Fix go-ipld-prime encoding function

[makew0rld]

dasl-testing/harnesses/boxo/main.go

Lines 161 to 189 in 98e3335

	// invalidEncode returns true if the provided CBOR cannot be encoded
	// after being decoded by a neutral decoder.
	// The second return value is the error.
	func invalidEncode(b []byte) (bool, string) {
	// TODO: decode using general CBOR library
	// This allows for only encoding to be tested rather than decode-strictness as well
	//
	// var data any
	// if err := cbor.Unmarshal(b, &data); err != nil {
	// return nil, err
	// }
	// return ipld.Marshal(dagcbor.Encode, &data, nil)
	// Currently we can't decode using a different library
	// Because ipld.Marshal requires knowing the full type/schema of whatever it's marshalling
	// It's really annoying but I guess it's to ensure it's only encoding things that already
	// conform to the IPLD schema.
	// So for now we decode with the dag-cbor decoder
	// In practice this still sort of works because the dag-cbor decoder is permissive,
	// in line with the dag-cbor spec.
	// "DAG-CBOR decoders may relax strictness requirements by default"
	// https://ipld.io/specs/codecs/dag-cbor/spec/#decode-strictness
	_, err := roundtrip(b)
	if err == nil {
	return false, ""
	}
	return true, err.Error()
	}

This contributes to bugs like #4 but also "tagged object (datetime)", where the encoding test for a tagged datetime fails, because the dag-cbor decoder stores it as a string (a separate bug of a non-strict decoder), and then the encoder just encodes the string without error.

serde_ipld_dagcbor also fails that test but for a different reason.

[makew0rld]

I asked in this issue about how to encode generic data, so hopefully the maintainers will respond.