File.byLine ought to return dups?

[Graham Fawcett]

Hi folks,

I expected the following program to print the lines of a file in
reverse:

    // bad.d
    import std.stdio;
    import std.range;
    
    void main() {
      auto f = File("bad.d");
      foreach(char[] line; retro(array(f.byLine())))
        writeln(line);
    }

However, this produces very unusual output: fragments of the same
lines are printed repeatedly. I suspect it's because the byLine()
'generator' is not dup'ing the arrays it reads from the file.

This works as expected:

    // good.d
    import std.stdio;
    import std.range;
    
    Retro!(char[][]) retroLines(File f) {
     char[][] lines;
      foreach(line; f.byLine())
        lines ~= line.dup;         // note the .dup
      return retro(lines);
     }
    
    void main() {
      auto f = File("good.d");
      foreach(line; retroLines(f))
        writeln(line);
    }

If you remove the '.dup', then this behaves badly as well.

So is this a bug in File.byLine, or am I just using it badly? :)

Thanks,
Graham