fix(ui): 'pumborder' parsing, shadow #36127

Problem:
1. Setting `pumborder=+,+,+,+,+,+,+,+` failed to render the custom
   border characters correctly. The issue occurred in `parse_winborder()`
   where it incorrectly used `p_winborder` instead of the `border_opt`
   parameter when the option value didn't contain commas.
2. In `pum_redraw()`, calling `parse_border_style()` directly with the
   option string failed to parse comma-separated border characters.
3. Missing documentation for PmenuShadow and PmenuShadowThrough
   highlight groups used by the shadow border style.
4. Coverity reports CID 631420: passing WinConfig (480 bytes) by value
   in `grid_draw_border()`.
5. crash when using `shadow` value on pumborder.

Solution:
1. Fix `parse_winborder()` to use `border_opt` parameter consistently,
   ensuring the correct option value is parsed regardless of which
   option (winborder/pumborder) is being set.
2. Update `pum_redraw()` to call `parse_winborder()` instead of
   `parse_border_style()`, properly handling both predefined styles
   and custom comma-separated border characters.
3. Add documentation for PmenuShadow (blended shadow areas) and
   PmenuShadowThrough (see-through corners) highlight groups.
4. Change `grid_draw_border()` to accept WinConfig by pointer.
5. When the "shadow" style is used, no additional row and column offset
   is applied, and the border width is reduced.

runtime/doc/news.txt

@@ -219,6 +219,7 @@ HIGHLIGHTS
 • |hl-DiffTextAdd| highlights added text within a changed line.
 • |hl-OkMsg| |hl-StderrMsg| |hl-StdoutMsg|
 • |hl-SnippetTabstopActive| highlights the currently active tabstop.
+• |hl-PmenuBorder |hl-PmenuShadow| |hl-PmenuShadowThrough| see 'pumborder'.
 
 LSP
 
@@ -301,6 +302,7 @@ OPTIONS
 • 'winborder' "bold" style, custom border style.
 • |g:clipboard| accepts a string name to force any builtin clipboard tool.
 • 'busy' sets a buffer "busy" status. Indicated in the default statusline.
+• 'pumborder' add a border to the popup menu.
 
 PERFORMANCE
 

runtime/doc/options.txt

@@ -4912,7 +4912,8 @@ A jump table for the options with a short description can be found at |Q_op|.
 'pumborder'		string	(default "")
 			global
 	Defines the default border style of popupmenu windows. Same as
-	'winborder'.
+	'winborder'. |hl-PmenuBorder| is used. When style is "shadow", the
+	|hl-PmenuShadow| and |hl-PmenuShadowThrough| are used.
 
 						*'pumheight'* *'ph'*
 'pumheight' 'ph'	number	(default 0)

runtime/doc/syntax.txt

@@ -5354,6 +5354,11 @@ Normal		Normal text.
 NormalFloat	Normal text in floating windows.
 							*hl-FloatBorder*
 FloatBorder	Border of floating windows.
+							*hl-FloatShadow*
+FloatShadow	Blended areas when border is shadow.
+							*hl-FLoatShadowThrough*
+FloatShadownThrough
+		shadow corners when border is shadow.
 							*hl-FloatTitle*
 FloatTitle	Title of floating windows.
 							*hl-FloatFooter*
@@ -5382,6 +5387,13 @@ PmenuMatch	Popup menu: Matched text in normal item. Combined with
 							*hl-PmenuMatchSel*
 PmenuMatchSel	Popup menu: Matched text in selected item. Combined with
 		|hl-PmenuMatch| and |hl-PmenuSel|.
+							*hl-PmenuBorder*
+PmenuBorder	Popup menu: border of popup menu.
+							*hl-PmenuShadow*
+PmenuShadow	Popup menu: blended areas when 'pumborder' is shadow.
+							*hl-PmenuShadowThrough*
+PmenuShadownThrough
+		Popup menu: shadow corners when 'pumborder' is shadow.
 							*hl-ComplMatchIns*
 ComplMatchIns	Matched text of the currently inserted completion.
 							*hl-PreInsert*

runtime/lua/vim/_meta/options.lua

@@ -5130,7 +5130,8 @@ vim.go.pumblend = vim.o.pumblend
 vim.go.pb = vim.go.pumblend
 
