mixology Ruby 1.9.3 capability

gem build fails with

Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

    /home/duke/.rvm/rubies/ruby-1.9.3-p0/bin/ruby extconf.rb

creating Makefile

make compiling mixology.c mixology.c: In function 'class_alloc': mixology.c:16:26: error: invalid application of 'sizeof' to incomplete type 'rb_classext_t' mixology.c:20:5: warning: implicit declaration of function 'RCLASS_IV_TBL' [-Wimplicit-function-declaration] mixology.c:20:24: error: lvalue required as left operand of assignment mixology.c:21:5: warning: implicit declaration of function 'RCLASS_M_TBL' [-Wimplicit-function-declaration] mixology.c:21:23: error: lvalue required as left operand of assignment mixology.c:22:5: warning: passing argument 1 of 'rb_class_get_superclass' makes integer from pointer without a cast [enabled by default] /home/duke/.rvm/rubies/ruby-1.9.3-p0/include/ruby-1.9.1/ruby/intern.h:527:7: note: expected 'VALUE' but argument is of type 'struct RClass ' mixology.c:22:23: error: lvalue required as left operand of assignment mixology.c:23:5: warning: implicit declaration of function 'RCLASS_IV_INDEX_TBL' [-Wimplicit-function-declaration] mixology.c:23:30: error: lvalue required as left operand of assignment mixology.c: In function 'remove_nested_module': mixology.c:36:25: error: lvalue required as left operand of assignment mixology.c: In function 'rb_unmix': mixology.c:54:37: error: lvalue required as left operand of assignment mixology.c: In function 'add_module': mixology.c:82:31: error: lvalue required as left operand of assignment mixology.c:85:26: error: lvalue required as left operand of assignment mixology.c:86:25: error: lvalue required as left operand of assignment mixology.c:87:25: error: lvalue required as left operand of assignment mixology.c:97:44: error: lvalue required as left operand of assignment make: ** [mixology.o] Error 1