RubyInstaller just released Ruby 2.3.0 for Windows.
Was able to install and compile
pg without problems, but execution fails with the following error:
C:/Ruby23-x64/lib/ruby/gems/2.3.0/gems/pg-0.18.4-x64-mingw32/lib/pg.rb:14:in require': cannot load such file -- 2.3/pg_ext (LoadError)
pg '0.18.4' does not have
/2.2/pg_ext.so are present.