From a97f905edd2f0d36c715313d12b879f036e3b554 Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Sun, 24 Aug 2025 19:38:11 -0500
Subject: [PATCH 01/13] Define `trio.Event.__bool__()` to reduce bugs

Closes #3238
---
 src/trio/_sync.py | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index ca373922b0..6f46245e31 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import math
-from typing import TYPE_CHECKING, Protocol
+from typing import TYPE_CHECKING, NoReturn, Protocol
 
 import attrs
 
@@ -112,6 +112,14 @@ def statistics(self) -> EventStatistics:
         """
         return EventStatistics(tasks_waiting=len(self._tasks))
 
+    if not TYPE_CHECKING:
+
+        def __bool__(self) -> NoReturn:
+            """Raise NotImplementedError."""
+            raise NotImplementedError(
+                "Trio events cannot be treated as bools; consider using 'event.is_set()'"
+            )
+
 
 class _HasAcquireRelease(Protocol):
     """Only classes with acquire() and release() can use the mixin's implementations."""

From 24a8f08bf8eb3245b0d2611054bb9c61d06c1da3 Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Sun, 24 Aug 2025 20:46:05 -0500
Subject: [PATCH 02/13] Don't do if type checking block, jedi doesn't like that

---
 src/trio/_sync.py | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index 6f46245e31..e5c5725c4d 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -112,13 +112,11 @@ def statistics(self) -> EventStatistics:
         """
         return EventStatistics(tasks_waiting=len(self._tasks))
 
-    if not TYPE_CHECKING:
-
-        def __bool__(self) -> NoReturn:
-            """Raise NotImplementedError."""
-            raise NotImplementedError(
-                "Trio events cannot be treated as bools; consider using 'event.is_set()'"
-            )
+    def __bool__(self) -> NoReturn:
+        """Raise NotImplementedError."""
+        raise NotImplementedError(
+            "Trio events cannot be treated as bools; consider using 'event.is_set()'"
+        )
 
 
 class _HasAcquireRelease(Protocol):

From 1ea6615510616b4f0b447b93dedd670c526f7e94 Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Sun, 24 Aug 2025 22:10:19 -0500
Subject: [PATCH 03/13] Switch to deprecated warning

---
 src/trio/_sync.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index e5c5725c4d..e95ae05374 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import math
-from typing import TYPE_CHECKING, NoReturn, Protocol
+from typing import TYPE_CHECKING, Protocol
 
 import attrs
 
@@ -16,6 +16,7 @@
     enable_ki_protection,
     remove_parking_lot_breaker,
 )
+from ._depreciate import warn_deprecated
 from ._util import final
 
 if TYPE_CHECKING:
@@ -112,11 +113,16 @@ def statistics(self) -> EventStatistics:
         """
         return EventStatistics(tasks_waiting=len(self._tasks))
 
-    def __bool__(self) -> NoReturn:
-        """Raise NotImplementedError."""
-        raise NotImplementedError(
-            "Trio events cannot be treated as bools; consider using 'event.is_set()'"
+    def __bool__(self) -> True:
+        """Return True and raise warning."""
+        warn_deprecated(
+            self.__bool__,
+            "0.30.1",
+            issue=3238,
+            instead=self.is_set,
+            use_triodeprecationwarning=True,
         )
+        return True
 
 
 class _HasAcquireRelease(Protocol):

From 68a4fad041414dc89dea264cea044a45d04d597f Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Mon, 25 Aug 2025 09:25:15 -0500
Subject: [PATCH 04/13] Don't use trio's deprecated warning, add test, add
 newsfragment

---
 newsfragments/3322.deprecated.txt | 1 +
 src/trio/_sync.py                 | 3 +--
 src/trio/_tests/test_sync.py      | 6 ++++++
 3 files changed, 8 insertions(+), 2 deletions(-)
 create mode 100644 newsfragments/3322.deprecated.txt

diff --git a/newsfragments/3322.deprecated.txt b/newsfragments/3322.deprecated.txt
new file mode 100644
index 0000000000..ca920129e2
--- /dev/null
+++ b/newsfragments/3322.deprecated.txt
@@ -0,0 +1 @@
+Implement `trio.Event.__bool__` and have it raise a `DeprecationWarning` and tell users to use `trio.Event.is_set` instead. Would be caught earlier with `mypy --enable-error-code=truthy-bool`, this is for users who don't use mypy.
diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index e95ae05374..8aac8528b1 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -16,7 +16,7 @@
     enable_ki_protection,
     remove_parking_lot_breaker,
 )
-from ._depreciate import warn_deprecated
+from ._deprecate import warn_deprecated
 from ._util import final
 
