Colliding function names in C++

bad.cc

int foo() {
  return 1;
}

char foo() {
  return 'c';
}

int main() {
  foo();
}

/*
$ g++ bad.cc
bad.cc: In function ‘char foo()’:
bad.cc:5:10: error: new declaration ‘char foo()’
bad.cc:1:5: error: ambiguates old declaration ‘int foo()’
*/

good.cc

int foo(int x) {
  return 1;
}

char foo(char x) {
  return 'c';
}

int main() {
  foo(7);
}