git-grep: clarification on parameters.

We forgot to make sure that there is no more than one pattern
parameter.  Also when looking for files in a directory called
'--others', it passed that path limiter without preceding the
end-of-options marker '--' to underlying git-ls-files, which
misunderstood it as one of its options instead.

	$ git grep --others -e Meta/Make Meta
	$ git grep -o -e Meta/Make Meta
	$ git grep -o Meta/Make Meta

look for a string "Meta/Make" from untracked files in Meta/
directory.

	$ git grep Meta/Make --others

looks for the same string from tracked files in ./--others
directory.

On the other hand,

	$ git grep -e Meta/Make --others

does not have a freestanding pattern, so everybody is parameter
and there is no path specifier.  It looks for the string in all
the untracked files without any path limiter.

[jc: updated with usability enhancements and documentation
cleanups from Sean.]

Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-grep.txt

@@ -8,7 +8,7 @@ git-grep - print lines matching a pattern
 
 SYNOPSIS
 --------
-'git-grep' [<option>...] <pattern> [<path>...]
+'git-grep' [<option>...] [-e] <pattern> [--] [<path>...]
 
 DESCRIPTION
 -----------
@@ -18,13 +18,24 @@ containing a match to the given pattern.
 
 OPTIONS
 -------
+`--`::
+	Signals the end of options; the rest of the parameters
+	are <path> limiters.
+
 <option>...::
 	Either an option to pass to `grep` or `git-ls-files`.
-	Some `grep` options, such as `-C` and `-m`, that take
-	parameters are known to `git-grep`.
+
+	The following are the specific `git-ls-files` options
+	that may be given: `-o`, `--cached`, `--deleted`, `--others`,
+	`--killed`, `--ignored`, `--modified`, `--exclude=*`,
+	`--exclude-from=*`, and `--exclude-per-directory=*`.
+
+	All other options will be passed to `grep`.
 
 <pattern>::
-	The pattern to look for.
+	The pattern to look for.  The first non option is taken
+	as the pattern; if your pattern begins with a dash, use
+	`-e <pattern>`.
 
 <path>...::
 	Optional paths to limit the set of files to be searched;

git-grep.sh

@@ -3,22 +3,32 @@
 # Copyright (c) Linus Torvalds, 2005
 #
 
-USAGE='<option>... <pattern> <path>...'
+USAGE='[<option>...] [-e] <pattern> [<path>...]'
 SUBDIRECTORY_OK='Yes'
 . git-sh-setup
 
+got_pattern () {
+	if [ -z "$no_more_patterns" ]
+	then
+		pattern="$1" no_more_patterns=yes
+	else
+		die "git-grep: do not specify more than one pattern"
+	fi
+}
+
+no_more_patterns=
 pattern=
 flags=()
 git_flags=()
 while : ; do
 	case "$1" in
-	--cached|--deleted|--others|--killed|\
-	--ignored|--exclude=*|\
+	-o|--cached|--deleted|--others|--killed|\
+	--ignored|--modified|--exclude=*|\
 	--exclude-from=*|\--exclude-per-directory=*)
 		git_flags=("${git_flags[@]}" "$1")
 		;;
 	-e)
-		pattern="$2"
+		got_pattern "$2"
 		shift
 		;;
 	-A|-B|-C|-D|-d|-f|-m)
@@ -26,7 +36,7 @@ while : ; do
 		shift
 		;;
 	--)
-		# The rest are git-ls-files paths (or flags)
+		# The rest are git-ls-files paths
 		shift
 		break
 		;;
@@ -34,10 +44,12 @@ while : ; do
 		flags=("${flags[@]}" "$1")
 		;;
 	*)
-		if [ -z "$pattern" ]; then
-			pattern="$1"
+		if [ -z "$no_more_patterns" ]
+		then
+			got_pattern "$1"
 			shift
 		fi
+		[ "$1" = -- ] && shift
 		break
 		;;
 	esac
@@ -46,5 +58,5 @@ done
 [ "$pattern" ] || {
 	usage
 }
-git-ls-files -z "${git_flags[@]}" "$@" |
-	xargs -0 grep "${flags[@]}" -e "$pattern"
+git-ls-files -z "${git_flags[@]}" -- "$@" |
+	xargs -0 grep "${flags[@]}" -e "$pattern" --