title: How to quell qmake's "WARNING: Failure to find:"?
body: <p>I'm using <code>PRE_TARGETDEPS</code> to generate source files, and I'm adding the generated source files to <code>SOURCES</code> for compilation.</p>
  
  <p>The output of my generator obviously doesn't exist at the time qmake is run, so qmake outputs <code>WARNING: Failure to find:</code> for each of the to-be-created source files.</p>
  
  <p>How can I quell this warning, since I know my <code>PRE_TARGETDEPS</code> is going to produce those files?</p>
  
  <p>Or, is there a better way to generate intermediate files using qmake?</p>
  
  <h2>Example</h2>
  
  <p>Here's a complete <code>test.pro</code> file that exhibits the problem:</p>
  
  <pre><code>TEMPLATE = lib
  
  preprocess.commands += cat test.cc.in | sed 's/a/0/g' &gt; test.0.cc ;
  preprocess.commands += cat test.cc.in | sed 's/a/1/g' &gt; test.1.cc ;
  preprocess.depends = test.cc.in
  QMAKE_EXTRA_TARGETS += preprocess
  PRE_TARGETDEPS += preprocess
  
  SOURCES = test.0.cc test.1.cc
  </code></pre>
  
  <p>Place this in an empty folder, and also create an empty <code>test.cc.in</code> file.  Run <code>qmake</code>, and you'll see these warnings:</p>
  
  <pre><code>WARNING: Failure to find: test.0.cc
  WARNING: Failure to find: test.1.cc
  </code></pre>