13956670a7
It may get extra merge base on truly pathological commit histories, but is a lot easier to understand, explain, and prove correctness. Signed-off-by: Junio C Hamano <junkio@cox.net>
291 lines
6.2 KiB
Bash
Executable File
291 lines
6.2 KiB
Bash
Executable File
#!/bin/sh
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#
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# Copyright (c) 2005 Junio C Hamano
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#
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. git-sh-setup || die "Not a git archive"
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LF='
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'
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usage () {
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die "git-merge [-n] [--no-commit] [-s <strategy>]... <merge-message> <head> <remote>+"
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}
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# all_strategies='resolve recursive stupid octopus'
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all_strategies='recursive octopus resolve stupid ours'
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default_strategies='resolve octopus'
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use_strategies=
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dropsave() {
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rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
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"$GIT_DIR/MERGE_SAVE" || exit 1
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}
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savestate() {
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# Stash away any local modifications.
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git-diff-index -z --name-only $head |
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cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
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}
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restorestate() {
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if test -f "$GIT_DIR/MERGE_SAVE"
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then
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git reset --hard $head
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cpio -iuv <"$GIT_DIR/MERGE_SAVE"
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git-update-index --refresh >/dev/null
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fi
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}
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finish () {
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test '' = "$2" || echo "$2"
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case "$merge_msg" in
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'')
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echo "No merge message -- not updating HEAD"
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;;
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*)
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git-update-ref HEAD "$1" "$head" || exit 1
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;;
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esac
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case "$no_summary" in
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'')
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git-diff-tree -p -M "$head" "$1" |
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git-apply --stat --summary
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;;
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esac
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}
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while case "$#" in 0) break ;; esac
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do
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case "$1" in
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-n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
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--no-summa|--no-summar|--no-summary)
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no_summary=t ;;
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--no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
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no_commit=t ;;
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-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
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--strateg=*|--strategy=*|\
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-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
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case "$#,$1" in
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*,*=*)
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strategy=`expr "$1" : '-[^=]*=\(.*\)'` ;;
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1,*)
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usage ;;
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*)
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strategy="$2"
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shift ;;
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esac
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case " $all_strategies " in
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*" $strategy "*)
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use_strategies="$use_strategies$strategy " ;;
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*)
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die "available strategies are: $all_strategies" ;;
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esac
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;;
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-*) usage ;;
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*) break ;;
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esac
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shift
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done
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case "$use_strategies" in
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'')
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use_strategies=$default_strategies
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;;
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esac
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test "$#" -le 2 && usage ;# we need at least two heads.
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merge_msg="$1"
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shift
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head_arg="$1"
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head=$(git-rev-parse --verify "$1"^0) || usage
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shift
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# All the rest are remote heads
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for remote
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do
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git-rev-parse --verify "$remote"^0 >/dev/null ||
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die "$remote - not something we can merge"
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done
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case "$#" in
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1)
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common=$(git-merge-base --all $head "$@")
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;;
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*)
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common=$(git-show-branch --merge-base $head "$@")
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;;
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esac
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echo "$head" >"$GIT_DIR/ORIG_HEAD"
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case "$#,$common,$no_commit" in
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*,'',*)
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# No common ancestors found. We need a real merge.
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;;
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1,"$1",*)
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# If head can reach all the merge then we are up to date.
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# but first the most common case of merging one remote
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echo "Already up-to-date."
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dropsave
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exit 0
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;;
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1,"$head",*)
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# Again the most common case of merging one remote.
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echo "Updating from $head to $1."
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git-update-index --refresh 2>/dev/null
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new_head=$(git-rev-parse --verify "$1^0") &&
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git-read-tree -u -m $head "$new_head" &&
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finish "$new_head" "Fast forward"
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dropsave
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exit 0
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;;
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1,?*"$LF"?*,*)
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# We are not doing octopus and not fast forward. Need a
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# real merge.
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;;
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1,*,)
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# We are not doing octopus, not fast forward, and have only
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# one common. See if it is really trivial.
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echo "Trying really trivial in-index merge..."
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git-update-index --refresh 2>/dev/null
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if git-read-tree --trivial -m -u $common $head "$1" &&
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result_tree=$(git-write-tree)
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then
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echo "Wonderful."
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result_commit=$(
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echo "$merge_msg" |
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git-commit-tree $result_tree -p HEAD -p "$1"
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) || exit
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finish "$result_commit" "In-index merge"
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dropsave
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exit 0
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fi
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echo "Nope."
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;;
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*)
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# An octopus. If we can reach all the remote we are up to date.
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up_to_date=t
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for remote
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do
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common_one=$(git-merge-base --all $head $remote)
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if test "$common_one" != "$remote"
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then
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up_to_date=f
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break
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fi
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done
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if test "$up_to_date" = t
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then
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echo "Already up-to-date. Yeeah!"
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dropsave
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exit 0
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fi
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;;
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esac
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# At this point, we need a real merge. No matter what strategy
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# we use, it would operate on the index, possibly affecting the
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# working tree, and when resolved cleanly, have the desired tree
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# in the index -- this means that the index must be in sync with
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# the $head commit. The strategies are responsible to ensure this.
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case "$use_strategies" in
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?*' '?*)
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# Stash away the local changes so that we can try more than one.
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savestate
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single_strategy=no
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;;
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*)
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rm -f "$GIT_DIR/MERGE_SAVE"
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single_strategy=yes
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;;
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esac
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result_tree= best_cnt=-1 best_strategy= wt_strategy=
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for strategy in $use_strategies
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do
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test "$wt_strategy" = '' || {
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echo "Rewinding the tree to pristine..."
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restorestate
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}
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case "$single_strategy" in
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no)
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echo "Trying merge strategy $strategy..."
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;;
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esac
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# Remember which strategy left the state in the working tree
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wt_strategy=$strategy
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git-merge-$strategy $common -- "$head_arg" "$@"
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exit=$?
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if test "$no_commit" = t && test "$exit" = 0
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then
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exit=1 ;# pretend it left conflicts.
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fi
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test "$exit" = 0 || {
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# The backend exits with 1 when conflicts are left to be resolved,
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# with 2 when it does not handle the given merge at all.
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if test "$exit" -eq 1
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then
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cnt=`{
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git-diff-files --name-only
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git-ls-files --unmerged
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} | wc -l`
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if test $best_cnt -le 0 -o $cnt -le $best_cnt
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then
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best_strategy=$strategy
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best_cnt=$cnt
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fi
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fi
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continue
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}
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# Automerge succeeded.
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result_tree=$(git-write-tree) && break
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done
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# If we have a resulting tree, that means the strategy module
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# auto resolved the merge cleanly.
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if test '' != "$result_tree"
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then
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parents="-p $head"
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for remote
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do
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parents="$parents -p $remote"
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done
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result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents) || exit
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finish "$result_commit" "Merge $result_commit, made by $wt_strategy."
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dropsave
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exit 0
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fi
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# Pick the result from the best strategy and have the user fix it up.
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case "$best_strategy" in
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'')
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restorestate
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die "No merge strategy handled the merge."
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;;
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"$wt_strategy")
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# We already have its result in the working tree.
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;;
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*)
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echo "Rewinding the tree to pristine..."
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restorestate
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echo "Using the $best_strategy to prepare resolving by hand."
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git-merge-$best_strategy $common -- "$head_arg" "$@"
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;;
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esac
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for remote
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do
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echo $remote
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done >"$GIT_DIR/MERGE_HEAD"
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echo $merge_msg >"$GIT_DIR/MERGE_MSG"
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die "Automatic merge failed/prevented; fix up by hand"
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