duplicate

build.sh

#!/bin/bash

clang++ -Wall impl.cpp sub.cpp -o impl.a -std=c++11
./impl.a

header_only.h

#pragma once

#include <iostream>

static int &P(int x = int()) { static int _{x}; return _; }
static int &p{P(8)};

struct Q {
	static int &q(int x = int()) { static int _{x}; return _; }
};
static int &q{Q::q(8)};

static const int T{24};

impl.cpp

#include <iostream>

#include "sub.h"

void print_p() {
	std::cout << "impl ++p: " << ++p << std::endl;
}

void print_q() {
	std::cout << "impl ++q: " << ++q << std::endl;
}

int main(int argc, char *argv[]) {
	sub_print_p();
	print_p();
	std::cout << std::endl;
	sub_print_q();
	print_q();
}

sub.cpp

void sub_print_p() {
	std::cout << "sub ++p: " << ++p << std::endl;
}

void sub_print_q() {
	std::cout << "sub ++q: " << ++q << std::endl;
}

sub.h

#pragma once

#include "header_only.h"

void sub_print_p();
void sub_print_q();