bzlrepro

a.cc

#include "a.h"
A::A() = default;
A::~A() = default;
int A::QueryX() { return x; }

a.h

#ifndef A_H_
#define A_H_
constexpr int kReallyX = 7;
class A {
 public:
  A();
  ~A();
  int QueryX();
  int x = kReallyX;
};
#endif  // A_H_

b.cc

#include "b.h"
B::B(A* a) : a(a) {}
B::~B() = default;
int B::QueryY() { return a->QueryX(); }

b.h

#ifndef B_H_
#define B_H_
#include "a.h"
class B {
 public:
  explicit B(A* a);
  ~B();
  int QueryY();
  A* a;
};
#endif  // B_H_

BUILD

package(default_visibility = ["//visibility:public"])

cc_library(
    name = "a",
    srcs = ["a.cc"],
    hdrs = ["a.h"],
)

cc_library(
    name = "b",
    srcs = ["b.cc"],
    hdrs = ["b.h"],
    deps = [":a"],
)

cc_binary(
    name = "c",
    srcs = ["c.cc"],
    deps = [":b"],
)

cc_binary(
    name = "d",
    srcs = ["d.cc"],
    deps = [":b"],
)

c.cc

#include <cstdio>
#include "b.h"
int main() {
  A a;
  B b(&a);
  printf("%d", b.QueryY());
  return 0;
}

d.cc

#include <cstdio>
#include "b.h"
int main() {
  A a;
  B b(&a);
  printf("kReallyX = %d\n", kReallyX);
  printf("B.QueryY() = %d\n", b.QueryY());
  return 0;
}