has to be a 64bit toolchain - ie by installing ruby 64 and hence the 64 bit dev toolchain OPENSSL_LIB_DIR=C:\OpenSSL-Win64 OPENSSL_INCLUDE_DIR=C:\OpenSSL-Win64\include
rust nightly via straight windows_package -
windows_package 'rust' do
source 'https://static.rust-lang.org/dist/2015-08-17/rust-nightly-x86_64-pc-windows-gnu.msi'
end