ui: Add 'rgb' parameter to ui_attach

When set to false, nvim will send cterm color numbers with `highlight_set`.

src/nvim/msgpack_rpc/remote_ui.c

@@ -61,8 +61,9 @@ static Object remote_ui_attach(uint64_t channel_id, uint64_t request_id,
     return NIL;
   }
 
-  if (args.size != 2 || args.items[0].type != kObjectTypeInteger
+  if (args.size != 3 || args.items[0].type != kObjectTypeInteger
       || args.items[1].type != kObjectTypeInteger
+      || args.items[2].type != kObjectTypeBoolean
       || args.items[0].data.integer <= 0 || args.items[1].data.integer <= 0) {
     api_set_error(error, Validation,
                   _("Arguments must be a pair of positive integers "
@@ -75,6 +76,7 @@ static Object remote_ui_attach(uint64_t channel_id, uint64_t request_id,
   UI *ui = xcalloc(1, sizeof(UI));
   ui->width = (int)args.items[0].data.integer;
   ui->height = (int)args.items[1].data.integer;
+  ui->rgb = args.items[2].data.boolean;
   ui->data = data;
   ui->resize = remote_ui_resize;
   ui->clear = remote_ui_clear;

src/nvim/syntax.c

@@ -6439,8 +6439,7 @@ do_highlight (
                     HL_TABLE()[idx].sg_cterm &= ~HL_BOLD;
                 }
                 color &= 7;             /* truncate to 8 colors */
-              } else if (t_colors == 16 || t_colors == 88
-                         || t_colors == 256) {
+              } else if (t_colors == 16 || t_colors == 88 || t_colors == 256) {
                 /*
                  * Guess: if the termcap entry ends in 'm', it is
                  * probably an xterm-like terminal.  Use the changed

src/nvim/ui.c

@@ -60,9 +60,6 @@ static struct {
   int top, bot, left, right;
 } sr;
 static int current_highlight_mask = 0;
-static HlAttrs current_attrs = {
-  false, false, false, false, false, -1, -1
-};
 static bool cursor_enabled = true;
 static int height, width;
 
@@ -187,13 +184,8 @@ void ui_resize(int new_width, int new_height)
   width = new_width;
   height = new_height;
 
-  if (normal_fg != -1) {
-    UI_CALL(update_fg, normal_fg);
-  }
-
-  if (normal_bg != -1) {
-    UI_CALL(update_bg, normal_bg);
-  }
+  UI_CALL(update_fg, (ui->rgb ? normal_fg : cterm_normal_fg_color - 1));
+  UI_CALL(update_bg, (ui->rgb ? normal_bg : cterm_normal_bg_color - 1));
 
   sr.top = 0;
   sr.bot = height - 1;
@@ -314,8 +306,7 @@ static void highlight_start(int mask)
     return;
   }
 
-  set_highlight_args(current_highlight_mask, &current_attrs);
-  UI_CALL(highlight_set, current_attrs);
+  set_highlight_args(current_highlight_mask);
 }
 
 static void highlight_stop(int mask)
@@ -328,26 +319,45 @@ static void highlight_stop(int mask)
     current_highlight_mask &= ~mask;
   }
 
-  set_highlight_args(current_highlight_mask, &current_attrs);
-  UI_CALL(highlight_set, current_attrs);
+  set_highlight_args(current_highlight_mask);
 }
 
-static void set_highlight_args(int mask, HlAttrs *attrs)
+static void set_highlight_args(int mask)
 {
+  HlAttrs rgb_attrs = { false, false, false, false, false, -1, -1 };
   attrentry_T *aep = NULL;
 
   if (mask > HL_ALL) {
     aep = syn_cterm_attr2entry(mask);
     mask = aep ? aep->ae_attr : 0;
   }
 
-  attrs->bold = mask & HL_BOLD;
-  attrs->underline = mask & HL_UNDERLINE;
-  attrs->undercurl = mask & HL_UNDERCURL;
-  attrs->italic = mask & HL_ITALIC;
-  attrs->reverse = mask & (HL_INVERSE | HL_STANDOUT);
-  attrs->foreground = aep && aep->fg_color >= 0 ? aep->fg_color : normal_fg;
-  attrs->background = aep && aep->bg_color >= 0 ? aep->bg_color : normal_bg;
+  rgb_attrs.bold = mask & HL_BOLD;
+  rgb_attrs.underline = mask & HL_UNDERLINE;
+  rgb_attrs.undercurl = mask & HL_UNDERCURL;
+  rgb_attrs.italic = mask & HL_ITALIC;
+  rgb_attrs.reverse = mask & (HL_INVERSE | HL_STANDOUT);
+  HlAttrs cterm_attrs = rgb_attrs;
+
+  if (aep) {
+    if (aep->fg_color != normal_fg) {
+      rgb_attrs.foreground = aep->fg_color;
+    }
+
+    if (aep->bg_color != normal_bg) {
+      rgb_attrs.background = aep->bg_color;
+    }
+
+    if (cterm_normal_fg_color != aep->ae_u.cterm.fg_color) {
+      cterm_attrs.foreground = aep->ae_u.cterm.fg_color - 1;
+    }
+
+    if (cterm_normal_bg_color != aep->ae_u.cterm.bg_color) {
+      cterm_attrs.background = aep->ae_u.cterm.bg_color - 1;
+    }
+  }
+
+  UI_CALL(highlight_set, (ui->rgb ? rgb_attrs : cterm_attrs));
 }
 
 static void parse_abstract_ui_codes(uint8_t *ptr, int len)

src/nvim/ui.h

@@ -13,6 +13,7 @@ typedef struct {
 typedef struct ui_t UI;
 
 struct ui_t {
+  bool rgb;
   int width, height;
   void *data;
   void (*resize)(UI *ui, int rows, int columns);

test/functional/ui/screen.lua

@@ -115,7 +115,7 @@ function Screen:set_default_attr_ids(attr_ids)
 end
 
 function Screen:attach()
-  request('ui_attach', self._width, self._height)
+  request('ui_attach', self._width, self._height, true)
   self._suspended = false
 end