refactor constraint into an optionalChecks bitmap

contracts/mocks/token/ERC721ConsecutiveEnumerableMock.sol

@@ -29,11 +29,11 @@ contract ERC721ConsecutiveEnumerableMock is ERC721Consecutive, ERC721Enumerable
     }
 
     function _update(
-        address from,
         address to,
-        uint256 tokenId
-    ) internal virtual override(ERC721Consecutive, ERC721Enumerable) {
-        super._update(from, to, tokenId);
+        uint256 tokenId,
+        bytes32 optionalChecks
+    ) internal virtual override(ERC721Consecutive, ERC721Enumerable) returns (address) {
+        return super._update(to, tokenId, optionalChecks);
     }
 
     // solhint-disable-next-line func-name-mixedcase

contracts/mocks/token/ERC721ConsecutiveMock.sol

@@ -42,11 +42,11 @@ contract ERC721ConsecutiveMock is ERC721Consecutive, ERC721Pausable, ERC721Votes
     }
 
     function _update(
-        address from,
         address to,
-        uint256 tokenId
-    ) internal virtual override(ERC721Consecutive, ERC721Pausable, ERC721Votes) {
-        return super._update(from, to, tokenId);
+        uint256 tokenId,
+        bytes32 optionalChecks
+    ) internal virtual override(ERC721Consecutive, ERC721Pausable, ERC721Votes) returns (address) {
+        return super._update(to, tokenId, optionalChecks);
     }
 
     // solhint-disable-next-line func-name-mixedcase

contracts/token/ERC721/ERC721.sol

@@ -19,6 +19,10 @@ import {IERC721Errors} from "../../interfaces/draft-IERC6093.sol";
 abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Errors {
     using Strings for uint256;
 
+    bytes32 internal constant CONSTRAINT_MINTED = bytes32(uint256(1) << 0);
+    bytes32 internal constant CONSTRAINT_NOT_MINTED = bytes32(uint256(1) << 1);
+    bytes32 internal constant CONSTRAINT_SPENDER_APPROVED_OR_OWNER = bytes32(uint256(1) << 2);
+
     // Token name
     string private _name;
 
@@ -155,7 +159,7 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Er
         if (to == address(0)) {
             revert ERC721InvalidReceiver(address(0));
         }
-        address owner = _updateWithConstraints(to, tokenId, _constraintApprovedOrOwner);
+        address owner = _update(to, tokenId, CONSTRAINT_MINTED | CONSTRAINT_SPENDER_APPROVED_OR_OWNER);
         if (owner != from) {
             revert ERC721IncorrectOwner(from, tokenId, owner);
         }
@@ -263,31 +267,35 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Er
      * @dev Transfers `tokenId` from its current owner to `to`, or alternatively mints (or burns) if the current owner
      * (or `to`) is the zero address.
      *
-     * The `constraints` argument is used to specify constraints, and eventually revert. For example this can be used
-     * to ensure that the current owner is what was expected.
+     * The `optionalChecks` argument is used to specify constraints, that the caller would want to be checked as part
+     * of the update.
      *
      * Emits a {Transfer} event.
      */
-    function _updateWithConstraints(
+    function _update(
         address to,
         uint256 tokenId,
-        function(address, address, uint256) view constraints
+        bytes32 optionalChecks
     ) internal virtual returns (address) {
         address from = _ownerOf(tokenId);
-        constraints(from, to, tokenId);
-        _update(from, to, tokenId);
-        return from;
-    }
 
-    /**
-     * @dev Transfers `tokenId` from its current owner to `to`, or alternatively mints (or burns) if the current owner
-     * (or `to`) is the zero address.
-     *
-     * All customizations to transfers, mints, and burns should be done by overriding this function.
-     *
-     * Emits a {Transfer} event.
-     */
-    function _update(address from, address to, uint256 tokenId) internal virtual {
+        // Perform optional checks
+        if (optionalChecks & CONSTRAINT_MINTED != 0 && from == address(0)) {
+            revert ERC721NonexistentToken(tokenId);
+        }
+
+        if (optionalChecks & CONSTRAINT_NOT_MINTED != 0 && from != address(0)) {
+            revert ERC721InvalidSender(address(0));
+        }
+
+        if (optionalChecks & CONSTRAINT_SPENDER_APPROVED_OR_OWNER != 0) {
+            address spender = _msgSender();
+            if (from != spender && !isApprovedForAll(from, spender) && getApproved(tokenId) != spender) {
+                revert ERC721InsufficientApproval(_msgSender(), tokenId);
+            }
+        }
+
+        // Execute the update
         if (from != address(0)) {
             delete _tokenApprovals[tokenId];
             unchecked {
@@ -304,6 +312,8 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Er
         _owners[tokenId] = to;
 
