以下のように debugger-linecache のbundle時に失敗したときの対応メモ。 Installing debugger-linecache (1.1.2) with native extensions Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension. /Users/interu/.rbenv/versions/1.9.3-p362/bin/ruby extconf.rb checking for vm_core.h... no checking for vm_core.h... no Makefile creation failed *****************************************************************