Add support for overline (SGR 53), from Ricardo Banffy.

attributes.c

@@ -31,7 +31,7 @@ attributes_tostring(int attr)
 	if (attr == 0)
 		return ("none");
 
-	len = xsnprintf(buf, sizeof buf, "%s%s%s%s%s%s%s%s%s%s%s%s",
+	len = xsnprintf(buf, sizeof buf, "%s%s%s%s%s%s%s%s%s%s%s%s%s",
 	    (attr & GRID_ATTR_BRIGHT) ? "bright," : "",
 	    (attr & GRID_ATTR_DIM) ? "dim," : "",
 	    (attr & GRID_ATTR_UNDERSCORE) ? "underscore," : "",
@@ -43,7 +43,8 @@ attributes_tostring(int attr)
 	    (attr & GRID_ATTR_UNDERSCORE_2) ? "double-underscore," : "",
 	    (attr & GRID_ATTR_UNDERSCORE_3) ? "curly-underscore," : "",
 	    (attr & GRID_ATTR_UNDERSCORE_4) ? "dotted-underscore," : "",
-	    (attr & GRID_ATTR_UNDERSCORE_5) ? "dashed-underscore," : "");
+	    (attr & GRID_ATTR_UNDERSCORE_5) ? "dashed-underscore," : "",
+	    (attr & GRID_ATTR_OVERLINE) ? "overline," : "");
 	if (len > 0)
 		buf[len - 1] = '\0';
 
@@ -73,7 +74,8 @@ attributes_fromstring(const char *str)
 		{ "double-underscore", GRID_ATTR_UNDERSCORE_2 },
 		{ "curly-underscore", GRID_ATTR_UNDERSCORE_3 },
 		{ "dotted-underscore", GRID_ATTR_UNDERSCORE_4 },
-		{ "dashed-underscore", GRID_ATTR_UNDERSCORE_5 }
+		{ "dashed-underscore", GRID_ATTR_UNDERSCORE_5 },
+		{ "overline", GRID_ATTR_OVERLINE }
 	};
 
 	if (*str == '\0' || strcspn(str, delimiters) == 0)

grid.c

@@ -790,6 +790,7 @@ grid_string_cells_code(const struct grid_cell *lastgc,
 		{ GRID_ATTR_UNDERSCORE_3, 43 },
 		{ GRID_ATTR_UNDERSCORE_4, 44 },
 		{ GRID_ATTR_UNDERSCORE_5, 45 },
+		{ GRID_ATTR_OVERLINE, 53 },
 	};
 	n = 0;
 

input.c

@@ -2070,6 +2070,12 @@ input_csi_dispatch_sgr(struct input_ctx *ictx)
 		case 49:
 			gc->bg = 8;
 			break;
+		case 53:
+			gc->attr |= GRID_ATTR_OVERLINE;
+			break;
+		case 55:
+			gc->attr &= ~GRID_ATTR_OVERLINE;
+			break;
 		case 90:
 		case 91:
 		case 92:

tmux.1

@@ -4091,6 +4091,7 @@ Set no attributes (turn off any active attributes).
 .Ic reverse ,
 .Ic hidden ,
 .Ic italics ,
+.Ic overline ,
 .Ic strikethrough ,
 .Ic double-underscore ,
 .Ic curly-underscore ,
@@ -4820,6 +4821,8 @@ to change the cursor colour from inside
 .Bd -literal -offset indent
 $ printf '\e033]12;red\e033\e\e'
 .Ed
+.It Em \&Smol
+Enable the overline attribute.
 .It Em \&Smulx
 Set a styled underline.
 The single parameter is one of: 0 for no underline, 1 for normal

tmux.h

@@ -431,6 +431,7 @@ enum tty_code_code {
 	TTYC_SITM,
 	TTYC_SMACS,
 	TTYC_SMCUP,
+	TTYC_SMOL,
 	TTYC_SMKX,
 	TTYC_SMSO,
 	TTYC_SMULX,
@@ -568,6 +569,7 @@ enum utf8_state {
 #define GRID_ATTR_UNDERSCORE_3 0x400
 #define GRID_ATTR_UNDERSCORE_4 0x800
 #define GRID_ATTR_UNDERSCORE_5 0x1000
+#define GRID_ATTR_OVERLINE 0x2000
 
 /* All underscore attributes. */
 #define GRID_ATTR_ALL_UNDERSCORE \

tty-term.c

@@ -252,6 +252,7 @@ static const struct tty_term_code_entry tty_term_codes[] = {
 	[TTYC_SMACS] = { TTYCODE_STRING, "smacs" },
 	[TTYC_SMCUP] = { TTYCODE_STRING, "smcup" },
 	[TTYC_SMKX] = { TTYCODE_STRING, "smkx" },
+	[TTYC_SMOL] = { TTYCODE_STRING, "Smol" },
 	[TTYC_SMSO] = { TTYCODE_STRING, "smso" },
 	[TTYC_SMULX] = { TTYCODE_STRING, "Smulx" },
 	[TTYC_SMUL] = { TTYCODE_STRING, "smul" },

tty.c

@@ -2199,6 +2199,8 @@ tty_attributes(struct tty *tty, const struct grid_cell *gc,
 		tty_putcode(tty, TTYC_INVIS);
 	if (changed & GRID_ATTR_STRIKETHROUGH)
 		tty_putcode(tty, TTYC_SMXX);
+	if (changed & GRID_ATTR_OVERLINE)
+		tty_putcode(tty, TTYC_SMOL);
 	if ((changed & GRID_ATTR_CHARSET) && tty_acs_needed(tty))
 		tty_putcode(tty, TTYC_SMACS);
 }