## Stream: new members

### Topic: Dependent PR

#### Anatole Dedecker (Jul 29 2020 at 20:29):

How do you make a PR that depends on things defined in another waiting PR ?

#### Yury G. Kudryashov (Jul 29 2020 at 20:30):

You can start a git branch from another branch.

#### Kevin Buzzard (Jul 29 2020 at 20:31):

And then in the PR comments say it's blocked by the other PR

#### Yury G. Kudryashov (Jul 29 2020 at 20:31):

git checkout -b new_name old_branch

#### Anatole Dedecker (Jul 29 2020 at 20:36):

I don't know why I was thinking it would cause problems, I had forgotten how git works :sweat_smile:

#### Patrick Massot (Jul 29 2020 at 20:37):

The system is far from perfect because GitHub doesn't have this concept, so it will show the full diff in the second PR by default. You need to explicitly filter out commits if you want to see what's new.

#### Patrick Massot (Jul 29 2020 at 20:37):

Usually stacked PRs like this are only a way to put pressure on reviewers.

#### Anatole Dedecker (Jul 29 2020 at 21:02):

Huh, I'll wait then

#### Yury G. Kudryashov (Jul 30 2020 at 03:48):

It's OK to open a PR now. This way people see why do you need the first PR.

#### Johan Commelin (Jul 30 2020 at 04:01):

Patrick Massot said:

Usually stacked PRs like this are only a way to put pressure on reviewers.

I think 1 layer of stacking can be useful. Like Yury said. But stacking more on top of that is typically not helpful.

#### Nicolò Cavalleri (Jul 30 2020 at 08:57):

Moreover, to see the differences with respect to the other PR and not the master branch (I guess to highlight the real new features), you can change the base branch on GitHub. If you do so, you should write it clearly in the description so that whoever merges it changes the base branch back to the master branch before the merge, otherwise the branch gets merged into an already approved PR but does not make it into mathlib

Last updated: May 12 2021 at 23:13 UTC