bigints allow type overflow when encoding

[8de2fdb0]

I have an issue with following generated snippet:

 encode(message: MyMessage, writer: _m0.Writer = _m0.Writer.create()): _m0.Writer {
    if (message.ref !== BigInt("0")) {
      writer.uint32(9).fixed64(message.ref.toString());
    }
  },

It uses --ts_proto_opt=forceLong=bigint and uses bigints as input.

If I use following number as input for the fixed64 the encoded protobuf value is 0

18_446_744_073_709_551_615n + 1n

So it basically overflows.

Is there any way to guard against this unexpected behaviour?

[jcready]

Are you expecting an error to be thrown or for it to just not encode the zero value (after overflow) because it's the default value?.

[8de2fdb0]

Good question, I could not find compiler spec for protoc and the protoc c++ implementation dos exactly the same, so I would consider that the correct behaviour based on the reference implementation.

On the other hand the rust implementation would catch that at compile-time, and this is a typescript library.

Are there any guards for overflows or malformed input used in ts-proto currently?

Maybe something like :

const MAX_FIXED64 = 18_446_744_073_709_551_615n;

 encode(message: MyMessage, writer: _m0.Writer = _m0.Writer.create()): _m0.Writer {
    if (message.ref > MAX_FIXED64) {
       throw new Error("value for ref field in MyMessage is larger then MAX_FIXED64");
    }
    if (message.ref !== BigInt("0")) {
      writer.uint32(9).fixed64(message.ref.toString());
    }
  },

[stephenh]

We have somewhat similar detection for Number/long overflows:

https://github.com/stephenh/ts-proto/blob/main/src/main.ts#L505

function longToNumber(long: Long): number {
  if (long.gt(globalThis.Number.MAX_SAFE_INTEGER)) {
    throw new globalThis.Error("Value is larger than Number.MAX_SAFE_INTEGER");
  }
  return long.toNumber();
}

So @8de2fdb0 if you wanted to work on a PR that did similar runtime detection of "incoming bigint will be larger than fixed64", that would sgtm.

I think it would be around in here:

https://github.com/stephenh/ts-proto/blob/main/src/main.ts#L1246

But not 100% sure. Thanks!

[8de2fdb0]

I opened #938

[stephenh]

Fixed in #938 , thanks @8de2fdb0 !