Re: preventing evil merges

Sandro Santilli [off-list ref] writes:

 git merge anotherbranch
 git add something
 git commit --amend

After the steps above the addition of "something" can't be found in
the history anymore, but the file is there.

This is a very common and sensible thing to do when dealing with
semantic conflict.  Imagine that you changed the name of a global
variable in the code on your current branch since the anotherbranch
you are pulling from forked from you.  Then imagine further that the 
anotherbranch added one location that refers to that variable.

Since they are not aware of the name change, they added the new
reference with the old variable name.  The part they added is a new
code, so it is very likely that there is no textual conflict when
you did "git merge anotherbranch".  But now the result is broken.

And you fix that semantic conflict by editing the file they added
the new reference to the variable under the old name and make it use
the variable with the new name.  You "git add something" and amend
the merge.

"git show" of the result will show you what happened, I think.

On Mon, Jun 3, 2013 at 7:20 PM, Junio C Hamano [off-list ref] wrote:

Sandro Santilli [off-list ref] writes:

quoted

 git merge anotherbranch
 git add something
 git commit --amend

After the steps above the addition of "something" can't be found in
the history anymore, but the file is there.

This is a very common and sensible thing to do when dealing with
semantic conflict.  Imagine that you changed the name of a global
variable in the code on your current branch since the anotherbranch
you are pulling from forked from you.  Then imagine further that the
anotherbranch added one location that refers to that variable.

Since they are not aware of the name change, they added the new
reference with the old variable name.  The part they added is a new
code, so it is very likely that there is no textual conflict when
you did "git merge anotherbranch".  But now the result is broken.

And you fix that semantic conflict by editing the file they added
the new reference to the variable under the old name and make it use
the variable with the new name.  You "git add something" and amend
the merge.

"git show" of the result will show you what happened, I think.

Also, you need to use --cc option of log to see the change in history
(in addition to -p):

    git log --cc -p