__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

Lisez d’abord gh-118532 et gh-118157, en vous concentrant sur _testsinglephase, le dict mis en cache et sa valeur file. Reproduisez l’échec du refcount sur la branche main de CPython, déterminez où l’incref manquant se produit et confirmez que le fix fonctionne sans le refleak du workaround, afin que l’interning puisse être supprimé.