feat(signs)!: place higher-priority signs from the left #27781

Problem:
Higher-priority signs may be hidden by lower-priority signs.

Solution:
Place higher-priority signs from the left.

Example:

    nvim_buf_set_extmark(0, ns, 0, -1, {sign_text='H', priority=1})
    nvim_buf_set_extmark(0, ns, 0, -1, {sign_text='W', priority=2})
    nvim_buf_set_extmark(0, ns, 0, -1, {sign_text='E', priority=3})

Before:

            |     |
          H | W E |
          ^ |     |
Not visible

After:

  |     |
  | E W | H
  |     | ^
          Not visible

Fixes #16632

1 files changed, 4 insertions, 3 deletions

diff --git a/src/nvim/decoration.c b/src/nvim/decoration.c
index bcfae50c8e..303d0318b5 100644
--- a/src/nvim/decoration.c
+++ b/src/nvim/decoration.c
@@ -740,14 +740,15 @@ void decor_redraw_signs(win_T *wp, buf_T *buf, int row, SignTextAttrs sattrs[],
 
   if (kv_size(signs)) {
     int width = wp->w_minscwidth == SCL_NUM ? 1 : wp->w_scwidth;
-    int idx = MIN(width, num_text) - 1;
+    int len = MIN(width, num_text);
+    int idx = 0;
     qsort((void *)&kv_A(signs, 0), kv_size(signs), sizeof(kv_A(signs, 0)), sign_item_cmp);
 
     for (size_t i = 0; i < kv_size(signs); i++) {
       DecorSignHighlight *sh = kv_A(signs, i).sh;
-      if (idx >= 0 && sh->text[0]) {
+      if (idx < len && sh->text[0]) {
         memcpy(sattrs[idx].text, sh->text, SIGN_WIDTH * sizeof(sattr_T));
-        sattrs[idx--].hl_id = sh->hl_id;
+        sattrs[idx++].hl_id = sh->hl_id;
       }
       if (*num_id == 0) {
         *num_id = sh->number_hl_id;