 if TYPE_CHECKING:
@@ -120,7 +120,6 @@ def __bool__(self) -> True:
             "0.30.1",
             issue=3238,
             instead=self.is_set,
-            use_triodeprecationwarning=True,
         )
         return True
 
diff --git a/src/trio/_tests/test_sync.py b/src/trio/_tests/test_sync.py
index 39f8d21f38..92655bbbc1 100644
--- a/src/trio/_tests/test_sync.py
+++ b/src/trio/_tests/test_sync.py
@@ -23,6 +23,12 @@ async def test_Event() -> None:
     assert not e.is_set()
     assert e.statistics().tasks_waiting == 0
 
+    with pytest.warns(
+        DeprecationWarning,
+        match=r"trio\.Event\.__bool__ is deprecated since Trio 0\.30\.1; use trio\.Event\.is_set instead \(https://github.com/python-trio/trio/issues/3238\)",
+    ):
+        e.__bool__()
+
     e.set()
     assert e.is_set()
     with assert_checkpoints():

From 93950f21531fb98766726529bcba6fb9bce9514d Mon Sep 17 00:00:00 2001
From: A5rocks <git@helvetica.moe>
Date: Tue, 26 Aug 2025 02:04:13 +0900
Subject: [PATCH 05/13] Apply suggestions from code review

---
 newsfragments/3322.deprecated.txt | 2 +-
 src/trio/_sync.py                 | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/newsfragments/3322.deprecated.txt b/newsfragments/3322.deprecated.txt
index ca920129e2..0e1b69f32b 100644
--- a/newsfragments/3322.deprecated.txt
+++ b/newsfragments/3322.deprecated.txt
@@ -1 +1 @@
-Implement `trio.Event.__bool__` and have it raise a `DeprecationWarning` and tell users to use `trio.Event.is_set` instead. Would be caught earlier with `mypy --enable-error-code=truthy-bool`, this is for users who don't use mypy.
+Implement ``bool(trio.Event)`` and have it raise a `DeprecationWarning` and tell users to use `trio.Event.is_set` instead. This is an alternative to ``mypy --enable-error-code=truthy-bool`` for users who don't use type checking.
diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index 8aac8528b1..2463188588 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -113,7 +113,7 @@ def statistics(self) -> EventStatistics:
         """
         return EventStatistics(tasks_waiting=len(self._tasks))
 
-    def __bool__(self) -> True:
+    def __bool__(self) -> Literal[True]:
         """Return True and raise warning."""
         warn_deprecated(
             self.__bool__,

From 68e7242b9da090b3077edf6db4a4837fdde317d5 Mon Sep 17 00:00:00 2001
From: A5rocks <git@helvetica.moe>
Date: Tue, 26 Aug 2025 02:08:23 +0900
Subject: [PATCH 06/13] Add necessary imports

---
 src/trio/_sync.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index 2463188588..4058349167 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import math
-from typing import TYPE_CHECKING, Protocol
+from typing import TYPE_CHECKING, Protocol, Literal
 
 import attrs
 

From 14e16fea4b9e47f69fec48ca2081bbe1c7d5bd32 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Mon, 25 Aug 2025 17:08:39 +0000
Subject: [PATCH 07/13] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 src/trio/_sync.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index 4058349167..89e49d6187 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import math
-from typing import TYPE_CHECKING, Protocol, Literal
+from typing import TYPE_CHECKING, Literal, Protocol
 
 import attrs
 

From 3b14df291c3cfb3ab6c8b32b221da92cd4491492 Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Mon, 25 Aug 2025 17:05:28 -0500
Subject: [PATCH 08/13] Add `if not TYPE_CHECKING`

---
 src/trio/_sync.py            | 20 +++++++++++---------
 src/trio/_tests/test_sync.py |  2 +-
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index 89e49d6187..eddf0094a1 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -113,15 +113,17 @@ def statistics(self) -> EventStatistics:
         """
         return EventStatistics(tasks_waiting=len(self._tasks))
 
