Bump version to 0.34.0

docs/source/history.rst

@@ -5,6 +5,41 @@ Release history
 
 .. towncrier release notes start
 
+trio 0.34.0 (2026-08-10)
+------------------------
+
+Features
+~~~~~~~~
+
+- `MemoryChannelStatistics` now has a ``peak_buffer_used`` field, which reports
+  the largest number of items that have ever been in the channel's buffer at
+  once. This makes it easier to pick a sensible ``max_buffer_size`` based on
+  data from a real run, instead of guessing. (`#1723 <https://github.com/python-trio/trio/issues/1723>`__)
+- Support Python 3.15, as of beta 4. Things may still change and so this
+  support may break in the future. (`#3456 <https://github.com/python-trio/trio/issues/3456>`__)
+
+
+Bugfixes
+~~~~~~~~
+
+- ``Nursery.start()`` now preserves the ``__cause__`` and ``__context__`` of
+  exceptions raised before ``task_status.started()`` is called. (`#3261 <https://github.com/python-trio/trio/issues/3261>`__)
+- Fixed incorrect error message in ``run_process``: the ``stdout`` pipe check now correctly says "stdout" instead of "stdin". (`#3409 <https://github.com/python-trio/trio/issues/3409>`__)
+- Fixed ``trio.Path.as_uri()`` on Python 3.14+ to avoid the deprecated ``pathlib.PurePath.as_uri()`` path. (`#3460 <https://github.com/python-trio/trio/issues/3460>`__)
+- Fixed ``trio.to_thread.run_sync``` workers leaking spawner's ``Context`` on ``py314t+`` free-threaded builds. (`#3472 <https://github.com/python-trio/trio/issues/3472>`__)
+
+
+Deprecations and removals
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+- Trying to use absolute deadlines on a `trio.CancelScope` constructed
+  with a relative deadline now raises, after being deprecated since Trio
+  0.27.0.
+
+  To switch a cancel scope from being relative to absolute, replace the
+  `trio.CancelScope` object instead of trying to mutate it. (`#3403 <https://github.com/python-trio/trio/issues/3403>`__)
+
+
 trio 0.33.0 (2026-02-14)
 ------------------------
 

src/trio/_core/_tests/test_asyncgen.py

@@ -278,7 +278,7 @@ async def test_fallback_when_no_hook_claims_it(
     async def well_behaved() -> AsyncGenerator[int, None]:
         yield 42
 
-    # noqas because we *want* to test delayed yield/await!
+    # these noqas are because we *want* to test delayed yield/await!
     async def yields_after_yield() -> AsyncGenerator[int, None]:
         with pytest.raises(GeneratorExit):
             yield 42  # noqa: ASYNC119

src/trio/_sync.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import math
-from typing import TYPE_CHECKING, Literal, Protocol, TypeVar
+from typing import TYPE_CHECKING, Literal, Protocol
 
 import attrs
 
@@ -16,31 +16,13 @@
     enable_ki_protection,
     remove_parking_lot_breaker,
 )
-from ._deprecate import warn_deprecated
 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
@@ -130,19 +112,11 @@ 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)",
-        stacklevel=2,
-    )
     def __bool__(self) -> Literal[True]:
-        """Return True and raise warning."""
-        warn_deprecated(
-            self.__bool__,
-            "0.31.0",
-            issue=3238,
-            instead=self.is_set,
+        """Raise error."""
+        raise NotImplementedError(
+            "Trio events cannot be treated as bools; consider using `event.is_set()` instead."
         )
-        return True
 
 
 class _HasAcquireRelease(Protocol):

src/trio/_tests/test_sync.py

@@ -19,10 +19,7 @@ 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\.31\.0; use trio\.Event\.is_set instead \(https://github.com/python-trio/trio/issues/3238\)",
-    ):
+    with pytest.raises(NotImplementedError):
         e.__bool__()
 
     e.set()

src/trio/_version.py

@@ -1,3 +1,3 @@
 # This file is imported from __init__.py and parsed by setuptools
 
-__version__ = "0.33.0+dev"
+__version__ = "0.34.0+dev"