1         FAQ - Why sparse?
   2 
   3 Q.  Why not just use gcc?
   4 
   5 A.  Gcc is big, complex, and the gcc maintainers are not interested in
   6     other uses of the gcc front-end.  In fact, gcc has explicitly
   7     resisted splitting up the front and back ends and having some common
   8     intermediate language because of religious license issues - you can
   9     have multiple front ends and back ends, but they all have to be part
  10     of gcc and licensed under the GPL. 
  11 
  12     This all (in my opinion) makes gcc development harder than it should
  13     be, and makes the end result very ungainly.  With "sparse", the
  14     front-end is very explicitly separated into its own independent
  15     project, and is totally independent from the users.  I don't want to
  16     know what you do in the back-end, because I don't think I _should_
  17     know or care. 
  18 
  19 
  20 Q.  Why not GPL?
  21 
  22 A.  See the previous question: I personally think that the front end
  23     must be a totally separate project from the back end: any other
  24     approach just leads to insanity.  However, at the same time clearly
  25     we cannot write intermediate files etc crud (since then the back end
  26     would have to re-parse the whole thing and would have to have its
  27     own front end and just do a lot of things that do not make any sense
  28     from a technical standpoint).
  29 
  30     I like the GPL, but as rms says, "Linus is just an engineer". I
  31     refuse to use a license if that license causes bad engineering
  32     decisions.  I want the front-end to be considered a separate
  33     project, yet the GPL considers the required linking to make the
  34     combined thing a derived work. Which is against the whole point
  35     of 'sparse'.
  36 
  37     I'm not interested in code generation. I'm not interested in what
  38     other people do with their back-ends.  I _am_ interested in making a
  39     good front-end, and "good" means that people find it usable. And
  40     they shouldn't be scared away by politics or licenses. If they want
  41     to make their back-end be BSD/MIT licensed, that's great. And if
  42     they want to have a proprietary back-end, that's ok by me too. It's
  43     their loss, not mine.
  44 
  45 
  46 Q.  Does it really parse C?
  47 
  48 A.  Yeah, well...  It parses a fairly complete subset of "extended C" as
  49     defined by gcc.  HOWEVER, since I don't believe in K&R syntax for
  50     function declarations or in giving automatic integer types, it
  51     doesn't do that.  If you don't give types to your variables, they
  52     won't have any types, and you can't use them.
  53 
  54     Similarly, it will be very unhappy about undeclared functions,
  55     rather than just assuming they have type "int". 
  56 
  57     Note that a large rationale for me doing this project is for type
  58     following, which to some degree explains why the thing is type-anal
  59     and refuses to touch the old-style pre-ANSI non-typed (or weakly
  60     typed) constructs. Maybe somebody else who is working on projects
  61     where pre-ANSI C makes sense might be more inclined to care about
  62     ancient C.  It's open source, after all. Go wild.
  63 
  64 
  65 Q.  What other sparse resources are available?
  66 
  67 A.  Wiki: http://sparse.wiki.kernel.org/index.php/Main_Page
  68 
  69     Mailing list: linux-sparse@vger.kernel.org
  70     See http://vger.kernel.org/vger-lists.html#linux-sparse for subscription
  71     instructions and links to archives
  72 
  73     Git repo: git://git.kernel.org/pub/scm/devel/sparse/sparse.git
  74     gitweb: http://git.kernel.org/?p=devel/sparse/sparse.git