Linker removes struct :(

README.md

This fails with gold or LLD linkers, but works fine with bfd. And it only fails when a static library is involved. (Using objects directly is fine)

(lldb) bt
* thread #1, name = 'app', stop reason = signal SIGSEGV
    frame #0: 0x0000000000000000
  * frame #1: 0x00000000002012e2 app`main + 34
    frame #2: 0x0000000000201095 app`_start(ap=<unavailable>, cleanup=<unav
ailable>) at crt1.c:74
(lldb) p lib_thing_impl
(void *) $0 = 0x0000000000000000
(lldb) p lib_thing_instance
(void *) $1 = 0x0000000000204008
(lldb) p *lib_thing_instance
(lldb)

app.c

#include <stdio.h>
#include "libstruct.h"
#include "libinit.h"

int main() {
  lib_init();
  printf("%d\n", lib_thing_instance->foo());
  return 0;
}

libinit.c

#include "libstruct.h"

void lib_init() {
  lib_thing_instance = &lib_thing_impl;
}

libinit.h

void lib_init();

libstruct.c

#include "libstruct.h"

static int foo() {
  return 69420;
}

struct lib_thing lib_thing_impl = {
  .foo = foo
};

libstruct.h

#pragma once

struct lib_thing {
	int (*foo)();
};

struct lib_thing *lib_thing_instance;

struct lib_thing lib_thing_impl;

Makefile

libstruct.o: libstruct.c libstruct.h
	cc -c -o $@ libstruct.c

libinit.o: libinit.c libinit.h
	cc -c -o $@ libinit.c

lib.a: libstruct.o libinit.o
	ar rcs $@ libstruct.o libinit.o

app: app.c lib.a
	cc -o $@ app.c lib.a