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Mac OS X Fragile Compatibility
Is your feature request related to a problem? Please describe.
The current implementation of go-macho only properly supports the non-fragile version of the Mac OS X Objective-C Runtime. Code that targeting the fragile version of the runtime may not be parsed correctly. In clang, the runtime can be defined through the -fobjc-runtime=${OBJC_RUNTIME} flag (https://clang.llvm.org/doxygen/classclang_1_1ObjCRuntime.html#af19fe070a7073df4ecc666b44137c4e5).
Describe the solution you'd like
Have a solution that is able to handle both runtime variants. If possible to distinguish the runtime used from the binary, implement full support, otherwise prioritize compatibility with the non-fragile runtime.
Describe alternatives you've considered
Not implement support for the Mac OS X Fragile Runtime and explicitly state that go-macho support the non-fragile runtime only. If possible, reject or warn about binaries using incompatible runtimes.
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Additional context
No response
Take a look at these files, I've complied them with gcc for all architectures supported during the transition from PowerPC to Intel. class-dump is able to parse the gcc-compiled binaries without a problem, but go-macho fails with different errors.
I also compiled the same thing with the latest version clang using different Objective-C runtimes. Strangely, even when using the default Objective-C runtime, go-macho is failing to decode types.
Btw, I was under the impression that older versions of Xcode used the GNU runtime by default, but that's not the case. On those versions, Xcode uses what LLVM calls the Mac OS X Fragile runtime. I couldn't make clang or gcc use runtimes that were not NeXT-like. It looks like no one ever bothered to support GNU-like runtimes on macOS, I've only been able to use them on Linux. But since those binaries are ELFs not Mach-Os, supporting them is definitely out of the scope of this project and we should focus on the NeXT-like runtimes.
Actually, I just figured out the ObjFW Runtime has a compiler of its own and was able to use it on macOS. It doesn't support cross-compilation though, so I could only generate binaries for Intel and Apple Silicon.
For extra reference, sharing two binaries from the Mac OS X 10.0 Public Beta. I think they will be the worst case we will ever see. go-macho, MachOExplorer, and MachOView have no idea how to parse them, but class-dump is able to process these binaries normally.