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.