Ensure whether specific code is emitted or not

Question

How can I ensure whether some specific code is not emitted?

Say, I tried to write something like a static switch (or static if) and I wish to detect whether second lambda operator ()'s body is emitted:

#include <type_traits>

namespace details
{

template< typename visitor, typename ...visitors >
struct composite_visitor
        : std::decay_t< visitor >
        , composite_visitor< visitors... >
{

    using std::decay_t< visitor >::operator ();
    using composite_visitor< visitors... >::operator ();

    composite_visitor(visitor & _visitor, visitors &... _visitors)
        : std::decay_t< visitor >(std::forward< visitor >(_visitor))
        , composite_visitor< visitors... >{_visitors...}
    { ; }

};

template< typename visitor >
struct composite_visitor< visitor >
        : std::decay_t< visitor >
{

    using std::decay_t< visitor >::operator ();

    composite_visitor(visitor & _visitor)
        : std::decay_t< visitor >(std::forward< visitor >(_visitor))
    { ; }

};

}

template< typename visitor, typename ...visitors >
details::composite_visitor< visitor, visitors... >
compose_visitors(visitor && _visitor, visitors &&... _visitors)
{
    return {_visitor, _visitors...};
}

#include <iostream>

#include <cstdlib>

template< int condition >
void
test()
{
    compose_visitors(
        [] (std::integral_constant< int, 0 >) { std::cout << 0 << std::endl; },
        [&] (std::integral_constant< int, 1 >) { std::cout << 1 << std::endl; },
        [] (std::integral_constant< int, 2 >) { std::cout << 2 << std::endl; }
    )(std::integral_constant< int, condition >{});
}

int
main()
{ 
    test< 0 >();
    //test< 1 >();
    test< 2 >();
    return EXIT_SUCCESS;
}

What is the tricks that allows me to detect a presence of specific code block into the resulting binary/.o/.a?

Previously one could do the following (for GCC):

• add -Wa,-adhlns="$@.lst" to CXXFLAGS;
• add asm volatile ("nop"); statement to code block you want to test;
• build, then run awk "/\#APP/, /\#NO_APP/" build/*.lst (instead of hash symbol there may be a slash) command to see inline assembly into *.lst files in build directory;
• if awk prints something, then particular code block is emitted.

LIVE DEMO

But I use clang and therefore can't use -Wa compiler parameter. What is a way for clang? I know I can emit assembly files (.S) using -S compiler option, but in big project it is hard to do in such a way if there is a dependency chain during building. How to emit assembly in addition to .o files?