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