GzipReader: internal_encoding option overwrites external_encoding

[olofheurgren]

(Ruby version 3.3.1)

Hi!

When I specify the internal_encoding option to GzipReader.open or GzipReader.new, this seems to override whatever was set by the external_encoding option.

Example:

When not specifying internal_encoding, we get the expected external_encoding:

Zlib::GzipReader.open('myfile.gz', external_encoding: 'iso-8859-1') do |gz|
  puts gz.external_encoding
end

output:

ISO-8859-1

But with internal_encoding specified, external_encoding is changed:

Zlib::GzipReader.open('myfile.gz', external_encoding: 'iso-8859-1', internal_encoding: 'utf-8') do |gz|
  puts gz.external_encoding
end

output:

UTF-8

This seems broken, right? I'm not getting the problem with File.open.

---

Additionally, I noticed GzipReader does not respond to internal_encoding:

Zlib::GzipReader.open('myfile.gz') do |gz|
  puts gz.internal_encoding
end

This throws NoMethodError with message:

undefined method `internal_encoding' for #<Zlib::GzipReader:0x00007f4c616a4e10> (NoMethodError)
Did you mean?  external_encoding

Regards, Olof