C++ code compiles to a different function names in object file (name mangling). You probably need to put a lot of ugly `#ifdef __cplusplus extern "C" {` boilerplate in your headers, otherwise C and C++ files will not compile together.
struct foo decl = {
.member = /* ... */
.next = &(struct nested_pointer) {
.nested_member = /* ... */,
},
.array = (struct nested_array[]) {
[0] = { /* ... */ },
}
};