This was my fault for recommending PyErr_SetFromWindowsErrWithUnicodeFilename without checking the header for deprecation. 

PyErr_SetFromWindowsErrWithUnicodeFilename is an internal function (added for PEP 277, circa 2.4), which was never documented in the C API. I don't follow why Serhiy deprecated it in 2016, since at the same time he updated it to use PyUnicode_FromWideChar instead of PyUnicode_FromUnicode. I see no fundamental difference in terms of resource usage between it and PyErr_SetExcFromWindowsErrWithFilename, which instead calls PyUnicode_DecodeFSDefault.

In this case, the section object (file mapping) name is useful information in the exception. If the deprecation isn't lifted, it puts the onus on us to implement this functionality -- i.e. PyUnicode_FromWideChar, PyErr_SetExcFromWindowsErrWithFilenameObjects, Py_XDECREF. Or maybe add a new PyErr_SetExcFromWindowsErrWithWideCharFilename function that takes a `const wchar_t *` string, and document it in the C API.