puppetlabs/puppet · error · ArgumentError

The argument 'code_string' must be a String, got %{type}

Error message

The argument 'code_string' must be a String, got %{type}

What it means

Compiler#parse_string parses and validates Puppet language source but first requires the argument to be a String. Unlike evaluate_string there is no nil special case here: parse_string(nil) raises ArgumentError with 'got NilClass'. The message reports the actual class, making the mismatch obvious.

Source

Thrown at lib/puppet/pal/compiler.rb:144

    #
    def evaluate_literal(ast)
      catch :not_literal do
        return Puppet::Pops::Evaluator::LiteralEvaluator.new().literal(ast)
      end
      # TRANSLATORS, the 'ast' is the name of a parameter, do not translate
      raise ArgumentError, _("The given 'ast' does not represent a literal value")
    end

    # Parses and validates a puppet language string and returns an instance of Puppet::Pops::Model::Program on success.
    # If the content is not valid an error is raised.
    #
    # @param code_string [String] a puppet language string to parse and validate
    # @param source_file [String] an optional reference to a file or other location in angled brackets
    # @return [Puppet::Pops::Model::Program] returns a `Program` instance on success
    #
    def parse_string(code_string, source_file = nil)
      unless code_string.is_a?(String)
        raise ArgumentError, _("The argument 'code_string' must be a String, got %{type}") % { type: code_string.class }
      end

      internal_evaluator.parse_string(code_string, source_file)
    end

    # Parses and validates a puppet language file and returns an instance of Puppet::Pops::Model::Program on success.
    # If the content is not valid an error is raised.
    #
    # @param file [String] a file with puppet language content to parse and validate
    # @return [Puppet::Pops::Model::Program] returns a `Program` instance on success
    #
    def parse_file(file)
      unless file.is_a?(String)
        raise ArgumentError, _("The argument 'file' must be a String, got %{type}") % { type: file.class }
      end

      internal_evaluator.parse_file(file)
    end

View on GitHub (pinned to e227c27540)

Solutions

1. Read the source fully first (File.read) and pass the resulting String
2. Default nil options to '' or skip the parse when the value is blank
3. Coerce Symbols intentionally with to_s before parsing

Example fix

# before
compiler.parse_string(options[:code])   # nil -> ArgumentError

# after
compiler.parse_string(options[:code] || '')

def code_string?(value)
  value.is_a?(String)
end

raise ArgumentError, 'code_string must be a String' unless code_string?(code)

When it happens

Trigger: parse_string(nil) from an unset option key; parse_string(:sym) from keyword-style code; passing a File or IO object instead of its contents.

Common situations: Optional config keys feeding the parser without defaults; reading a file but passing the handle instead of File.read output; Symbols leaking from options hashes into PAL calls.

Related errors

• The argument 'file' must be a String, got %{type}
• The argument 'puppet_code' must be a String, got %{type}
• Expected an instance of Puppet::SSL::Verifier but was passed
• The given 'ast' does not represent a literal value
• Given data_type value is not a data type, got '%{type}'

AI-assisted analysis of puppetlabs/puppet@e227c27540 (2026-08-21). Data as JSON: /api/errors/6940a815c4b246c4. Report an issue: GitHub.