 --- Defines the default border style of popupmenu windows. Same as
---- 'winborder'.
+--- 'winborder'. `hl-PmenuBorder` is used. When style is "shadow", the
+--- `hl-PmenuShadow` and `hl-PmenuShadowThrough` are used.
 ---
 --- @type string
 vim.o.pumborder = ""

src/nvim/api/win_config.c

@@ -1079,7 +1079,7 @@ static void generate_api_error(win_T *wp, const char *attribute, Error *err)
 }
 
 /// Parses a border style name or custom (comma-separated) style.
-bool parse_winborder(WinConfig *fconfig, const char *border_opt, Error *err)
+bool parse_winborder(WinConfig *fconfig, char *border_opt, Error *err)
 {
   if (!fconfig) {
     return false;
@@ -1088,7 +1088,7 @@ bool parse_winborder(WinConfig *fconfig, const char *border_opt, Error *err)
 
   if (strchr(border_opt, ',')) {
     Array border_chars = ARRAY_DICT_INIT;
-    char *p = p_winborder;
+    char *p = border_opt;
     char part[MAX_SCHAR_SIZE] = { 0 };
     int count = 0;
 
@@ -1116,7 +1116,7 @@ bool parse_winborder(WinConfig *fconfig, const char *border_opt, Error *err)
 
     style = ARRAY_OBJ(border_chars);
   } else {
-    style = CSTR_TO_OBJ(p_winborder);
+    style = CSTR_TO_OBJ(border_opt);
   }
 
   parse_border_style(style, fconfig, err);

src/nvim/drawscreen.c

@@ -658,7 +658,7 @@ int update_screen(void)
     win_grid_alloc(wp);
 
     if (wp->w_redr_border || wp->w_redr_type >= UPD_NOT_VALID) {
-      grid_draw_border(&wp->w_grid_alloc, wp->w_config, wp->w_border_adj, (int)wp->w_p_winbl,
+      grid_draw_border(&wp->w_grid_alloc, &wp->w_config, wp->w_border_adj, (int)wp->w_p_winbl,
                        wp->w_ns_hl_attr);
     }
 

src/nvim/grid.c

@@ -1115,9 +1115,9 @@ static int get_bordertext_col(int total_col, int text_width, AlignTextPos align)
 }
 
 /// draw border on floating window grid
-void grid_draw_border(ScreenGrid *grid, WinConfig config, int *adj, int winbl, int *hl_attr)
+void grid_draw_border(ScreenGrid *grid, WinConfig *config, int *adj, int winbl, int *hl_attr)
 {
-  int *attrs = config.border_attr;
+  int *attrs = config->border_attr;
   int default_adj[4] = { 1, 1, 1, 1 };
   if (adj == NULL) {
     adj = default_adj;
@@ -1128,7 +1128,7 @@ void grid_draw_border(ScreenGrid *grid, WinConfig config, int *adj, int winbl, i
   }
 
   for (int i = 0; i < 8; i++) {
-    chars[i] = schar_from_str(config.border_chars[i]);
+    chars[i] = schar_from_str(config->border_chars[i]);
   }
 
   int irow = grid->rows - adj[0] - adj[2];
@@ -1144,9 +1144,9 @@ void grid_draw_border(ScreenGrid *grid, WinConfig config, int *adj, int winbl, i
       grid_line_put_schar(i + adj[3], chars[1], attrs[1]);
     }
 
-    if (config.title) {
-      int title_col = get_bordertext_col(icol, config.title_width, config.title_pos);
-      grid_draw_bordertext(config.title_chunks, title_col, winbl, hl_attr, kBorderTextTitle);
+    if (config->title) {
+      int title_col = get_bordertext_col(icol, config->title_width, config->title_pos);
+      grid_draw_bordertext(config->title_chunks, title_col, winbl, hl_attr, kBorderTextTitle);
     }
     if (adj[1]) {
       grid_line_put_schar(icol + adj[3], chars[2], attrs[2]);
@@ -1179,9 +1179,9 @@ void grid_draw_border(ScreenGrid *grid, WinConfig config, int *adj, int winbl, i
       grid_line_put_schar(i + adj[3], chars[ic], attrs[ic]);
     }
 
