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[DRAFT][clang-format] helper script for resolving downstream reformat… #80462

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[DRAFT][clang-format] helper script for resolving downstream reformat… #80462

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[DRAFT][clang-format] helper script for resolving downstream reformat…
pogo59 Feb 2, 2024
642196b
Rewrite as a standalone script
pogo59 Feb 6, 2024
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79 changes: 79 additions & 0 deletions llvm/utils/git/clang-format-merge-resolver.sh
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This script should have mode 0755 (executable) instead of 0644 to be able to invoke it with the documented command-line.

Original file line number Diff line number Diff line change
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#!/usr/bin/env bash

# Usage:
# If clang-format is not on PATH:
# export CLANG_FORMAT_PATH=/path/to/clang-format
# Run this script to resolve the formatting conflicts and leave only
# the non-formatting conflicts for you to resolve manually.

# Find the .git directory.
GIT_DIR=$(git rev-parse --git-dir)

# Are we in the midst of a merge? If not, this is the wrong tool.
if [ ! -e $GIT_DIR/MERGE_HEAD ]; then
echo Not doing a merge?
exit -1
fi

# Find the "current" "other" and "base" commits.
# The commit we are merging into.
read CURRENT < $GIT_DIR/ORIG_HEAD
# The commit being merged into CURRENT.
read OTHER < $GIT_DIR/MERGE_HEAD
# Where it all started.
BASE=$(git merge-base $CURRENT $OTHER)

# Set up a place to keep temp files.
MYTEMP=$(mktemp -d)
trap 'rm -rf $MYTEMP' EXIT

# Find clang-format the same way code-format-helper.py does.
if [ -x "$CLANG_FORMAT_PATH" ]
then
CLANG_FORMAT=$CLANG_FORMAT_PATH
else
CLANG_FORMAT=$(which clang-format)
if [ ! $? ]
then
echo clang-format not found on PATH
exit -1
fi
fi

# resolve_one_file will perform formatting-conflict resolution on one file.
# If any conflicts remain, informs the user, otherwise will git-add the
# resolved file.
resolve_one_file() {
file=$1
echo Resolving "$file"...

# Get formatted copies of the base, current, and other files.
git show "$BASE:$file" | $CLANG_FORMAT --style=file --assume-filename="$file" > "$MYTEMP/base"
git show "$OTHER:$file" | $CLANG_FORMAT --style=file --assume-filename="$file" > "$MYTEMP/other"
git show "$CURRENT:$file" | $CLANG_FORMAT --style=file --assume-filename="$file" > "$MYTEMP/current"
Comment on lines +51 to +53
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The technique of figuring out $BASE/$OTHER/$CURRENT commits and using them here is fragile (because likely incomplete) and also unneeded because git already has these 3 versions of the file in its index for an unresolved conflict.

To use the versions from the git index, I can suggest either this (syntax explained here):

git show ":1:$file" | $CLANG_FORMAT ... >"$MYTEMP/base"
git show ":2:$file" | $CLANG_FORMAT ... >"$MYTEMP/current"
git show ":3:$file" | $CLANG_FORMAT ... >"$MYTEMP/other"

Or this (explained here):

read -r basetmp currenttmp othertmp rem < <(git checkout-index --stage=all "$file")
$CLANG_FORMAT ... -i "$basetmp"
$CLANG_FORMAT ... -i "$currenttmp"
$CLANG_FORMAT ... -i "$othertmp"

In both versions, all the logic for figuring out $BASE/$OTHER/$CURRENT can be dropped. In the second version, git creates suitable temp files, so you don't need $MYTEMP (but you would still be responsible to cleanup the temp files).


# Merge the formatted files and report failures.
git merge-file -Lcurrent -Lbase -Lother "$MYTEMP/current" "$MYTEMP/base" "$MYTEMP/other"
STATUS=$?
if [ $STATUS -lt 0 ]
then
echo git merge-file failed for "$file"
else
mv "$MYTEMP/current" "$file"
if [ $STATUS -eq 0 ]
then
git add "$file"
else
echo Conflicts remain in $file
fi
fi
}

# Find all the conflicted files, and operate on each one.
# `git status --porcelain` identifies conflicted files with 'UU ' prefix.
# No other prefix is relevant here.
git status --porcelain | grep '^UU ' | cut -c 4- | \
while read -r file
do
resolve_one_file "$file"
done
Comment on lines +75 to +79
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This will only work if you invoke the script from the top-level directory of the working copy? I think you can in any case get a valid filename by prefixing it with the output git rev-parse --show-cdup. But be sure to check if that is sufficient for the other commands inside resolve_one_file. (If too difficult, the script could error out when not in the top-level.)