title: how to force recompile when changing Makefile flags?
body: <p>I am compiling some project with dependency so i won't have to recompile each time, but when i am adding -Dsome_flags to my CFLAGS, it is not recompiling.</p>
  
  <pre><code>dep: $(CPPS)
      $(CC) $(CFLAGS) $(INC) -M $(CPPS) &gt; dep
  </code></pre>
  
  <p>i add to my CFLAS -DDEBUG_FLAG and it forces me to do make clean and make instead of make.</p>