Infinite Loop on Mac GCC

test.cpp

#include <iostream>

int foo(int m) {
  std::cout << 1 << std::endl;
  std::cout << 2 << std::endl;
}

void bar() {
  foo(0);
}

int main() {
  foo(0);
}

$ g++ --version
g++ (Homebrew GCC 8.2.0) 8.2.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ g++ -O1 test.cpp   
test.cpp: In function 'int foo(int)':
test.cpp:6:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^

$ ./a.out
1
2
1
2
(snip)
zsh: segmentation fault  ./a.out