Swift 5.0 Method Internals Unearthed

So far, we've been looking at a simple program to try to see how methods are defined internally in compiled Swift 5.0 programs. In our simple example, essentially a hello world example printing from a small class, we have been able to find the class definition itself but we haven't been able to see where the methods are defined. We traced through the compiled program and found this:

__objc_class__TtC9swift_cmd7Printer_data:
0000000100002120 struct __objc_data {
  0x80, // flags
  16, // instance start
  32, // instance size
  0x0,
  0x0, // ivar layout
  aTtc9swiftcmd7p, // name
  0x0, // base methods
  0x0, // base protocols
  __objc_class__TtC9swift_cmd7Printer_ivars, // ivars
  0x0, // weak ivar layout
  0x0 // base properties
  }

But it doesn't have any associated method definitions. In Objective-C, there's a list of method descriptors that contain pointers to functions, so we expected to find the same thing here. We didn't.

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