git/git-merge-octopus.sh
Junio C Hamano 17cf939724 octopus: do not do AND'ed merge base.
When doing an octopus, we incorrectly used the previous merge
base as the reference to compute next merge base.  This was
unnecessary, because that can never be better than using the
original HEAD.  And that is far simpler as well ;-).

Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-11-11 00:50:24 -08:00

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#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano
#
# Resolve two or more trees.
#
LF='
'
# The first parameters up to -- are merge bases; the rest are heads.
bases= head= remotes= sep_seen=
for arg
do
case ",$sep_seen,$head,$arg," in
*,--,)
sep_seen=yes
;;
,yes,,*)
head=$arg
;;
,yes,*)
remotes="$remotes$arg "
;;
*)
bases="$bases$arg "
;;
esac
done
# Reject if this is not an Octopus -- resolve should be used instead.
case "$remotes" in
?*' '?*)
;;
*)
exit 2 ;;
esac
# MRC is the current "merge reference commit"
# MRT is the current "merge result tree"
MRC=$head MSG= PARENT="-p $head"
MRT=$(git-write-tree)
CNT=1 ;# counting our head
NON_FF_MERGE=0
for SHA1 in $remotes
do
common=$(git-merge-base --all $MRC $SHA1) ||
die "Unable to find common commit with $SHA1"
case "$common" in
?*"$LF"?*)
die "Not trivially mergeable."
;;
$SHA1)
echo "Already up-to-date with $SHA1"
continue
;;
esac
CNT=`expr $CNT + 1`
PARENT="$PARENT -p $SHA1"
if test "$common,$NON_FF_MERGE" = "$MRC,0"
then
# The first head being merged was a fast-forward.
# Advance MRC to the head being merged, and use that
# tree as the intermediate result of the merge.
# We still need to count this as part of the parent set.
echo "Fast forwarding to: $SHA1"
git-read-tree -u -m $head $SHA1 || exit
MRC=$SHA1 MRT=$(git-write-tree)
continue
fi
NON_FF_MERGE=1
echo "Trying simple merge with $SHA1"
git-read-tree -u -m $common $MRT $SHA1 || exit 2
next=$(git-write-tree 2>/dev/null)
if test $? -ne 0
then
echo "Simple merge did not work, trying automatic merge."
git-merge-index -o git-merge-one-file -a ||
exit 2 ; # Automatic merge failed; should not be doing Octopus
next=$(git-write-tree 2>/dev/null)
fi
# We have merged the other branch successfully. Ideally
# we could implement OR'ed heads in merge-base, and keep
# a list of commits we have merged so far in MRC to feed
# them to merge-base, but we approximate it by keep using
# the current MRC. We used to update it to $common, which
# was incorrectly doing AND'ed merge-base here, which was
# unneeded.
MRT=$next
done
exit 0