title: bool __builtin_sadd_overflow (int a, int b, int *res) not declared
body: <p>I found the "integer overflow builtins" in the gcc manual, but it is not known to the compiler</p>
  
  <pre><code>'__builtin_sadd_overflow' was not declared in this scope
  </code></pre>
  
  <p>Called using</p>
  
  <pre><code>int x=0x7fffffff;
  __builtin_sadd_overflow(2,x, &amp;x);
  </code></pre>
  
  <p>The compiler version is</p>
  
  <pre><code>gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2
  </code></pre>
  
  <p>on i686.</p>
  
  <p>Here is the manual: <a href="https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html" rel="nofollow">https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html</a></p>