git-clone: Support changing the origin branch with -o
[git.git] / git-merge.sh
1 #!/bin/sh
2 #
3 # Copyright (c) 2005 Junio C Hamano
4 #
5
6
7 USAGE='[-n] [--no-commit] [-s <strategy>]... <merge-message> <head> <remote>+'
8 . git-sh-setup
9
10 LF='
11 '
12
13 all_strategies='recursive octopus resolve stupid ours'
14 default_strategies='recursive'
15 use_strategies=
16
17 dropsave() {
18         rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
19                  "$GIT_DIR/MERGE_SAVE" || exit 1
20 }
21
22 savestate() {
23         # Stash away any local modifications.
24         git-diff-index -z --name-only $head |
25         cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
26 }
27
28 restorestate() {
29         if test -f "$GIT_DIR/MERGE_SAVE"
30         then
31                 git reset --hard $head
32                 cpio -iuv <"$GIT_DIR/MERGE_SAVE"
33                 git-update-index --refresh >/dev/null
34         fi
35 }
36
37 finish () {
38         test '' = "$2" || echo "$2"
39         case "$merge_msg" in
40         '')
41                 echo "No merge message -- not updating HEAD"
42                 ;;
43         *)
44                 git-update-ref HEAD "$1" "$head" || exit 1
45                 ;;
46         esac
47
48         case "$no_summary" in
49         '')
50                 git-diff-tree -p -M "$head" "$1" |
51                 git-apply --stat --summary
52                 ;;
53         esac
54 }
55
56 while case "$#" in 0) break ;; esac
57 do
58         case "$1" in
59         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
60                 --no-summa|--no-summar|--no-summary)
61                 no_summary=t ;;
62         --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
63                 no_commit=t ;;
64         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
65                 --strateg=*|--strategy=*|\
66         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
67                 case "$#,$1" in
68                 *,*=*)
69                         strategy=`expr "$1" : '-[^=]*=\(.*\)'` ;;
70                 1,*)
71                         usage ;;
72                 *)
73                         strategy="$2"
74                         shift ;;
75                 esac
76                 case " $all_strategies " in
77                 *" $strategy "*)
78                         use_strategies="$use_strategies$strategy " ;;
79                 *)
80                         die "available strategies are: $all_strategies" ;;
81                 esac
82                 ;;
83         -*)     usage ;;
84         *)      break ;;
85         esac
86         shift
87 done
88
89 test "$#" -le 2 && usage ;# we need at least two heads.
90
91 merge_msg="$1"
92 shift
93 head_arg="$1"
94 head=$(git-rev-parse --verify "$1"^0) || usage
95 shift
96
97 # All the rest are remote heads
98 remoteheads=
99 for remote
100 do
101         remotehead=$(git-rev-parse --verify "$remote"^0) ||
102             die "$remote - not something we can merge"
103         remoteheads="${remoteheads}$remotehead "
104 done
105 set x $remoteheads ; shift
106
107 case "$#" in
108 1)
109         common=$(git-merge-base --all $head "$@")
110         ;;
111 *)
112         common=$(git-show-branch --merge-base $head "$@")
113         ;;
114 esac
115 echo "$head" >"$GIT_DIR/ORIG_HEAD"
116
117 case "$#,$common,$no_commit" in
118 *,'',*)
119         # No common ancestors found. We need a real merge.
120         ;;
121 1,"$1",*)
122         # If head can reach all the merge then we are up to date.
123         # but first the most common case of merging one remote
124         echo "Already up-to-date."
125         dropsave
126         exit 0
127         ;;
128 1,"$head",*)
129         # Again the most common case of merging one remote.
130         echo "Updating from $head to $1."
131         git-update-index --refresh 2>/dev/null
132         new_head=$(git-rev-parse --verify "$1^0") &&
133         git-read-tree -u -m $head "$new_head" &&
134         finish "$new_head" "Fast forward"
135         dropsave
136         exit 0
137         ;;
138 1,?*"$LF"?*,*)
139         # We are not doing octopus and not fast forward.  Need a
140         # real merge.
141         ;;
142 1,*,)
143         # We are not doing octopus, not fast forward, and have only
144         # one common.  See if it is really trivial.
145         echo "Trying really trivial in-index merge..."
