[PATCH] Add diagnostic capabilities in LLVM (frontend part)

[Quentin Colombet]

  Ping?

  @Dmitri Gribenko
  The name of the added warning is clearly debatable and in particular I do not have on strong opinion on them (especially regarding the backend- prefix).
  I did not find any equivalent for the inline-asm diagnostic in GCC, thus there is nothing to match here AFAICT.
  Regarding the stack-size thing, the closest thing in GCC is frame-larger-than. Since we cannot, AFAIK, set an integer value to a warning in clang, we cannot match this for now.

  @Hal
  I do not have a good answer for the demangling of function’s name in the reporting. I believe this could be addressed later and in probably a better way by front-end people.
  In other words, we can make a RFC for this after this specific plumbing lands.
  The bottom line is, I do not think we should hold on this patch because of that.

  Thanks for your feedbacks.

  -Quentin

http://llvm-reviews.chandlerc.com/D2430