docs: apply current colorscheme to default highlight groups

Problem: Not all default highlight groups show their actual colors.
Solution: Refactor `vimhelp.lua` and apply it to all relevant lists (UI
groups, syntax groups, treesitter groups, LSP groups, diagnostic groups).

1 files changed, 23 insertions, 2 deletions

diff --git a/runtime/ftplugin/help.lua b/runtime/ftplugin/help.lua
index bf3408c2d9..67c417b1be 100644
--- a/runtime/ftplugin/help.lua
+++ b/runtime/ftplugin/help.lua
@@ -2,6 +2,27 @@
 vim.treesitter.start()
 
 -- add custom highlights for list in `:h highlight-groups`
-if vim.endswith(vim.fs.normalize(vim.api.nvim_buf_get_name(0)), '/doc/syntax.txt') then
-  require('vim.vimhelp').highlight_groups()
+local bufname = vim.fs.normalize(vim.api.nvim_buf_get_name(0))
+if vim.endswith(bufname, '/doc/syntax.txt') then
+  require('vim.vimhelp').highlight_groups({
+    { start = [[\*group-name\*]], stop = '^======', match = '^(%w+)\t' },
+    { start = [[\*highlight-groups\*]], stop = '^======', match = '^(%w+)\t' },
+  })
+elseif vim.endswith(bufname, '/doc/treesitter.txt') then
+  require('vim.vimhelp').highlight_groups({
+    {
+      start = [[\*treesitter-highlight-groups\*]],
+      stop = [[\*treesitter-highlight-spell\*]],
+      match = '^@[%w%p]+',
+    },
+  })
+elseif vim.endswith(bufname, '/doc/diagnostic.txt') then
+  require('vim.vimhelp').highlight_groups({
+    { start = [[\*diagnostic-highlights\*]], stop = '^======', match = '^(%w+)' },
+  })
+elseif vim.endswith(bufname, '/doc/lsp.txt') then
+  require('vim.vimhelp').highlight_groups({
+    { start = [[\*lsp-highlight\*]], stop = '^------', match = '^(%w+)' },
+    { start = [[\*lsp-semantic-highlight\*]], stop = '^======', match = '^@[%w%p]+' },
+  })
 end