bpo-1635741: Fix unicode_dealloc() for mortal interned string#21270
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When unicode_dealloc() is called on a mortal interned string, the string reference counter is now reset at zero, rather than leaking one reference.
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vstinner commented Jul 1, 2020
| PyDict_DelItem(). */ | ||
| assert(Py_REFCNT(unicode) ==0); | ||
| Py_SET_REFCNT(unicode, 3); | ||
| if (PyDict_DelItem(interned, unicode) !=0){ |
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Can we skip PyDict_DelItem() and set interned unicode's refcnt = 0 directly in here?
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We cannot remove the PyDict_DelItem() call.
PyUnicode_InternInPlace() uses black magic: it ignores 2 references (key and value) of the interned dictionary.
We must remove the string from the interned dictionary. Otherwise, the dictionary will contain a dangling pointer when unicode_dealloc() completes: using the dict is likely to crash in this case.
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vstinner commented Jul 3, 2020
Technically, this change is mostly a cleanup, since the object is destroyed anyway a few lines below. |
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When unicode_dealloc() is called on a mortal interned string, the
string reference counter is now reset at zero, rather than leaking
one reference.
https://bugs.python.org/issue1635741