Eryk Sun added the comment:
Notes on fix-22273-02.diff:
In the second pass over _fields_, you can (should) use dict->length and
dict->proto for array types instead of the _length_ and _type_ attributes.
When reassigning stgdict->ffi_type_pointer.elements, if
use_broken_old_ctypes_semantics is false, then you also have to allocate space
for and copy the elements from the base class if any (i.e. if basedict &&
basedict->length > 0).
Regarding structs with bitfields and unions, we could add an stgdict flag to
prevent passing them as arguments in the Unix X86_64 ABI -- e.g. add a flag
named TYPEFLAG_NONARGTYPE (0x400). ConvParam (callproc.c) and
converters_from_argtypes (_ctypes.c) would raise an ArgumentError or TypeError
in this case. Subclasses of structs and unions would inherit this flag value in
StructUnionType_new.
The first pass in PyCStructUnionType_update_stgdict can set arrays_seen and
bitfields_seen. Also, per the above suggestion, isArgType can be added.
Moreover, since we don't have to worry about bitfields if we forbid passing
structs with bitfields in this ABI, then MAX_ELEMENTS can be reduced to 8. For
example:
#ifdef X86_64
#define MAX_ELEMENTS 8
isArgType = (!(stgdict->flags & TYPEFLAG_NONARGTYPE) &&
isStruct && !bitfields_seen);
if (!isArgType) {
stgdict->flags |= TYPEFLAG_NONARGTYPE;
} else if (size <= 16 && arrays_seen) {
ffi_type *actual_types[MAX_ELEMENTS + 1];
int actual_type_index = 0;
/* second pass over _fields_ */
}
This is speculative based on how we address passing unions and structs with
bitfields in the 64-bit Unix ABI. Raising a descriptive exception is at least
an improvement over abruptly aborting the process.
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue22273>
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