title: pre-compilation message in C
body: <p>I'm writing a function that configures external interrupts in ATMEGA32 using C language</p>
  
  <pre><code>    typedef enum{
          LOW_LVL,
          CHANGE,
          FALLING,
          RISING
          }TRIGGER;
  
      void configExtInt(uint8_t ExtIntNo, TRIGGER trig){
          sei();
          if (ExtIntNo == INT0){
  
          }else if (ExtIntNo == INT1){
  
          }else if (ExtIntNo == INT2){
  
          }else{
              cli();
          /* warning message here*/
          }
      }
  </code></pre>
  
  <p>I want to display a warning message during compilation in case the user of my function provided parameter other than INT0, INT1, INT2 to my function.</p>
  
  <p>For example :</p>
  
  <pre><code>configExtInt (INT3, FALLING);
  </code></pre>
  
  <p>Is that possible?</p>