[adenzhou1350]

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Changes

No linked issue.

Avoid a cancellation checkpoint between creating a temporary directory and returning from TemporaryDirectory.__aenter__. If cancellation arrives during creation, the second worker call can raise before the async with body starts, so __aexit__ never runs and a retained manager keeps the directory until explicit cleanup or finalization.

Return the created directory's name directly, matching stdlib TemporaryDirectory.__enter__, which only returns that attribute. Pending cancellation then reaches the body's checkpoint and the existing shielded __aexit__ removes the directory. The regression cancels from the creation worker and keeps the manager alive.

Validation on native CPython 3.12.13: the regression fails on all four backend variants on both Windows and Linux without the fix; the fixed tempfile module passes 84 tests on each platform (asyncio, winloop/uvloop, eager asyncio, Trio). Changed-file Ruff 0.16.10 checks and formatting pass on Linux. Optional Blockbuster instrumentation and the full suite were not run.

This fixes acquisition, not the explicit cleanup() cancellation case covered by #1316. No API or documented usage changes.

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Fixed big bad boo-boo in task groups

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[agronholm]

Returning the name directly without to_thread.run_sync() seems sensible, but wouldn't the same issue occur with an already-cancelled scope when entering the async context manager? It would create the directory and then react to cancellation afterwards.

[adenzhou1350]

I checked this on asyncio and Trio (Python 3.12): with an already-cancelled scope, the initial to_thread.run_sync() checkpoint raises before calling the constructor (zero calls), so no directory is created.

The regression covers cancellation while the constructor is running. With the default abandon_on_cancel=False, that call returns the directory despite pending cancellation. Returning .name then lets async with enter its body; cancellation at the next checkpoint runs the shielded __aexit__. The former second run_sync(__enter__) instead raised before the body was entered, leaving cleanup dependent on the retained manager's lifetime.

[agronholm]

LGTM.