Error installing ruby-debug-base19

The ruby-debug19 gems are used for interactive debugging with Ruby 1.9 (the gems without 19 on the end are for Ruby 1.8). To use the debugging feature in Rubymine (which is awesome if you haven't tried it yet) you need to install these gems (ruby-debug-base19 and ruby-debug-ide19). I had previously used these with no problems, but yesterday when I tried installing ruby-debug-base19 on a new Ubuntu 10 system with Ruby 1.9.1 yesterday I got the following error:

make
gcc -I. -I/usr/local/include/ruby-1.9.1/i686-linux -I/usr/local/include/ruby-1.9.1/ruby/backward -I/usr/local/include/ruby-1.9.1 -I. -DHAVE_VM_CORE_H -DHAVE_ISEQ_H -DHAVE_INSNS_INC -DHAVE_INSNS_INFO_INC -DHAVE_EVAL_INTERN_H -I/usr/local/include/ruby-1.9.1/ruby-1.9.1-p376 -fPIC  -O2 -g -Wall -Wno-parentheses  -o breakpoint.o -c breakpoint.c
gcc -I. -I/usr/local/include/ruby-1.9.1/i686-linux -I/usr/local/include/ruby-1.9.1/ruby/backward -I/usr/local/include/ruby-1.9.1 -I. -DHAVE_VM_CORE_H -DHAVE_ISEQ_H -DHAVE_INSNS_INC -DHAVE_INSNS_INFO_INC -DHAVE_EVAL_INTERN_H -I/usr/local/include/ruby-1.9.1/ruby-1.9.1-p376 -fPIC  -O2 -g -Wall -Wno-parentheses  -o ruby_debug.o -c ruby_debug.c
ruby_debug.c: In function ‘ruby_method_ptr’:
ruby_debug.c:141: error: ‘rb_method_entry_t’ undeclared (first use in this function)
ruby_debug.c:141: error: (Each undeclared identifier is reported only once
ruby_debug.c:141: error: for each function it appears in.)
ruby_debug.c:141: error: ‘method’ undeclared (first use in this function)
ruby_debug.c:142: warning: implicit declaration of function ‘rb_method_entry’
ruby_debug.c: In function ‘debug_event_hook’:
ruby_debug.c:719: error: ‘rb_method_entry_t’ undeclared (first use in this function)
ruby_debug.c:719: error: ‘me’ undeclared (first use in this function)
make: *** [ruby_debug.o] Error 1

Apparently version 0.11.24 of ruby-debug-base19 was released on August 22, 2010, and it won't install correctly on Ruby 1.9.1. This version fixed support in Ruby 1.9.2, but broke 1.9.1 support. I went back to the previous version and it works fine. So to install the ruby-debug19 gems on a Ruby 1.9.1 system, run these two commands:

sudo gem install ruby-debug-base19 -v=0.11.23
sudo gem install ruby-debug-ide19

One important note! If you've already attempted to install the latest version of ruby-debug-base19 and gotten the failure, ruby-debug-ide19 may fail, even if you install the working version of ruby-debug-base19. You have to actually delete the files for 0.11.24 of ruby-debug-base19, and then reinstall ruby-debug-ide19. For me on a Ubuntu system where Ruby was compiled from source:

sudo rm -rf /usr/local/lib/ruby/gems/1.9.1/gems/ruby-debug-base19-0.11.24
sudo gem install ruby-debug-ide19

Also this bug has been reported on as ticket #28512.