyObject *iterable = TOP(); PyObject *iterable = TOP();
PyObject *iter = _PyCoro_GetAwaitableIter(iterable); PyObject *iter = _PyCoro_GetAwaitableIter(iterable);
if (iter == NULL) {
format_awaitable_error(Py_TYPE(iterable),
_Py_OPCODE(next_instr[-2]));
}
Py_DECREF(iterable); Py_DECREF(iterable);
if (iter != NULL && PyCoro_CheckExact(iter)) { if (iter != NULL && PyCoro_CheckExact(iter)) {
@ -4948,6 +4954,25 @@ format_exc_unbound(PyCodeObject *co, int oparg)
} }
} }
static void
format_awaitable_error(PyTypeObject *type, int prevopcode)
{
if (type->tp_as_async == NULL || type->tp_as_async->am_await == NULL) {
if (prevopcode == BEFORE_ASYNC_WITH) {
PyErr_Format(PyExc_TypeError,
"'async with' received an object from __aenter__ "
"that does not implement __await__: %.100s",
type->tp_name);
}
else if (prevopcode == WITH_CLEANUP_START) {
PyErr_Format(PyExc_TypeError,
"'async with' received an object from __aexit__ "
"that does not implement __await__: %.100s",
type->tp_name);
}
}
}
static PyObject * static PyObject *
unicode_concatenate(PyObject *v, PyObject *w, unicode_concatenate(PyObject *v, PyObject *w,
PyFrameObject *f, const _Py_CODEUNIT *next_instr) PyFrameObject *f, const _Py_CODEUNIT *next_instr)