title: Why can't I insert a breakpoint here (I might add all my friends can, and I see no other way to solve this)
body: <pre><code>(gdb) list 1,20
  1   int swap_n_add(int *xp, int *yp)
  2   {
  3       int x = *xp;
  4       int y = *yp;
  5   
  6       *xp = y;
  7       *yp = x;
  8       return x + y;
  9   }
  10  
  11  int main() {
  12      int a1 = 534;
  13      int a2 = 1057;
  14      int sum = swap_n_add(&amp;a1, &amp;a2);
  15      int diff = a1 - a2;
  16  
  17      return sum * diff;
  18  }
  (gdb) b 18
  No line 18 in file "swap_n_add.c".
  </code></pre>
  
  <p>I want to check the value main returns, so I put a breakpoint at 18 to inspect the register there (<code>info register</code>). But it says that line doesn't exist, despite it... saying it does exist. And my friends with identical code can put it there.</p>