-    if (config.footer) {
-      int footer_col = get_bordertext_col(icol, config.footer_width, config.footer_pos);
-      grid_draw_bordertext(config.footer_chunks, footer_col, winbl, hl_attr, kBorderTextFooter);
+    if (config->footer) {
+      int footer_col = get_bordertext_col(icol, config->footer_width, config->footer_pos);
+      grid_draw_bordertext(config->footer_chunks, footer_col, winbl, hl_attr, kBorderTextFooter);
     }
     if (adj[1]) {
       grid_line_put_schar(icol + adj[3], chars[4], attrs[4]);

src/nvim/options.lua

@@ -6727,7 +6727,8 @@ local options = {
       values = { '', 'double', 'single', 'shadow', 'rounded', 'solid', 'bold', 'none' },
       desc = [=[
         Defines the default border style of popupmenu windows. Same as
-        'winborder'.
+        'winborder'. |hl-PmenuBorder| is used. When style is "shadow", the
+        |hl-PmenuShadow| and |hl-PmenuShadowThrough| are used.
       ]=],
       short_desc = N_('border of popupmenu'),
       type = 'string',

src/nvim/optionstr.c

@@ -2125,7 +2125,7 @@ const char *did_set_winbar(optset_T *args)
   return did_set_statustabline_rulerformat(args, false, false);
 }
 
-static bool parse_border_opt(const char *border_opt)
+static bool parse_border_opt(char *border_opt)
 {
   WinConfig fconfig = WIN_CONFIG_INIT;
   Error err = ERROR_INIT;

src/nvim/popupmenu.c

@@ -298,6 +298,9 @@ void pum_display(pumitem_T *array, int size, int selected, bool array_changed, i
   pum_rl = (State & MODE_CMDLINE) == 0 && curwin->w_p_rl;
 
   int pum_border_size = *p_pumborder != NUL ? 2 : 0;
+  if (strequal(p_pumborder, opt_winborder_values[3])) {
+    pum_border_size -= 1;
+  }
 
   do {
     // Mark the pum as visible already here,
@@ -605,19 +608,34 @@ void pum_redraw(void)
     pum_border_width = 2;
     fconfig.border = true;
     Error err = ERROR_INIT;
-    parse_border_style(CSTR_AS_OBJ(p_pumborder), &fconfig, &err);
-    // shadow style uses different highlights for different positions
-    if (strcmp(p_pumborder, opt_winborder_values[3]) == 0) {
+    if (!parse_winborder(&fconfig, p_pumborder, &err)) {
+      if (ERROR_SET(&err)) {
+        emsg(err.msg);
+      }
+      api_clear_error(&err);
+      return;
+    }
+
+    // Shadow style: only adds border on right and bottom edges
+    if (strequal(p_pumborder, opt_winborder_values[3])) {
+      fconfig.shadow = true;
+      pum_border_width = 1;
       int blend = SYN_GROUP_STATIC("PmenuShadow");
       int through = SYN_GROUP_STATIC("PmenuShadowThrough");
-      int attrs[] = { 0, 0, through, blend, blend, blend, through, 0 };
-      memcpy(fconfig.border_attr, attrs, sizeof(attrs));
-    } else {
-      // Non-shadow styles use PumBorder highlight for all border chars
+      fconfig.border_hl_ids[2] = through;
+      fconfig.border_hl_ids[3] = blend;
+      fconfig.border_hl_ids[4] = blend;
+      fconfig.border_hl_ids[5] = blend;
+      fconfig.border_hl_ids[6] = through;
+    }
+
+    // convert border highlight IDs to attributes, use PmenuBorder as default
+    for (int i = 0; i < 8; i++) {
       int attr = hl_attr_active[HLF_PBR];
-      for (int i = 0; i < 8; i++) {
-        fconfig.border_attr[i] = attr;
+      if (fconfig.border_hl_ids[i]) {
+        attr = hl_get_ui_attr(-1, HLF_PBR, fconfig.border_hl_ids[i], false);
       }
+      fconfig.border_attr[i] = attr;
     }
     api_clear_error(&err);
   }
@@ -653,9 +671,11 @@ void pum_redraw(void)
   // avoid set border for mouse menu
   int mouse_menu = State != MODE_CMDLINE && pum_grid.zindex == kZIndexCmdlinePopupMenu;
   if (!mouse_menu && fconfig.border) {
-    grid_draw_border(&pum_grid, fconfig, NULL, 0, NULL);
-    row++;
-    col_off++;
+    grid_draw_border(&pum_grid, &fconfig, NULL, 0, NULL);
+    if (!fconfig.shadow) {
+      row++;
+      col_off++;
+    }
   }
 
