Fix #589

doc/cmp.txt

@@ -383,6 +383,8 @@ completion.autocomplete~
 formatting.format~
   `fun(entry: cmp.Entry, vim_item: vim.CompletedItem): vim.CompletedItem`
   The function to customize the completion menu appearance. See |complete-items|.
+  NOTE: The `vim.CompletedItem` can have special properties `abbr_hl_group`,
+  `kind_hl_group` and `menu_hl_group`.
 
                                                   *cmp-config.formatting.fields*
 formatting.fields~

lua/cmp/entry.lua

@@ -213,17 +213,17 @@ entry.get_view = function(self, suggest_offset, entries_buf)
       view.abbr.text = item.abbr or ''
       view.abbr.bytes = #view.abbr.text
       view.abbr.width = vim.fn.strdisplaywidth(view.abbr.text)
-      view.abbr.hl_group = self:is_deprecated() and 'CmpItemAbbrDeprecated' or 'CmpItemAbbr'
+      view.abbr.hl_group = item.abbr_hl_group or (self:is_deprecated() and 'CmpItemAbbrDeprecated' or 'CmpItemAbbr')
       view.kind = {}
       view.kind.text = item.kind or ''
       view.kind.bytes = #view.kind.text
       view.kind.width = vim.fn.strdisplaywidth(view.kind.text)
-      view.kind.hl_group = 'CmpItemKind' .. (types.lsp.CompletionItemKind[self:get_kind()] or '')
+      view.kind.hl_group = item.kind_hl_group or ('CmpItemKind' .. (types.lsp.CompletionItemKind[self:get_kind()] or ''))
       view.menu = {}
       view.menu.text = item.menu or ''
       view.menu.bytes = #view.menu.text
       view.menu.width = vim.fn.strdisplaywidth(view.menu.text)
-      view.menu.hl_group = 'CmpItemMenu'
+      view.menu.hl_group = item.menu_hl_group or 'CmpItemMenu'
       view.dup = item.dup
     end)
     return view

lua/cmp/types/vim.lua

@@ -7,6 +7,9 @@
 ---@field public empty "1"|nil
 ---@field public dup "1"|nil
 ---@field public id any
+---@field public abbr_hl_group string|nil
+---@field public kind_hl_group string|nil
+---@field public menu_hl_group string|nil
 
 ---@class vim.Position
 ---@field public row number