Merge branch 'maint'
[git] / git-merge.sh
1 #!/bin/sh
2 #
3 # Copyright (c) 2005 Junio C Hamano
4 #
5
6 USAGE='[-n] [--summary] [--[no-]commit] [--[no-]squash] [--[no-]ff] [-s <strategy>] [-m=<merge-message>] <commit>+'
7
8 SUBDIRECTORY_OK=Yes
9 . git-sh-setup
10 require_work_tree
11 cd_to_toplevel
12
13 test -z "$(git ls-files -u)" ||
14         die "You are in the middle of a conflicted merge."
15
16 LF='
17 '
18
19 all_strategies='recur recursive octopus resolve stupid ours subtree'
20 default_twohead_strategies='recursive'
21 default_octopus_strategies='octopus'
22 no_fast_forward_strategies='subtree ours'
23 no_trivial_strategies='recursive recur subtree ours'
24 use_strategies=
25
26 allow_fast_forward=t
27 allow_trivial_merge=t
28
29 dropsave() {
30         rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
31                  "$GIT_DIR/MERGE_SAVE" || exit 1
32 }
33
34 savestate() {
35         # Stash away any local modifications.
36         git diff-index -z --name-only $head |
37         cpio -0 -o >"$GIT_DIR/MERGE_SAVE"
38 }
39
40 restorestate() {
41         if test -f "$GIT_DIR/MERGE_SAVE"
42         then
43                 git reset --hard $head >/dev/null
44                 cpio -iuv <"$GIT_DIR/MERGE_SAVE"
45                 git update-index --refresh >/dev/null
46         fi
47 }
48
49 finish_up_to_date () {
50         case "$squash" in
51         t)
52                 echo "$1 (nothing to squash)" ;;
53         '')
54                 echo "$1" ;;
55         esac
56         dropsave
57 }
58
59 squash_message () {
60         echo Squashed commit of the following:
61         echo
62         git log --no-merges ^"$head" $remoteheads
63 }
64
65 finish () {
66         if test '' = "$2"
67         then
68                 rlogm="$GIT_REFLOG_ACTION"
69         else
70                 echo "$2"
71                 rlogm="$GIT_REFLOG_ACTION: $2"
72         fi
73         case "$squash" in
74         t)
75                 echo "Squash commit -- not updating HEAD"
76                 squash_message >"$GIT_DIR/SQUASH_MSG"
77                 ;;
78         '')
79                 case "$merge_msg" in
80                 '')
81                         echo "No merge message -- not updating HEAD"
82                         ;;
83                 *)
84                         git update-ref -m "$rlogm" HEAD "$1" "$head" || exit 1
85                         git gc --auto
86                         ;;
87                 esac
88                 ;;
89         esac
90         case "$1" in
91         '')
92                 ;;
93         ?*)
94                 if test "$show_diffstat" = t
95                 then
96                         # We want color (if set), but no pager
97                         GIT_PAGER='' git diff --stat --summary -M "$head" "$1"
98                 fi
99                 ;;
100         esac
101
102         # Run a post-merge hook
103         if test -x "$GIT_DIR"/hooks/post-merge
104         then
105             case "$squash" in
106             t)
107                 "$GIT_DIR"/hooks/post-merge 1
108                 ;;
109             '')
110                 "$GIT_DIR"/hooks/post-merge 0
111                 ;;
112             esac
113         fi
114 }
115
116 merge_name () {
117         remote="$1"
118         rh=$(git rev-parse --verify "$remote^0" 2>/dev/null) || return
119         bh=$(git show-ref -s --verify "refs/heads/$remote" 2>/dev/null)
120         if test "$rh" = "$bh"
121         then
122                 echo "$rh               branch '$remote' of ."
123         elif truname=$(expr "$remote" : '\(.*\)~[1-9][0-9]*$') &&
124                 git show-ref -q --verify "refs/heads/$truname" 2>/dev/null
125         then
126                 echo "$rh               branch '$truname' (early part) of ."
