ci: check capture names in queries

scripts/check-queries.lua

@@ -1,13 +1,47 @@
 -- Execute as `nvim --headless -c "luafile ./scripts/check-queries.lua"`
+
+local function extract_captures()
+  local lines = vim.fn.readfile("CONTRIBUTING.md")
+  local captures = {}
+  local current_query
+
+  for _, line in ipairs(lines) do
+    if vim.startswith(line, "### ") then
+      current_query = vim.fn.tolower(line:sub(5))
+    elseif vim.startswith(line, "@") and current_query then
+      if not captures[current_query] then
+        captures[current_query] = {}
+      end
+
+      table.insert(captures[current_query], vim.split(line:sub(2), " ", true)[1])
+    end
+  end
+
+  return captures
+end
+
 local function do_check()
   local parsers = require 'nvim-treesitter.parsers'.available_parsers()
   local queries = require 'nvim-treesitter.query'
   local query_types = queries.built_in_query_groups
 
+  local captures = extract_captures()
+
   for _, lang in pairs(parsers) do
     for _, query_type in pairs(query_types) do
       print('Checking '..lang..' '..query_type)
-      queries.get_query(lang, query_type)
+      local query = queries.get_query(lang, query_type)
+
+      if query then
+        for _, capture in ipairs(query.captures) do
+          if not vim.startswith(capture, "_") -- We ignore things like _helper
+            and captures[query_type]
+            and not capture:find("^[A-Z]") -- Highlight groups
+            and not vim.tbl_contains(captures[query_type], capture) then
+            error(string.format("Invalid capture @%s in %s for %s.", capture, query_type, lang))
+          end
+        end
+      end
     end
   end
 end