Deprecate concurrency.run_until_first_complete

setup.cfg

@@ -29,6 +29,7 @@ filterwarnings=
     ignore: The 'variables' alias has been deprecated. Please use 'variable_values' instead\.:DeprecationWarning
     # Workaround for Python 3.9.7 (see https://bugs.python.org/issue45097)
     ignore:The loop argument is deprecated since Python 3\.8, and scheduled for removal in Python 3\.10\.:DeprecationWarning:asyncio
+    ignore: run_until_first_complete is deprecated and will be removed in a future version.:DeprecationWarning
 
 [coverage:run]
 source_pkgs = starlette, tests

starlette/concurrency.py

@@ -1,6 +1,7 @@
 import functools
 import sys
 import typing
+import warnings
 
 import anyio
 
@@ -20,6 +21,12 @@
 
 
 async def run_until_first_complete(*args: typing.Tuple[typing.Callable, dict]) -> None:
+    warnings.warn(
+        "run_until_first_complete is deprecated "
+        "and will be removed in a future version.",
+        DeprecationWarning,
+    )
+
     async with anyio.create_task_group() as task_group:
 
         async def run(func: typing.Callable[[], typing.Coroutine]) -> None: