1 files changed, 27 insertions, 0 deletions
diff --git a/scripts/linters/no_format_trailing_comma.rb b/scripts/linters/no_format_trailing_comma.rb
new file mode 100644
index 0000000..3e474a7
--- /dev/null
+++ b/scripts/linters/no_format_trailing_comma.rb
@@ -0,0 +1,27 @@
+def no_format_trailing_comma(root_dir, excludes = [])
+  crates_dir = root_dir.join('crates')
+  raw = `grep -rn --include='*.rs' -e ',)' #{crates_dir}`
+
+  errors = []
+  raw.each_line do |line|
+    line = line.chomp
+    path, lineno, content = line.split(':', 3)
+    next if content.nil?
+
+    relative = Pathname.new(path).relative_path_from(root_dir).to_s
+    next if excludes.include?(relative)
+
+    # `(,)` is a macro repetition fragment (e.g. `$(,)?`).
+    next if content.match?(/\(,\)/)
+
+    errors << "#{relative}:#{lineno}: trailing `,)` before a closing paren"
+  end
+
+  return true if errors.empty?
+
+  puts 'Found `,)` introduced by formatting. Remove it.'
+  errors.each do |err|
+    puts "  #{err}"
+  end
+  false
+end