127         elif test "$remote" = "FETCH_HEAD" -a -r "$GIT_DIR/FETCH_HEAD"
128         then
129                 sed -e 's/      not-for-merge   /               /' -e 1q \
130                         "$GIT_DIR/FETCH_HEAD"
131         else
132                 echo "$rh               commit '$remote'"
133         fi
134 }
135
136 parse_option () {
137         case "$1" in
138         -n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
139                 --no-summa|--no-summar|--no-summary)
140                 show_diffstat=false ;;
141         --summary)
142                 show_diffstat=t ;;
143         --sq|--squ|--squa|--squas|--squash)
144                 allow_fast_forward=t squash=t no_commit=t ;;
145         --no-sq|--no-squ|--no-squa|--no-squas|--no-squash)
146                 allow_fast_forward=t squash= no_commit= ;;
147         --c|--co|--com|--comm|--commi|--commit)
148                 allow_fast_forward=t squash= no_commit= ;;
149         --no-c|--no-co|--no-com|--no-comm|--no-commi|--no-commit)
150                 allow_fast_forward=t squash= no_commit=t ;;
151         --ff)
152                 allow_fast_forward=t squash= no_commit= ;;
153         --no-ff)
154                 allow_fast_forward=false squash= no_commit= ;;
155         -s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
156                 --strateg=*|--strategy=*|\
157         -s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
158                 case "$#,$1" in
159                 *,*=*)
160                         strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
161                 1,*)
162                         usage ;;
163                 *)
164                         strategy="$2"
165                         shift ;;
166                 esac
167                 case " $all_strategies " in
168                 *" $strategy "*)
169                         use_strategies="$use_strategies$strategy " ;;
170                 *)
171                         die "available strategies are: $all_strategies" ;;
172                 esac
173                 ;;
174         -m=*|--m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
175                 merge_msg=`expr "z$1" : 'z-[^=]*=\(.*\)'`
176                 have_message=t
177                 ;;
178         -m|--m|--me|--mes|--mess|--messa|--messag|--message)
179                 shift
180                 case "$#" in
181                 1)      usage ;;
182                 esac
183                 merge_msg="$1"
184                 have_message=t
185                 ;;
186         -*)     usage ;;
187         *)      return 1 ;;
188         esac
189         shift
190         args_left=$#
191 }
192
193 parse_config () {
194         while test $# -gt 0
195         do
196                 parse_option "$@" || usage
197                 while test $args_left -lt $#
198                 do
199                         shift
200                 done
201         done
202 }
203
204 test $# != 0 || usage
205
206 have_message=
207
208 if branch=$(git-symbolic-ref -q HEAD)
209 then
210         mergeopts=$(git config "branch.${branch#refs/heads/}.mergeoptions")
211         if test -n "$mergeopts"
212         then
213                 parse_config $mergeopts
214         fi
215 fi
216
217 while parse_option "$@"
218 do
219         while test $args_left -lt $#
220         do
221                 shift
222         done
223 done
224
225 if test -z "$show_diffstat"; then
226     test "$(git config --bool merge.diffstat)" = false && show_diffstat=false
227     test -z "$show_diffstat" && show_diffstat=t
228 fi
229
230 # This could be traditional "merge <msg> HEAD <commit>..."  and the
231 # way we can tell it is to see if the second token is HEAD, but some
232 # people might have misused the interface and used a committish that
233 # is the same as HEAD there instead.  Traditional format never would
234 # have "-m" so it is an additional safety measure to check for it.
235
236 if test -z "$have_message" &&
237         second_token=$(git rev-parse --verify "$2^0" 2>/dev/null) &&
238         head_commit=$(git rev-parse --verify "HEAD" 2>/dev/null) &&
239         test "$second_token" = "$head_commit"
240 then
241         merge_msg="$1"
242         shift
243         head_arg="$1"
244         shift
245 elif ! git rev-parse --verify HEAD >/dev/null 2>&1
246 then
247         # If the merged head is a valid one there is no reason to
248         # forbid "git merge" into a branch yet to be born.  We do
249         # the same for "git pull".
250         if test 1 -ne $#
251         then
252                 echo >&2 "Can merge only exactly one commit into empty head"
253                 exit 1
254         fi
255
256         rh=$(git rev-parse --verify "$1^0") ||
257                 die "$1 - not something we can merge"
258
259         git update-ref -m "initial pull" HEAD "$rh" "" &&
260         git read-tree --reset -u HEAD
261         exit
262
263 else
264         # We are invoked directly as the first-class UI.
265         head_arg=HEAD
266
267         # All the rest are the commits being merged; prepare
268         # the standard merge summary message to be appended to
269         # the given message.  If remote is invalid we will die
270         # later in the common codepath so we discard the error
271         # in this loop.
