On Fri, Sep 12, 2025 at 6:38 AM Guo Tingsheng <CoriCraft16@xxxxxxxxxxx> wrote:
>
> Hello Git developers,
>
> I would like to report a potential issue in Git's merge behavior, where semantically independent changes at the same position are reported as a conflict, even though they could be merged automatically.
>
> Environment:
> - git version: 2.43.0
> - OS: Ubuntu 24.04 LTS
>
> Steps to reproduce:
> 1. Start with a file containing only:
>
> public class Calculator {
> }
>
> 2. On branch A, add a new method `add`:
>
> @@ -1,1 +1,3 @@
> public class Calculator {
> + public static double add(double a, double b) {
> + return a + b;
> + }
>
> 3. On branch B, add a new method `subtract`:
>
> @@ -1,1 +1,3 @@
> public class Calculator {
> + public static double subtract(double a, double b) {
> + return a - b;
> + }
>
> 4. Merge branch A and branch B.
>
> Expected result:
> - The merge should succeed automatically, producing a file that contains both methods (order does not matter).
> For example:
>
> public class Calculator {
> public static double add(double a, double b) {
> return a + b;
> }
> public static double subtract(double a, double b) {
> return a - b;
> }
> }
>
> Actual result:
> - Git reports a conflict and aborts the merge, requiring manual conflict resolution.
>
> Additional information:
> - Although the two changes occur at the same location in the file, they are independent additions with no semantic overlap.
> - It would be desirable for Git's merge algorithm to automatically combine such changes, as the final merged state is deterministic and conflict-free.
> - This limitation may impact developer productivity in real-world projects where multiple contributors extend the same class or configuration file independently.
Thanks for the report, but how is Git supposed to know that they are
independent changes with no semantic overlap? Git doesn't understand
the semantics of the files it tracks. It has no idea whether the
things being added are functions, or statements/expressions within a
function, or college essays, or hand-written recipes, or data dumps,
or anything else. It would need to know those semantics, which would
probably require something on the level of use of AI to determine that
the changes are independent non-competing additions with no semantic
overlap and that you want to keep both. Instead, it knows which lines
are the same between the two sides, and which have been modified since
the common point of history.
Without this knowledge about the meaning of the content, assuming both
are wanted is wrong. It would mean that all the other cases where two
sides each add lines would also end up with both sets of lines, even
when those are conflicting lines in a recipe or conflicting statements
in a function, or whatever. When both sides modify the same area in
different ways, it's a potential conflict that needs to be given back
to the user to resolve.
