diffpkg: add colored output option with default of auto

contrib/completion/zsh/_devtools.in

@@ -6,6 +6,7 @@ m4_include(lib/valid-tags.sh)
 m4_include(lib/valid-repos.sh)
 
 _binary_arch=${_arch[*]:0:-1}
+_colors=(never always auto)
 
 _archbuild_args=(
 	'-c[Recreate the chroot before building]'
@@ -49,6 +50,7 @@ _diffpkg_args=(
 	'(-m --makepkg-config)'{-m,--makepkg-config}'[Location of a makepkg config file]:makepkg_config:_files -g "*.conf(.)"'
 	'(-u -U --unified)'{-u,-U,--unified}'[Output 3 lines of unified context]'
 	'(-y --side-by-side)'{-y,--side-by-side}'[Output in two columns]'
+	'--color=[Color output]:when:($_colors[*])'
 	'(-v --verbose)'{-v,--verbose}'[Provide more detailed/unfiltered output]'
 	'(-h --help)'{-h,--help}'[Display usage]'
 	'*:packages:_devtools_completions_all_packages'

doc/man/diffpkg.1.asciidoc

@@ -39,6 +39,9 @@ Options
 Output Options
 --------------
 
+*--color*[='WHEN']::
+	Color output; 'WHEN' is `'never'`, `'always'`, or `'auto'`; Plain *--color* means *--color='auto'*
+
 *-u, -U, --unified*::
 	Output 3 lines of unified context
 

src/diffpkg.in

@@ -28,6 +28,8 @@ usage() {
 		    -h, --help           Show this help text
 
 		OUTPUT OPTIONS
+		    --color[=WHEN]       Color output; WHEN is 'never', 'always', or 'auto';
+		                         Plain --color means --color='auto'
 		    -u, -U, --unified    Output 3 lines of unified context
 		    -y, --side-by-side   Output in two columns
 
@@ -47,6 +49,7 @@ PKGINFO=0
 BUILDINFO=0
 
 DIFFMODE=--side-by-side
+DIFFCOLOR=--color
 DIFFOPTIONS=(--expand-tabs)
 
 # option checking
@@ -88,6 +91,15 @@ while (( $# )); do
 			DIFFMODE=--side-by-side
 			shift
 			;;
+		--color|--color=*)
+			if [[ $2 == never || $2 == always || $2 == auto ]]; then
+				DIFFCOLOR="--color=$2"
+				shift 2
+				continue
+			fi
+			DIFFCOLOR="$1"
+			shift
+			;;
 		--)
 			shift
 			break
@@ -108,7 +120,7 @@ if (( VERBOSE )); then
 else
 	DIFFOPTIONS+=(--suppress-common-lines)
 fi
-DIFFOPTIONS+=("${DIFFMODE}")
+DIFFOPTIONS+=("${DIFFMODE}" "${DIFFCOLOR}")
 
 if ! (( DIFFOSCOPE || TARLIST || PKGINFO || BUILDINFO )); then
 	TARLIST=1