anchor.diff:  	-- see https://github.com/keplerproject/luarocks/pull/443#issuecomment-152792516
   	local wsdks = {
   		["MSVCR100"] = "v7.1", -- shipped with Visual Studio 2010 compilers.
  +		["MSVCR100D"] = "v7.1", -- shipped with Visual Studio 2010 compilers.
   		["MSVCR90"] = "v6.1", -- shipped with Visual Studio 2008 compilers.
  +		["MSVCR90D"] = "v6.1", -- shipped with Visual Studio 2008 compilers.
   	}
   	local wsdkver = wsdks[vars.LUA_RUNTIME]
   	if not wsdkver then
  +    print(S[[    Cannot auto-detect Windows SDK version from $LUA_RUNTIME]])
   		return nil
   	end
   
   	local key = "HKLM\\Software\\Microsoft\\Microsoft SDKs\\Windows\\"..wsdkver
  -	return get_registry(key, "InstallationFolder")
  -end
  +  print("   checking: "..key)
  +  local dir = get_registry(key, "InstallationFolder")
  +  if dir then
  +    print("        Found: "..dir)
  +    return dir
  +  end
  +  print("        No SDK found")
  +	return nil
  +end
  +
   -- returns the batch command to setup msvc compiler path.
  +-- or an empty string (eg. "") if not found
   local function get_msvc_env_setup_cmd()
  +  print(S[[Looking for Microsoft toolchain matching runtime $LUA_RUNTIME and architecture $UNAME_M]])
  +
   	assert(type(vars.UNAME_M) == "string", "requires vars.UNAME_M to be set before calling this function.")
   	local x64 = vars.UNAME_M=="x86_64"
   
  
positive.code: vars.LUA_LIB_NAMES = "lua5.1.lib lua51.lib lua5.1.dll lua51.dll liblua.dll.a"
  vars.LUA_RUNTIME = nil
  vars.UNAME_M = nil
  
  local FORCE = false
  local FORCE_CONFIG = false
  local INSTALL_LUA = false
  local USE_MINGW = false
  local REGISTRY = true
  local NOADMIN = false
  local PROMPT = true
  
negative.code: 		end
  	end
  
  	-- finally, we can't detect more, just don't setup the msvc compiler in luarocks.bat.
  	return ""
  end
  
  