Windows users and `render file: 'path_to_file'`

Unlike developers on *nix machines, Windows users have to be explicit about rendering file. render can’t figure it out because it tries to find ?/ in it’s first argument if it’s a string or symbol.

‘/’ is the *nix file separator. Windows uses ''. Ruby’s File::SEPARATOR, since 1.9.x knows the right separator to use depending on the operating system. Using that would let Rails developers on Windows look normal and save them some keystrokes

Windows supports both, and so does Ruby: https://github.com/ruby/ruby/blob/trunk/file.c#L2751-L2756

Then the guide on rendering needs an update. It’s says it’s mandatory to specify file when passing a file path argument to render.