bpo-46752: Slight improvements to TaskGroup API (GH-31398)

* Remove task group names (for now)

We're not sure that they are needed, and once in the code
we would never be able to get rid of them.

Yury wrote:

> Ideally, there should be a way for someone to build a "trace"
> of taskgroups/task leading to the current running task.
> We could do that using contextvars, but I'm not sure we should
> do that in 3.11.

* Pass optional name on to task in create_task()

* Remove a bunch of unused stuff

Lib/asyncio/taskgroups.py

@@ -3,10 +3,6 @@
 
 __all__ = ["TaskGroup"]
 
-import itertools
-import textwrap
-import traceback
-import types
 import weakref
 
 from . import events
@@ -15,12 +11,7 @@ from . import tasks
 
 class TaskGroup:
 
-    def __init__(self, *, name=None):
-        if name is None:
-            self._name = f'tg-{_name_counter()}'
-        else:
-            self._name = str(name)
-
+    def __init__(self):
         self._entered = False
         self._exiting = False
         self._aborting = False
@@ -33,11 +24,8 @@ class TaskGroup:
         self._base_error = None
         self._on_completed_fut = None
 
-    def get_name(self):
-        return self._name
-
     def __repr__(self):
-        msg = f'<TaskGroup {self._name!r}'
+        msg = f'<TaskGroup'
         if self._tasks:
             msg += f' tasks:{len(self._tasks)}'
         if self._unfinished_tasks:
@@ -152,12 +140,13 @@ class TaskGroup:
             me = BaseExceptionGroup('unhandled errors in a TaskGroup', errors)
             raise me from None
 
-    def create_task(self, coro):
+    def create_task(self, coro, *, name=None):
         if not self._entered:
             raise RuntimeError(f"TaskGroup {self!r} has not been entered")
         if self._exiting and self._unfinished_tasks == 0:
             raise RuntimeError(f"TaskGroup {self!r} is finished")
         task = self._loop.create_task(coro)
+        tasks._set_task_name(task, name)
         task.add_done_callback(self._on_task_done)
         self._unfinished_tasks += 1
         self._tasks.add(task)
@@ -230,6 +219,3 @@ class TaskGroup:
             #                                 # after TaskGroup is finished.
             self._parent_cancel_requested = True
             self._parent_task.cancel()
-
-
-_name_counter = itertools.count(1).__next__