[llvm-dev] [cfe-dev] Phabricator -> GitHub PRs?

[Joerg Sonnenberger via llvm-dev]

On Wed, Jan 15, 2020 at 01:30:34PM -0600, David Greene via cfe-dev wrote:
> Emilio Cobos Álvarez <emilio at crisal.io> writes:
> 
> > [1] or [2] are recentish examples that come to mind, but it happens
> > fairly often. Of course for a bunch of simpler changes one revision is
> > enough.
> 
> I think you forgot to include links.  :)
> 
> > The use cases are similar to the "I have one PR with multiple commits"
> > in GitHub, but with the advantage of being able to review them
> > individually, and thus they can land upstream sooner.
> 
> Downstream we strongly suggest people use a one-commit-per-PR model.
> That does incur some additional overhead but I personally haven't found
> it to be an issue.  Usually if I have a series of dependent patches,
> then I need to merge the first one before I can do the second one, etc.

One typical case for a patch series is if you need infrastructure in a
number of places in place first. Sending all changes at once allow
others to see where you are going, independent of whether the individual
pieces are acceptable immediately or not. Yes, this can mean later
patches need to be reworked for larger structural changes, but that
doesn't necessarily invalidate review remarks already made.

The other case is reworking a pass to handle a couple of similar, but not
identical cases. It might not be possible to take out patch 2 in a
series in this case, but most often the review changes here are smaller
"stylistic" issues without huge impact on later steps.

Joerg