Solidity compile error. (Contract should be marked as abstract.) - node.js

Question

I have two questions.
1) I am getting the following error:
TypeError: Contract "MyToken" should be marked as abstract.
--> contracts/MyToken.sol:8:1:
According to my understanding, contract should be abstract when there is a unimplemented function. Here I have the function foo. But still getting this error?
2) Also I want write a constructor which passes totalSupply_ to the contract. Is it possible to implement in the way I have done?
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;
//import '#openzeppelin/contracts/token/ERC20/IERC20.sol';
import '#openzeppelin/contracts/token/ERC20/ERC20.sol';
contract MyToken is ERC20 {
uint256 private _totalSupply;
string private _name;
string private _symbol;
constructor(string memory name_,string memory symbol_, uint totalSupply_ ) {
_name = name_;
_symbol = symbol_;
_totalSupply = totalSupply_;
}
function foo() external returns (uint) {
uint temp;
temp = 1+1;
return temp;
}
}

Answer 1

You are inheriting from ERC20 but you are not calling its constructor
constructor(string memory name_,string memory symbol_,uint totalSupply_)ERC20("name","SYM") {
_name = name_;
_symbol = symbol_;
_totalSupply = totalSupply_;
}
In your case you have to call ERC20("name","SYM") because ERC20 is inheriting from an abstract Context class.
contract ERC20 is Context, IERC20, IERC20Metadata {
if you did not inherit from Context you would not have to call ERC20("name","SYM")
contract ERC20 is IERC20, IERC20Metadata {
Since you are calling ERC20("name","SYM") you are actually setting name and symbol so you dont have to set them in MyToken constructor:
uint256 private _totalSupply;
constructor(uint totalSupply_ )ERC20("name","SYM") {
_totalSupply = totalSupply_;
}

Answer 2

Try this:
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.0;
//import '#openzeppelin/contracts/token/ERC20/IERC20.sol';
import '#openzeppelin/contracts/token/ERC20/ERC20.sol';
contract MyToken is ERC20 {
uint256 private _totalSupply;
constructor(string memory name_,string memory symbol_, uint totalSupply_ ) ERC20(name_, symbol_) {
_totalSupply = totalSupply_;
}
function foo() external returns (uint) {
uint temp;
temp = 1+1;
return temp;
}
}