Why does this Ragel file generate implicit conversion errors? (Ragel with D)

Question

I have the following (very simple) Ragel file scanner.rl:

void lex(string data) {
    int cs, act, top;
    auto p = data.ptr;
    typeof(p)
        pe = &data[$ -1],
        eof = pe,
        ts,
        te;

    %%{
        machine scanner;

        identifier = alpha . alnum**;

        main := |*
            identifier => { ("Identifier: " + data[ts..te]).writeln; };
            space;
        *|;

        write data;
        write init;
        write exec;
    }%%
}

void main() {
    "this is a test".lex;
}

I convert scanner.rl to scanner.d using ragel -D scanner.rl. When I try to compile the resulting D file with dmd scanner.d, I get the following error messages:

scanner.d(97): Error: cannot implicitly convert expression (&_scanner_actions[cast(ulong)_scanner_from_state_actions[cast(ulong)cs]]) of type const(byte)* to byte* scanner.d(110): Error: cannot implicitly convert expression (&_scanner_trans_keys[cast(ulong)_scanner_key_offsets[cast(ulong)cs]]) of type const(char)* to char* scanner.d(166): Error: cannot implicitly convert expression (&_scanner_actions[cast(ulong)_scanner_trans_actions[cast(ulong)_trans]]) of type const(byte)* to byte* scanner.rl(22): Error: cannot implicitly convert expression (ts) of type immutable(char)* to ulong scanner.d(186): Error: cannot implicitly convert expression (&_scanner_actions[cast(ulong)_scanner_to_state_actions[cast(ulong)cs]]) of type const(byte)* to byte*

Perhaps I'm missing something important?

Answer 1

Are you sure ragel is generating D2 code? Looks like it is missing const.... looking at ragel's source code, looks like ragel -D generates D1 and ragel -E generates D2, though this isn't documented in --help!