Teach git-completion.bash how to complete git-merge.

Now that git-merge is high-level Porcelain users are going to expect
to be able to use it from the command line, in which case we really
should also be able to complete ref names as parameters.

I'm also including completion support for the merge strategies
that are supported by git-merge.sh, should the user wish to use a
different strategy than their default.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

contrib/completion/git-completion.bash

@@ -81,6 +81,16 @@ __git_remotes ()
 	done
 }
 
+__git_merge_strategies ()
+{
+	sed -n "/^all_strategies='/{
+		s/^all_strategies='//
+		s/'//
+		p
+		q
+		}" "$(git --exec-path)/git-merge"
+}
+
 __git_complete_file ()
 {
 	local pfx ls ref cur="${COMP_WORDS[COMP_CWORD]}"
@@ -240,6 +250,24 @@ _git_log ()
 	esac
 }
 
+_git_merge ()
+{
+	local cur="${COMP_WORDS[COMP_CWORD]}"
+	case "$cur" in
+	--*)
+		COMPREPLY=($(compgen -W "
+			--no-commit --no-summary --squash
+			" -- "$cur"))
+		return
+	esac
+	if [ $COMP_CWORD -gt 1 -a X-s = "X${COMP_WORDS[COMP_CWORD-1]}" ]
+	then
+		COMPREPLY=($(compgen -W "$(__git_merge_strategies)" -- "$cur"))
+	else
+		COMPREPLY=($(compgen -W "$(__git_refs)" -- "$cur"))
+	fi
+}
+
 _git_merge_base ()
 {
 	local cur="${COMP_WORDS[COMP_CWORD]}"
@@ -348,6 +376,7 @@ _git ()
 	log)         _git_log ;;
 	ls-remote)   _git_ls_remote ;;
 	ls-tree)     _git_ls_tree ;;
+	merge)       _git_merge;;
 	merge-base)  _git_merge_base ;;
 	pull)        _git_pull ;;
 	push)        _git_push ;;
@@ -376,6 +405,7 @@ complete -o default -o nospace -F _git_fetch git-fetch
 complete -o default -o nospace -F _git_log git-log
 complete -o default            -F _git_ls_remote git-ls-remote
 complete -o default -o nospace -F _git_ls_tree git-ls-tree
+complete -o default            -F _git_merge git-merge
 complete -o default            -F _git_merge_base git-merge-base
 complete -o default -o nospace -F _git_pull git-pull
 complete -o default -o nospace -F _git_push git-push