title: unknown type name "pthread_barrier_t"
body: <p>I am trying to parallelize an algorithm in C. I want to use <code>pthread_barrier_t</code> but my Ubuntu wsl can't find it for some reason. I have <code>pthread.h</code> included and I can use the rest of the pthread functions. <code>libthread.a</code> is installed.</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  #include &lt;pthread.h&gt;
  
  /* Error occurs here */
  pthread_barrier_t barrier;
  </code></pre>
  
  <p>Exact error is: <em>"identifier pthread_barrier_t is undefined"</em></p>
  
  <p>I saw elsewhere it could be the way I'm compiling.</p>
  
  <p>Compiling as follows:</p>
  
  <pre><code>gcc -o test test.c -Wall -std=c99 -lpthread -lm
  </code></pre>
  
  <p>Also, VS Code can't identify the function.</p>