Reline behaves oddly with redirect (nontty output)

[mtasaka]

Forwarded from cucumber/aruba testsute issue cucumber/aruba#910 , then from https://bugs.ruby-lang.org/issues/20052

Looks line reline behaves oddly with redirect (non tty)

With ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x86_64-linux] and Readline (version 8.2):

$ echo 'foo' | ruby -e 'require "readline"; puts Readline.readline(">")' > bar.log ; cat bar.log 
> foo
foo

With ruby 3.3.0dev (2023-12-09 master 1cbe114d1c) [x86_64-linux] and Reline (version 4.1): (Reline installed from gem install)

$ echo 'foo' | ruby -e 'require "reline"; puts Reline.readline(">")' > bar.log ; cat bar.log 
>>> f>f>fo>fo>foo>foofoo

[tompng]

I think it is Reline's bug. Reline's output should make the terminal screen to show:

>foo
foo

My understanding is that Reline does not aim to output exactly the same byte sequence as Readline. Reline's output can contain escape sequences or control characters like "\r>\r>f\r>foo\nfoo\n". Fixing this bug might not make the mentioned test pass.

Note that Readline's output sometimes contains different escape sequence depending on version or environment.

printf "ruby\x01\x04R\n" | ruby -rreadline -e 'puts Readline.readline(">")'
# output(readline 8.2): ">ruby\r\e[C\e[1Puby\r\e[CRuby\b\b\b\nRuby\n"
# output(readline 8.1): ">ruby\r>\e[1P\e[1@R\nRuby\n"
# terminal screen: ">Ruby\nRuby\n"