closure wonkiness

[Ellery Newcomer]

Hello.

I have a function that starts off as follows. When peek is called for
the first time, f should be -2. It turns out to be garbage. f doesn't
get modified anywhere but peek and consume. peek doesn't get called
until lexer has returned. This is D 2.031. Is it me or the compiler?

public Token delegate() lexer(InputStream inpp, OutputStream outpp){
    char[] buffer = new char[buffsize];
    char[] line;
    int b = 0;
    int f = -2;
    InputStream inp = inpp;
    OutputStream outp = outpp;
    bool eof(){
        return f == -2 && inp.eof;
    }
    char consume(){
        if(eof) return char.init;
        if(f == -2){
            f=-1;
            line = inp.readLine(buffer);
        }
        if( f == line.length - 1){
            f = -2;
            return '\n';
        }
        return line[++f];
    }
    char peek(){
        if(eof()) return char.init;
        writeln(f);
        if(f == -2){
            f = -1;
            line = inp.readLine(buffer);
        }
        if(f == line.length - 1){
            return '\n';
        }
        return line[f+1];
    }