Demonstrate that classes default to external linkage.

cmd

$ clang++ test.cc test2.cc -o test && ./test
foo() == 1
bar() == 1

test.cc

#include <stdio.h>
int bar();

// Collides with another class defined in test2.cc.
class Test {
  int member_;
 public:
  // I thought I'd need to make the constructor __attribute__((noinline)), but it fails this way too.
  Test() : member_(1) {}
  int get() { return member_; }
};

int foo() {
  Test t;
  return t.get();
}

int main() {
  printf("foo() == %d\n", foo());
  printf("bar() == %d\n", bar());
}

test2.cc

int bar();

// Collides with another class defined in test.cc.
class Test {
  int member_;
 public:
  // I thought I'd need to make the constructor __attribute__((noinline)), but it fails this way too.
  Test() : member_(42) {}
  int get() { return member_; }
};

int bar() {
  Test t;
  return t.get();
}