272         merge_name=$(for remote
273                 do
274                         merge_name "$remote"
275                 done | git fmt-merge-msg
276         )
277         merge_msg="${merge_msg:+$merge_msg$LF$LF}$merge_name"
278 fi
279 head=$(git rev-parse --verify "$head_arg"^0) || usage
280
281 # All the rest are remote heads
282 test "$#" = 0 && usage ;# we need at least one remote head.
283 set_reflog_action "merge $*"
284
285 remoteheads=
286 for remote
287 do
288         remotehead=$(git rev-parse --verify "$remote"^0 2>/dev/null) ||
289             die "$remote - not something we can merge"
290         remoteheads="${remoteheads}$remotehead "
291         eval GITHEAD_$remotehead='"$remote"'
292         export GITHEAD_$remotehead
293 done
294 set x $remoteheads ; shift
295
296 case "$use_strategies" in
297 '')
298         case "$#" in
299         1)
300                 var="`git config --get pull.twohead`"
301                 if test -n "$var"
302                 then
303                         use_strategies="$var"
304                 else
305                         use_strategies="$default_twohead_strategies"
306                 fi ;;
307         *)
308                 var="`git config --get pull.octopus`"
309                 if test -n "$var"
310                 then
311                         use_strategies="$var"
312                 else
313                         use_strategies="$default_octopus_strategies"
314                 fi ;;
315         esac
316         ;;
317 esac
318
319 for s in $use_strategies
320 do
321         for ss in $no_fast_forward_strategies
322         do
323                 case " $s " in
324                 *" $ss "*)
325                         allow_fast_forward=f
326                         break
327                         ;;
328                 esac
329         done
330         for ss in $no_trivial_strategies
331         do
332                 case " $s " in
333                 *" $ss "*)
334                         allow_trivial_merge=f
335                         break
336                         ;;
337                 esac
338         done
339 done
340
341 case "$#" in
342 1)
343         common=$(git merge-base --all $head "$@")
344         ;;
345 *)
346         common=$(git show-branch --merge-base $head "$@")
347         ;;
348 esac
349 echo "$head" >"$GIT_DIR/ORIG_HEAD"
350
351 case "$allow_fast_forward,$#,$common,$no_commit" in
352 ?,*,'',*)
353         # No common ancestors found. We need a real merge.
354         ;;
355 ?,1,"$1",*)
356         # If head can reach all the merge then we are up to date.
357         # but first the most common case of merging one remote.
358         finish_up_to_date "Already up-to-date."
359         exit 0
360         ;;
361 t,1,"$head",*)
362         # Again the most common case of merging one remote.
363         echo "Updating $(git rev-parse --short $head)..$(git rev-parse --short $1)"
364         git update-index --refresh 2>/dev/null
365         msg="Fast forward"
366         if test -n "$have_message"
367         then
368                 msg="$msg (no commit created; -m option ignored)"
369         fi
370         new_head=$(git rev-parse --verify "$1^0") &&
371         git read-tree -v -m -u --exclude-per-directory=.gitignore $head "$new_head" &&
372         finish "$new_head" "$msg" || exit
373         dropsave
374         exit 0
375         ;;
376 ?,1,?*"$LF"?*,*)
377         # We are not doing octopus and not fast forward.  Need a
378         # real merge.
379         ;;
380 ?,1,*,)
381         # We are not doing octopus, not fast forward, and have only
382         # one common.
383         git update-index --refresh 2>/dev/null
384         case "$allow_trivial_merge" in
385         t)
386                 # See if it is really trivial.
387                 git var GIT_COMMITTER_IDENT >/dev/null || exit
388                 echo "Trying really trivial in-index merge..."
389                 if git read-tree --trivial -m -u -v $common $head "$1" &&
390                    result_tree=$(git write-tree)
391                 then
392                         echo "Wonderful."
393                         result_commit=$(
394                                 printf '%s\n' "$merge_msg" |
395                                 git commit-tree $result_tree -p HEAD -p "$1"
396                         ) || exit
397                         finish "$result_commit" "In-index merge"
398                         dropsave
399                         exit 0
400                 fi
401                 echo "Nope."
402         esac
403         ;;
404 *)
405         # An octopus.  If we can reach all the remote we are up to date.
406         up_to_date=t
407         for remote
408         do
409                 common_one=$(git merge-base --all $head $remote)
410                 if test "$common_one" != "$remote"
411                 then
412                         up_to_date=f
413                         break
414                 fi
415         done
416         if test "$up_to_date" = t
417         then
418                 finish_up_to_date "Already up-to-date. Yeeah!"