-    def __bool__(self) -> Literal[True]:
-        """Return True and raise warning."""
-        warn_deprecated(
-            self.__bool__,
-            "0.30.1",
-            issue=3238,
-            instead=self.is_set,
-        )
-        return True
+    if not TYPE_CHECKING:
+
+        def __bool__(self) -> Literal[True]:
+            """Return True and raise warning."""
+            warn_deprecated(
+                self.__bool__,
+                "0.31.0",
+                issue=3238,
+                instead=self.is_set,
+            )
+            return True
 
 
 class _HasAcquireRelease(Protocol):
diff --git a/src/trio/_tests/test_sync.py b/src/trio/_tests/test_sync.py
index 92655bbbc1..6096510d3f 100644
--- a/src/trio/_tests/test_sync.py
+++ b/src/trio/_tests/test_sync.py
@@ -25,7 +25,7 @@ async def test_Event() -> None:
 
     with pytest.warns(
         DeprecationWarning,
-        match=r"trio\.Event\.__bool__ is deprecated since Trio 0\.30\.1; use trio\.Event\.is_set instead \(https://github.com/python-trio/trio/issues/3238\)",
+        match=r"trio\.Event\.__bool__ is deprecated since Trio 0\.31\.0; use trio\.Event\.is_set instead \(https://github.com/python-trio/trio/issues/3238\)",
     ):
         e.__bool__()
 

From 4347db2244465558857d7d085560b6bf6b971c79 Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Mon, 25 Aug 2025 17:09:24 -0500
Subject: [PATCH 09/13] Revert and use `typing_extensions.deprecated` instead

---
 pyproject.toml    |  2 ++
 src/trio/_sync.py | 22 +++++++++++-----------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/pyproject.toml b/pyproject.toml
index bec87cfef0..8241677bcd 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -50,6 +50,8 @@ dependencies = [
     # cffi is required on Windows, except on PyPy where it is built-in
     "cffi>=1.14; os_name == 'nt' and implementation_name != 'pypy'",
     "exceptiongroup; python_version < '3.11'",
+    # using typing_extensions.depreciated in _sync.py
+    "typing_extensions >= 4.15.0",
 ]
 dynamic = ["version"]
 
diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index eddf0094a1..ec698992b3 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -4,6 +4,7 @@
 from typing import TYPE_CHECKING, Literal, Protocol
 
 import attrs
+from typing_extensions import deprecated
 
 import trio
 
@@ -113,17 +114,16 @@ def statistics(self) -> EventStatistics:
         """
         return EventStatistics(tasks_waiting=len(self._tasks))
 
-    if not TYPE_CHECKING:
-
-        def __bool__(self) -> Literal[True]:
-            """Return True and raise warning."""
-            warn_deprecated(
-                self.__bool__,
-                "0.31.0",
-                issue=3238,
-                instead=self.is_set,
-            )
-            return True
+    @deprecated
+    def __bool__(self) -> Literal[True]:
+        """Return True and raise warning."""
+        warn_deprecated(
+            self.__bool__,
+            "0.31.0",
+            issue=3238,
+            instead=self.is_set,
+        )
+        return True
 
 
 class _HasAcquireRelease(Protocol):

From 2a723ffacdb67c5f699064d446e65c57d82a8ae7 Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Mon, 25 Aug 2025 17:23:55 -0500
Subject: [PATCH 10/13] Add `typing_extensions` to requirements

---
 test-requirements.in  | 1 +
 test-requirements.txt | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/test-requirements.in b/test-requirements.in
index 90776153c4..1c33b6522c 100644
--- a/test-requirements.in
+++ b/test-requirements.in
@@ -8,6 +8,7 @@ trustme               # for the ssl + DTLS tests
 pylint                # for pylint finding all symbols tests
 jedi; implementation_name == "cpython"                  # for jedi code completion tests
 cryptography>=41.0.0  # cryptography<41 segfaults on pypy3.10
+typing_extensions >= 4.15.0
 
 # Tools
 black; implementation_name == "cpython"
diff --git a/test-requirements.txt b/test-requirements.txt
index 3d12554ce6..c11c47e7af 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -187,7 +187,7 @@ types-pyyaml==6.0.12.20250822
     # via -r test-requirements.in
 types-setuptools==80.9.0.20250822
     # via types-cffi
-typing-extensions==4.14.1
+typing-extensions==4.15.0
     # via
     #   -r test-requirements.in
     #   astroid

From e34ce248d6d1713a1986d13c93f2f49dda457228 Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Mon, 25 Aug 2025 17:29:56 -0500
Subject: [PATCH 11/13] Add message properly

---
 src/trio/_sync.py    | 5 ++++-
 test-requirements.in | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index ec698992b3..0744f2cea7 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -114,7 +114,10 @@ def statistics(self) -> EventStatistics:
         """
         return EventStatistics(tasks_waiting=len(self._tasks))
 
