title: What is the default build configuration of cmake
body: <p>In <a href="https://stackoverflow.com/a/20423820/1015678">this</a> answer, it says Debug is the default cmake build configuration.</p>
  
  <p>But I have a different observation:</p>
  
  <p>I have following in my CMakeLists.txt to choose debug and release versions of a lib according to the current build configuration.</p>
  
  <pre><code>target_link_libraries(MyApp debug Widgets_d)
  target_link_libraries(MyApp optimized Widgets)
  </code></pre>
  
  <p>It seems that when I invoke cmake without sepcifying -DCMAKE_BUILD_TYPE flag, Widgets is used instead of Widgets_d (When I delete Widgets and try to build, make complains that lib is not there). So that means by default the build configuration is optimized, not debug.</p>
  
  <p>So what actually is the default build configuration? If it is debug, what could be wrong with my CMakelists.txt?</p>