std: add instances for contract dispatch desugaring

[d-xo]

This adds the core datatype definitions and class / instance definitions that allow us to desugar a surface level contract definition into a single entrypoint that dispatches to the contracts methods based on it's function selector hash.

An example desugaring can be seen at the end of the file. At a high level each surface level contract object will have a main generated that calls RunContract.exec on an instance of the Contract datatype reflecting the structure of the given contract. The defined typeclass instances will handle the dispatch generation and abi encoding/decoding.

Still to do:

• receive()
• move callvalue check to the top level if all methods are not payable
• public / external

Pending a decision on our implementation of compile time eval it also relies on the desugaring stage to precompute the selector hash and insert that directly into the bytecode.

You can test the desugaring logic as follows. This will call the add2 method with 2 and 3 abi encoded, and then display the result:

$ ./runsol.sh std/dispatch.solc --calldata "add2(uint256,uint256)" 2 3
Processing: std/dispatch.solc
Compiling to core...
Emitting core for contract C
Writing to output1.core
Generating Yul...
found main
writing output to dispatch.yul
Compiling to bytecode...
Hex output: dispatch.hex
Executing...
"Return: 0x0000000000000000000000000000000000000000000000000000000000000005"
Decoded: 5

[d-xo]

Using the builtin bool type gave me a bunch of specializer errors I didn't understand. I'll try to find a minimal reproducer and submit a bug.

[mbenke]

For the record

• fails if a contract has more than one method
• problems with argumentless methods (e.g. function one() -> uint256 { return uint256(1); }

It also would be good to split the library part from the example