Can GitLab handle multiple changes to a file

Solution 1:

When there is such conflict, there is usually a problem which is raised during the merging, saying something like: "a conflict needs to be resolved. Solve it and commit the changes". Then the different sections in conflicts are separated with >>>>>>>>>> and <<<<<<<<< with the ids of the commits, inside the concerned files.

Then the developer needs to resolve the conflict and commit the merge. The dev has the possibility of saying resolve using our version or resolve using their version. It's pretty rough, because then the others changes are ignored completely.

And in this regard, I would say that it is not a problem of git or gitlab, but of the developer who merged the commits the lazy way (resolve using our version) without knowing what he was doing and the implications...

If you need to restore the ignored changes you will have to come back in the commit before the merge, and solve it by hand (you can try to merge the branch again as well).

I advise you using a visual editor while resolving conflicts (e.g. 'meld' or 'sublime merge').