README.mdのHow to compile and installの 2つ目の手順にて autoconf を実行したところ、以下のエラーが発生しました。
$ autoconf
configure.ac:7: error: Autoconf version 2.67 or higher is required
configure.ac:7: the top level
autom4te: /usr/bin/m4 failed with exit status: 63
checking for ruby... /usr/bin/ruby
downloading config.guess ... done
tool/downloader.rb:212:in `download': failed to download config.guess (RuntimeError)
NoMethodError: undefined method `to_path' for #<Pathname:tool/config.guess>: https://raw.githubusercontent.com/gcc-mirror/gcc/master/config.guess
from tool/downloader.rb:54:in `download'
from tool/downloader.rb:344
from tool/downloader.rb:328:in `each'
from tool/downloader.rb:328
configure: error: cannot run /bin/sh tool/config.sub
I believe this is asking for a section on build requirements to be added to the README, which seems useful for me. I added a pull request for this: https://github.com/ruby/ruby/pull/4582. I'm not sure if there are missing requirements, or the minimum versions of bison or automake that we support, so additional review would be helpful.
I'm not sure that this is section is complete (may be missing
requirements), or accurate (minimum automake or bison versions
may not be correct). However, I think it's useful, and we can
adjust it in the future to add requirements or adjust
requirement versions.