[3.11] gh-110378: Close invalid generators in contextmanager and asynccontextmanager...

contextmanager and asynccontextmanager context managers now close an invalid
underlying generator object that yields more then one value.
(cherry picked from commit 96fed66a65097eac2dc528ce29c9ba676bb07689)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Co-authored-by: Łukasz Langa <lukasz@langa.pl>

diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index 58e9a498878d01b2eaaf18fd5d497248720e43d9..4a338f5c637db5f6cac09892cb0f63bd505d0293 100644 (file)
--- a/Lib/contextlib.py
+++ b/Lib/contextlib.py
@@ -145,7 +145,10 @@ class _GeneratorContextManager(
             except StopIteration:
                 return False
             else:
-                raise RuntimeError("generator didn't stop")
+                try:
+                    raise RuntimeError("generator didn't stop")
+                finally:
+                    self.gen.close()
         else:
             if value is None:
                 # Need to force instantiation so we can reliably
@@ -187,7 +190,10 @@ class _GeneratorContextManager(
                     raise
                 exc.__traceback__ = traceback
                 return False
-            raise RuntimeError("generator didn't stop after throw()")
+            try:
+                raise RuntimeError("generator didn't stop after throw()")
+            finally:
+                self.gen.close()
 
 class _AsyncGeneratorContextManager(
     _GeneratorContextManagerBase,
@@ -212,7 +218,10 @@ class _AsyncGeneratorContextManager(
             except StopAsyncIteration:
                 return False
             else:
-                raise RuntimeError("generator didn't stop")
+                try:
+                    raise RuntimeError("generator didn't stop")
+                finally:
+                    await self.gen.aclose()
         else:
             if value is None:
                 # Need to force instantiation so we can reliably
@@ -254,7 +263,10 @@ class _AsyncGeneratorContextManager(
                     raise
                 exc.__traceback__ = traceback
                 return False
-            raise RuntimeError("generator didn't stop after athrow()")
+            try:
+                raise RuntimeError("generator didn't stop after athrow()")
+            finally:
+                await self.gen.aclose()
 
 
 def contextmanager(func):

diff --git a/Lib/test/test_contextlib.py b/Lib/test/test_contextlib.py
index ec06785b5667a6c1d3e9cc5a7fa7f5a8e4726b88..093f2593a4a464b0e89ab634c4842b0a8c8f8ccc 100644 (file)
--- a/Lib/test/test_contextlib.py
+++ b/Lib/test/test_contextlib.py
@@ -156,9 +156,24 @@ class ContextManagerTestCase(unittest.TestCase):
                 yield
         ctx = whoo()
         ctx.__enter__()
-        self.assertRaises(
-            RuntimeError, ctx.__exit__, TypeError, TypeError("foo"), None
-        )
+        with self.assertRaises(RuntimeError):
+            ctx.__exit__(TypeError, TypeError("foo"), None)
+        if support.check_impl_detail(cpython=True):
+            # The "gen" attribute is an implementation detail.
+            self.assertFalse(ctx.gen.gi_suspended)
+
+    def test_contextmanager_trap_second_yield(self):
+        @contextmanager
+        def whoo():
+            yield
+            yield
+        ctx = whoo()
+        ctx.__enter__()
+        with self.assertRaises(RuntimeError):
+            ctx.__exit__(None, None, None)
+        if support.check_impl_detail(cpython=True):
+            # The "gen" attribute is an implementation detail.
+            self.assertFalse(ctx.gen.gi_suspended)
 
     def test_contextmanager_except(self):
         state = []

diff --git a/Misc/NEWS.d/next/Library/2023-10-07-13-50-12.gh-issue-110378.Y4L8fl.rst b/Misc/NEWS.d/next/Library/2023-10-07-13-50-12.gh-issue-110378.Y4L8fl.rst
new file mode 100644 (file)
index 0000000..ef5395f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-10-07-13-50-12.gh-issue-110378.Y4L8fl.rst
@@ -0,0 +1,3 @@
+:func:`~contextlib.contextmanager` and
+:func:`~contextlib.asynccontextmanager` context managers now close an invalid
+underlying generator object that yields more then one value.