On Thu, 2015-08-20 at 13:57 -0400, Jason Merrill wrote: > I hear that at Cauldron people were generally supportive of switching > over to git as the primary GCC repository, and talked about me being > involved in that transition. Does anyone have more information about > this discussion? > > Our current workflow translates over to a git master pretty easily: > basically, in the current git-svn workflow, replace git svn rebase and > git svn dcommit with git pull --rebase and git push. > > It should be pretty straightforward to use the existing git mirror as > the master repository; the main adjustment I'd want to make is rewriting > the various subdirectory branches to be properly represented in git. > This is straightforward, but we'll want to stop SVN commits to > subdirectory branches shortly before the changeover. > > It would be good to have a more explicit policy on branch/tag creation, > rebasing, and deletion in the git world where branches are lighter > weight and so more transient.
If we're going to migrate to git (I hope so), can we also please *slightly* revise the policy on commit messages, to add meaningful titles to commits? Currently: https://www.gnu.org/software/gcc/svnwrite.html#checkin says: "The log message for that checkin should be the complete ChangeLog entry for the change." and the subsection "Commit the changes to the central repository" below https://www.gnu.org/software/gcc/svnwrite.html#example has an example showing this. In the git world, the first line of the commit message has special meaning, being treated as the "title" of the commit. Quoting the git docs [1]: "Though not required, it’s a good idea to begin the commit message with a single short (less than 50 character) line summarizing the change, followed by a blank line and then a more thorough description. The text up to the first blank line in a commit message is treated as the commit title, and that title is used throughout Git. For example, git-format-patch[1] turns a commit into email, and it uses the title on the Subject line and the rest of the commit in the body." For gcc, I suggest that the first line of the commit message should be a representative title, typically the "Subject" line of the relevant gcc-patches thread (without any "[PATCH]" prefix), and this should be followed by the ChangeLog entry as before as the "more thorough description" that the git docs speak of. Looking at the commit history, many contributors appear to be already applying this policy when committing to svn (I'm one of them); it makes the history much easier to read from git (otherwise the title is typically something like "gcc/" or just a datestamp and email, which isn't as helpful). Try running "git shortlog" on a git mirror of the current repo to see what I mean. For example: https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=227033 which when viewed from git has the title: "[ARM] Hide existing float16 intrinsics unless we have a scalar __fp16 type". I'm merely proposing doing this going forward, *not* to attempt any kind of retroactive history-editing (ugh). I can write it up for the website if people agree it's a good policy. Hope this is constructive. Dave [1] http://git-scm.com/docs/git-commit (see "DISCUSSION")
