git-merge: make it usable as the first class UI

This teaches the oft-requested syntax git merge $commit to implement merging the named commit to the current branch. This hopefully would make "git merge" usable as the first class UI instead of being a mere backend for "git pull". Most notably, $commit above can be any committish, so you can say for example: git merge js/shortlog~2 to merge early part of a topic branch without merging the rest of it. A custom merge message can be given with the new --message=<msg> parameter. The message is prepended in front of the usual "Merge ..." message autogenerated with fmt-merge-message. Signed-off-by: Junio C Hamano <junkio@cox.net>
gitster · Nov 22, 2006 · 17bcdad · 17bcdad
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diff --git a/Documentation/git-merge.txt b/Documentation/git-merge.txt
@@ -8,12 +8,14 @@ git-merge - Grand Unified Merge Driver
 
 SYNOPSIS
 --------
-'git-merge' [-n] [--no-commit] [-s <strategy>]... <msg> <head> <remote> <remote>...
-
+[verse]
+'git-merge' [-n] [--no-commit] [--squash] [-s <strategy>]...
+	[--reflog-action=<action>]
+	-m=<msg> <remote> <remote>...
 
 DESCRIPTION
 -----------
-This is the top-level user interface to the merge machinery
+This is the top-level interface to the merge machinery
 which drives multiple merge strategy scripts.
 
 
@@ -27,13 +29,19 @@ include::merge-options.txt[]
 	to give a good default for automated `git-merge` invocations.
 
 <head>::
-	our branch head commit.
+	Our branch head commit.  This has to be `HEAD`, so new
+	syntax does not require it
 
 <remote>::
-	other branch head merged into our branch.  You need at
+	Other branch head merged into our branch.  You need at
 	least one <remote>.  Specifying more than one <remote>
 	obviously means you are trying an Octopus.
 
+--reflog-action=<action>::
+	This is used internally when `git-pull` calls this command
+	to record that the merge was created by `pull` command
+	in the `ref-log` entry that results from the merge.
+
 include::merge-strategies.txt[]
 
 

diff --git a/git-merge.sh b/git-merge.sh
@@ -3,7 +3,8 @@
 # Copyright (c) 2005 Junio C Hamano
 #
 
-USAGE='[-n] [--no-commit] [--squash] [-s <strategy>]... <merge-message> <head> <remote>+'
+USAGE='[-n] [--no-commit] [--squash] [-s <strategy>] [--reflog-action=<action>] [-m=<merge-message>] <commit>+'
+
 . git-sh-setup
 
 LF='
@@ -92,7 +93,7 @@ finish () {
 
 case "$#" in 0) usage ;; esac
 
-rloga=
+rloga= have_message=
 while case "$#" in 0) break ;; esac
 do
 	case "$1" in
@@ -125,17 +126,63 @@ do
 	--reflog-action=*)
 		rloga=`expr "z$1" : 'z-[^=]*=\(.*\)'`
 		;;
+	-m=*|--m=*|--me=*|--mes=*|--mess=*|--messa=*|--messag=*|--message=*)
+		merge_msg=`expr "z$1" : 'z-[^=]*=\(.*\)'`
+		have_message=t
+		;;
+	-m|--m|--me|--mes|--mess|--messa|--messag|--message)
+		shift
+		case "$#" in
+		1)	usage ;;
+		esac
+		merge_msg="$1"
+		have_message=t
+		;;
 	-*)	usage ;;
 	*)	break ;;
 	esac
 	shift
 done
 
-merge_msg="$1"
-shift
-head_arg="$1"
-head=$(git-rev-parse --verify "$1"^0) || usage
-shift
+# This could be traditional "merge <msg> HEAD <commit>..."  and the
+# way we can tell it is to see if the second token is HEAD, but some
+# people might have misused the interface and used a committish that
+# is the same as HEAD there instead.  Traditional format never would
+# have "-m" so it is an additional safety measure to check for it.
+
+if test -z "$have_message" &&
+	second_token=$(git-rev-parse --verify "$2^0" 2>/dev/null) &&
+	head_commit=$(git-rev-parse --verify "HEAD" 2>/dev/null) &&
+	test "$second_token" = "$head_commit"
+then
+	merge_msg="$1"
+	shift
+	head_arg="$1"
+	shift
+else
+	# We are invoked directly as the first-class UI.
+	head_arg=HEAD
+
+	# All the rest are the commits being merged; prepare
+	# the standard merge summary message to be appended to
+	# the given message.  If remote is invalid we will die
+	# later in the common codepath so we discard the error
+	# in this loop.
+	merge_name=$(for remote
+		do
+			rh=$(git-rev-parse --verify "$remote"^0 2>/dev/null)
+			if git show-ref -q --verify "refs/heads/$remote"
+			then
+				what=branch
+			else
+				what=commit
+			fi
+			echo "$rh		$what '$remote'"
+		done | git-fmt-merge-msg
+	)
+	merge_msg="${merge_msg:+$merge_msg$LF$LF}$merge_name"
+fi
+head=$(git-rev-parse --verify "$head_arg"^0) || usage
 
 # All the rest are remote heads
 test "$#" = 0 && usage ;# we need at least one remote head.