title: How do I set basic options with meson?
body: <p>I'm trying to configure a project with meson. Specifically, I'm trying to set some of the options.</p>
  <p><code>meson config</code> tells me, among other things:</p>
  <pre><code>Core options:
    Option          Current Value Possible Values                                          Description                                             
    ------          ------------- ---------------                                          -----------                                             
    buildtype       debug         [plain, debug, debugoptimized, release, minsize, custom] Build type to use                                       
  
  Base options:
    Option      Current Value Possible Values                                               Description                                   
    ------      ------------- ---------------                                               -----------                                   
    b_lto       false         [true, false]                                                 Use link time optimization                    
  </code></pre>
  <p>(other options were clipped from this printout of course.)</p>
  <p>So, I write:</p>
  <pre><code>meson build . --buildtype=release
  </code></pre>
  <p>in my build directory, and this goes fine - no warnings or errors (I double-checked that the option value had changed). Then I write:</p>
  <pre><code>meson build . --b_lto=true
  </code></pre>
  <p>but this gets me:</p>
  <pre><code>meson: error: unrecognized arguments: --b_lto=true
  </code></pre>
  <p>I also tried <code>-b_lto=true</code>, <code>--b_lto true</code>, <code>b_lto=true</code> and <code>b_lto true</code>. And all of those without the <code>true</code> value. No luck.</p>
  <p>How do I set these &quot;base options&quot; then?</p>