#115 Merge conflict silently and incorrectly resolved
Version 0.95.5 for Windows.
--- File A (base):
a
b
c
d
e
f
--- File B:
a
f
--- File C
a
b
c
XX
d
e
f
KDiff3 claims to be able to resolve this automatically, giving the result:
a
XX
f
But this is not necessarily valid. Imagine that a, bcde, and f are three source code functions. One programmer has deleted the function bcde completely, while another one has modified it by inserting XX. This merge result will give you XX floating out in the middle of nowhere between a and f. Obviously the compiler will catch this, but in other circumstances this merge behaviour could result in much more subtle bugs.
So situations like this cannot be automatically merged, and must be marked as requiring user intervention. Otherwise, I simply can't trust KDiff3 enough to use it, despite all of its other excellent features.
Discussion
Hi Malcolm,
If you need a guarantee, then I'm sorry that I can't provide it. To my knowledge there exists no merge algorithm that can give guarantees that an automatic merge always gives you the correct result. But there are some tools that warn the user if a change from one branch is "near" the change of another branch.
Nevertheless in the long time I'm using KDiff3 I very rarely came upon problems. (One such possible problem would be if two people move a piece of code to different places. After the merge it would appear twice.)
If you are new to 3-way-merging I recommend to review all automatic decisions of KDiff3 (or other tools). This is good practice anyway, especially if you have knowledge about the code in question.
More often than not a detectable conflict is near a problematic place.
Even if you don't trust the result of the automatic merge, I would think KDiff3 will aid you while inspecting and correcting the outcome.
Cheers,
Joachim