How to merge large number of changes info common repo?

Question

There are two developers working on branches dev1 and dev2, respectively, and usually every time one of them commits a change they do a PR into a common dev branch.
Both developers have made a bunch of big changes, some of which may affect the same files.

Developer 1 has done a PR and merged their changes into dev. Now Developer 2 wants to merge their changes into dev as well but is worried there will be conflicts.

Rather than just doing a PR from dev2 into dev, what's the best way for Developer 2 to see what the result of this merge will be?
For example, should they checkout dev2 locally and do a git fetch from dev, and then fix any merge conflicts? Or do a git merge from dev2 into dev?

Answer 1

This is the procedure I would recommend:

1. Dev2 merge from common dev to dev2 branch.
2. Solve conflicts locally.
3. Do a pull request from dev2 branch to common dev branch. (There won't be any conflicts because they have been resolved in the previous merge.)

Tip: when merging from common dev branch into yours it is easier to accept all remote changes and only then carefully pick and apply your own changes.