git上的奇怪冲突

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 OA and after OB:

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.