color.c: alias RGB colors 8-15 to aixterm colors

This results in shorter output, and is _probably_ more portable. There
is at least one environment (GitHub Actions) which supports 16-color
mode but not 256-color mode. It's possible there are environments
which go the other way, but it seems unlikely.

Signed-off-by: Eyal Soha <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: eyal0

color.c

@@ -136,11 +136,16 @@ static int parse_color(struct color *out, const char *name, int len)
 		else if (val < 0) {
 			out->type = COLOR_NORMAL;
 			return 0;
-		/* Rewrite low numbers as more-portable standard colors. */
+		/* Rewrite 0-7 as more-portable standard colors. */
 		} else if (val < 8) {
 			out->type = COLOR_ANSI;
 			out->value = val + COLOR_FOREGROUND_ANSI;
 			return 0;
+		/* Rewrite 8-15 as more-portable aixterm colors. */
+		} else if (val < 16) {
+			out->type = COLOR_ANSI;
+			out->value = val - 8 + COLOR_FOREGROUND_BRIGHT_ANSI;
+			return 0;
 		} else if (val < 256) {
 			out->type = COLOR_256;
 			out->value = val;

t/t4026-color.sh

@@ -82,6 +82,10 @@ test_expect_success '0-7 are aliases for basic ANSI color names' '
 	color "0 7" "[30;47m"
 '
 
+test_expect_success '8-15 are aliases for aixterm color names' '
+	color "12 13" "[94;105m"
+'
+
 test_expect_success '256 colors' '
 	color "254 bold 255" "[1;38;5;254;48;5;255m"
 '