gh-93453: No longer create an event loop in get_event_loop() (#98440)

asyncio.get_event_loop() now always return either running event loop or
the result of get_event_loop_policy().get_event_loop() call. The latter
should now raise an RuntimeError if no current event loop was set
instead of creating and setting a new event loop.

It affects also a number of asyncio functions and constructors which
call get_event_loop() implicitly: ensure_future(), shield(), gather(),
etc.

DeprecationWarning is no longer emitted if there is no running event loop but
the current event loop was set.

Co-authored-by: Łukasz Langa <lukasz@langa.pl>

2 files changed, 4 insertions, 87 deletions

diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index cabcaec..60369d8 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -357,7 +357,7 @@ set_running_loop(asyncio_state *state, PyObject *loop)
 
 
 static PyObject *
-get_event_loop(asyncio_state *state, int stacklevel)
+get_event_loop(asyncio_state *state)
 {
     PyObject *loop;
     PyObject *policy;
@@ -369,13 +369,6 @@ get_event_loop(asyncio_state *state, int stacklevel)
         return loop;
     }
 
-    if (PyErr_WarnEx(PyExc_DeprecationWarning,
-                     "There is no current event loop",
-                     stacklevel))
-    {
-        return NULL;
-    }
-
     policy = PyObject_CallNoArgs(state->asyncio_get_event_loop_policy);
     if (policy == NULL) {
         return NULL;
@@ -538,7 +531,7 @@ future_init(FutureObj *fut, PyObject *loop)
 
     if (loop == Py_None) {
         asyncio_state *state = get_asyncio_state_by_def((PyObject *)fut);
-        loop = get_event_loop(state, 1);
+        loop = get_event_loop(state);
         if (loop == NULL) {
             return -1;
         }
@@ -3229,20 +3222,7 @@ _asyncio_get_event_loop_impl(PyObject *module)
 /*[clinic end generated code: output=2a2d8b2f824c648b input=9364bf2916c8655d]*/
 {
     asyncio_state *state = get_asyncio_state(module);
-    return get_event_loop(state, 1);
-}
-
-/*[clinic input]
-_asyncio._get_event_loop
-    stacklevel: int = 3
-[clinic start generated code]*/
-
-static PyObject *
-_asyncio__get_event_loop_impl(PyObject *module, int stacklevel)
-/*[clinic end generated code: output=9c1d6d3c802e67c9 input=d17aebbd686f711d]*/
-{
-    asyncio_state *state = get_asyncio_state(module);
-    return get_event_loop(state, stacklevel-1);
+    return get_event_loop(state);
 }
 
 /*[clinic input]
@@ -3620,7 +3600,6 @@ PyDoc_STRVAR(module_doc, "Accelerator module for asyncio");
 
 static PyMethodDef asyncio_methods[] = {
     _ASYNCIO_GET_EVENT_LOOP_METHODDEF
-    _ASYNCIO__GET_EVENT_LOOP_METHODDEF
     _ASYNCIO_GET_RUNNING_LOOP_METHODDEF
     _ASYNCIO__GET_RUNNING_LOOP_METHODDEF
     _ASYNCIO__SET_RUNNING_LOOP_METHODDEF
diff --git a/Modules/clinic/_asynciomodule.c.h b/Modules/clinic/_asynciomodule.c.h
index 11db478..f2fbb35 100644
--- a/Modules/clinic/_asynciomodule.c.h
+++ b/Modules/clinic/_asynciomodule.c.h
@@ -987,68 +987,6 @@ _asyncio_get_event_loop(PyObject *module, PyObject *Py_UNUSED(ignored))
     return _asyncio_get_event_loop_impl(module);
 }
 
-PyDoc_STRVAR(_asyncio__get_event_loop__doc__,
-"_get_event_loop($module, /, stacklevel=3)\n"
-"--\n"
-"\n");
-
-#define _ASYNCIO__GET_EVENT_LOOP_METHODDEF    \
-    {"_get_event_loop", _PyCFunction_CAST(_asyncio__get_event_loop), METH_FASTCALL|METH_KEYWORDS, _asyncio__get_event_loop__doc__},
-
-static PyObject *
-_asyncio__get_event_loop_impl(PyObject *module, int stacklevel);
-
-static PyObject *
-_asyncio__get_event_loop(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
-{
-    PyObject *return_value = NULL;
-    #if defined(Py_BUILD_CORE) && !defined(Py_BUILD_CORE_MODULE)
-
-    #define NUM_KEYWORDS 1
-    static struct {
-        PyGC_Head _this_is_not_used;
-        PyObject_VAR_HEAD
-        PyObject *ob_item[NUM_KEYWORDS];
-    } _kwtuple = {
-        .ob_base = PyVarObject_HEAD_INIT(&PyTuple_Type, NUM_KEYWORDS)
-        .ob_item = { &_Py_ID(stacklevel), },
-    };
-    #undef NUM_KEYWORDS
-    #define KWTUPLE (&_kwtuple.ob_base.ob_base)
-
-    #else  // !Py_BUILD_CORE
-    #  define KWTUPLE NULL
-    #endif  // !Py_BUILD_CORE
-
-    static const char * const _keywords[] = {"stacklevel", NULL};
-    static _PyArg_Parser _parser = {
-        .keywords = _keywords,
-        .fname = "_get_event_loop",
-        .kwtuple = KWTUPLE,
-    };
-    #undef KWTUPLE
-    PyObject *argsbuf[1];
-    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
-    int stacklevel = 3;
-
-    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 1, 0, argsbuf);
-    if (!args) {
-        goto exit;
-    }
-    if (!noptargs) {
-        goto skip_optional_pos;
-    }
-    stacklevel = _PyLong_AsInt(args[0]);
-    if (stacklevel == -1 && PyErr_Occurred()) {
-        goto exit;
-    }
-skip_optional_pos:
-    return_value = _asyncio__get_event_loop_impl(module, stacklevel);
-
-exit:
-    return return_value;
-}
-
 PyDoc_STRVAR(_asyncio_get_running_loop__doc__,
 "get_running_loop($module, /)\n"
 "--\n"
@@ -1304,4 +1242,4 @@ _asyncio__leave_task(PyObject *module, PyObject *const *args, Py_ssize_t nargs,
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=550bc6603df89ed9 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=83580c190031241c input=a9049054013a1b77]*/