update solidity version to ^0.7.0 (#122)

* update solc version to ^0.7.0

* interfaces back to solidity >0.6.0 <0.8.0

* update solc to 0.7.6

* back to 0.7.4

* upgrade to 0.7.6, fix EXTCODESIZE check

* versions >0.5.0 <0.8.0 for xdomain msgers

packages/contracts/buidler.config.ts

@@ -22,7 +22,7 @@ const config: BuidlerConfig = {
     timeout: 50000,
   },
   solc: {
-    version: '0.7.4',
+    version: '0.7.6',
     optimizer: { enabled: true, runs: 200 },
   },
   typechain: {

packages/contracts/contracts/optimistic-ethereum/OVM/bridge/OVM_BaseCrossDomainMessenger.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 pragma experimental ABIEncoderV2;
 
 /* Interface Imports */

packages/contracts/contracts/optimistic-ethereum/OVM/bridge/OVM_L1CrossDomainMessenger.sol

 // SPDX-License-Identifier: MIT
-pragma solidity ^0.7.0;
+pragma solidity >0.5.0 <0.8.0;
 pragma experimental ABIEncoderV2;
 
 /* Library Imports */

packages/contracts/contracts/optimistic-ethereum/OVM/bridge/OVM_L2CrossDomainMessenger.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 pragma experimental ABIEncoderV2;
 
 /* Library Imports */

packages/contracts/contracts/optimistic-ethereum/OVM/precompiles/OVM_ETH.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 
 /* Interface Imports */
 import { iOVM_ERC20 } from "../../iOVM/precompiles/iOVM_ERC20.sol";

packages/contracts/contracts/optimistic-ethereum/OVM/precompiles/OVM_L2ToL1MessagePasser.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 
 /* Interface Imports */
 import { iOVM_L2ToL1MessagePasser } from "../../iOVM/precompiles/iOVM_L2ToL1MessagePasser.sol";

packages/contracts/contracts/optimistic-ethereum/iOVM/bridge/iOVM_BaseCrossDomainMessenger.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 pragma experimental ABIEncoderV2;
 
 /**

packages/contracts/contracts/optimistic-ethereum/iOVM/bridge/iOVM_L2CrossDomainMessenger.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 pragma experimental ABIEncoderV2;
 
 /* Interface Imports */

packages/contracts/contracts/optimistic-ethereum/iOVM/precompiles/iOVM_ERC20.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 
 /**
  * @title iOVM_ERC20

packages/contracts/contracts/optimistic-ethereum/iOVM/precompiles/iOVM_L1MessageSender.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 
 /**
  * @title iOVM_L1MessageSender

packages/contracts/contracts/optimistic-ethereum/iOVM/precompiles/iOVM_L2ToL1MessagePasser.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 
 /**
  * @title iOVM_L2ToL1MessagePasser

packages/contracts/contracts/optimistic-ethereum/libraries/codec/Lib_OVMCodec.sol

 // SPDX-License-Identifier: MIT
-pragma solidity ^0.7.0;
+pragma solidity >0.5.0 <0.8.0;
 pragma experimental ABIEncoderV2;
 
 /* Library Imports */

packages/contracts/contracts/optimistic-ethereum/libraries/resolver/Lib_AddressManager.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 
 /* Contract Imports */
 import { Ownable } from "./Lib_Ownable.sol";

packages/contracts/contracts/optimistic-ethereum/libraries/resolver/Lib_AddressResolver.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 
 /* Library Imports */
 import { Lib_AddressManager } from "./Lib_AddressManager.sol";

packages/contracts/contracts/optimistic-ethereum/libraries/resolver/Lib_Ownable.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 
 /**
  * @title Ownable

packages/contracts/contracts/optimistic-ethereum/libraries/trie/Lib_SecureMerkleTrie.sol

 // SPDX-License-Identifier: MIT
-pragma solidity ^0.7.0;
+pragma solidity >0.5.0 <0.8.0;
 pragma experimental ABIEncoderV2;
 
 /* Library Imports */

packages/contracts/contracts/optimistic-ethereum/libraries/utils/Lib_ReentrancyGuard.sol

 // SPDX-License-Identifier: MIT
 // +build ovm
-pragma solidity >0.6.0 <0.8.0;
+pragma solidity >0.5.0 <0.8.0;
 
 /**
  * @dev Contract module that helps prevent reentrant calls to a function.

packages/contracts/test/contracts/OVM/execution/OVM_ExecutionManager/ovmCREATEEOA.spec.ts

@@ -69,7 +69,7 @@ const test_ovmCREATEEOA: TestDefinition = {
             address: '0x17ec8597ff92C3F44523bDc65BF0f1bE632917ff',
           },
           expectedReturnStatus: true,
-          expectedReturnValue: 1682,
+          expectedReturnValue: 1678,
         },
       ],
     },