GCC SVN vs. BZR/LP

[Andrew Stubbs]

Re my recent email "Upstream GCC feature freeze", I think we're agreed 
that we need to create a branch that tracks GCC 4.6 development, but has 
our own performance improvements included. The question is where to host it?

Option 1: Launchpad/bzr

Pros:
  * We need no permission to do it
  * The branch will naturally evolve into our 4.6 release series in time.
  * The 3-way merge works well (if slowly)
  * We can include patches that we have no intention of posting upstream 
ever
  * Our patch tracker will Just Work.
  * Merge requests will be available.

Cons:
  * Bzr ;)
  * It's hidden away from the view of most GCC developers


Option 2: GCC SVN branch

Pros:
  * We can work in the open, submitting patches via gcc-patches, as usual
  * The final merge to GCC trunk (come stage 1) will be eased, a little

Cons:
  * We can't really apply anything we want just for ourselves
    * we may end up maintaining an LP branch shadowing the svn branch
  * When we do want to do 4.6 in LP, we'll have to backport all our 
patches from 4.7, and this may no longer be straightforward.
  * Write permissions not clear.
    * Although I think you can just go ahead and do it?

OK, so I'm sure I've missed some big ones. Please discuss! ;)

I think the big question here is, when will we start wanting to make 
(unstable/experimental) Linaro GCC 4.6 releases? If we want to do it 
early, then we'll have no choice but to have an LP branch to release from.

Andrew