Some elements are missing completion options

[Giels]

If I have

    let mut file = try!(File::open(file_path).map_err(|e| e.to_string()));
    let mut contents = String::new();

Then contents.<C-x C-o> gives a good list of completion options, all appropriate for String, showing that vim-racer is indeed working properly. However, file.<C-x C-o> doesn't find anything: Pattern not found. Things like read_to_string, which are properly defined for File, can successfully be used, and the program successfully compiles, however.

[Shougo]

@Giels You should ask it in racer issue.
I don't know this is supported in racer.