JS: Constant SC_SPEC_DOC_LIMIT doesn't get replaced with a JavaScript XDR constant

[wildework]

What version are you using?

I'm using the 6e42b01e1ceb25c251d4c4d45443d7e0f228822a commit version.

What did you do?

From the root folder of the repository, I call xdrgen.

./bin/xdrgen -o ../stellar_sdk/xdr -l javascript -n stellar ../stellar-xdr/*.x

Every instance of SC_SPEC_DOC_LIMIT is not replaced with a constant lookup, here's one example.

struct SCSpecUDTStructFieldV0
{
    string doc<SC_SPEC_DOC_LIMIT>;
    string name<30>;
    SCSpecTypeDef type;
};

What did you expect to see?

xdr.struct("ScSpecUdtStructFieldV0", [
  ["doc", xdr.string(xdr.lookup("SC_SPEC_DOC_LIMIT"))],
  ["name", xdr.string(30)],
  ["type", xdr.lookup("ScSpecTypeDef")],
]);

What did you see instead?

xdr.struct("ScSpecUdtStructFieldV0", [
  ["doc", xdr.string(SC_SPEC_DOC_LIMIT)],
  ["name", xdr.string(30)],
  ["type", xdr.lookup("ScSpecTypeDef")],
]);

[wildework]

Also, the same issue appears withSCVAL_LIMIT in this instance.

union SCObject switch (SCObjectType type)
{
case SCO_VEC:
    SCVec vec;
case SCO_MAP:
    SCMap map;
case SCO_U64:
    uint64 u64;
case SCO_I64:
    int64 i64;
case SCO_U128:
    Int128Parts u128;
case SCO_I128:
    Int128Parts i128;
case SCO_BYTES:
    opaque bin<SCVAL_LIMIT>;
case SCO_CONTRACT_CODE:
    SCContractCode contractCode;
case SCO_ADDRESS:
    SCAddress address;
case SCO_NONCE_KEY:
    SCAddress nonceAddress;
};

Where I get the JavaScript generated without xdr.lookup.

xdr.union("ScObject", {
  switchOn: xdr.lookup("ScObjectType"),
  switchName: "type",
  switches: [
    ["scoVec", "vec"],
    ["scoMap", "map"],
    ["scoU64", "u64"],
    ["scoI64", "i64"],
    ["scoU128", "u128"],
    ["scoI128", "i128"],
    ["scoBytes", "bin"],
    ["scoContractCode", "contractCode"],
    ["scoAddress", "address"],
    ["scoNonceKey", "nonceAddress"],
  ],
  arms: {
    vec: xdr.lookup("ScVec"),
    map: xdr.lookup("ScMap"),
    u64: xdr.lookup("Uint64"),
    i64: xdr.lookup("Int64"),
    u128: xdr.lookup("Int128Parts"),
    i128: xdr.lookup("Int128Parts"),
    bin: xdr.varOpaque(SCVAL_LIMIT),
    contractCode: xdr.lookup("ScContractCode"),
    address: xdr.lookup("ScAddress"),
    nonceAddress: xdr.lookup("ScAddress"),
  },
});

This line in particular.

bin: xdr.varOpaque(SCVAL_LIMIT),

Here's another example.

struct ContractCodeEntry {
    ExtensionPoint ext;

    Hash hash;
    opaque code<SCVAL_LIMIT>;
};

I get no xdr.lookup.

xdr.struct("ContractCodeEntry", [
  ["ext", xdr.lookup("ExtensionPoint")],
  ["hash", xdr.lookup("Hash")],
  ["code", xdr.varOpaque(SCVAL_LIMIT)],
]);

[leighmcculloch]

@paulbellamy Did you encounter any issues with constants when generating the code for js-stellar-base? We've had the SCVAL_LIMIT constant in the XDR for months at this point, and it looks like we generated the code just fine in https://github.com/stellar/js-stellar-base/blob/master/src/generated/next_generated.js.

[leighmcculloch]

What did you expect to see?

xdr.struct("ScSpecUdtStructFieldV0", [
  ["doc", xdr.string(SC_SPEC_DOC_LIMIT)],
  ["name", xdr.string(30)],
  ["type", xdr.lookup("ScSpecTypeDef")],
]);

What did you see instead?

xdr.struct("ScSpecUdtStructFieldV0", [
  ["doc", xdr.string(xdr.lookup("SC_SPEC_DOC_LIMIT"))],
  ["name", xdr.string(30)],
  ["type", xdr.lookup("ScSpecTypeDef")],
]);

@wildework Are you asking that every location should use lookup, or should not use lookup? I just want to confirm that because the issue description says the lookup shouldn't be there, but the following comment with examples sounds like the lookup should be there.

[wildework]

@leighmcculloch most instances of SCVAL_LIMIT are fine, it's just the ones I shared that don't work, like in this example.

xdr.varOpaque(SCVAL_LIMIT)

As a constant SCVAL_LIMIT is never defined, nor is any other constant. js-xdr is only retrieving constants using xdr.lookup method.

[wildework]

@leighmcculloch And sorry about the mix-up, I flipped the order for "expect" and "did see". I have fixed my original post with the correct order now. And just to be explicit - we need to use xdr.lookup(), as per my comment above.

[ire-and-curses]

@wildework What are the direct consequences for you of this bug? Trying to understand the impact and therefore the urgency.

[wildework]

@ire-and-curses For me, it's a matter of manually editing the generated JS code.

I've already solved this downstream in my sdk https://github.com/useSoroban/sdk/blob/trunk/source/xdr.js#L748 so this bug only affects people that will be using the official Stellar JavaScript SDK and trying to parse data of types that rely on SC_SPEC_DOC_LIMIT.

[Shaptic]

it looks like we generated the code just fine in https://github.com/stellar/js-stellar-base/blob/master/src/generated/next_generated.js

not quite, @leighmcculloch: https://github.com/stellar/js-stellar-base/blob/f508a02f239df9810a35e3704d2081dbdf05a3c9/src/generated/next_generated.js#L7931-L7952

It seems to fail in the case of unions and structs that use the constant to define an array's size, e.g. struct Name { type name<CONSTANT> }; won't do an xdr.lookup("CONSTANT").

[Shaptic]

Basically, there are no downstream risks because we have to fix this manually anyway to release new versions of stellar-base@soroban (it won't build otherwise). However, it's still an annoying amount of manual work that'd be great to fix.

(Note that this wasn't done for stellar-base@latest as noted by Leigh above in #152 (comment) because the vNext XDR isn't used, only generated. This is an oversight, admittedly, but it harms nobody because they can't access it.)