         emit Transfer(from, to, tokenId);
+
+        return from;
     }
 
     /**
@@ -322,7 +332,7 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Er
         if (to == address(0)) {
             revert ERC721InvalidReceiver(address(0));
         }
-        _updateWithConstraints(to, tokenId, _constraintNotMinted);
+        _update(to, tokenId, CONSTRAINT_NOT_MINTED);
     }
 
     /**
@@ -337,7 +347,7 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Er
      * Emits a {Transfer} event.
      */
     function _burn(uint256 tokenId) internal {
-        _updateWithConstraints(address(0), tokenId, _constraintMinted);
+        _update(address(0), tokenId, CONSTRAINT_MINTED);
     }
 
     /**
@@ -355,7 +365,7 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Er
         if (to == address(0)) {
             revert ERC721InvalidReceiver(address(0));
         }
-        address owner = _updateWithConstraints(to, tokenId, _constraintMinted);
+        address owner = _update(to, tokenId, CONSTRAINT_MINTED);
         if (owner != from) {
             revert ERC721IncorrectOwner(from, tokenId, owner);
         }
@@ -393,34 +403,6 @@ abstract contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Er
         }
     }
 
-    /**
-     * @dev Constraint: revert if token is already minted
-     */
-    function _constraintNotMinted(address from, address, uint256) internal pure {
-        if (from != address(0)) {
-            revert ERC721InvalidSender(address(0));
-        }
-    }
-
-    /**
-     * @dev Constraint: revert if token is not yet minted
-     */
-    function _constraintMinted(address from, address, uint256 tokenId) internal pure {
-        if (from == address(0)) {
-            revert ERC721NonexistentToken(tokenId);
-        }
-    }
-
-    /**
-     * @dev Constraint: check that the caller is the current owner, or approved by the current owner
-     */
-    function _constraintApprovedOrOwner(address owner, address, uint256 tokenId) internal view {
-        address spender = _msgSender();
-        if (spender != owner && !isApprovedForAll(owner, spender) && getApproved(tokenId) != spender) {
-            revert ERC721InsufficientApproval(_msgSender(), tokenId);
-        }
-    }
-
     /**
      * @dev Private function to invoke {IERC721Receiver-onERC721Received} on a target address.
      * The call is not executed if the target address is not a contract.

contracts/token/ERC721/extensions/ERC721Burnable.sol

@@ -19,6 +19,6 @@ abstract contract ERC721Burnable is Context, ERC721 {
      * - The caller must own `tokenId` or be an approved operator.
      */
     function burn(uint256 tokenId) public virtual {
-        _updateWithConstraints(address(0), tokenId, _constraintApprovedOrOwner);
+        _update(address(0), tokenId, CONSTRAINT_MINTED | CONSTRAINT_SPENDER_APPROVED_OR_OWNER);
     }
 }

contracts/token/ERC721/extensions/ERC721Consecutive.sol

@@ -138,8 +138,8 @@ abstract contract ERC721Consecutive is IERC2309, ERC721 {
      * Warning: Using {ERC721Consecutive} prevents minting during construction in favor of {_mintConsecutive}.
      * After construction, {_mintConsecutive} is no longer available and minting through {_update} becomes available.
      */
-    function _update(address from, address to, uint256 tokenId) internal virtual override {
-        super._update(from, to, tokenId);
+    function _update(address to, uint256 tokenId, bytes32 optionalChecks) internal virtual override returns (address) {
+        address from = super._update(to, tokenId, optionalChecks);
 
         // only mint after construction
         if (from == address(0) && address(this).code.length == 0) {
@@ -154,6 +154,8 @@ abstract contract ERC721Consecutive is IERC2309, ERC721 {
         ) {
             _sequentialBurn.set(tokenId);
         }
+
+        return from;
     }
 
