Re: [PATCH] rebase -i: auto-squash commits

[Michael Haggerty <mhagger@alum.mit.edu>]

Nanako Shiraishi wrote:
> When the commit log message begins with "squash to ...", and there
> is a commit whose title begins with the same ..., automatically
> modify the todo list of rebase -i so that the commit marked for
> squashing come right after the commit to be modified, and change
> the action of the moved commit from pick to squash.

It seems to me that even this requires more steps than strictly
necessary, namely a commit then a rebase, and conveying the information
from the commit step to the rebase step is somewhat awkward.  Since I
have to specify a magic commit message to trigger this behavior, I
obviously know at the time of the commit that I want to squash the new
changes onto an older commit.  So why not implement this functionality
as a variant of "commit"?  Something like:

git commit --fix=old-commit

which would commit the changes in index as an amendment to the specified
old-commit (requiring no new log message) and then rebase later commits
on top of the new (combined) commit.

If a conflict arises while applying the changes in index to old-commit,
then probably the whole process should be undone and aborted.  If a
conflict arises while rebasing later commits on top of the combined
commit, then the usual rebase conflict-handling machinery would be invoked.

Michael