Re: I want "fast forward my workdir to upstream if it's safe"

[Jeff King <peff@peff.net>]

On Fri, May 08, 2009 at 08:53:22AM +0200, Andreas Ericsson wrote:

>> (2b) is a bit harder, but do-able:
>>
>>   git diff-tree --name-only HEAD $upstream | sort >them
>>   (git diff-files --name-only; git diff-index --name-only) | sort >us
>>   test -z "`comm -12 us them`"
>>
>> (2c) is the trickiest (and of course, therefore probably the one you
>> want ;) ).  I'm not sure there is a simple way to do it short of hacking
>> git-merge to actually try the merge and roll it back. Because you really
>> have to deal not just with merging actual text file content but with
>> custom merge drivers.
>>
>
> The "rolling back" part is about as simple as
> * never touch the worktree (only use in-index merge)
> * preserve the last HEAD commit object name
> * preserve the index

If you are just doing in-index merge, then (2b) works fine. You know you
aren't doing any file-level merging. The advantage of (2c) is that
non-conflicting merges in files would are "safe".

-Peff