Heads up: Mesa/LLVM rebase and OpenGTL retirement in F20

[Adam Jackson]

On Fri, 2014-03-28 at 11:38 -0400, Bill Nottingham wrote:
> Adam Jackson (ajax at redhat.com) said: 
> > Can you (or anyone else) elaborate on the issues you're concerned with
> > here?  If I'm going to have to play Simon Says about this I'd like some
> > opportunity to address (or at least investigate) concerns ahead of time.
> 
> 1) the removal of OpenGTL mid-stream breaking user or other apps
> (and we can't truly remove it anyway - it stays in the F20 release repo)
> 
> This may be solvable by use of the patch mentioned elsewhere in this thread.

Yeah, I'm happy to apply that patch.  I'm not sure I could do much
validation on it beyond running OpenGTL's own tests though (or, I guess,
pulling an old version of calligra and trying to exercise it that way).

> 2) as the policy is to not update ABI on libraries, it requires an
> exception. Concerns would be about the number of apps affected, coordinating
> the release of all dependent apps, how likely user/other apps might be
> broken by this ABI update.

In terms of Fedora proper, it's a pretty short list:

- eclipse-cdt-llvm, syntastic-llvm, gedit-code-assistance, and
kate-plugin-cpphelper all use clang to do various levels of realtime
parsing for things like syntax highlighting and etc; depressingly
there's even a libclang.so (yep, not versioned!) whose abi has almost
certainly changed, which the latter two do use, so probably they should
be rebuilt even in f21

- xorg-x11-drv-vmware -> mesa-libxatracker -> llvm-libs; testable by
booting a kvm with a vmware gpu (I think, there's been multiple
generations and the one kvm emulates might not be one requiring the
xatracker bits) or, obviously, under vmware

- pocl is an opencl implementation with no consumers, but with a
testsuite

- pure is a programming language with a test suite; I don't know of any
other packages containing pure code though (rimshot)

- OpenGTL is covered above

- dragonegg is an llvm backend for gcc, with a test suite

- gambas3 is a visual basic clone; it does not appear to have a test
suite, but the IDE is at least self-hosting

- python{,3}-llvmpy are python wrappers around libLLVM, with a test
suite

- ghc apparently uses llvm as a backend on arm; I'm assuming it has a
test suite because Haskell

And, of course, mesa-{dri,vdpau}-drivers contain drivers using LLVM.
So, ~12 packages outside llvm and mesa, not all of which necessarily
need an update (depends how much clang's output changes between 3.3 and
3.4).  Excluding mesa these are mostly "leaf" packages, well outside the
critical path, typically self-contained, and quite unlikely to break
booting to the desktop for anyone.

That most of them appear to have test suites is heartening, the irony is
that running them for the llvm rebase would almost certainly be more
verification than went into them for F20 gold.  Still, we can at least
establish a baseline and compare for regressions.

That said, I haven't looked for other consumers in outside repositories,
and I can't possibly know every llvm-using app in the world even if I
did look.

- ajax