Strange conflict on git

Question

I read an article about three-way merges (diff3). It gives an example about how is detects a conflict. The example is :

A=[1,4,5,2,3,6]
O=[1,2,3,4,5,6] <<< Origin
B=[1,2,4,5,3,6]

In the first time it computes the diff between O-A and after O-B:

A=[1,4,5,2,3,   ,6]
O=[1,   ,2,3,4,5,6] 

and

O=[1,2,3,4,5, ,6] 
B=[1,2, ,4,5,3,6]

After it makes diff3 parse:

A=[1,4,5,2,   3    ,6]
O=[1,   ,2, 3,4,5  ,6] <<< Origin
B=[1,   ,2, 4,5,3  ,6]

And after it detects the conflict :

1
4
5
2
<<<<<<<<<A
3
|||||||O
3
4
5
=======
4
5
3
>>>>>>B
6

Following this method to detect the conflict, i try a simple example : initially i have the document :

a;
b;

i make an updates user 1 update "a;", to "a=0;" user 2 update "b;", to "b=0;" I obtain this result :

xx
<<<<<<< A
int a=0;
int b;
||||||| O
int a;
int b;
=======
int a;
int b=0;
>>>

When i merge these two documents i have a conflict even if i don't change at the same position (a and b are not at the same position)! some one can explain me why i have this conflict ?

Answer 1

This question is very similar to this one, and the answer also is: That's because each diff hunk does not only consist of the literal difference but also of some lines of context that are required to locate the difference in a file that has some lines added / removed and thus the hunk offset changes. A difference in the context is also a conflict because depending on what patch you would apply first you're changing the context for the other patch.