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#!/bin/bash
#
# Purpose: manually associate missed renames in merge conflicts
#
# Usage: git merge-associate <our-target> <base> <theirs>
#
# Example: After a failed rename detection A/a -> B/b which results
# in CONFLICT (delete/modify) for A/a and corresponding "deleted by us"
# messages in git status, the following invocation can be used to manually
# establish the link:
#
# git merge-associate B/b :1:A/a :3:A/a
#
# or using a shell with brace expansion:
#
# git merge-associate B/b :{1,3}:A/a
#
# This registers
# - :1:A/a as :1:B/b
# - HEAD:B/b as :2:B/b
# - :3:A/a as :3:B/b
# and replaces B/b with a merge-conflict version using "git checkout -m -- B/b".
#
# After manual resolution of B/b and "git add B/b", A/a can be resolved by
# "git rm A/a"
#
set -e
#set -x
get_tree()
{
SPEC="${!1}"
TREE=""
if [[ -z "$SPEC" ]]; then
TREE="EMPTY"
elif [[ "$SPEC" =~ ^:(.): ]]; then
TREE="INDEX:${BASH_REMATCH[1]}"
elif [[ "$SPEC" =~ ^: ]]; then
TREE="INDEX:0"
elif [[ "$SPEC" =~ ^([^:]+): ]]; then
TREE=${BASH_REMATCH[1]}
else # no colon, considered as HEAD
eval ${1}="HEAD:${!1}"
TREE="HEAD"
fi
eval ${1}_TREE="$TREE"
eval ${1}_BASENAME="${SPEC##*:}"
}
get_mode_and_sha()
{
eval SPEC="\${$1}"
eval TREE="\${$1_TREE}"
eval BASENAME="\${$1_BASENAME}"
RESULT_MODE=""
RESULT_SHA=""
case "$TREE" in
EMPTY)
RESULT_MODE="100644"
RESULT_SHA="e69de29bb2d1d6434b8b29ae775ad8c2e48c5391"
;;
INDEX:*)
[[ "$TREE" =~ :(.) ]]
REQ_STAGE=${BASH_REMATCH[1]}
while read MODE SHA STAGE FILEPATH; do
if ! [ "$STAGE" = "$REQ_STAGE" ]; then
continue
fi
RESULT_MODE="$MODE"
RESULT_SHA="$SHA"
break
done < <(git ls-files --stage "$BASENAME")
;;
*)
while read MODE TYPE SHA FILEPATH; do
RESULT_MODE="$MODE"
RESULT_SHA="$SHA"
done < <(git ls-tree "$TREE" "$BASENAME")
;;
esac
if [ -z "$RESULT_MODE" ] ; then
echo "Could not determine mode for $SPEC"
exit 1
fi
if [ -z "$RESULT_SHA" ] ; then
echo "Could not determine SHA1 for $SPEC"
exit 1
fi
eval $1_SHA="$RESULT_SHA"
eval $1_MODE="$RESULT_MODE"
}
if [ "$#" -ne 3 ]; then
echo "Usage: git merge-associate <our-target> <base> <theirs>"
exit 1
fi
TARGET="$1"
BASE="$2"
THEIRS="$3"
for VAR in TARGET BASE THEIRS; do
get_tree $VAR
get_mode_and_sha $VAR
done
git update-index --index-info <<EOI
000000 0000000000000000000000000000000000000000 0 $TARGET_BASENAME
$BASE_MODE $BASE_SHA 1 $TARGET_BASENAME
$TARGET_MODE $TARGET_SHA 2 $TARGET_BASENAME
$THEIRS_MODE $THEIRS_SHA 3 $TARGET_BASENAME
EOI
git checkout -m -- $TARGET_BASENAME
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