Merge branch 'phase/release2_0' of github-scalac:input-output-hk/mantis into rpc-tests-fixes

Author: kapke

src/ets/resources/ets

@@ -376,7 +376,21 @@ case object EXTCODEHASH extends OpCode(0x3F, 1, 1, _.G_balance) with ConstGas {
   protected def exec[W <: WorldStateProxy[W, S], S <: Storage[S]](state: ProgramState[W, S]): ProgramState[W, S] = {
     val (accountAddress, stack1) = state.stack.pop
     val address = Address(accountAddress)
-    val accountExists = state.world.accountExists(address)
+
+    /**
+      * Specification of EIP1052 - https://eips.ethereum.org/EIPS/eip-1052, says that we should return 0
+      * In case the account does not exist 0 is pushed to the stack.
+      *
+      * But the interpretation is, that account does not exists if:
+      *   - it do not exists or,
+      *   - is empty according to eip161 rules (account is considered empty when it has no code and zero nonce and zero balance)
+      *
+      * Example of existing check in geth:
+      * https://github.com/ethereum/go-ethereum/blob/aad3c67a92cd4f3cc3a885fdc514ba2a7fb3e0a3/core/state/statedb.go#L203
+      *
+      *
+      */
+    val accountExists = !state.world.isAccountDead(address)
 
     val codeHash =
       if (accountExists) {

src/main/scala/io/iohk/ethereum/vm/OpCode.scala

@@ -191,7 +191,9 @@ class OpCodeFunSpec extends FunSuite with OpCodeTesting with Matchers with Prope
       val stateOutWithAccount = executeOp(op, stateInWithAccount)
 
       withStackVerification(op, stateInWithAccount, stateOutWithAccount) {
-        val stack2 = stack1.push(UInt256(codeHash))
+        // if account is empty we should push 0 onto stack
+        val toPushOnStack =  if (codeHash == Account.EmptyCodeHash) UInt256.Zero else UInt256(codeHash)
+        val stack2 = stack1.push(toPushOnStack)
         stateOutWithAccount shouldEqual stateInWithAccount.withStack(stack2).step()
       }
     }

src/test/scala/io/iohk/ethereum/vm/OpCodeFunSpec.scala

@@ -10,10 +10,10 @@ class StackSpec extends FunSuite with Matchers with PropertyChecks {
   val maxStackSize = 32
   val stackGen = Generators.getStackGen(maxSize = maxStackSize)
   val intGen = Gen.choose(0, maxStackSize).filter(_ >= 0)
-  val nonFullStackGen = stackGen.filter(stack => stack.size < stack.maxSize)
-  val fullStackGen = intGen.flatMap(Generators.getStackGen)
   val uint256Gen = Generators.getUInt256Gen()
   val uint256ListGen = Generators.getListGen(0, 16, uint256Gen)
+  val fullStackGen = intGen.flatMap(n => Generators.getStackGen(n, n, uint256Gen, n))
+  val nonFullStackGen = Generators.getStackGen(maxElems = maxStackSize - 1, maxSize = maxStackSize, valueGen = uint256Gen)
 
   test("pop single element") {
     forAll(stackGen) { stack =>