Solidity 0.6.x features: Array Slices

Starting from version 0.6.0, Solidity supports array slices. Array slices are handy when you want to reference a contiguous portion of an array but do not want to perform a full copy of that portion. For now, array slices are only supported for calldata arrays. [Read More]

Solidity 0.6.8 Release Announcement

Solidity v0.6.8 fixes three important bugs in the code generator and introduces a recommendation to use SPDX license identifiers. Furthermore, support for WebAssembly has been extended and it is now possible to access the min and max values of an integer type directly. Please upgrade if you are using array slices, backslashes in string literals for ABIEncoderV2 or are concerned about non-payable constructors. [Read More]

Solidity 0.6.x features: Saving Storage Costs with Immutables

With version 0.6.5, Solidity introduced the immutable keyword for state variables. Immutable state variables can only be assigned during contract creation, but will remain constant throughout the life-time of a deployed contract. The big advantage of immutables is that reading them is significantly cheaper than reading from regular state variables, since immutables will not be stored in storage, but their values will be directly inserted into the runtime code. [Read More]

Solidity Summit 2020 Goes Interspace

Tl;dr: As already announced on Twitter, we transformed the Solidity Summit, which was initially planned to be an in-person meeting in Berlin, into an online event. Today, we are excited to share that the summit will be powered by Interspace.Chat. Interspace is a virtual meeting infrastructure based on self-hosted Jitsi video chat rooms. Check out the Solidity Summit’s preliminary event agenda here and make sure to register if you want to partipate! [Read More]

Solidity Memory Array Creation Overflow Bug

On the 28th of March, a bug in the Solidity code generator was reported through the Ethereum Foundation Bounty program, by John Toman of Certora. The bug is fixed with version 0.6.5, released on 2020-04-06. The bug is present in all prior versions of Solidity. We assigned a severity level of “low” because we found the bug to be uncommon and at the same time hard to exploit. [Read More]

Solidity 0.6.x features: fallback and receive functions

In versions of Solidity before 0.6.x, developers typically used the fallback function to handle logic in two scenarios: contract received ether and no data contract received data but no function matched the function called The main use case of the pre-0.6.x fallback function is to receive ether and react to it, a typical pattern used by token-style contracts to reject transfers, emit events or forward the ether. The function executes when a contract is called without any data e.g. via... [Read More]

Solidity 0.6.x features: try/catch statement

This post was originally published on the Ethereum blog. The try/catch syntax introduced in 0.6.0 is arguably the biggest leap in error handling capabilities in Solidity, since reason strings for revert and require were released in v0.4.22. Both try and catch have been reserved keywords since v0.5.9 and now we can use them to handle failures in external function calls without rolling back the complete transaction (state changes in the called function are still rolled back, but the ones in... [Read More]

Solidity Storage Array Bugs

This post was originally published on the Ethereum blog. This blog post is about two bugs connected to storage arrays which are otherwise unrelated. Both have been present in the compiler for a long time and have only been discovered now even though a contract containing them should very likely show malfunctions in tests. Daenam Kim with help from Nguyen Pham, both from Curvegrid discovered an issue where invalid data is stored in connection with arrays of signed integers. This... [Read More]

Solidity Optimizer and ABIEncoderV2 Bugs

This post was originally published on the Ethereum blog. Through the Ethereum bug bounty program, we received a report about a flaw within the new experimental ABI encoder (referred to as ABIEncoderV2). Upon investigation, it was found that the component suffers from a few different variations of the same type. The first part of this announcement explains this bug in detail. The new ABI encoder is still marked as experimental, but we nevertheless think that this deserves a prominent announcement... [Read More]

Solidity Bugfix Release

This post was originally published on the Ethereum blog. The latest version 0.4.25 release of Solidity fixes two important bugs. Another important bug has already been fixed in version 0.4.22 but it was only discovered recently that the bug existed. Note that the Ethereum Foundation runs a bounty program for the code generator part of Solidity. [Read More]