     /**

contracts/token/ERC721/extensions/ERC721Enumerable.sol

@@ -76,8 +76,8 @@ abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
     /**
      * @dev See {ERC721-_update}.
      */
-    function _update(address from, address to, uint256 tokenId) internal virtual override {
-        super._update(from, to, tokenId);
+    function _update(address to, uint256 tokenId, bytes32 optionalChecks) internal virtual override returns (address) {
+        address from = super._update(to, tokenId, optionalChecks);
 
         if (from == address(0)) {
             _addTokenToAllTokensEnumeration(tokenId);
@@ -89,6 +89,8 @@ abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
         } else if (from != to) {
             _addTokenToOwnerEnumeration(to, tokenId);
         }
+
+        return from;
     }
 
     /**

contracts/token/ERC721/extensions/ERC721Pausable.sol

@@ -27,8 +27,8 @@ abstract contract ERC721Pausable is ERC721, Pausable {
      *
      * - the contract must not be paused.
      */
-    function _update(address from, address to, uint256 tokenId) internal virtual override {
+    function _update(address to, uint256 tokenId, bytes32 optionalChecks) internal virtual override returns (address) {
         _requireNotPaused();
-        super._update(from, to, tokenId);
+        return super._update(to, tokenId, optionalChecks);
     }
 }

contracts/token/ERC721/extensions/ERC721Royalty.sol

@@ -29,11 +29,13 @@ abstract contract ERC721Royalty is ERC2981, ERC721 {
     /**
      * @dev See {ERC721-_update}. This override additionally clears the royalty information for the token.
      */
-    function _update(address from, address to, uint256 tokenId) internal virtual override {
-        super._update(from, to, tokenId);
+    function _update(address to, uint256 tokenId, bytes32 optionalChecks) internal virtual override returns (address) {
+        address from = super._update(to, tokenId, optionalChecks);
 
         if (to == address(0)) {
             _resetTokenRoyalty(tokenId);
         }
+
+        return from;
     }
 }

contracts/token/ERC721/extensions/ERC721URIStorage.sol

@@ -68,11 +68,13 @@ abstract contract ERC721URIStorage is IERC4906, ERC721 {
      * token-specific URI was set for the token, and if so, it deletes the token URI from
      * the storage mapping.
      */
-    function _update(address from, address to, uint256 tokenId) internal virtual override {
-        super._update(from, to, tokenId);
+    function _update(address to, uint256 tokenId, bytes32 optionalChecks) internal virtual override returns (address) {
+        address from = super._update(to, tokenId, optionalChecks);
 
         if (to == address(0) && bytes(_tokenURIs[tokenId]).length != 0) {
             delete _tokenURIs[tokenId];
         }
+
+        return from;
     }
 }

contracts/token/ERC721/extensions/ERC721Votes.sol

@@ -20,9 +20,12 @@ abstract contract ERC721Votes is ERC721, Votes {
      *
      * Emits a {IVotes-DelegateVotesChanged} event.
      */
-    function _update(address from, address to, uint256 tokenId) internal virtual override {
-        super._update(from, to, tokenId);
+    function _update(address to, uint256 tokenId, bytes32 optionalChecks) internal virtual override returns (address) {
+        address from = super._update(to, tokenId, optionalChecks);
+
         _transferVotingUnits(from, to, 1);
+
+        return from;
     }
 
     /**

contracts/token/ERC721/extensions/ERC721Wrapper.sol

@@ -50,7 +50,7 @@ abstract contract ERC721Wrapper is ERC721, IERC721Receiver {
         uint256 length = tokenIds.length;
         for (uint256 i = 0; i < length; ++i) {
             uint256 tokenId = tokenIds[i];
-            _updateWithConstraints(address(0), tokenId, _constraintApprovedOrOwner);
+            _update(address(0), tokenId, CONSTRAINT_MINTED | CONSTRAINT_SPENDER_APPROVED_OR_OWNER);
             // Checks were already performed at this point, and there's no way to retake ownership or approval from
             // the wrapped tokenId after this point, so it's safe to remove the reentrancy check for the next line.
             // slither-disable-next-line reentrancy-no-eth