completion: make compatible with zsh

Modify git-completion.bash so that it also works with zsh when using
bashcompinit.  In particular:

declare -F
    Zsh doesn't have the same 'declare -F' as bash, but 'declare -f'
    is the same, and it works just as well for our purposes.

${var:2}
    Zsh does not implement ${var:2} to skip the first 2 characters, but
    ${var#??} works in both shells to replace the first 2 characters
    with nothing.  Thanks to Jonathan Nieder for the suggestion.

for (( n=1; "$n" ... ))
    Zsh does not allow "$var" in arithmetic loops.  Instead, pre-compute
    the endpoint and use the variables without $'s or quotes.

shopt
    Zsh uses 'setopt', which has a different syntax than 'shopt'.  Since
    'shopt' is used infrequently in git-completion, we provide
    a bare-bones emulation.

emulate -L bash
KSH_TYPESET
    Zsh offers bash emulation, which turns on a set of features to
    closely resemble bash. In particular, this enables SH_WORDSPLIT,
    which splits scalar variables on word boundaries in 'for' loops.
    We also need to set KSH_TYPESET, to fix "local var=$(echo foo bar)"
    issues.

The last set of options are turned on only in _git and _gitk.  Some of
the sub-functions may not work correctly if called directly.

Signed-off-by: Mark Lodato <lodatom@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -21,6 +21,11 @@
 #    2) Added the following line to your .bashrc:
 #        source ~/.git-completion.sh
 #
+#       Or, add the following lines to your .zshrc:
+#        autoload bashcompinit
+#        bashcompinit
+#        source ~/.git-completion.sh
+#
 #    3) Consider changing your PS1 to also show the current branch:
 #        PS1='[\u@\h \W$(__git_ps1 " (%s)")]\$ '
 #
@@ -138,11 +143,12 @@ __git_ps1_show_upstream ()
 		# get the upstream from the "git-svn-id: ..." in a commit message
 		# (git-svn uses essentially the same procedure internally)
 		local svn_upstream=($(git log --first-parent -1 \
-					--grep="^git-svn-id: \(${svn_url_pattern:2}\)" 2>/dev/null))
+					--grep="^git-svn-id: \(${svn_url_pattern#??}\)" 2>/dev/null))
 		if [[ 0 -ne ${#svn_upstream[@]} ]]; then
 			svn_upstream=${svn_upstream[ ${#svn_upstream[@]} - 2 ]}
 			svn_upstream=${svn_upstream%@*}
-			for ((n=1; "$n" <= "${#svn_remote[@]}"; ++n)); do
+			local n_stop="${#svn_remote[@]}"
+			for ((n=1; n <= n_stop; ++n)); do
 				svn_upstream=${svn_upstream#${svn_remote[$n]}}
 			done
 
@@ -2339,6 +2345,11 @@ _git ()
 {
 	local i c=1 command __git_dir
 
+	if [[ -n $ZSH_VERSION ]]; then
+		emulate -L bash
+		setopt KSH_TYPESET
+	fi
+
 	while [ $c -lt $COMP_CWORD ]; do
 		i="${COMP_WORDS[c]}"
 		case "$i" in
@@ -2372,17 +2383,22 @@ _git ()
 	fi
 
 	local completion_func="_git_${command//-/_}"
-	declare -F $completion_func >/dev/null && $completion_func && return
+	declare -f $completion_func >/dev/null && $completion_func && return
 
 	local expansion=$(__git_aliased_command "$command")
 	if [ -n "$expansion" ]; then
 		completion_func="_git_${expansion//-/_}"
-		declare -F $completion_func >/dev/null && $completion_func
+		declare -f $completion_func >/dev/null && $completion_func
 	fi
 }
 
 _gitk ()
 {
+	if [[ -n $ZSH_VERSION ]]; then
+		emulate -L bash
+		setopt KSH_TYPESET
+	fi
+
 	__git_has_doubledash && return
 
 	local cur="${COMP_WORDS[COMP_CWORD]}"
@@ -2417,3 +2433,29 @@ if [ Cygwin = "$(uname -o 2>/dev/null)" ]; then
 complete -o bashdefault -o default -o nospace -F _git git.exe 2>/dev/null \
 	|| complete -o default -o nospace -F _git git.exe
 fi
+
+if [[ -n $ZSH_VERSION ]]; then
+	shopt () {
+		local option
+		if [ $# -ne 2 ]; then
+			echo "USAGE: $0 (-q|-s|-u) <option>" >&2
+			return 1
+		fi
+		case "$2" in
+		nullglob)
+			option="$2"
+			;;
+		*)
+			echo "$0: invalid option: $2" >&2
+			return 1
+		esac
+		case "$1" in
+		-q)	setopt | grep -q "$option" ;;
+		-u)	unsetopt "$option" ;;
+		-s)	setopt "$option" ;;
+		*)
+			echo "$0: invalid flag: $1" >&2
+			return 1
+		esac
+	}
+fi