[Users] Reformatting Carpet's source code

[Roland Haas]

Hello all,

>> Yes, thank you! The first half hour of the talk exactly described my
>> experience, and my arguments above:
>> - formatting is much more than indenting
>> - clang-format is amazing
>> - it saves developers a lot of time
>>
>> I'm inclined to make the first half hour of this talk "required reading"
>> to participate in this discussion...
Done so (yesterday). I agree with the statement that when refactoring
code one should really use clang-format. I certainly have had exactly
the experience described in the talk, however in my case I had to merge
a diverged branch back into master and the diverged branch author had
changed indentation all over the place. Having had an agree upon and
automatically enforced formatting style with have simplified this work
enormously.

So, I change my mind and agree that using clang-format even for Carpet
would be good (hoping that indeed there will be refactoring and
simplification of the code to follow). It would be less disruptive if
clang-format was used only for new commits yet this may not be practical
since its formatting will likely look different from what we currently use.

Before reformatting the "official" Carpet codebase I would try it out
first and add a custom clang-format option set to handle CCTK_LOOP and
BEGIN_XXX macros properly.

To support 'diff' I would suggest for users to make a
always-used-clang-format copy of their repository like so:

for b in `git branch | awk '/master/||/AMRToy/{next} {print $NF}'` ; do
 echo $b
  rm -rf .git-rewrite *
  git checkout -f $b
  git filter-branch --tree-filter \
    'find . -name \*.[hc][hc] -print0 | xargs --null clang-format-3.5
--style=llvm -i' $b
  rm -r .git/refs/original/
done

which takes however about 1.5hrs per branch and skips the branches
listed in the awk command. One can then bisect on this repo.

To rebase current development branches onto a reformatted master one can
do (eg for a branch "map"):

BRANCH=map

BRANCHPOINT=$(git rev-list origin/master..$BRANCH | tail -n1)
git filter-branch --tree-filter 'find . -name \*.[hc][hc] -print0 |
xargs --null clang-format-3.5 --style=llvm -i' $BRANCHPOINT~2..$BRANCH

BRANCHPOINT=$(git rev-list origin/master..$BRANCH | tail -n1)
git rebase --onto master $BRANCHPOINT $BRANCH

where the "~2" makes sure that all of the original $BRANCHes commits
appear on to of a reformatted source tree. This will fail if there are
merges happening to close to the branching points.

Yours,
Roland