fix(lsp): prevent duplicate lines seperated by newlines (#15284)

runtime/lua/vim/lsp/util.lua

@@ -1160,6 +1160,8 @@ function M.stylize_markdown(bufnr, contents, opts)
   -- Clean up
   contents = M._trim(contents, opts)
 
+  -- Insert blank line separator after code block?
+  local add_sep = opts.separator == nil and true or opts.separator
   local stripped = {}
   local highlights = {}
   -- keep track of lnums that contain markdown
@@ -1186,9 +1188,24 @@ function M.stylize_markdown(bufnr, contents, opts)
           start = start + 1;
           finish = #stripped;
         })
+        -- add a separator, but not on the last line
+        if add_sep and i < #contents then
+          table.insert(stripped, "---")
+          markdown_lines[#stripped] = true
+        end
       else
+        -- strip any emty lines or separators prior to this separator in actual markdown
+        if line:match("^---+$") then
+          while markdown_lines[#stripped] and (stripped[#stripped]:match("^%s*$") or stripped[#stripped]:match("^---+$")) do
+            markdown_lines[#stripped] = false
+            table.remove(stripped, #stripped)
+          end
+        end
+        -- add the line if its not an empty line following a separator
+        if not (line:match("^%s*$") and markdown_lines[#stripped] and stripped[#stripped]:match("^---+$")) then
           table.insert(stripped, line)
           markdown_lines[#stripped] = true
+        end
         i = i + 1
       end
     end
@@ -1196,7 +1213,7 @@ function M.stylize_markdown(bufnr, contents, opts)
 
   -- Compute size of float needed to show (wrapped) lines
   opts.wrap_at = opts.wrap_at or (vim.wo["wrap"] and api.nvim_win_get_width(0))
-  local width, height = M._make_floating_popup_size(stripped, opts)
+  local width = M._make_floating_popup_size(stripped, opts)
 
   local sep_line = string.rep("─", math.min(width, opts.wrap_at or width))
 
@@ -1206,26 +1223,6 @@ function M.stylize_markdown(bufnr, contents, opts)
     end
   end
 
-  -- Insert blank line separator after code block
-  local insert_separator = opts.separator
-  if insert_separator == nil then insert_separator = true end
-  if insert_separator then
-    local offset = 0
-    for _, h in ipairs(highlights) do
-      h.start = h.start + offset
-      h.finish = h.finish + offset
-      -- check if a seperator already exists and use that one instead of creating a new one
-      if h.finish + 1 <= #stripped then
-        if stripped[h.finish + 1] ~= sep_line then
-          table.insert(stripped, h.finish + 1, sep_line)
-          offset = offset + 1
-          height = height + 1
-        end
-      end
-    end
-  end
-
-
   vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, stripped)
 
   local idx = 1