Kgio::Pipe.new results in a stack overflow

[eregon]

CRuby:

$ ruby -e 'require "kgio"; p Kgio::Pipe.new'      
[#<Kgio::Pipe:fd 7>, #<Kgio::Pipe:fd 8>]
$ ruby -e 'require "kgio"; p Kgio::Pipe.ancestors'
[Kgio::Pipe, Kgio::PipeMethods, Kgio::DefaultWaiters, IO, File::Constants, Enumerable, Object, Kernel, BasicObject]

TruffleRuby:

$ ruby -e 'require "kgio"; p Kgio::Pipe.new'      
[ruby] WARNING StackOverflowError
[ruby] WARNING StackOverflowError
[ruby] WARNING StackOverflowError
[ruby] WARNING StackOverflowError
<internal:core> core/truffle/ffi/pointer.rb:245:in `new': stack level too deep (SystemStackError)
	from com.oracle.svm.core.graal.snippets.StackOverflowCheckImpl.newStackOverflowError0(StackOverflowCheckImpl.java:333)
	from <internal:core> core/truffle/io_operations.rb:103:in `create_pipe'
	from <internal:core> core/io.rb:681:in `pipe'
	from <internal:core> core/truffle/io_operations.rb:109:in `create_pipe'
	from <internal:core> core/io.rb:681:in `pipe'
	from <internal:core> core/truffle/io_operations.rb:109:in `create_pipe'
	from <internal:core> core/io.rb:681:in `pipe'
	from <internal:core> core/truffle/io_operations.rb:109:in `create_pipe'
	from <internal:core> core/io.rb:681:in `pipe'
...
	from <internal:core> core/truffle/io_operations.rb:109:in `create_pipe'
	from <internal:core> core/io.rb:681:in `pipe'
	from <internal:core> core/truffle/io_operations.rb:109:in `create_pipe'
	from <internal:core> core/io.rb:681:in `pipe'
	from <internal:core> core/truffle/io_operations.rb:109:in `create_pipe'
	from <internal:core> core/io.rb:681:in `pipe'
	from -e:1:in `<main>'

The issue seems to be we assume IO and subclasses have a def initialize(fd, mode=nil) or so constructor but that doesn't seem true for Kgio::Pipe which inherits from IO, and so read_class.new(fds[0], IO::RDONLY) doesn't work as expected.

Found in sinatra/sinatra#1799

[andrykonchin]

Fixed in ca0c55e