If you like clean coherent formatted code, you may already use something like clang-format and git hook to ensure format when commit

If you like clean history, you might use a log of rebase.

Sometimes during conflit, format is lost, but it’s pita to fix it afterwards without introducing some commit out of the clean history

Update 2022-05-10

I have switch to pre-commit.ci to perform pre-commit hook and formating, applying the same principle, I run

git rebase --strategy-option=theirs -x 'git reset --soft HEAD~1 && git commit -C HEAD@{1}' origin/master 

Which reset and reapply commits, hence triggering pre-commit hook. Then conflict resolution is nearly the same, I use the following oneliner to fix all possible conflicts

git add -u && git commit -C HEAD@{1} && git rebase --continue          

Older version

I use run-clang-format script with rebase and exec. This will stop rebase if format is not respected

git rebase --exec "./run-clang-format.py -r -i \
--style file --extensions inl,cpp,hpp src/" \
new-base-branch

When it stops, you can examine the situation with

git status

git diff

Once everything looks good (in case of conflict, simply use remote, and reformat)

git add -u && \
git commit -m"fix format" && \
git rebase --continue

Then rebase -i again so you can squash/fix all “fix format” commits with their immediate ancestor.

TODO : explain a bit more