More git commands (3)

21. How to create a git diff patch?
git diff -U999999 other-branch  > file
git diff change_id  > file

22. git merge  when conflicts
I modified both the same file on branch dev and branch master
when I try to merge what I have on dev to master, I have a conflict
You can manually merge them and mark them as merged. However, if you
don't need the master changeset, you can discard that one, so it will
automatically merge successfully.
First use git reset to go back to the state that doesn't have you changes
git checkout master
git reset --hard 472fc9d1f1236af7c8183b89670e6c4035503ab8
And then:
git merge dev

23. git stash


24. git pull
before push do:
 git pull --rebase
 to rebase you currrent branch, if no conflicts you can push directly.

25. What could cause you fail to build? Some error from the new changes?
If you are on dev branch and try to pull from master, git won't update your dev branch
using remote origin master, you have to switch master branch and do a git pull --rebase there.
Make sure you do a git pull for both clang and llvm master.