Feature or enhancement

The_struct module has a few small issues:

• The use ofPyDict_GetItemWithError returns a borrowed reference (should usePyDict_GetItemRef)
• Thestate->cache is lazily created; we should instead create it during_structmodule_exec
• We wantstate->cache to be an immutable reference to a mutable dict. (Thedict will be thread-safe.) UsePyDict_Clear to empty the dict instead of clearing the reference.

See the commit from thenogil-3.12 fork for context:colesbury/nogil-3.12@ada9b73feb. Note that in CPython the relevant function isPyDict_GetItemRef notPyDict_FetchItemWithError.

Linked PRs

• gh-112062: Make_struct module thread-safe in--disable-gil builds #112094