title: C Unknown type name 'my_structure'
body: <p>I have this code:</p>
  
  <p><code>main.h</code></p>
  
  <pre><code>#ifndef MAINH
  #define MAINH
  ...
  #include "my_struct.h"
  void some_func(my_structure *x);
  ...
  #endif
  </code></pre>
  
  <p>and</p>
  
  <p><code>my_struct.h</code></p>
  
  <pre><code>#ifndef UTILSH
  #define UTILSH
  ...
  #include "main.h"
  ...
  typedef struct abcd {
      int a;
  } my_structure;
  ...
  #endif
  </code></pre>
  
  <p>but I'm getting this when I try to compile: <code>error: unknown type name ‘my_structure’</code></p>
  
  <p>Any idea why?</p>