Adapt the FFI backend code for FFI 1.11.1

Author: eregon

lib/truffle/ffi.rb

@@ -22,7 +22,6 @@ def self.find_type_size(type)
   end
 
   module Platform
-    CPU = RbConfig::CONFIG['host_cpu']
     # eregon: I would like to use rbconfig/sizeof here, but the linker requires
     # ffi, and the linker is needed to build the rbconfig/sizeof C extension,
     # so we need to break the cycle.
@@ -35,7 +34,6 @@ module Platform
 
 # Require the pure-Ruby Truffle NFI backend
 require_relative 'truffle/ffi_backend/last_error'
-require_relative 'truffle/ffi_backend/data_converter'
 require_relative 'truffle/ffi_backend/type'
 require_relative 'truffle/ffi_backend/struct_layout'
 require_relative 'truffle/ffi_backend/struct'

lib/truffle/truffle/ffi_backend/data_converter.rb

@@ -200,35 +200,4 @@ def to_s
       alias_method :to_str, :to_s
     end
   end
-
-  class StructByReference
-    include DataConverter
-
-    attr_reader :struct_class
-
-    def initialize(struct_class)
-      unless Class === struct_class and struct_class < FFI::Struct
-        raise TypeError, 'wrong type (expected subclass of FFI::Struct)'
-      end
-      @struct_class = struct_class
-    end
-
-    def native_type
-      FFI::Type::POINTER
-    end
-
-    def to_native(value, ctx)
-      return Pointer::NULL if value.nil?
-
-      unless @struct_class === value
-        raise TypeError, "wrong argument type #{value.class} (expected #{@struct_class})"
-      end
-
-      value.pointer
-    end
-
-    def from_native(value, ctx)
-      @struct_class.new(value)
-    end
-  end
 end