OpenZeppelin Confidential Contracts is an experimental library for developing applications on the Zama fhEVM. Prior to 0.3.1, the ERC7984 contract tracked confidential total supply with an euint64 value, and an overflowing internal _mint operation could fail silently. The wrap and onTransferReceived functions in contracts/token/ERC7984/extensions/ERC7984ERC20Wrapper.sol did not handle that failure, so a user could transfer the underlying token without receiving the corresponding confidential wrapped token. With the default rate(), the wrapper fills after approximately 18.4 trillion tokens, and subsequent wrapping requests can cause loss of funds. This issue is fixed in version 0.3.1.

Affected: npm: @openzeppelin/confidential-contracts

### Impact The `ERC7984` contract tracks total supply using a confidential `euint64` value. If a call to the internal `_mint` function would result in the total supply overflowing, the call fails silently. The `wrap` and `onTransferReceived` functions in `ERC7984ERC20Wrapper` assume that `_mint` won't fail silently and do not check the return value. If the mint function fails silently, users do not receive the confidential wrapped token but still send the underlying token, resulting in a loss of funds.

By default (without overriding `rate()`, the wrapper fills up after wrapping ~18.4 trillion tokens. There are very few tokens of value with sufficient total supply to result in the filling of the wrapper. That said, we recommend upgrading to `0.3.1` to remove this issue.

### Patches This issue has been patched in the `0.3.1` release.