msg.gas -> gasleft() : msg.gas has been deprecated in favor of gasleft()
change type "address" of variable to "address payable" if the "send" or "transfer" function is used for this variable: "send" and "transfer" are only available for objects of type "address payable", not "address".
make function payable for the following compiler error: "msg.value" and "callvalue()" can only be used in payable public functions. Make the function "payable" or use an internal function to avoid this error.
Add datalocation for return parameters: Data location must be "memory" or "calldata" for return parameter in function, but none was given.
Add datalocation for variables: Data location must be "storage", "memory" or "calldata" for variable, but none was given. - Change "block.blockhash()" to "blockhash()": "block.blockhash()" has been deprecated in favor of "blockhash()"
Make contract abstract: Contract "xxxx" should be marked as abstract.
Mark function as virtual: Functions without implementation must be marked virtual.
Add override keyword for functions, which override a method: Overriding function is missing "override" specifier.
msg.gas has been deprecated in favor of gasleft()"send" and "transfer" are only available for objects of type "address payable", not "address"."msg.value" and "callvalue()" can only be used in payable public functions. Make the function "payable" or use an internal function to avoid this error.Data location must be "memory" or "calldata" for return parameter in function, but none was given.Data location must be "storage", "memory" or "calldata" for variable, but none was given.- Change "block.blockhash()" to "blockhash()":"block.blockhash()" has been deprecated in favor of "blockhash()"Contract "xxxx" should be marked as abstract.Functions without implementation must be marked virtual.Overriding function is missing "override" specifier.