symbol_clash.py

a_cpp = """#include <iostream>

namespace foo::bar {
inline namespace baz {
int inc(int x) {
  std::cout << "do inc from lib_a" << std::endl;
  return x + 1;
}
} // inline namespace baz
void do_a(int x) {
  std::cout << "inc(" << x << ") = " << inc(x) << std::endl;
}
} // namespace foo::bar
"""

b_cpp = """#include <iostream>
namespace foo::bar {
inline namespace baz {
int inc(int x) {
  std::cout << "inc from lib_b" << std::endl;
  return x + 2;
}
} // inline namespace baz

void do_b(int x) {
  std::cout << "inc(inc(" << x << ")) = " << inc(inc(x)) << std::endl;
}
} // namespace foo::bar
"""

main_cpp = """
// Forward declarations
namespace foo::bar {
  void do_a(int);
  void do_b(int);
};

int main(int argc, const char *argv[]) {
  using namespace foo::bar;
  do_a(argc);
  do_b(argc);
  return 0;
}
"""

if __name__ == "__main__":
    # Create files
    with open("a.cpp", "wt") as f:
        f.write(a_cpp)
    with open("b.cpp", "wt") as f:
        f.write(b_cpp)
    with open("main.cpp", "wt") as f:
        f.write(main_cpp)

    # Compile libs
    from subprocess import check_call
    check_call(f"c++ -shared -std=c++17 -O3 -fPIC -oliba.so a.cpp", shell=True)
    check_call(f"c++ -shared -std=c++17 -O3 -fPIC -olibb.so b.cpp", shell=True)

    print("Link main with liba and libb and run, observe that inc from liba is used")
    check_call(f"c++ -std=c++17 -O3 -fPIC main.cpp -la -lb -L. -Wl,-rpath=.", shell=True)
    check_call("./a.out", shell=True)
    print("Invert link order and run again, observe thank inc from libb is used")
    check_call(f"c++ -std=c++17 -O3 -fPIC main.cpp -lb -la -L. -Wl,-rpath=.", shell=True)
    check_call("./a.out", shell=True)