title: Assignment of variadic function fails with incompatible pointer type
body: <p>I'm using ceedling with the 'fake funcion framework'(<a href="https://github.com/meekrosoft/fff/blob/master/fff.h" rel="nofollow noreferrer">fff</a>).</p>
  
  <p>I declare a custom fake for my debug_printf function.</p>
  
  <p>My debug.h</p>
  
  <pre><code>#ifndef DEBUG_H
  #define DEBUG_H
  
  void debug_printf(const char*, ...);
  
  #endif // DEBUG_H
  </code></pre>
  
  <p>My some.h</p>
  
  <pre><code>#ifndef SOME_H
  #define SOME_H
  
  void f(void);
  
  #endif // SOME_H
  </code></pre>
  
  <p>My some.c</p>
  
  <pre><code>#include "some.h"
  
  #include "debug.h"
  
  void f()
  {
    debug_printf("test");
  }
  </code></pre>
  
  <p>My test_some.c</p>
  
  <pre><code>#include "fff.h"
  
  #include "some.h"
  
  #include &lt;stdio.h&gt;
  #include &lt;stdarg.h&gt;
  
  DEFINE_FFF_GLOBALS;
  
  FAKE_VOID_FUNC2_VARARG(debug_printf, const char*, ...);
  
  void debug_printf_custom(const char* fmt, ...)
  {
    va_list ap;
  
    va_start(ap, fmt);
    vprintf(fmt, ap);
    va_end(ap);
  }
  
  void test_f(void)
  {
    debug_printf_fake.custom_fake = debug_printf_custom;
    f();
  }
  
  int main(void)
  {
    test_f();
    return 0;
  }
  </code></pre>
  
  <p>When I try to run the test I've got the message:</p>
  
  <pre><code>&gt; gcc test_some.c some.c -o test
  
  test_some.c: In function ‘test_f’:
  test_some.c:23:35: warning: assignment from incompatible pointer type [-Wincompatible-pointer-types]
       debug_printf_fake.custom_fake = debug_printf_custom;
                                     ^
  </code></pre>
  
  <p>What should I change to get the correct pointer type.</p>