ruby / io-console

Using MRI Ruby and JRuby loading "io/console" extends StringIO with extra methods.

For example:

require "stringio"
sio = StringIO.new
sio.respond_to?(:getch) # => false

then loading "io/console" adds getch support:

require "io/console"
sio.respond_to?(:getch) # => true

With TruffleRuby, that's not the case:

require "io/console"
sio.respond_to?(:getch) # => false

I'm using TruffleRuby v20.1.0 locally and the failure is also happening in the Travis CI

Hopefully, this helps to identify the issue and apologies if this is already fixed.

/cc @eregon @bjfish @chrisseaton

Thanks for the report.
Currently TruffleRuby and JRuby use a separate implementation for io/console than this gem (#10/#11, 41b6f09).

It looks like JRuby has that behavior with
https://github.com/jruby/jruby/blob/9.2.8.0/lib/ruby/stdlib/io/console/common.rb#L23-L34
I'll copy that logic over to TruffleRuby.

The C extension OTOH does this with a hidden (lowercase!) constant in

io-console/ext/io/console/console.c

Line 1646 in 2b8ba02

VALUE mReadable = rb_define_module_under(rb_cIO, "generic_readable");

Which looks funny for:

$ ruby -rstringio -e 'p StringIO.ancestors'
[StringIO, IO::generic_writable, IO::generic_readable, Enumerable, Data, Object, Kernel, BasicObject]

TruffleRuby doesn't support yet such constants, and it's actually the first error with:

$ chruby truffleruby-dev
$ gem i io-console:0.5.5
$ ruby -rio/console.so -e0                             
/home/eregon/.rubies/truffleruby-dev/lib/truffle/truffle/cext.rb:1081:in `const_defined?': wrong constant name generic_readable (NameError)
	from /home/eregon/.rubies/truffleruby-dev/lib/truffle/truffle/cext.rb:1081:in `rb_define_module_under'
	from define.c:26:in `rb_define_module_under'
	from /home/eregon/.rubies/truffleruby-dev/lib/gems/gems/io-console-0.5.5/ext/io/console/console.c:1637:in `InitVM_console'

Fixed in oracle/truffleruby@75b6f5f, thanks for the report.

TruffleRuby v20.1.0 doesn't patch StringIO