Is there a way to annotate that a PR depends on another PR

Question

If I create a Pull Request from a branch

git checkout -b branch-for-first-PR
# edits and commits
git push origin branch-for-first-PR

do some work in it, and then want to experiment with building on that while the first PR is getting reviewed I might do

git checkout branch-for-first-PR
git checkout -b branch-for-second-PR
# edits and commits
git push origin branch-for-second-PR

The problem that I'm having is that the diffs for the second PR show all the changes in the first which is confusing for reviewers.

Is there a structured way to indicate to code review tools (I'm just using Github at this point) that one patch depends on another patch under review? Ideally something like Google's internal DIFFBASE= that gives the reviewer the option of ignoring hunks that are unchanged from the first PR.

Answer 1

I would think that as long as the first branch is not yet merged to e.g. master then your second PR will show all changes from the first as well.

If branch-for-first-PR is merged then your second PR will show only the changes done there.

branch1 --------------------------------
            |
            --- branch 2 ---
                           |
                           --- branch 3

Diff between branch 1 and branch 3 will also show changes done in branch2, but if:

branch1 --------------------------------------
            |              | Merge to branch 1
            --- branch 2 ---
                           |
                           --- branch 3 --- 

If Branch 2 is merged into branch1 at the start of branch 3 then :

Diff between branch1 and branch 3 will only show branch3 changes