Re: Can git tell me which uncommitted files clash with the incoming changes?

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Mon, Dec 17 2018, Jeff King wrote:

> On Mon, Dec 17, 2018 at 08:08:49AM -0500, Mark Kharitonov wrote:
>
>>     C:\Dayforce\test [master ↓2 +0 ~2 -0 !]> git pull
>>     error: Your local changes to the following files would be
>> overwritten by merge:
>>             2.txt
>>     Please commit your changes or stash them before you merge.
>>     Aborting
>>     Updating 2dc8bd0..ea343f8
>>     C:\Dayforce\test [master ↓2 +0 ~2 -0 !]>
>>
>> Does git have a command that can tell me which uncommitted files cause
>> the this error? I can see them displayed by git pull, but I really do
>> not want to parse git pull output.
>
> That message is generated by merge-recursive, I believe after it's
> figured out which files would need to be touched.
>
> I don't offhand know of a way to get that _exact_ answer from another
> plumbing command. But in practice it would probably be reasonable to ask
> for the diff between your current branch and what you plan to merge, and
> cross-reference that with the list of files with local changes.
>
> Something like:
>
>   git pull ;# this fails, but FETCH_HEAD is left over
>
>   git diff-tree -z --name-only HEAD FETCH_HEAD >one
>   git diff-index -z --name-only HEAD >two
>   comm -z -12 one two
>
> would work on Linux, but "comm -z" is not portable (and I suspect you
> may not have comm at all on Windows). You can probably find a way to
> show the common elements of the two lists using the scripting language
> of your choice.
>
> The answer that gives will be overly broad (e.g., in a case where our
> local branch had touched file "foo" but other side had not, we'd
> consider "foo" as a difference the two-point diff-tree, whereas a real
> 3-way merge would realize that we'd keep our version of "foo"). But it
> might be good enough for your purposes.

Isn't this done more simply with just running the merge with
git-merge-tree? Maybe I'm missing something. E.g. earlier I had a
conflict between a WIP series of mine in next in
parse-options-cb.c. Just using git-merge-tree and grepping for conflict
markers gives me what conflicted:

    $ git merge-tree origin/master unconditional-abbrev-2 origin/next|grep -E -e '^(merged|changed in both|  (base|our|their|result))' -e '^\+======='
    [...]
    merged
      result 100644 d70c6d9afb94c77c285fe8ee3237f7a40867157a packfile.h
      our    100644 6c4037605d0dfee59a084c440506f1af11708d63 packfile.h
    changed in both
      base   100644 8c9edce52f63bcb1085b119b3a2264a97b1fb374 parse-options-cb.c
      our    100644 1afc11a9901dba25dc0f6151e5d9a7654b6e3192 parse-options-cb.c
      their  100644 e2f3eaed072f77d63890ec814d810199f57248d5 parse-options-cb.c
    +=======
    [...]

Or more simply, you can "grep -q" for '^\+=======' to ask "does this
conflict?".