NFS XDR spec does not parse properly

[SriRamanujam]

I'm interested in using this library to autogen bindings for the NFS protocol (https://tools.ietf.org/html/rfc5662). Unfortunately, the spec has revealed several parsing issues.

In no particular order:

1. Unsigned 64-bit (hyper) integers are parsed as signed hyper integers

NFS4_UINT_MAX = 0xffffffffffffffff;

2. Empty structs throw a parsing error:

struct mode_masked64 {

};

thread 'main' panicked at 'Could not xdrgen lib/nfs41.x: Error(Msg("parse error: Eof: struct mode_masked64 {\n\n};\n"), State { next_error: None, backtrace: None })', libcore/result.rs:945:5

3. Some unions fail to parse correctly:

enum nfsstat4 {
        NFS4ERR_BADIOMODE      = 10049,
        NFS4ERR_BADLAYOUT      = 10050,
        NFS4ERR_BAD_SESSION_DIGEST = 10051,
        NFS4ERR_BADSESSION     = 10052,
        NFS4ERR_BADSLOT        = 10053,
        NFS4ERR_COMPLETE_ALREADY = 10054,
        NFS4ERR_CONN_NOT_BOUND_TO_SESSION = 10055,
        NFS4ERR_DELEG_ALREADY_WANTED = 10056,
        NFS4ERR_LAYOUTTRYLATER = 10058,
        NFS4ERR_LAYOUTUNAVAILABLE = 10059,
        NFS4ERR_NOMATCHING_LAYOUT = 10060,
        NFS4ERR_RECALLCONFLICT = 10061,
        NFS4ERR_UNKNOWN_LAYOUTTYPE = 10062
};

struct ACCESS4resok {
        uint32_t        supported;
        uint32_t        access;
};

union ACCESS4res switch (nfsstat4 status) {
 case NFS4_OK:
         ACCESS4resok   resok4;
 default:
         void;
};

thread 'main' panicked at 'Could not xdrgen lib/nfs41.x: Error(Msg("incompat selector Named(\"status\", Ident(\"nfsstat4\", None)) case Ident(\"NFS4_OK\")")

I stopped here, but you get the idea. I'm not sure how much of this is due to a bad spec and how much of this is due to parsing difficulties, but considering these examples are from the canonical RFC laying out the XDR protocol for NFSv4 I have to assume it's probably correct.