Unfortunately, historically GCC used to have a number of bugs in its encoding code. The NeXT runtime expects GCC to emit type encodings in this historical format (compatible with GCC-3.3), so when using the NeXT runtime, GCC will introduce on purpose a number of incorrect encodings:
enum
s are always encoded as ’i’ (int) even if they are actually unsigned or long. In addition to that, the NeXT runtime uses a different encoding for bitfields. It encodes them as b
followed by the size, without a bit offset or the underlying field type.
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https://gcc.gnu.org/onlinedocs/gcc-7.3.0/gcc/Legacy-type-encoding.html