revive: Precompiles should return dummy code when queried

[athei]

Fixes paritytech/contract-issues#111

This fixes both the RPC and the opcodes EXTCODESIZE and EXTCODEHASH.

Also removed the disabled host function is_contract. Contracts do use EXTCODESIZE to determine if something is a contract exclusively.

Need to add some differential tests to our test suite to make sure that the RPC matches geth behaviour:

On kitchensink:

# primitive precompiles should not return error but 0x
$ cast code 0x0000000000000000000000000000000000000001
0x

# this is the erc pre-compile
$ cast code 0x0000000000000000000000000000000000010000
0x60006000fd

[pgherveou]

Why would This

cast code 0x0000000000000000000000000000000000010000
0x60006000fd

return something different than the 0x1 - 0x9 precompiles

Are there example of precompiles on ethereum that returns something else than 0x

[athei]

Why would This

cast code 0x0000000000000000000000000000000000010000 0x60006000fd

return something different than the 0x1 - 0x9 precompiles

Because we access those pre-compiles via a Solidity interface. As opposed via YUL assembly as we do for 0x1-0x9 pre-compiles. And Solidity does emit checks if a contract exists via EXTCODESIZE before calling it into it. Depending on version and function return type. So without this change Solidity will not be able to call them.

Are there example of precompiles on ethereum that returns something else than 0x

Not on main net. Because those are all accessed via assembly circumventing Solidity.

[athei]

/cmd prdoc --audience runtime_dev

[pgherveou]

added tests paritytech/evm-test-suite#100

[athei]

Test suite seems to fail due to this bug: paritytech/revive#344

But there is no released version with the fix, yet. @xermicus

[xermicus]

I'll try to cut a release with the fix right now.

[xermicus]

Fixed version is released.