Add bugs and Makefile

Makefile

@@ -0,0 +1,5 @@
+check:
+	git apply "bugs/$(bug).patch" && forge test
+
+clean:
+	git checkout src/WETH9.sol

bugs/bug1.patch

@@ -0,0 +1,13 @@
+diff --git a/src/WETH9.sol b/src/WETH9.sol
+index cd55b98..ccb40cb 100644
+--- a/src/WETH9.sol
++++ b/src/WETH9.sol
+@@ -33,7 +33,7 @@ contract WETH9 {
+     }
+
+     function deposit() public payable {
+-        balanceOf[msg.sender] += msg.value;
++        balanceOf[msg.sender] += 1;
+         emit Deposit(msg.sender, msg.value);
+     }
+

bugs/bug2.patch

@@ -0,0 +1,13 @@
+diff --git a/src/WETH9.sol b/src/WETH9.sol
+index cd55b98..961f03b 100644
+--- a/src/WETH9.sol
++++ b/src/WETH9.sol
+@@ -40,7 +40,7 @@ contract WETH9 {
+     function withdraw(uint256 wad) public {
+         require(balanceOf[msg.sender] >= wad);
+         balanceOf[msg.sender] -= wad;
+-        payable(msg.sender).transfer(wad);
++        payable(msg.sender).transfer(1);
+         emit Withdrawal(msg.sender, wad);
+     }
+

bugs/bug3.patch

@@ -0,0 +1,12 @@
+diff --git a/src/WETH9.sol b/src/WETH9.sol
+index cd55b98..6e74bd5 100644
+--- a/src/WETH9.sol
++++ b/src/WETH9.sol
+@@ -29,7 +29,6 @@ contract WETH9 {
+     mapping(address => mapping(address => uint256)) public allowance;
+
+     fallback() external payable {
+-        deposit();
+     }
+
+     function deposit() public payable {

bugs/bug4.patch

@@ -0,0 +1,22 @@
+diff --git a/src/WETH9.sol b/src/WETH9.sol
+index cd55b98..26cec99 100644
+--- a/src/WETH9.sol
++++ b/src/WETH9.sol
+@@ -59,15 +59,8 @@ contract WETH9 {
+     }
+
+     function transferFrom(address src, address dst, uint256 wad) public returns (bool) {
+-        require(balanceOf[src] >= wad);
+-
+-        if (src != msg.sender && allowance[src][msg.sender] != type(uint256).max) {
+-            require(allowance[src][msg.sender] >= wad);
+-            allowance[src][msg.sender] -= wad;
+-        }
+-
+-        balanceOf[src] -= wad;
+-        balanceOf[dst] += wad;
++        balanceOf[src] -= wad;
++        balanceOf[dst] += 1;
+
+         emit Transfer(src, dst, wad);
+

test/handlers/Handler.sol

@@ -2,47 +2,10 @@
 pragma solidity ^0.8.13;
 
 import {Test} from "forge-std/Test.sol";
+import {AddressSet, LibAddressSet} from "../helpers/AddressSet.sol";
 import {WETH9} from "../../src/WETH9.sol";
 
-uint256 constant ETH_SUPPLY = 120_500_000;
-
-struct AddressSet {
-    address[] addrs;
-    mapping(address => bool) saved;
-}
-
-library LibAddressSet {
-    function add(AddressSet storage s, address addr) internal {
-        if (!s.saved[addr]) {
-            s.addrs.push(addr);
-            s.saved[addr] = true;
-        }
-    }
-
-    function contains(AddressSet storage s, address addr) internal view returns (bool) {
-        return s.saved[addr];
-    }
-
-    function count(AddressSet storage s) internal view returns (uint256) {
-        return s.addrs.length;
-    }
-
-    function forEach(AddressSet storage s, function(address) external func) internal {
-        for (uint256 i; i < s.addrs.length; ++i) {
-            func(s.addrs[i]);
-        }
-    }
-
-    function reduce(AddressSet storage s, uint256 acc, function(uint256,address) external returns (uint256) func)
-        internal
-        returns (uint256)
-    {
-        for (uint256 i; i < s.addrs.length; ++i) {
-            acc = func(acc, s.addrs[i]);
-        }
-        return acc;
-    }
-}
+uint256 constant ETH_SUPPLY = 120_500_000 ether;
 
 contract Handler is Test {
     using LibAddressSet for AddressSet;

test/helpers/AddressSet.sol

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.13;
+
+struct AddressSet {
+    address[] addrs;
+    mapping(address => bool) saved;
+}
+
+library LibAddressSet {
+    function add(AddressSet storage s, address addr) internal {
+        if (!s.saved[addr]) {
+            s.addrs.push(addr);
+            s.saved[addr] = true;
+        }
+    }
+
+    function contains(AddressSet storage s, address addr) internal view returns (bool) {
+        return s.saved[addr];
+    }
+
+    function count(AddressSet storage s) internal view returns (uint256) {
+        return s.addrs.length;
+    }
+
+    function forEach(AddressSet storage s, function(address) external func) internal {
+        for (uint256 i; i < s.addrs.length; ++i) {
+            func(s.addrs[i]);
+        }
+    }
+
+    function reduce(AddressSet storage s, uint256 acc, function(uint256,address) external returns (uint256) func)
+        internal
+        returns (uint256)
+    {
+        for (uint256 i; i < s.addrs.length; ++i) {
+            acc = func(acc, s.addrs[i]);
+        }
+        return acc;
+    }
+}