title: Can a Makefile target invoke commands even if a prerequisite fails?
body: <p>Here's a skeleton Makefile just to make it easier to describe the problem:</p>
  
  <pre><code>all_tests : unit_tests other_tests_1 other_tests_2 ... other_tests_N
  
  unit_tests : set1_summary.txt set2_summary.txt ... setN_summary.txt
  
  %_summary.txt : %_details.txt
      perl createSummary.pl --in $^ -out $@
  
  %_details.txt : test_harness
      ./test_harness --test-set $*
  </code></pre>
  
  <p>So I have a test runner that produces a file with detailed results, and then a filtering mechanism to create a summary file.</p>
  
  <p>Now, the test runner application returns an error code if any of the items in the test set fails, which will correctly abort the "all_tests" target and never invoke the other_test targets. However, I would like to run the details -> summary transformation unconditionally, since that is relevant even for a failed test run. </p>
  
  <p>I've tried some different variants but the only method I could get to work was wrapping the whole command chain into a Perl script, storing away the result of the first command and using that as return value for the whole script.</p>
  
  <p>But that does not feel like a very neat solution, especially since the "actual" command set is a bit more complex than what this skeleton shows. Do you know any purely GNU Make-based method to accomplish this?</p>