puppetlabs/puppet · error · ArgumentError

Parsing of 'type "%{assignment_string}"' failed with message

Error message

Parsing of 'type "%{assignment_string}"' failed with message: <%{message}>.
Called from <%{ruby_file_location}>

What it means

The local_types DSL collects type aliases for a function. Each type call parses the string 'type <assignment>' with the Pops parser; a parse failure raises this ArgumentError, embedding the parser message and the Ruby file and line that made the call (via caller(1,1)). This is a definition-time error in the function's Ruby source.

Source

Thrown at lib/puppet/functions.rb:635

    # in string form without the leading 'type' keyword.
    # Calls to local_type must be made before the first parameter definition or an error will
    # be raised.
    #
    # @param assignment_string [String] a string on the form 'AliasType = ExistingType'
    # @api public
    #
    def type(assignment_string)
      # Get location to use in case of error - this produces ruby filename and where call to 'type' occurred
      # but strips off the rest of the internal "where" as it is not meaningful to user.
      #
      rb_location = caller(1, 1).first
      begin
        result = parser.parse_string("type #{assignment_string}", nil)
      rescue StandardError => e
        rb_location = rb_location.gsub(/:in.*$/, '')
        # Create a meaningful location for parse errors - show both what went wrong with the parsing
        # and in which ruby file it was found.
        raise ArgumentError, _("Parsing of 'type \"%{assignment_string}\"' failed with message: <%{message}>.\n" \
                               "Called from <%{ruby_file_location}>") % {
                                 assignment_string: assignment_string,
                                 message: e.message,
                                 ruby_file_location: rb_location
                               }
      end
      unless result.body.is_a?(Puppet::Pops::Model::TypeAlias)
        rb_location = rb_location.gsub(/:in.*$/, '')
        raise ArgumentError, _("Expected a type alias assignment on the form 'AliasType = T', got '%{assignment_string}'.\n" \
                               "Called from <%{ruby_file_location}>") % {
                                 assignment_string: assignment_string,
                                 ruby_file_location: rb_location
                               }
      end
      @local_types << result.body
    end
  end

View on GitHub (pinned to e227c27540)

Solutions

1. Read the embedded parse message; it pinpoints the syntax problem in the assignment string.
2. Use the exact form 'AliasName = TypeReference', for example 'MyList = Array[String]'.
3. Test the string standalone: Puppet::Pops::Parser::Parser.new.parse_string('type MyList = Array[String]').
4. Keep one alias per type call instead of packing several assignments together.

Example fix

# before
 local_types { type 'MyList = Array[' }

# after
 local_types { type 'MyList = Array[String]' }

# Validate alias assignment strings in CI exactly as local_types will parse them
parser = Puppet::Pops::Parser::Parser.new
['MyList = Array[String]', 'MyMap = Hash[String, Integer]'].each do |s|
  parser.parse_string("type #{s}")
end

When it happens

Trigger: local_types { type 'MyList = Array[' } inside a create_function block: the assignment string has a syntax error, so parser.parse_string raises and the wrapper adds the Ruby location.

Common situations: Unbalanced brackets or a stray character in alias assignments; writing an expression instead of an assignment; typos that break the Puppet language grammar rather than just naming an unknown type.

Related errors

• Expected a type alias assignment on the form 'AliasType = T'
• The parameter '$#{name}' is invalid: #{e.message}
• Function Load Error for function '%{function_name}': %{messa
• Functions must be based on Puppet::Pops::Functions::Function
• Function Creation Error, cannot create a default dispatcher

AI-assisted analysis of puppetlabs/puppet@e227c27540 (2026-08-21). Data as JSON: /api/errors/3971fe90fe955737. Report an issue: GitHub.