Fix compilation errors, upgrade Solidity

.circleci/config.yml

@@ -11,7 +11,7 @@ jobs:
     steps:
       - run:
         |
-          sudo wget https://github.com/ethereum/solidity/releases/download/v0.8.10/solc-static-linux -O /usr/local/bin/solc
+          sudo wget https://github.com/ethereum/solidity/releases/download/v0.8.15/solc-static-linux -O /usr/local/bin/solc
           sudo chmod +x /usr/local/bin/solc
       - checkout
       - restore_cache:
@@ -79,7 +79,7 @@ jobs:
     steps:
       - run:
         |
-          sudo wget https://github.com/ethereum/solidity/releases/download/v0.8.10/solc-static-linux -O /usr/local/bin/solc
+          sudo wget https://github.com/ethereum/solidity/releases/download/v0.8.15/solc-static-linux -O /usr/local/bin/solc
           sudo chmod +x /usr/local/bin/solc
       - checkout
       - restore_cache:

Dockerfile

@@ -1,7 +1,7 @@
 FROM mhart/alpine-node:13.8.0
 
 RUN apk update && apk add --no-cache --virtual build-dependencies git python g++ make
-RUN wget https://github.com/ethereum/solidity/releases/download/v0.8.10/solc-static-linux -O /bin/solc && chmod +x /bin/solc
+RUN wget https://github.com/ethereum/solidity/releases/download/v0.8.15/solc-static-linux -O /bin/solc && chmod +x /bin/solc
 
 RUN mkdir -p /compound-protocol
 WORKDIR /compound-protocol

contracts/BaseJumpRateModelV2.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./InterestRateModel.sol";
 

contracts/CDaiDelegate.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./CErc20Delegate.sol";
 

contracts/CErc20.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./CToken.sol";
 

contracts/CErc20Delegate.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./CErc20.sol";
 

contracts/CErc20Delegator.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./CTokenInterfaces.sol";
 

contracts/CErc20Immutable.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./CErc20.sol";
 

contracts/CEther.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./CToken.sol";
 

contracts/CToken.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./ComptrollerInterface.sol";
 import "./CTokenInterfaces.sol";

contracts/CTokenInterfaces.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./ComptrollerInterface.sol";
 import "./InterestRateModel.sol";

contracts/Comptroller.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./CToken.sol";
 import "./ErrorReporter.sol";

contracts/ComptrollerG7.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./CToken.sol";
 import "./ErrorReporter.sol";

contracts/ComptrollerInterface.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 abstract contract ComptrollerInterface {
     /// @notice Indicator that this is a Comptroller contract (for inspection)

contracts/ComptrollerStorage.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./CToken.sol";
 import "./PriceOracle.sol";

contracts/DAIInterestRateModelV3.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./JumpRateModelV2.sol";
 
@@ -66,7 +66,7 @@ contract DAIInterestRateModelV3 is JumpRateModelV2 {
      * @param reserveFactorMantissa The current reserve factor the market has
      * @return The supply rate per block (as a percentage, and scaled by BASE)
      */
-    function getSupplyRate(uint cash, uint borrows, uint reserves, uint reserveFactorMantissa) override public view returns (uint) {
+    function getSupplyRate(uint cash, uint borrows, uint reserves, uint reserveFactorMantissa) override(InterestRateModel, BaseJumpRateModelV2) public view returns (uint) {
         uint protocolRate = super.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa);
 
         uint underlying = cash + borrows - reserves;

contracts/EIP20Interface.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 /**
  * @title ERC 20 Token Standard Interface

contracts/EIP20NonStandardInterface.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 /**
  * @title EIP20NonStandardInterface

contracts/ErrorReporter.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 contract ComptrollerErrorReporter {
     enum Error {

contracts/ExponentialNoError.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 /**
  * @title Exponential module for storing fixed-precision decimals

contracts/Governance/Comp.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 contract Comp {
     /// @notice EIP-20 token name for this token

contracts/Governance/GovernorAlpha.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 contract GovernorAlpha {
     /// @notice The name of this contract

contracts/Governance/GovernorBravoDelegate.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: BSD-3-Clause
-pragma solidity ^0.8.10;
+pragma solidity ^0.8.15;
 
 import "./GovernorBravoInterfaces.sol";