Fix .gitignore: stop tracking ignored files

backend/lib/openzeppelin-contracts/certora/specs/ERC20FlashMint.spec

@@ -0,0 +1,48 @@
+import "helpers/helpers.spec"
+import "methods/IERC20.spec"
+import "methods/IERC3156.spec"
+
+methods {
+    // non standard ERC3156 functions
+    flashFeeReceiver() returns (address) envfree
+
+    // function summaries below
+    _mint(address account, uint256 amount)              => specMint(account, amount)
+    _burn(address account, uint256 amount)              => specBurn(account, amount)
+    _transfer(address from, address to, uint256 amount) => specTransfer(from, to, amount)
+}
+
+/*
+┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
+│ Ghost: track mint and burns in the CVL                                                                              │
+└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
+*/
+ghost mapping(address => uint256)                     trackedMintAmount;
+ghost mapping(address => uint256)                     trackedBurnAmount;
+ghost mapping(address => mapping(address => uint256)) trackedTransferedAmount;
+
+function specMint(address account, uint256 amount)              returns bool { trackedMintAmount[account] = amount;        return true; }
+function specBurn(address account, uint256 amount)              returns bool { trackedBurnAmount[account] = amount;        return true; }
+function specTransfer(address from, address to, uint256 amount) returns bool { trackedTransferedAmount[from][to] = amount; return true; }
+
+/*
+┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
+│ Rule: When doing a flashLoan, "amount" is minted and burnt, additionally, the fee is either burnt                   │
+│ (if the fee recipient is 0) or transferred (if the fee recipient is not 0)                                          │
+└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
+*/
+rule checkMintAndBurn(env e) {
+    address receiver;
+    address token;
+    uint256 amount;
+    bytes data;
+
+    uint256 fees = flashFee(token, amount);
+    address recipient = flashFeeReceiver();
+
+    flashLoan(e, receiver, token, amount, data);
+
+    assert trackedMintAmount[receiver] == amount;
+    assert trackedBurnAmount[receiver] == amount + (recipient == 0 ? fees : 0);
+    assert (fees > 0 && recipient != 0) => trackedTransferedAmount[receiver][recipient] == fees;
+}