-    @deprecated
+    @deprecated(
+        "trio.Event.__bool__ is deprecated since Trio 0.31.0, use trio.Event.is_set instead (https://github.com/python-trio/trio/issues/3238)",
+        stacklevel=2,
+    )
     def __bool__(self) -> Literal[True]:
         """Return True and raise warning."""
         warn_deprecated(
diff --git a/test-requirements.in b/test-requirements.in
index 1c33b6522c..21ae962140 100644
--- a/test-requirements.in
+++ b/test-requirements.in
@@ -8,7 +8,6 @@ trustme               # for the ssl + DTLS tests
 pylint                # for pylint finding all symbols tests
 jedi; implementation_name == "cpython"                  # for jedi code completion tests
 cryptography>=41.0.0  # cryptography<41 segfaults on pypy3.10
-typing_extensions >= 4.15.0
 
 # Tools
 black; implementation_name == "cpython"
@@ -40,3 +39,4 @@ outcome
 sniffio
 # 1.2.1 fixes types
 exceptiongroup >= 1.2.1; python_version < "3.11"
+typing_extensions >= 4.15.0

From c3a0a762c343e5e4876725da18714bc79f38314f Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Mon, 25 Aug 2025 17:40:22 -0500
Subject: [PATCH 12/13] `,` -> `;`

---
 src/trio/_sync.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index 0744f2cea7..03d2c0cc4a 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -115,7 +115,7 @@ def statistics(self) -> EventStatistics:
         return EventStatistics(tasks_waiting=len(self._tasks))
 
     @deprecated(
-        "trio.Event.__bool__ is deprecated since Trio 0.31.0, use trio.Event.is_set instead (https://github.com/python-trio/trio/issues/3238)",
+        "trio.Event.__bool__ is deprecated since Trio 0.31.0; use trio.Event.is_set instead (https://github.com/python-trio/trio/issues/3238)",
         stacklevel=2,
     )
     def __bool__(self) -> Literal[True]:

From 02c3794913a04a030f1f2ea76fb67b69abd90c3c Mon Sep 17 00:00:00 2001
From: CoolCat467 <52022020+CoolCat467@users.noreply.github.com>
Date: Mon, 25 Aug 2025 20:29:00 -0500
Subject: [PATCH 13/13] Remove `typing_extensions` requirement

---
 pyproject.toml       |  2 --
 src/trio/_sync.py    | 20 ++++++++++++++++++--
 test-requirements.in |  1 -
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/pyproject.toml b/pyproject.toml
index 8241677bcd..bec87cfef0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -50,8 +50,6 @@ dependencies = [
     # cffi is required on Windows, except on PyPy where it is built-in
     "cffi>=1.14; os_name == 'nt' and implementation_name != 'pypy'",
     "exceptiongroup; python_version < '3.11'",
-    # using typing_extensions.depreciated in _sync.py
-    "typing_extensions >= 4.15.0",
 ]
 dynamic = ["version"]
 
diff --git a/src/trio/_sync.py b/src/trio/_sync.py
index 03d2c0cc4a..d026f4bc37 100644
--- a/src/trio/_sync.py
+++ b/src/trio/_sync.py
@@ -1,10 +1,9 @@
 from __future__ import annotations
 
 import math
-from typing import TYPE_CHECKING, Literal, Protocol
+from typing import TYPE_CHECKING, Literal, Protocol, TypeVar
 
 import attrs
-from typing_extensions import deprecated
 
 import trio
 
@@ -21,10 +20,27 @@
 from ._util import final
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
     from types import TracebackType
 
+    from typing_extensions import deprecated
+
     from ._core import Task
     from ._core._parking_lot import ParkingLotStatistics
+else:
+    T = TypeVar("T")
+
+    def deprecated(
+        message: str,
+        /,
+        *,
+        category: type[Warning] | None = DeprecationWarning,
+        stacklevel: int = 1,
+    ) -> Callable[[T], T]:
+        def wrapper(f: T) -> T:
+            return f
+
+        return wrapper
 
 
 @attrs.frozen
diff --git a/test-requirements.in b/test-requirements.in
index 21ae962140..90776153c4 100644
--- a/test-requirements.in
+++ b/test-requirements.in
@@ -39,4 +39,3 @@ outcome
 sniffio
 # 1.2.1 fixes types
 exceptiongroup >= 1.2.1; python_version < "3.11"
-typing_extensions >= 4.15.0