inline不成反蚀一小时

$ cat a.cpp
#include <string>
#include <iostream>
using namespace std;
inline void fn() {
  string  s = "aaa\n";
  cout << s;
}
void bbb();
int main() { fn(); bbb(); }

$ cat b.cpp
#include <string>
#include <iostream>
using namespace std;
inline void fn() {
  string  s = "bbb\n";
  cout << s;
}
void bbb() { fn(); }

$ g++ -Wall a.cpp b.cpp
$ a.out
aaa
aaa

在b.cpp中把inline去掉，结果是bbb bbb

a.cpp中也去掉inline：结果是：multiple definition of `fn()'

某个fn static或都static，应该，而且确实，aaa, bbb

还有这个：printf("%d %d\n"), $1.size(), $3.size();