Upgrade to solidity 6.12

contracts/@openzeppelin/contracts-ethereum-package/contracts/GSN/Context.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity 0.6.12;
 
 import "../../../upgrades/contracts/Initializable.sol";
 

contracts/@openzeppelin/contracts-ethereum-package/contracts/access/Roles.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity 0.6.12;
 
 /**
  * @title Roles

contracts/@openzeppelin/contracts-ethereum-package/contracts/math/Math.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity 0.6.12;
 
 /**
  * @dev Standard math utilities missing in the Solidity language.

contracts/@openzeppelin/contracts-ethereum-package/contracts/math/SafeMath.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity 0.6.12;
 
 /**
  * @dev Wrappers over Solidity's arithmetic operations with added overflow

contracts/@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/ERC20.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity 0.6.12;
 
 import "../../../../upgrades/contracts/Initializable.sol";
 
@@ -42,14 +42,14 @@ contract ERC20 is Initializable, Context, IERC20 {
     /**
      * @dev See {IERC20-totalSupply}.
      */
-    function totalSupply() public view returns (uint256) {
+    function totalSupply() public view override returns (uint256) {
         return _totalSupply;
     }
 
     /**
      * @dev See {IERC20-balanceOf}.
      */
-    function balanceOf(address account) public view returns (uint256) {
+    function balanceOf(address account) public view override returns (uint256) {
         return _balances[account];
     }
 
@@ -61,15 +61,15 @@ contract ERC20 is Initializable, Context, IERC20 {
      * - `recipient` cannot be the zero address.
      * - the caller must have a balance of at least `amount`.
      */
-    function transfer(address recipient, uint256 amount) public returns (bool) {
+    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
         _transfer(_msgSender(), recipient, amount);
         return true;
     }
 
     /**
      * @dev See {IERC20-allowance}.
      */
-    function allowance(address owner, address spender) public view returns (uint256) {
+    function allowance(address owner, address spender) public view override returns (uint256) {
         return _allowances[owner][spender];
     }
 
@@ -80,7 +80,7 @@ contract ERC20 is Initializable, Context, IERC20 {
      *
      * - `spender` cannot be the zero address.
      */
-    function approve(address spender, uint256 amount) public returns (bool) {
+    function approve(address spender, uint256 amount) public override returns (bool) {
         _approve(_msgSender(), spender, amount);
         return true;
     }
@@ -97,7 +97,7 @@ contract ERC20 is Initializable, Context, IERC20 {
      * - the caller must have allowance for `sender`'s tokens of at least
      * `amount`.
      */
-    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
+    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
         _transfer(sender, recipient, amount);
         _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
         return true;

contracts/@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/ERC20Detailed.sol

@@ -1,12 +1,12 @@
-pragma solidity ^0.5.0;
+pragma solidity 0.6.12;
 
 import "../../../../upgrades/contracts/Initializable.sol";
 import "./IERC20.sol";
 
 /**
  * @dev Optional functions from the ERC20 standard.
  */
-contract ERC20Detailed is Initializable, IERC20 {
+abstract contract ERC20Detailed is Initializable, IERC20 {
     string private _name;
     string private _symbol;
     uint8 private _decimals;

contracts/@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/IERC20.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity 0.6.12;
 
 /**
  * @dev Interface of the ERC20 standard as defined in the EIP. Does not include

contracts/@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/SafeERC20.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.0;
+pragma solidity 0.6.12;
 
 import "./IERC20.sol";
 import "../../math/SafeMath.sol";

contracts/@openzeppelin/contracts-ethereum-package/contracts/utils/Address.sol

@@ -1,4 +1,4 @@
-pragma solidity ^0.5.5;
+pragma solidity 0.6.12;
 
 /**
  * @dev Collection of functions related to the address type
@@ -64,7 +64,7 @@ library Address {
         require(address(this).balance >= amount, "Address: insufficient balance");
 
         // solhint-disable-next-line avoid-call-value
-        (bool success, ) = recipient.call.value(amount)("");
+        (bool success, ) = recipient.call{value:amount}("");
         require(success, "Address: unable to send value, recipient may have reverted");
     }
 }

contracts/ERC1404.sol

@@ -1,19 +1,19 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 import "./@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/IERC20.sol";
 
-contract ERC1404 is IERC20 {
+abstract contract ERC1404 is IERC20 {
     /// @notice Detects if a transfer will be reverted and if so returns an appropriate reference code
     /// @param from Sending address
     /// @param to Receiving address
     /// @param value Amount of tokens being transferred
     /// @return Code by which to reference message for rejection reasoning
     /// @dev Overwrite with your custom transfer restriction logic
-    function detectTransferRestriction (address from, address to, uint256 value) public view returns (uint8);
+    function detectTransferRestriction (address from, address to, uint256 value) public virtual view returns (uint8);
 
