Unexpected merge conflict - bug maybe?

[Jacob Burckhardt]

address@hidden writes:
> I would appreciate help understanding how the merge conflict 
> that I am about to describe can logically happen. (I am 
> using cvs 1.11).
...
> I got a 
> merge conflict on a file that had never been modified on 
> SUB_BRANCH. I checked the history of the file on BRANCH. 
> It has undergone just one revision since the creation of 
> SUB_BRANCH. Can anyone explain how this might happen?! 

cvs-1.11 and earlier versions had a bug which can cause this.
cvs-1.11.1 has a fix for it.

> 
> Trying to understand this, a question arose - when performing 
> the merge from BRANCH_TAG_1 to BRANCH_TAG_2, how does CVS determine
> what constitutes a merge. That is, how does it know whether any of 
> the differences being applied conflict with any changes that may have 
> been made on SUB_BRANCH? Does CVS it compare the applied differences 
> with all of the changes that have been made to SUB_BRANCH since it's 
> creation? Correct?

No.  It does not compare to "the changes that have been made to
SUB_BRANCH".  It compares it to the changes between BRANCH_TAG_1 and
the files in your working directory.

That is, there are two changes:

"Changes 1" are the changes from BRANCH_TAG_1 to BRANCH_TAG_2.

"Changes 2" are the changes from BRANCH_TAG_1 to the files in your
working directory.

CVS compares "Changes 1" to "Changes 2" and if they both change the
same area in a file, then CVS marks it as a conflict.