c++gccg++

Dump class/struct member variables in g++

Is there a flag in g++ or tools to dump the member variables of a struct/class? To illustrate, consider source code like this

struct A { virtual void m() {}; };
struct B : public A { int b; virtual void n() = 0; };
struct C : public B { int c1, c2; void o(); };
struct D : public C { virtual void n() {}; A d; };

I want to get something similar to

A:   0 = (vptr)

B:   0 = (vptr)
     4 = b

C:   0 = (vptr)
     4 = b
     8 = c1
    12 = c2

D:   0 = (vptr)
     4 = b
     8 = c1
    12 = c2
    16 = d

(-fdump-class-hierarchy does not work. It only prints the member functions.)

(Assume I don't know the classes A to D, or there are so many classes that I don't want to list them out myself.)

(Specifically, I want to dump the member variables of https://github.com/apple-oss-distributions/xnu/blob/xnu-1456.1.26/iokit/IOKit/IOUserClient.h).

Solution

  • Use the right tool for the right job. g++ isn't much of a hierarchy viewing tool.

    You can always use a external tool like doxygen, that can dump graphviz diagrams.

    For power-solutions there is gcc-xml, that can dump your whole program into an xml file that you can parse at will.