   // Never display more than we have

test/functional/ui/popupmenu_spec.lua

@@ -1061,6 +1061,8 @@ describe('builtin popupmenu', function()
         [111] = { background = Screen.colors.Plum1, foreground = Screen.colors.DarkBlue },
         [112] = { background = Screen.colors.Plum1, foreground = Screen.colors.DarkGreen },
         [113] = { background = Screen.colors.Yellow, foreground = Screen.colors.Black },
+        [114] = { background = Screen.colors.Grey0, blend = 100 },
+        [115] = { background = Screen.colors.Grey0, blend = 80 },
         -- popup non-selected item
         n = { background = Screen.colors.Plum1 },
         -- popup scrollbar knob
@@ -9130,6 +9132,106 @@ describe('builtin popupmenu', function()
           ]])
         end
       end)
+      it('custom pumborder characters', function()
+        command('set pumborder=+,+,=,+,+,-,+,+')
+        feed('S<C-x><C-o>')
+        if not multigrid then
+          screen:expect([[
+            one^                           |
+            ++++++++++++++++={n:1info}{1:        }|
+            +{12:one            }+{1:             }|
+            +{n:two            }+{1:             }|
+            +{n:three          }+{1:             }|
+            +---------------+{1:             }|
+            {1:~                             }|*4
+            {5:-- }{6:match 1 of 3}               |
+          ]])
+        end
+      end)
+      it('pumborder with shadow', function()
+        command('set pumborder=shadow')
+        feed('S<C-x><C-o>')
+        if multigrid then
+          screen:expect({
+            grid = [[
+            ## grid 1
+              [2:------------------------------]|*10
+              [3:------------------------------]|
+            ## grid 2
+              one^                           |
+              {1:~                             }|*9
+            ## grid 3
+              {5:-- }{6:match 1 of 3}               |
+            ## grid 4
+              {n:1info}|
+            ## grid 5
+              {12:one            }{114: }|
+              {n:two            }{115: }|
+              {n:three          }{115: }|
+              {114: }{115:               }|
+            ]],
+            win_pos = {
+              [2] = {
+                height = 10,
+                startcol = 0,
+                startrow = 0,
+                width = 30,
+                win = 1000,
+              },
+            },
+            float_pos = {
+              [5] = { -1, 'NW', 2, 1, 0, false, 100, 2, 1, 0 },
+              [4] = { 1001, 'NW', 1, 1, 17, false, 50, 1, 1, 17 },
+            },
+            win_viewport = {
+              [2] = {
+                win = 1000,
+                topline = 0,
+                botline = 2,
+                curline = 0,
+                curcol = 3,
+                linecount = 1,
+                sum_scroll_delta = 0,
+              },
+              [4] = {
+                win = 1001,
+                topline = 0,
+                botline = 1,
+                curline = 0,
+                curcol = 0,
+                linecount = 1,
+                sum_scroll_delta = 0,
+              },
+            },
+            win_viewport_margins = {
+              [2] = {
+                bottom = 0,
+                left = 0,
+                right = 0,
+                top = 0,
+                win = 1000,
+              },
+              [4] = {
+                bottom = 0,
+                left = 0,
+                right = 0,
+                top = 0,
+                win = 1001,
+              },
+            },
+          })
+        else
+          screen:expect([[
+            one^                           |
+            {12:one            }{114: }{1: }{n:1info}{1:        }|
+            {n:two            }{115: }{1:              }|
+            {n:three          }{115: }{1:              }|
+            {114: }{115:               }{1:              }|
+            {1:~                             }|*5
+            {5:-- }{6:match 1 of 3}               |
+          ]])
+        end
+      end)
     end)
   end
 

test/old/testdir/gen_opt_test.vim

@@ -300,6 +300,7 @@ let test_values = {
       \		'alpha,hex,bin'],
       \		['xxx']],
       \ 'patchmode': [['', 'xxx', '.x'], [&backupext, '*']],
+      \ 'pumborder': [['rounded', 'none', 'single', 'solid'], ['xxx', 'none,solid']],
       "\ 'previewpopup': [['', 'height:13', 'width:20', 'highlight:That',
       "\ "		'align:item', 'align:menu', 'border:on', 'border:off',
       "\ "		'width:10,height:234,highlight:Mine'],