__file__ for Some Dynamic Extension Modules has a Broken Refcount

Bug report

Bug description:

In gh-118532 I was getting crashes when the _testsinglephase module's cached copy of __dict__ was finalized. I worked around it in that PR by doing an unconditional incref, but that introduced a refleak for other cases. At the time, I wasn't able to determine if gh-118532 was the source of the refcount problem or if it only exposed an existing problem.

While working on gh-118157 I narrowed the problem down to the __file__ value in the cached __dict__ and resolved it by interning the string. However, the underlying problem remains: somewhere along the line there seems to be a missing incref.

That needs to be located and fixed, and then the interning can be dropped.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Trước tiên, hãy đọc gh-118532 và gh-118157, tập trung vào _testsinglephase, dict được lưu trong bộ nhớ đệm và giá trị file của nó. Tái hiện lỗi refcount trên main branch của CPython, truy vết nơi xảy ra incref bị thiếu và xác nhận rằng fix hoạt động mà không có refleak của workaround, để có thể loại bỏ interning.