bpo-34793: Drop old-style context managers in asyncio.locks (GH-17533)

Lib/asyncio/locks.py

@@ -3,96 +3,13 @@
 __all__ = ('Lock', 'Event', 'Condition', 'Semaphore', 'BoundedSemaphore')
 
 import collections
-import types
 import warnings
 
 from . import events
-from . import futures
 from . import exceptions
-from .import coroutines
-
-
-class _ContextManager:
-    """Context manager.
-
-    This enables the following idiom for acquiring and releasing a
-    lock around a block:
-
-        with (yield from lock):
-            <block>
-
-    while failing loudly when accidentally using:
-
-        with lock:
-            <block>
-
-    Deprecated, use 'async with' statement:
-        async with lock:
-            <block>
-    """
-
-    def __init__(self, lock):
-        self._lock = lock
-
-    def __enter__(self):
-        # We have no use for the "as ..."  clause in the with
-        # statement for locks.
-        return None
-
-    def __exit__(self, *args):
-        try:
-            self._lock.release()
-        finally:
-            self._lock = None  # Crudely prevent reuse.
 
 
 class _ContextManagerMixin:
-    def __enter__(self):
-        raise RuntimeError(
-            '"yield from" should be used as context manager expression')
-
-    def __exit__(self, *args):
-        # This must exist because __enter__ exists, even though that
-        # always raises; that's how the with-statement works.
-        pass
-
-    @types.coroutine
-    def __iter__(self):
-        # This is not a coroutine.  It is meant to enable the idiom:
-        #
-        #     with (yield from lock):
-        #         <block>
-        #
-        # as an alternative to:
-        #
-        #     yield from lock.acquire()
-        #     try:
-        #         <block>
-        #     finally:
-        #         lock.release()
-        # Deprecated, use 'async with' statement:
-        #     async with lock:
-        #         <block>
-        warnings.warn("'with (yield from lock)' is deprecated "
-                      "use 'async with lock' instead",
-                      DeprecationWarning, stacklevel=2)
-        yield from self.acquire()
-        return _ContextManager(self)
-
-    # The flag is needed for legacy asyncio.iscoroutine()
-    __iter__._is_coroutine = coroutines._is_coroutine
-
-    async def __acquire_ctx(self):
-        await self.acquire()
-        return _ContextManager(self)
-
-    def __await__(self):
-        warnings.warn("'with await lock' is deprecated "
-                      "use 'async with lock' instead",
-                      DeprecationWarning, stacklevel=2)
-        # To make "with await lock" work.
-        return self.__acquire_ctx().__await__()
-
     async def __aenter__(self):
         await self.acquire()
         # We have no use for the "as ..."  clause in the with