     /// @notice Returns a human-readable message for a given restriction code
     /// @param restrictionCode Identifier for looking up a message
     /// @return Text showing the restriction's reasoning
     /// @dev Overwrite with your custom message and restrictionCode handling
-    function messageForTransferRestriction (uint8 restrictionCode) public view returns (string memory);
+    function messageForTransferRestriction (uint8 restrictionCode) public virtual view returns (string memory);
 }

contracts/Migrations.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 contract Migrations {
     address public owner;

contracts/Proxy.sol

@@ -1,25 +1,26 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 contract Proxy {
     // Code position in storage is keccak256("PROXIABLE") = "0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7"
+    uint256 constant PROXIABLE_MEM_SLOT = 0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7;
     // constructor(bytes memory constructData, address contractLogic) public {
     constructor(address contractLogic) public {
         // Verify a valid address was passed in
         require(contractLogic != address(0), "Contract Logic cannot be 0x0");
 
         // save the code address
         assembly { // solium-disable-line
-            sstore(0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7, contractLogic)
+            sstore(PROXIABLE_MEM_SLOT, contractLogic)
         }
     }
 
-    function() external payable {
+    fallback() external payable {
         assembly { // solium-disable-line
-            let contractLogic := sload(0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7)
+            let contractLogic := sload(PROXIABLE_MEM_SLOT)
             let ptr := mload(0x40)
-            calldatacopy(ptr, 0x0, calldatasize)
-            let success := delegatecall(gas, contractLogic, ptr, calldatasize, 0, 0)
-            let retSz := returndatasize
+            calldatacopy(ptr, 0x0, calldatasize())
+            let success := delegatecall(gas(), contractLogic, ptr, calldatasize(), 0, 0)
+            let retSz := returndatasize()
             returndatacopy(ptr, 0, retSz)
             switch success
             case 0 {

contracts/TokenSoftToken.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 import "./capabilities/Proxiable.sol";
 import "./@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/ERC20Detailed.sol";
@@ -50,6 +50,8 @@ contract TokenSoftToken is Proxiable, ERC20Detailed, ERC1404, OwnerRole, Whiteli
     function detectTransferRestriction (address from, address to, uint256)
         public
         view
+        virtual
+        override
         returns (uint8)
     {
         // Check the paused status of the contract
@@ -80,6 +82,8 @@ contract TokenSoftToken is Proxiable, ERC20Detailed, ERC1404, OwnerRole, Whiteli
     function messageForTransferRestriction (uint8 restrictionCode)
         public
         view
+        virtual
+        override
         returns (string memory)
     {
         if (restrictionCode == SUCCESS_CODE) {
@@ -112,6 +116,8 @@ contract TokenSoftToken is Proxiable, ERC20Detailed, ERC1404, OwnerRole, Whiteli
      */
     function transfer (address to, uint256 value)
         public
+        virtual
+        override(ERC20, IERC20)
         notRestricted(msg.sender, to, value)
         returns (bool success)
     {
@@ -123,6 +129,8 @@ contract TokenSoftToken is Proxiable, ERC20Detailed, ERC1404, OwnerRole, Whiteli
      */
     function transferFrom (address from, address to, uint256 value)
         public
+        virtual
+        override(ERC20, IERC20)
         notRestricted(from, to, value)
         returns (bool success)
     {

contracts/TokenSoftTokenV2.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 import "./TokenSoftToken.sol";
 import "./capabilities/Blacklistable.sol";
@@ -8,10 +8,11 @@ contract TokenSoftTokenV2 is TokenSoftToken, Blacklistable, RevocableToAddress {
 
   // ERC1404 Error codes and messages
   uint8 public constant FAILURE_BLACKLIST = 3;
-  string public constant FAILURE_BLACKLIST_MESSAGE = "The transfer was restricted due to blacklist configuration.";
+  string public constant FAILURE_BLACKLIST_MESSAGE = "Restricted due to blacklist";
 
   function detectTransferRestriction (address from, address to, uint256 amt)
         public
+        override
         view
         returns (uint8)
     {
@@ -21,18 +22,43 @@ contract TokenSoftTokenV2 is TokenSoftToken, Blacklistable, RevocableToAddress {
             return FAILURE_BLACKLIST;
         }
 