146         git-update-index --refresh 2>/dev/null
147         if git-read-tree --trivial -m -u $common $head "$1" &&
148            result_tree=$(git-write-tree)
149         then
150             echo "Wonderful."
151             result_commit=$(
152                 echo "$merge_msg" |
153                 git-commit-tree $result_tree -p HEAD -p "$1"
154             ) || exit
155             finish "$result_commit" "In-index merge"
156             dropsave
157             exit 0
158         fi
159         echo "Nope."
160         ;;
161 *)
162         # An octopus.  If we can reach all the remote we are up to date.
163         up_to_date=t
164         for remote
165         do
166                 common_one=$(git-merge-base --all $head $remote)
167                 if test "$common_one" != "$remote"
168                 then
169                         up_to_date=f
170                         break
171                 fi
172         done
173         if test "$up_to_date" = t
174         then
175                 echo "Already up-to-date. Yeeah!"
176                 dropsave
177                 exit 0
178         fi
179         ;;
180 esac
181
182 case "$use_strategies" in
183 '')
184         case "$#" in
185         1)
186                 use_strategies="$default_strategies" ;;
187         *)
188                 use_strategies=octopus ;;
189         esac            
190         ;;
191 esac
192
193 # At this point, we need a real merge.  No matter what strategy
194 # we use, it would operate on the index, possibly affecting the
195 # working tree, and when resolved cleanly, have the desired tree
196 # in the index -- this means that the index must be in sync with
197 # the $head commit.  The strategies are responsible to ensure this.
198
199 case "$use_strategies" in
200 ?*' '?*)
201     # Stash away the local changes so that we can try more than one.
202     savestate
203     single_strategy=no
204     ;;
205 *)
206     rm -f "$GIT_DIR/MERGE_SAVE"
207     single_strategy=yes
208     ;;
209 esac
210
211 result_tree= best_cnt=-1 best_strategy= wt_strategy=
212 for strategy in $use_strategies
213 do
214     test "$wt_strategy" = '' || {
215         echo "Rewinding the tree to pristine..."
216         restorestate
217     }
218     case "$single_strategy" in
219     no)
220         echo "Trying merge strategy $strategy..."
221         ;;
222     esac
223
224     # Remember which strategy left the state in the working tree
225     wt_strategy=$strategy
226
227     git-merge-$strategy $common -- "$head_arg" "$@"
228     exit=$?
229     if test "$no_commit" = t && test "$exit" = 0
230     then
231         exit=1 ;# pretend it left conflicts.
232     fi
233
234     test "$exit" = 0 || {
235
236         # The backend exits with 1 when conflicts are left to be resolved,
237         # with 2 when it does not handle the given merge at all.
238
239         if test "$exit" -eq 1
240         then
241             cnt=`{
242                 git-diff-files --name-only
243                 git-ls-files --unmerged
244             } | wc -l`
245             if test $best_cnt -le 0 -o $cnt -le $best_cnt
246             then
247                 best_strategy=$strategy
248                 best_cnt=$cnt
249             fi
250         fi
251         continue
252     }
253
254     # Automerge succeeded.
255     result_tree=$(git-write-tree) && break
256 done
257
258 # If we have a resulting tree, that means the strategy module
259 # auto resolved the merge cleanly.
260 if test '' != "$result_tree"
261 then
262     parents="-p $head"
263     for remote
264     do
265         parents="$parents -p $remote"
266     done
267     result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents) || exit
268     finish "$result_commit" "Merge $result_commit, made by $wt_strategy."
269     dropsave
270     exit 0
271 fi
272
273 # Pick the result from the best strategy and have the user fix it up.
274 case "$best_strategy" in
275 '')
276         restorestate
277         echo >&2 "No merge strategy handled the merge."
278         exit 2
279         ;;
280 "$wt_strategy")
281         # We already have its result in the working tree.
282         ;;
283 *)
284         echo "Rewinding the tree to pristine..."
285         restorestate
286         echo "Using the $best_strategy to prepare resolving by hand."
287         git-merge-$best_strategy $common -- "$head_arg" "$@"
288         ;;
289 esac
290 for remote
291 do
292         echo $remote
293 done >"$GIT_DIR/MERGE_HEAD"
294 echo $merge_msg >"$GIT_DIR/MERGE_MSG"
295
296 die "Automatic merge failed/prevented; fix up by hand"