.git-slash-config

[merge "clang_format"]
   name = clang-format merge driver
   driver = /tmp/merge_driver.sh %O %A %B %L %P
   recursive = binary

.gitattributes

*.cpp merge=clang_format
*.h merge=clang_format

merge_driver.sh

#!/bin/bash
BASE="$1"
OURS="$2"
OTHERS="$3"
PATH_FYI="$5"
clang-format -i -style=file "$BASE"
clang-format -i -style=file "$OURS"
clang-format -i -style=file "$OTHERS"
echo "clang-format merge driver. Merging $PATH_FYI"
echo git merge-file -p "1:$OURS" "2:$BASE" "3:$OTHERS" \> "$OURS.tmp"

git merge-file -p "$OURS" "$BASE" "$OTHERS" --theirs > "$OURS.tmp"
clang-format -i -style=file "$OURS.tmp" # one last format
RET=$?
mv "$OURS.tmp" "$OURS"
exit $RET

YOU SHOULD REMOVE THIS DRIVER AFTER REBASING YOUR PR!

First, rebase to the commit before everything goes to hell:

git rebase -i 2115e8a4a6814e32107b5205ff5c95bbd3c6e99c

Then, install the merge_driver and rebase to master, fixing any conflicts:

git rebase -i master

Finally, run a pass overtop of everything to reformat anything that didn't conflict:

git rebase -i master --exec "git reset --soft HEAD~ && git clang-format --style file && git commit -a -C ORIG_HEAD"