419                 exit 0
420         fi
421         ;;
422 esac
423
424 # We are going to make a new commit.
425 git var GIT_COMMITTER_IDENT >/dev/null || exit
426
427 # At this point, we need a real merge.  No matter what strategy
428 # we use, it would operate on the index, possibly affecting the
429 # working tree, and when resolved cleanly, have the desired tree
430 # in the index -- this means that the index must be in sync with
431 # the $head commit.  The strategies are responsible to ensure this.
432
433 case "$use_strategies" in
434 ?*' '?*)
435     # Stash away the local changes so that we can try more than one.
436     savestate
437     single_strategy=no
438     ;;
439 *)
440     rm -f "$GIT_DIR/MERGE_SAVE"
441     single_strategy=yes
442     ;;
443 esac
444
445 result_tree= best_cnt=-1 best_strategy= wt_strategy=
446 merge_was_ok=
447 for strategy in $use_strategies
448 do
449     test "$wt_strategy" = '' || {
450         echo "Rewinding the tree to pristine..."
451         restorestate
452     }
453     case "$single_strategy" in
454     no)
455         echo "Trying merge strategy $strategy..."
456         ;;
457     esac
458
459     # Remember which strategy left the state in the working tree
460     wt_strategy=$strategy
461
462     git-merge-$strategy $common -- "$head_arg" "$@"
463     exit=$?
464     if test "$no_commit" = t && test "$exit" = 0
465     then
466         merge_was_ok=t
467         exit=1 ;# pretend it left conflicts.
468     fi
469
470     test "$exit" = 0 || {
471
472         # The backend exits with 1 when conflicts are left to be resolved,
473         # with 2 when it does not handle the given merge at all.
474
475         if test "$exit" -eq 1
476         then
477             cnt=`{
478                 git diff-files --name-only
479                 git ls-files --unmerged
480             } | wc -l`
481             if test $best_cnt -le 0 -o $cnt -le $best_cnt
482             then
483                 best_strategy=$strategy
484                 best_cnt=$cnt
485             fi
486         fi
487         continue
488     }
489
490     # Automerge succeeded.
491     result_tree=$(git write-tree) && break
492 done
493
494 # If we have a resulting tree, that means the strategy module
495 # auto resolved the merge cleanly.
496 if test '' != "$result_tree"
497 then
498     if test "$allow_fast_forward" = "t"
499     then
500         parents=$(git show-branch --independent "$head" "$@")
501     else
502         parents=$(git rev-parse "$head" "$@")
503     fi
504     parents=$(echo "$parents" | sed -e 's/^/-p /')
505     result_commit=$(printf '%s\n' "$merge_msg" | git commit-tree $result_tree $parents) || exit
506     finish "$result_commit" "Merge made by $wt_strategy."
507     dropsave
508     exit 0
509 fi
510
511 # Pick the result from the best strategy and have the user fix it up.
512 case "$best_strategy" in
513 '')
514         restorestate
515         case "$use_strategies" in
516         ?*' '?*)
517                 echo >&2 "No merge strategy handled the merge."
518                 ;;
519         *)
520                 echo >&2 "Merge with strategy $use_strategies failed."
521                 ;;
522         esac
523         exit 2
524         ;;
525 "$wt_strategy")
526         # We already have its result in the working tree.
527         ;;
528 *)
529         echo "Rewinding the tree to pristine..."
530         restorestate
531         echo "Using the $best_strategy to prepare resolving by hand."
532         git-merge-$best_strategy $common -- "$head_arg" "$@"
533         ;;
534 esac
535
536 if test "$squash" = t
537 then
538         finish
539 else
540         for remote
541         do
542                 echo $remote
543         done >"$GIT_DIR/MERGE_HEAD"
544         printf '%s\n' "$merge_msg" >"$GIT_DIR/MERGE_MSG"
545 fi
546
547 if test "$merge_was_ok" = t
548 then
549         echo >&2 \
550         "Automatic merge went well; stopped before committing as requested"
551         exit 0
552 else
553         {
554             echo '
555 Conflicts:
556 '
557                 git ls-files --unmerged |
558                 sed -e 's/^[^   ]*      /       /' |
559                 uniq
560         } >>"$GIT_DIR/MERGE_MSG"
561         git rerere
562         die "Automatic merge failed; fix conflicts and then commit the result."
563 fi