extcodesize returns wrong value on contracts being constructed

[elopez]

extcodesize on a contract being constructed should return 0, but on echidna it returns non-0. Here's a testcase:

pragma solidity ^0.5.0;

contract C {

  uint sz;

  constructor() public {
    uint x;
    address t = address(this);
    assembly { x := extcodesize(t) }
    sz = x;
  }

  function echidna_test_zero() public returns (bool) {
    return sz == 0;
  }
}

[incertia]

i believe this is more of an hevm regression than an echidna issue

in particular, we have to run constructors as a RuntimeCode "bytecode here" rather than an InitCode "bytecode here" and hevm likely implements extcodesize for RuntimeCode as a non-constructor.

[incertia]

jk

i think we can get around this by manually setting state . code. in particular,

vm & env . contracts . at addr ?= initialContract (InitCode bc)
loadContract addr
vm & state . code .= bc

[incertia]

check out the PR, i am almost certain it is the right thing to do

extcodesize

[ggrieco-tob]

Fixed in #454 and #465