Re: How to automatically correct an almost correct auto-merge?

Hi,


Briefly:

Neighboring areas of a file are modified in two branches.  Git
merges the two branches without conflicts, but the result is not
semantically correct.  How can I teach git to produce the correct
merge result when performing the same merge later on?


Longer:

The following commands create a file and two branches, both of them
modifying the file by adding lines in the same area:

git init cat>file<<\EOF 1

2 EOF git add file git commit -m file git apply<<\EOF diff --git
a/file b/file index 1c3e7efc..121366a2 100644 --- a/file +++ b/file

@@ -1,3 +1,5 @@ 1

+a + 2 EOF git commit -a -m a git checkout -b branch HEAD^ git

apply<<\EOF diff --git a/file b/file index 1c3e7efc..f2e91d4f 100644

--- a/file +++ b/file @@ -1,3 +1,6 @@ 1 +b + +c

2 EOF git commit -a -m 'b c' git checkout master


At this point I merge 'branch' and git produces the following
result:

$ git merge branch Auto-merging file Merge made by the 'recursive'
strategy. file |    3 +++ 1 files changed, 3 insertions(+), 0
deletions(-) $ cat file 1 b

c

a

2


Now, these changes and the merge above are the minimal receipe which
corresponds to a real merge I'm having trouble with at dayjob.  Just
imagine that '1' and '2' are the beginning and end of a function,
'b' is the declaration of a new local variable, and 'a' and 'c' are
new code blocks.  As it happens, the semantically correct result
would be the following:

1 b

a

c

2

i.e. 'a' must be executed before 'c'.

I corrected the merge result manually, but these two branches are
merged a couple of times a day into an integration branch, and they
will likely cook for a few weeks, which means a lot of merges, and a
lot of manual corrections.  So I'm looking for a way to teach git to
produce the semantically correct merge result.  Something like
'rerere' would be great, but of course I can't use 'rerere' in this
case, because there are no merge conflicts at all...

Any ideas?  Did someone deal with similar issues before?