As Victor noted, inventing our own encoding scheme just for this use case
isn't desirable, although it's certainly a good fallback option that will
ensure the feature remains feasible even if trying to handle the Unicode
issues at the C compiler level proves too challenging.

The other aspect is that changes to the extension module initialisation API
always need to go into a PEP regardless, since we need to ensure such
changes are usable for both handwritten extensions and extension module
generators like Cython, cffi and SWIG.