diff options
| -rw-r--r-- | lib/prism/polyfill/string.rb | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/lib/prism/polyfill/string.rb b/lib/prism/polyfill/string.rb index 582266d956..3fa9b5a0c5 100644 --- a/lib/prism/polyfill/string.rb +++ b/lib/prism/polyfill/string.rb @@ -1,7 +1,9 @@ # frozen_string_literal: true -# Polyfill for String#unpack1 with the offset parameter. -if String.instance_method(:unpack1).parameters.none? { |_, name| name == :offset } +# Polyfill for String#unpack1 with the offset parameter. Not all Ruby engines +# have Method#parameters implemented, so we check the arity instead if +# necessary. +if (unpack1 = String.instance_method(:unpack1)).respond_to?(:parameters) ? unpack1.parameters.none? { |_, name| name == :offset } : (unpack1.arity == 1) String.prepend( Module.new { def unpack1(format, offset: 0) # :nodoc: |