[3.12] 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>

diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index b5acbcb9e6d77cfe5bf1f42fa14905b4d6ae53fb..2efed2d9ec47425605fbb4639cc848566441d465 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 0f8351ab8108a64f587d41218a45975efbd8e272..b15829414e5dbba29316afab1b97dc4968f11dd9 100644 (file)
--- a/Lib/test/test_contextlib.py
+++ b/Lib/test/test_contextlib.py
@@ -157,9 +157,24 @@ 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/Lib/test/test_contextlib_async.py b/Lib/test/test_contextlib_async.py
index 3d43ed0fcab1686764695443185509a3686d3738..e519dffee78b44a771b9154affe14dab89187d2b 100644 (file)
--- a/Lib/test/test_contextlib_async.py
+++ b/Lib/test/test_contextlib_async.py
@@ -204,6 +204,9 @@ class AsyncContextManagerTestCase(unittest.TestCase):
         await ctx.__aenter__()
         with self.assertRaises(RuntimeError):
             await ctx.__aexit__(TypeError, TypeError('foo'), None)
+        if support.check_impl_detail(cpython=True):
+            # The "gen" attribute is an implementation detail.
+            self.assertFalse(ctx.gen.ag_suspended)
 
     @_async_test
     async def test_contextmanager_trap_no_yield(self):
@@ -225,6 +228,9 @@ class AsyncContextManagerTestCase(unittest.TestCase):
         await ctx.__aenter__()
         with self.assertRaises(RuntimeError):
             await ctx.__aexit__(None, None, None)
+        if support.check_impl_detail(cpython=True):
+            # The "gen" attribute is an implementation detail.
+            self.assertFalse(ctx.gen.ag_suspended)
 
     @_async_test
     async def test_contextmanager_non_normalised(self):

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.