ambiguous struct fields in HPyType_Spec

[mattip]

Currently HPyType_Spec uses HPyType_BuiltinShape which is an enum and long in its typedef

hpy/hpy/devel/include/hpy/hpytype.h

Line 102 in f611473

unsigned long flags;

hpy/hpy/devel/include/hpy/hpytype.h

Line 131 in f611473

HPyType_BuiltinShape builtin_shape;

These are ambiguous since enum does not have to be int and long is 4 bytes on windows but 8 everywhere else.

Also the struct is not aligned, it needs padding around the HPyType_BuiltinShape to align on 8 bytes.

[fangerer]

Sorry, overlooked this issue.
However, I don't really understand what you mean. Do you mean that, for ABI stability, we should use fixed-width types like uint64_t or similar?

[mattip]

We should not have enum nor 'long' in publicly-facing API, since thy are not well defined. Something like uint64_t would be preferable, and would align the struct.

[fangerer]

Agreed. IIRC, we used unsigned long for flags since we first tried to make our struct compatible with CPython's PyType_Spec but we dismissed that anyway.
For the enum, we basically didn't think about that. An enum just seemed to be the right thing since there is a limited set of valid values.