I'm building a macro which can take many types of things as arguments; both existing rules and raw source files.

By convention, as described in the Labels section of the manual, rules should be passed with the leading colon, so when calling my macro and passing a filegroup, I pass srcs = ":my_srcgroup".

When I try to determine if this is an existing rule or a file in my macro, I do:

for src in srcs:
  if native.existing_rule(src)
    # some things for filegroups
  else:
    # other things for file names

Unfortunately, native.existing_rule does not understand the leading-colon syntax for rules, and therefore always returns false for any rule name starting with a :

I have a workaround but it's ugly:

for src in srcs:
  rule_name = src
  if rule_name.startswith(':'):
    rule_name = rule_name[1:]
  rule = native.existing_rule(rule_name)
  print(src, rule)
  if rule:
    # some things for filegroups
  else:
    # other things for file names