title: How to enable warning in each occurrences "implicit declaration of function"?
body: <p>I get &quot;implicit declaration of function&quot; for first occurrence in code but the other occurrences are not highlighted I would like to se all of them at once. As shown below.</p>
  <p>I am using: GNU Tools for ARM Embedded Processors (arm-none-eabi-gcc) Version: 2.4-201503242026</p>
  <pre><code>    writeReg(ADDR_IP_TR0,saved_TR0); &lt;------ There is implicit declaration of function
      writeReg(ADDR_IP_TR2,saved_TR2); &lt;------ Nothing
      writeReg(ADDR_IP_TR3,saved_TR3); &lt;------ Nothing
      writeReg(ADDR_IP_TR5,saved_TR5); &lt;------ Nothing
      writeReg(ADDR_IP_TR9,saved_TR9); &lt;------ Nothing
  </code></pre>
  <p>I am looking for switch that will enable highlighting of all occurrences like this:</p>
  <pre><code>    writeReg(ADDR_IP_TR0,saved_TR0); &lt;------ There is implicit declaration of function
      writeReg(ADDR_IP_TR2,saved_TR2); &lt;------ There is implicit declaration of function
      writeReg(ADDR_IP_TR3,saved_TR3); &lt;------ There is implicit declaration of function
      writeReg(ADDR_IP_TR5,saved_TR5); &lt;------ There is implicit declaration of function
      writeReg(ADDR_IP_TR9,saved_TR9); &lt;------ There is implicit declaration of function
  </code></pre>
  <p>I have found that flag <code>-Werror-implicit-function-declaration</code> will turn this specific warning in to an error.</p>
  <p>If you know how to do this please let me know.</p>