Remove the -d flag to tmux and just use op/AX to detect default colours.

Irritatingly, although op can be used to tell if a terminal supports default
colours, it can't be used to set them because in some terminfo descriptions it
resets attributes as a side-effect (acts as sgr0) and in others it doesn't, so
it is not possible to determine reliably what the terminal state will be
afterwards. So if AX is missing and op is present, tmux just sends sgr0.

Anyone using -d for a terminal who finds they actually needed it can replace it
using terminal-overrides, but please let me know as it is probably an omission
from terminfo.

1 files changed, 23 insertions, 14 deletions

diff --git a/tty.c b/tty.c
index 596779e1..d329e15b 100644
--- a/tty.c
+++ b/tty.c
@@ -1236,13 +1236,21 @@ tty_attributes_fg(struct tty *tty, const struct grid_cell *gc)
 			tty_reset(tty);
 	}
 
-	if (fg == 8 &&
-	    !(tty->term->flags & TERM_HASDEFAULTS) &&
-	    !(tty->term_flags & TERM_HASDEFAULTS))
-		fg = 7;
-	if (fg == 8)
-		tty_puts(tty, "\033[39m");
-	else
+	if (fg == 8) {
+		if (tty_term_has(tty->term, TTYC_AX)) {
+			/* AX is an extension that means \033[39m works. */
+			tty_puts(tty, "\033[39m");	
+		} else if (tty_term_has(tty->term, TTYC_OP)) {
+			/*
+			 * op can be used to look for default colours but there
+			 * is no point in using it - with some terminals it
+			 * does SGR0 and others not, so SGR0 is needed anyway
+			 * to put the terminal into a known state.
+			 */
+			tty_reset(tty);
+		} else
+			tty_putcode1(tty, TTYC_SETAF, 7);
+	} else
 		tty_putcode1(tty, TTYC_SETAF, fg);
 }
 
@@ -1262,12 +1270,13 @@ tty_attributes_bg(struct tty *tty, const struct grid_cell *gc)
 			bg &= 7;
 	}
 
-	if (bg == 8 &&
-	    !(tty->term->flags & TERM_HASDEFAULTS) &&
-	    !(tty->term_flags & TERM_HASDEFAULTS))
-		bg = 0;
-	if (bg == 8)
-		tty_puts(tty, "\033[49m");
-	else
+	if (bg == 8) {
+		if (tty_term_has(tty->term, TTYC_AX)) {
+			tty_puts(tty, "\033[49m");	
+		} else if (tty_term_has(tty->term, TTYC_OP))
+			tty_reset(tty);
+		else
+			tty_putcode1(tty, TTYC_SETAB, 0);
+	} else
 		tty_putcode1(tty, TTYC_SETAB, bg);
 }