git-clone: check out "master" by default.
[git/git.git] / git-merge.sh
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1#!/bin/sh
2#
3# Copyright (c) 2005 Junio C Hamano
4#
5
6. git-sh-setup || die "Not a git archive"
7
8LF='
9'
10
11usage () {
12 die "git-merge [-n] [-s <strategy>]... <merge-message> <head> <remote>+"
13}
14
e4cf17ce 15# all_strategies='resolve recursive stupid octopus'
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e4cf17ce 17all_strategies='recursive octopus resolve stupid'
2276aa6c 18default_strategies='resolve octopus'
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19use_strategies=
20
21dropheads() {
22 rm -f -- "$GIT_DIR/MERGE_HEAD" || exit 1
23}
24
25summary() {
26 case "$no_summary" in
27 '')
28 git-diff-tree -p -M $head "$1" |
29 git-apply --stat --summary
30 ;;
31 esac
32}
33
34while case "$#" in 0) break ;; esac
35do
36 case "$1" in
37 -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
38 --no-summa|--no-summar|--no-summary)
39 no_summary=t ;;
40 -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
41 --strateg=*|--strategy=*|\
42 -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
43 case "$#,$1" in
44 *,*=*)
45 strategy=`expr "$1" : '-[^=]*=\(.*\)'` ;;
f88ed172 46 1,*)
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47 usage ;;
48 *)
49 strategy="$2"
50 shift ;;
51 esac
52 case " $all_strategies " in
53 *" $strategy "*)
54 use_strategies="$use_strategies$strategy " ;;
55 *)
56 die "available strategies are: $all_strategies" ;;
57 esac
58 ;;
59 -*) usage ;;
60 *) break ;;
61 esac
62 shift
63done
64
65case "$use_strategies" in
66'')
67 use_strategies=$default_strategies
68 ;;
69esac
70test "$#" -le 2 && usage ;# we need at least two heads.
71
72merge_msg="$1"
73shift
8cc01e50 74head_arg="$1"
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75head=$(git-rev-parse --verify "$1"^0) || usage
76shift
77
78# All the rest are remote heads
79for remote
80do
81 git-rev-parse --verify "$remote"^0 >/dev/null ||
82 die "$remote - not something we can merge"
83done
84
85common=$(git-show-branch --merge-base $head "$@")
86echo "$head" >"$GIT_DIR/ORIG_HEAD"
87
88case "$#,$common" in
89*,'')
8cc01e50 90 die "Unable to find common commit between $head_arg and $*"
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91 ;;
921,"$1")
93 # If head can reach all the merge then we are up to date.
94 # but first the most common case of merging one remote
95 echo "Already up-to-date. Yeeah!"
96 dropheads
97 exit 0
98 ;;
991,"$head")
100 # Again the most common case of merging one remote.
101 echo "Updating from $head to $1."
102 git-update-index --refresh 2>/dev/null
103 git-read-tree -u -m $head "$1" || exit 1
104 git-rev-parse --verify "$1^0" > "$GIT_DIR/HEAD"
105 summary "$1"
106 dropheads
107 exit 0
108 ;;
1091,*)
110 # We are not doing octopus and not fast forward. Need a
111 # real merge.
112 ;;
113*)
114 # An octopus. If we can reach all the remote we are up to date.
115 up_to_date=t
116 for remote
117 do
118 common_one=$(git-merge-base $head $remote)
119 if test "$common_one" != "$remote"
120 then
121 up_to_date=f
122 break
123 fi
124 done
125 if test "$up_to_date" = t
126 then
127 echo "Already up-to-date. Yeeah!"
128 dropheads
129 exit 0
130 fi
131 ;;
132esac
133
134# At this point we need a real merge. Require that the tree matches
135# exactly our head.
136
137git-update-index --refresh &&
138test '' = "`git-diff-index --cached --name-only $head`" || {
139 die "Need real merge but the working tree has local changes."
140}
141
142result_tree= best_cnt=-1 best_strategy= wt_strategy=
143for strategy in $use_strategies
144do
145 test "$wt_strategy" = '' || {
146 echo "Rewinding the tree to pristine..."
147 git reset --hard $head
148 }
149 echo "Trying merge strategy $strategy..."
150 wt_strategy=$strategy
8cc01e50 151 git-merge-$strategy $common -- $head_arg "$@" || {
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152
153 # The backend exits with 1 when conflicts are left to be resolved,
154 # with 2 when it does not handle the given merge at all.
155
156 exit=$?
157 if test "$exit" -eq 1
158 then
159 cnt=`{
160 git-diff-files --name-only
161 git-ls-files --unmerged
162 } | wc -l`
163 if test $best_cnt -le 0 -o $cnt -le $best_cnt
164 then
165 best_strategy=$strategy
166 best_cnt=$cnt
167 fi
168 fi
169 continue
170 }
171
172 # Automerge succeeded.
173 result_tree=$(git-write-tree) && break
174done
175
176# If we have a resulting tree, that means the strategy module
177# auto resolved the merge cleanly.
178if test '' != "$result_tree"
179then
180 parents="-p $head"
181 for remote
182 do
183 parents="$parents -p $remote"
184 done
185 result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents)
186 echo "Committed merge $result_commit, made by $wt_strategy."
187 echo $result_commit >"$GIT_DIR/HEAD"
188 summary $result_commit
189 dropheads
190 exit 0
191fi
192
193# Pick the result from the best strategy and have the user fix it up.
194case "$best_strategy" in
195'')
196 git reset --hard $head
197 die "No merge strategy handled the merge."
198 ;;
199"$wt_strategy")
200 # We already have its result in the working tree.
201 ;;
202*)
203 echo "Rewinding the tree to pristine..."
204 git reset --hard $head
205 echo "Using the $best_strategy to prepare resolving by hand."
8cc01e50 206 git-merge-$best_strategy $common -- $head_arg "$@"
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207 ;;
208esac
209for remote
210do
211 echo $remote
212done >"$GIT_DIR/MERGE_HEAD"
213die "Automatic merge failed; fix up by hand"