TOB-FUEL-13: Specification about ABI encoding is outdated

[xgreenx]

Description

The ABI encoding specification is missing the variable-length array type. The implementation also supports the Vector type as shown in the following figure. Though, the Vector type is not documented in the specification. The same is true for tuples.

Figure 13.1: Enumeration of supported Token types. (fuels-rs/packages/fuels-core/src/types.rs#71–94)

71    #[derive(Debug, Clone, PartialEq, EnumString)]
 72    #[strum(ascii_case_insensitive)]
 73    pub enum Token {
 74       // Used for unit type variants in Enum. An "empty" enum is not represented
as Enum<empty box>,
 75       // because this way we can have both unit and non-unit type variants.
 76       Unit,
 77       U8(u8),
 78       U16(u16),
 79       U32(u32),
 80       U64(u64),
 81       U128(u128),
 82       U256(U256),
 83       Bool(bool),
 84       B256([u8; 32]),
 85       Array(Vec<Token>),
 86       Vector(Vec<Token>),
 87       String(StringToken),
 88       Struct(Vec<Token>),
 89       #[strum(disabled)]
 90       Enum(Box<EnumSelector>),
 91       Tuple(Vec<Token>),
 92       RawSlice(Vec<u64>),
 93       Bytes(Vec<u8>),
 94    }

Recommendations

Short term, extend the specification and add a specification for vectors and tuples.
Long term, implement a definition of ready (DoR) for issues, which requires code reviewers to verify that the specification matches the code.

[xgreenx]

Related specification issue FuelLabs/fuel-specs#505

[digorithm]

Closing this because it seems to be resolved by #1066.

[iqdecay]

Just to clarify: the issue is with the fuels-specs repo, not fuels-rs. #1066 didn't fix this issue, simply clarified how coding/decoding happened, but not how those types are coded/decoded, especially not Vectors. Currently working on improving the specs.