-        return super.detectTransferRestriction(from, to, amt);
+        return TokenSoftToken.detectTransferRestriction(from, to, amt);
     }
 
   function messageForTransferRestriction (uint8 restrictionCode)
         public
+        override
         view
         returns (string memory)
     {
         if (restrictionCode == FAILURE_BLACKLIST) {
             return FAILURE_BLACKLIST_MESSAGE;
         }
 
-        return super.messageForTransferRestriction(restrictionCode);
+        return TokenSoftToken.messageForTransferRestriction(restrictionCode);
+    }
+
+    /**
+    Overrides the parent class token transfer function to enforce restrictions.
+     */
+    function transfer (address to, uint256 value)
+        public
+        override(TokenSoftToken, ERC20)
+        notRestricted(msg.sender, to, value)
+        returns (bool success)
+    {
+        return TokenSoftToken.transfer(to, value);
+    }
+
+    /**
+    Overrides the parent class token transferFrom function to enforce restrictions.
+     */
+    function transferFrom (address from, address to, uint256 value)
+        public
+        override(TokenSoftToken, ERC20)
+        notRestricted(from, to, value)
+        returns (bool success)
+    {
+        return TokenSoftToken.transferFrom(from, to, value);
     }
 }

contracts/capabilities/Blacklistable.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 import "../roles/BlacklisterRole.sol";
 
@@ -28,10 +28,10 @@ contract Blacklistable is BlacklisterRole {
      */
     function _addToBlacklist(address addressToAdd) internal {
         // Verify a valid address was passed in
-        require(addressToAdd != address(0), "Cannot add address 0x0 to the blacklist.");
+        require(addressToAdd != address(0), "Cannot add 0x0");
 
         // Verify the address is on the blacklist before it can be removed
-        require(!addressBlacklists[addressToAdd], "Address specified already on the black list.");
+        require(!addressBlacklists[addressToAdd], "Already on list");
 
         // Set the address's white list ID
         addressBlacklists[addressToAdd] = true;
@@ -45,10 +45,10 @@ contract Blacklistable is BlacklisterRole {
      */
     function _removeFromBlacklist(address addressToRemove) internal {
         // Verify a valid address was passed in
-        require(addressToRemove != address(0), "Cannot remove address 0x0 from the blacklist.");
+        require(addressToRemove != address(0), "Cannot remove 0x0");
 
         // Verify the address is on the blacklist before it can be removed
-        require(addressBlacklists[addressToRemove], "Address specified is not on the black list.");
+        require(addressBlacklists[addressToRemove], "Not on list");
 
         // Zero out the previous white list
         addressBlacklists[addressToRemove] = false;

contracts/capabilities/Burnable.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 import "../@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/ERC20.sol";
 import "../roles/BurnerRole.sol";

contracts/capabilities/Mintable.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 import "../@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/ERC20.sol";
 import "../roles/MinterRole.sol";

contracts/capabilities/Pausable.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 import "../roles/PauserRole.sol";
 

contracts/capabilities/Proxiable.sol

@@ -1,29 +1,30 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 contract Proxiable {
     // Code position in storage is keccak256("PROXIABLE") = "0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7"
+    uint256 constant PROXIABLE_MEM_SLOT = 0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7;
 
     event CodeAddressUpdated(address newAddress);
 
     function _updateCodeAddress(address newAddress) internal {
         require(
-            bytes32(0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7) == Proxiable(newAddress).proxiableUUID(),
+            bytes32(PROXIABLE_MEM_SLOT) == Proxiable(newAddress).proxiableUUID(),
             "Not compatible"
         );
         assembly { // solium-disable-line
-            sstore(0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7, newAddress)
+            sstore(PROXIABLE_MEM_SLOT, newAddress)
         }
 
         emit CodeAddressUpdated(newAddress);
     }
 
     function getLogicAddress() public view returns (address logicAddress) {
         assembly { // solium-disable-line
-            logicAddress := sload(0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7)
+            logicAddress := sload(PROXIABLE_MEM_SLOT)
         }
     }
 
     function proxiableUUID() public pure returns (bytes32) {
-        return 0xc5f16f0fcc639fa48a6947836d9850f504798523bf8c9a3a87d5876cf622bcf7;
+        return bytes32(PROXIABLE_MEM_SLOT);
     }
 }

contracts/capabilities/Revocable.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 import "../@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/ERC20.sol";
 import "../roles/RevokerRole.sol";

contracts/capabilities/RevocableToAddress.sol

@@ -1,4 +1,4 @@
-pragma solidity 0.5.16;
+pragma solidity 0.6.12;
 
 import "../@openzeppelin/contracts-ethereum-package/contracts/token/ERC20/ERC20.sol";
 import "../roles/RevokerRole.sol";